Sample records for amphiphilic block copolymers

  1. Ionization of amphiphilic acidic block copolymers. (United States)

    Colombani, Olivier; Lejeune, Elise; Charbonneau, Céline; Chassenieux, Christophe; Nicolai, Taco


    The ionization behavior of an amphiphilic diblock copolymer poly(n-butyl acrylate(50%)-stat-acrylic acid(50%))(100)-block-poly(acrylic acid)(100) (P(nBA(50%)-stat-AA(50%))(100)-b-PAA(100), DH50) and of its equivalent triblock copolymer P(nBA(50%)-stat-AA(50%))(100)-b-PAA(200)-b-P(nBA(50%)-stat-AA(50%))(100) (TH50) were studied by potentiometric titration either in pure water or in 0.5 M NaCl. These polymers consist of a hydrophilic acidic block (PAA) connected to a hydrophobic block, P(nBA(50%)-stat-AA(50%))(100), whose hydrophobic character has been mitigated by copolymerization with hydrophilic units. We show that all AA units, even those in the hydrophobic block could be ionized. However, the AA units within the hydrophobic block were less acidic than those in the hydrophilic block, resulting in the preferential ionization of the latter block. The preferential ionization of PAA over that of P(nBA(50%)-stat-AA(50%))(100) was stronger at higher ionic strength. Remarkably, the covalent bonds between the PAA and P(nBA(50%)-stat-AA(50%))(100) blocks in the diblock or the triblock did not affect the ionization of each block, although the self-association of the block copolymers into spherical aggregates modified the environment of the PAA blocks compared to when PAA was molecularly dispersed.

  2. Amphiphilic block copolymers for drug delivery. (United States)

    Adams, Monica L; Lavasanifar, Afsaneh; Kwon, Glen S


    Amphiphilic block copolymers (ABCs) have been used extensively in pharmaceutical applications ranging from sustained-release technologies to gene delivery. The utility of ABCs for delivery of therapeutic agents results from their unique chemical composition, which is characterized by a hydrophilic block that is chemically tethered to a hydrophobic block. In aqueous solution, polymeric micelles are formed via the association of ABCs into nanoscopic core/shell structures at or above the critical micelle concentration. Upon micellization, the hydrophobic core regions serve as reservoirs for hydrophobic drugs, which may be loaded by chemical, physical, or electrostatic means, depending on the specific functionalities of the core-forming block and the solubilizate. Although the Pluronics, composed of poly(ethylene oxide)-block-poly(propylene oxide)-block-poly(ethylene oxide), are the most widely studied ABC system, copolymers containing poly(L-amino acid) and poly(ester) hydrophobic blocks have also shown great promise in delivery applications. Because each ABC has unique advantages with respect to drug delivery, it may be possible to choose appropriate block copolymers for specific purposes, such as prolonging circulation time, introduction of targeting moieties, and modification of the drug-release profile. ABCs have been used for numerous pharmaceutical applications including drug solubilization/stabilization, alteration of the pharmacokinetic profile of encapsulated substances, and suppression of multidrug resistance. The purpose of this minireview is to provide a concise, yet detailed, introduction to the use of ABCs and polymeric micelles as delivery agents as well as to highlight current and past work in this area. Copyright 2003 Wiley-Liss, Inc. and the American Pharmacists Association

  3. Preparation of amphiphilic block copolymer containing triazene ...

    Indian Academy of Sciences (India)

    −7. M). Experiments of fluorescence quenching with various metal cations (UO2+. 2 , Fe2+, Fe3+, Ni2+, Cu2+, Co2+, Pb2+ and Hg2+) suggested that such a block copolymer could ..... from the intersection of straight-line segments, drawn through the points on ... copolymer displays a strong emission around 400 nm, which is ...

  4. Preparation of amphiphilic block copolymer containing triazene ...

    Indian Academy of Sciences (India)

    The lower rate constant in film state (film = 1.3 × 10−3 s-1), shows that the higher mobility of polymeric chains in solution allow a more rapid orientation, favourable to the triazene bond cleavage. The capability of block copolymer to form micelles in aqueous environment and implicitly, its critical micelle concentration (CMC) ...

  5. Poly(phenylene ether Based Amphiphilic Block Copolymers

    Directory of Open Access Journals (Sweden)

    Edward N. Peters


    Full Text Available Polyphenylene ether (PPE telechelic macromonomers are unique hydrophobic polyols which have been used to prepare amphiphilic block copolymers. Various polymer compositions have been synthesized with hydrophilic blocks. Their macromolecular nature affords a range of structures including random, alternating, and di- and triblock copolymers. New macromolecular architectures can offer tailored property profiles for optimum performance. Besides reducing moisture uptake and making the polymer surface more hydrophobic, the PPE hydrophobic segment has good compatibility with polystyrene (polystyrene-philic. In general, the PPE contributes to the toughness, strength, and thermal performance. Hydrophilic segments go beyond their affinity for water. Improvements in the interfacial adhesion between polymers and polar substrates via hydrogen bonding and good compatibility with polyesters (polyester-philic have been exhibited. The heterogeneity of domains in these PPE based block copolymer offers important contributions to diverse applications.

  6. Amphiphilic block co-polymers: preparation and application in nanodrug and gene delivery. (United States)

    Xiong, Xiao-Bing; Binkhathlan, Ziyad; Molavi, Ommoleila; Lavasanifar, Afsaneh


    Self-assembly of amphiphilic block co-polymers composed of poly(ethylene oxide) (PEO) as the hydrophilic block and poly(ether)s, poly(amino acid)s, poly(ester)s and polypropyleneoxide (PPO) as the hydrophobic block can lead to the formation of nanoscopic structures of different morphologies. These structures have been the subject of extensive research in the past decade as artificial mimics of lipoproteins and viral vectors for drug and gene delivery. The aim of this review is to provide an overview of the synthesis of commonly used amphiphilic block co-polymers. It will also briefly go over some pharmaceutical applications of amphiphilic block co-polymers as "nanodelivery systems" for small molecules and gene therapeutics. Copyright © 2012 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

  7. Supramolecular self-assembly of nonlinear amphiphilic and double hydrophilic block copolymers in aqueous solutions. (United States)

    Ge, Zhishen; Liu, Shiyong


    Supramolecular self-assembly of block copolymers in aqueous solution has received ever-increasing interest over the past few decades due to diverse biological and technological applications in drug delivery, imaging, sensing and catalysis. In addition to relative block lengths, molecular weights and solution conditions, chain architectures of block copolymers can also dramatically affect their self-assembling properties in selective solvents. This feature article mainly focuses on recent developments in the field of supramolecular self-assembly of amphiphilic and double hydrophilic block copolymers (DHBCs) possessing nonlinear chain topologies, including miktoarm star polymers, dendritic-linear block copolymers, cyclic block copolymers and comb-shaped copolymer brushes. Copyright © 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  8. Novel fluorescent amphiphilic block copolymers: photophysics behavior and interactions with DNA

    Directory of Open Access Journals (Sweden)


    Full Text Available In this study, novel amphiphilic fluorescent copolymers poly(N-vinylpyrrolidone-b-poly(N-methacryloyl-N'-(α-naphthylthiourea (PVP-b-PNT were synthesized via ATRP with poly(N-vinylpyrrolidone-Cl as macroinitiator and N-methacryloyl-N'-α-naphthylthiourea (NT as hydrophobic segment. PVP-b-PNT copolymers were characterized by 1H NMR, GPC-MALLS and fluorescence measurements. The aggregation behavior of PVP-b-PNT in water was investigated by transmission electron microscope (TEM and dynamic light scattering (DLS measurement. The photophysics behavior of PVP-b-PNT showed that block copolymer formed strong excimer. The interaction of DNA with the block copolymer made the excimer of block copolymer quench. The cytotoxicity result of PVP-b-PNT in cell culture in vitro indicated that this copolymer PVP-b-PNT had good biocompatibility.

  9. Functionalized surfaces of polylactide modified by Langmuir-Blodgett films of amphiphilic block copolymers

    Czech Academy of Sciences Publication Activity Database

    Kubies, Dana; Machová, Luďka; Brynda, Eduard; Lukáš, Jaromír; Rypáček, František


    Roč. 14, č. 2 (2003), s. 143-149 ISSN 0957-4530 R&D Projects: GA ČR GA203/99/0576 Institutional research plan: CEZ:AV0Z4050913 Keywords : polylactide * Langmuir - Blodgett films * amphiphilic block copolymers Subject RIV: CD - Macromolecular Chemistry Impact factor: 0.930, year: 2003

  10. Platform Approach to Produce Polymer Nanoparticles with Modular Functionality from Amphiphilic Block Copolymer Stabilizers (United States)


    Bonilla, A.; Herk, A. M.; Heuts , J. P. A. Preparation of hairy particles and antifouling films using brush-type amphiphilic block copolymer...surfactants in emulsion polymerization. Macromolecules 2010, 43 (6), 2721–2731. 5. Muñoz-Bonilla, A.; Herk, A. M.; Heuts , J. P. A. Adding stimuli

  11. Small angle neutron scattering study of the micelle structure of amphiphilic block copolymers

    International Nuclear Information System (INIS)

    Yamaoka, H.; Matsuoka, H.; Sumaru, K.; Hanada, S.


    The amphiphilic block copolymers of vinyl ether were prepared by living cationic polymerization. The partially deuterated copolymers for SANS experiments were especially synthesized by introducing deuterated phenyl units in the hydrophobic chain. SANS measurements were performed for aqueous solutions of these copolymers by changing H 2 O/D 2 O ratios. The SANS profiles indicate that the micelles in the present system exhibit a core-shell structure and that the size and shape of micelles are largely dependent on the length of hydrophobic chain. The micelle of shorter hydrophobic chain was found to be nearly spherical, whereas the micelle of longer hydrophobic chain was confirmed to have an ellipsoidal shape

  12. Amphiphilic block copolymer/poly(dimethylsiloxane) (PDMS) blends and nanocomposites for improved fouling-release. (United States)

    Martinelli, Elisa; Suffredini, Marianna; Galli, Giancarlo; Glisenti, Antonella; Pettitt, Michala E; Callow, Maureen E; Callow, James A; Williams, David; Lyall, Graeme


    Amphiphilic diblock copolymers, Sz6 and Sz12, consisting of a poly(dimethylsiloxane) block (average degree of polymerisation = 132) and a PEGylated-fluoroalkyl modified polystyrene block (Sz, average degree of polymerisation = 6, 12) were prepared by atom transfer radical polymerization (ATRP). Coatings were obtained from blends of either block copolymer (1-10 wt%) with a poly(dimethylsiloxane) (PDMS) matrix. The coating surface presented a simultaneous hydrophobic and lipophobic character, owing to the strong surface segregation of the lowest surface energy fluoroalkyl chains of the block copolymer. Surface chemical composition and wettability of the films were affected by exposure to water. Block copolymer Sz6 was also blended with PDMS and a 0.1 wt% amount of multiwall carbon nanotubes (CNT). The excellent fouling-release (FR) properties of these new coatings against the macroalga Ulva linza essentially resulted from the inclusion of the amphiphilic block copolymer, while the addition of CNT did not appear to improve the FR properties.

  13. Facile synthesis and characterization of novel biodegradable amphiphilic block copolymers bearing pendant hydroxyl groups

    Energy Technology Data Exchange (ETDEWEB)

    Hu, Gaicen; Fan, Xiaoshan; Xu, Bingcan; Zhang, Delong; Hu, Zhiguo, E-mail:


    Novel amphiphilic block copolymers bearing pendant hydroxyl groups polylactide-b–poly(3,3-bis(Hydroxymethyl–triazolylmethyl) oxetane)-b–polylactide (PLA-b–PHMTYO-b–PLA) were synthesized via a facile and efficient method. First, the block copolymer intermediates polylactide-b–poly(3,3-Diazidomethyloxetane)-b–polylactide (PLA-b–PBAMO-b–PLA) were synthesized through ring-opening polymerization of lactide using PBAMO as a macroinitiator. Following “Click” reaction of PLA-b–PBAMO-b–PLA with propargyl alcohol provided the targeted amphiphilic block copolymers PLA-b–PHMTYO-b–PLA with pendant hydroxyl groups. The composition and structure of prepared copolymers were characterized by {sup 1}H nuclear magnetic resonance ({sup 1}H NMR) spectroscopy, Fourier transform infrared (FT-IR) and gel permeation chromatography (GPC). The self-assembly behavior of the copolymers in water was investigated by transmission electron microscope (TEM), dynamic light scattering (DLS) and static light scattering (SLS). The results showed that the novel copolymers PLA-b–PHMTYO-b–PLA self-assembled into spherical micelles with diameters ranging from 100 nm to 200 nm in aqueous solution. These copolymers also exhibited low critical micellar concentrations (CMC: 6.9 × 10{sup −4} mg/mL and 3.9 × 10{sup −5} mg/mL, respectively). In addition, the in vitro cytotoxicity of these copolymers was determined in the presence of L929 cells. The results showed that the block copolymers PLA-b–PHMTYO-b–PLA exhibited better biocompatibility. Therefore, these well-defined copolymers are expected to find some applications in drug delivery or tissue engineering. - Highlights: • The method to synthesize PLA-b–PHMTYO-b–PLA is relatively facile and efficient. • PLA-b–PHMTYO-b–PLA self-assembles into spherical micelles with low CMC in water. • PLA-b–PHMTYO-b–PLA exhibits better biocompatibility and biodegradability.

  14. Anti-Biofouling Properties of Comblike Block Copolymers with Amphiphilic Side Chains

    International Nuclear Information System (INIS)

    Krishnan, S.; Ayothi, R.; Hexemer, A.; Finlay, J.; Sohn, K.; Perry, R.; Ober, C.; Kramer, E.; Callow, M.


    Surfaces of novel block copolymers with amphiphilic side chains were studied for their ability to influence the adhesion of marine organisms. The surface-active polymer, obtained by grafting fluorinated molecules with hydrophobic and hydrophilic blocks to a block copolymer precursor, showed interesting bioadhesion properties. Two different algal species, one of which adhered strongly to hydrophobic surfaces, and the other, to hydrophilic surfaces, showed notably weak adhesion to the amphiphilic surfaces. Both organisms are known to secrete adhesive macromolecules, with apparently different wetting characteristics, to attach to underwater surfaces. The ability of the amphiphilic surface to undergo an environment-dependent transformation in surface chemistry when in contact with the extracellular polymeric substances is a possible reason for its antifouling nature. Near-edge X-ray absorption fine structure spectroscopy (NEXAFS) was used, in a new approach based on angle-resolved X-ray photoelectron spectroscopy (XPS), to determine the variation in chemical composition within the top few nanometers of the surface and also to study the surface segregation of the amphiphilic block. A mathematical model to extract depth-profile information from the normalized NEXAFS partial electron yield is developed

  15. Amphiphilic block copolymers as efficiency boosters in microemulsions a SANS investigation of the role of polymers

    CERN Document Server

    Endo, H; Mihailescu, M; Monkenbusch, M; Gompper, G; Richter, D; Jakobs, B; Sottmann, T; Strey, R


    The effect of amphiphilic block copolymers on ternary microemulsions (water, oil and non-ionic surfactant) is investigated. Small amounts of PEP-PEO block copolymer lead to a dramatic expansion of the one-phase region where water and oil can be solubilized by the mediation of surfactant molecules. Small-angle neutron-scattering experiments employing a high-precision two-dimensional contrast-variation technique demonstrate that the polymer is distributed uniformly on the surfactant membrane, where it modifies the membrane curvature elasticity. Furthermore, a new approach to determine the bending rigidity of an amphiphilic membrane is proposed, which is precise enough to measure the logarithmic scale dependence of the bending rigidity and its universal prefactor in bicontinuous microemulsions. (orig.)

  16. Self-assembled structures of amphiphilic ionic block copolymers: Theory, self-consistent field modeling and experiment

    NARCIS (Netherlands)

    Borisov, O.V.; Zhulina, E.B.; Leermakers, F.A.M.; Muller, A.H.E.


    We present an overview of statistical thermodynamic theories that describe the self-assembly of amphiphilic ionic/hydrophobic diblock copolymers in dilute solution. Block copolymers with both strongly and weakly dissociating (pH-sensitive) ionic blocks are considered. We focus mostly on structural

  17. Preparation and morphology control of amphiphilic block copolymer thin films using mixed solvent vapors

    Energy Technology Data Exchange (ETDEWEB)

    Xie, Chan, E-mail: [Beijing National Laboratory for Molecular Sciences, Key Laboratory of Polymer Chemistry and Physics of Ministry of Education, College of Chemistry and Molecular Engineering, Peking University, Beijing, 100871 (China); School of Material Science and Engineering, Nanchang Hangkong University, Jiangxi, Nanchang, 330063 (China); Zhou, Yu; Zhou, Feng; Wu, Hongwei; Zou, Dechun; Fan, Xinghe [Beijing National Laboratory for Molecular Sciences, Key Laboratory of Polymer Chemistry and Physics of Ministry of Education, College of Chemistry and Molecular Engineering, Peking University, Beijing, 100871 (China); Shen, Zhihao, E-mail: [Beijing National Laboratory for Molecular Sciences, Key Laboratory of Polymer Chemistry and Physics of Ministry of Education, College of Chemistry and Molecular Engineering, Peking University, Beijing, 100871 (China)


    Graphical abstract: A series of well-defined amphiphilic block copolymer (BCP), poly[N,N-(dimethylamino)ethyl methacrylate]-block-polystyrene (PDMAEMA-b-PS), was synthesized using the ARGET ATRP method. Solvent annealing was applied for controlling the thin-film morphologies. A vertical nanocylinder structure forms in the thin film annealed under the vapors of binary mixed solvents from water and tetrahydrofuran which have a strong selectivity for the minority PDMAEMA block. - Highlights: • Well-defined amphiphilic diblock copolymers synthesized. • Systematic study on morphologies in thin films controlled by annealing under vapors of mixed solvents. - Abstract: A well-defined amphiphilic diblock copolymer, poly[N,N-(dimethylamino)ethyl methacrylate]-block-polystyrene (PDMAEMA-b-PS), was synthesized using activators regenerated by electron transfer atom transfer radical polymerization. The formation and transition of morphologies in PDMAEMA-b-PS thin films annealed under the vapors of water, tetrahydrofuran, and their binary mixed solvents were first investigated by using atomic force microscopy and scanning electron microscopy. By changing the composition of the annealing solvent, morphological evolution with increasing vapor preferential affinity was observed. A vertical nanocylinder structure forms in the PDMAEMA-b-PS thin film when it is annealed under a mixed solvent vapor with Δχ ∼ −0.975 having a strong preferential affinity for the minority PDMAEMA block at ambient temperature. The self-assembly of PDMAEMA-b-PS thin films provides a new convenient way to fabricate stimuli-responsive substrates with potential applications in adhesion control, wetting, and binding or release of functional molecules at surfaces.

  18. Formation of nanophases in epoxy thermosets containing amphiphilic block copolymers with linear and star-like topologies. (United States)

    Wang, Lei; Zhang, Chongyin; Cong, Houluo; Li, Lei; Zheng, Sixun; Li, Xiuhong; Wang, Jie


    In this work, we investigated the effect of topological structures of block copolymers on the formation of the nanophase in epoxy thermosets containing amphiphilic block copolymers. Two block copolymers composed of poly(ε-caprolactone) (PCL) and poly(2,2,2-trifluoroethyl acrylate) (PTFEA) blocks were synthesized to possess linear and star-shaped topologies. The star-shaped block copolymer composed a polyhedral oligomeric silsesquioxane (POSS) core and eight poly(ε-caprolactone)-block-poly(2,2,2-trifluoroethyl acrylate) (PCL-b-PTFEA) diblock copolymer arms. Both block copolymers were synthesized via the combination of ring-opening polymerization and reversible addition-fragmentation chain transfer/macromolecular design via the interchange of xanthate (RAFT/MADIX) process; they were controlled to have identical compositions of copolymerization and lengths of blocks. Upon incorporating both block copolymers into epoxy thermosets, the spherical PTFEA nanophases were formed in all the cases. However, the sizes of PTFEA nanophases from the star-like block copolymer were significantly lower than those from the linear diblock copolymer. The difference in the nanostructures gave rise to the different glass transition behavior of the nanostructured thermosets. The dependence of PTFEA nanophases on the topologies of block copolymers is interpreted in terms of the conformation of the miscible subchain (viz. PCL) at the surface of PTFEA microdomains and the restriction of POSS cages on the demixing of the thermoset-philic block (viz. PCL).

  19. Polydispersity-Driven Block Copolymer Amphiphile Self-Assembly into Prolate-Spheroid Micelles

    Energy Technology Data Exchange (ETDEWEB)

    Schmitt, Andrew L.; Repollet-Pedrosa, Milton H.; Mahanthappa, Mahesh K. (UW)


    The aqueous self-assembly behavior of polydisperse poly(ethylene oxide-b-1,4-butadiene-b-ethylene oxide) (OBO) macromolecular triblock amphiphiles is examined to discern the implications of continuous polydispersity in the hydrophobic block on the resulting aqueous micellar morphologies of otherwise monodisperse polymer surfactants. The chain length polydispersity and implicit composition polydispersity of these samples furnishes a distribution of preferred interfacial curvatures, resulting in dilute aqueous block copolymer dispersions exhibiting coexisting spherical and rod-like micelles with vesicles in a single sample with a O weight fraction, w{sub O}, of 0.18. At higher w{sub O} = 0.51-0.68, the peak in the interfacial curvature distribution shifts and we observe the formation of only American football-shaped micelles. We rationalize the formation of these anisotropically shaped aggregates based on the intrinsic distribution of preferred curvatures adopted by the polydisperse copolymer amphiphiles and on the relief of core block chain stretching by chain-length-dependent intramicellar segregation.

  20. pH-Sensitive Amphiphilic Block-Copolymers for Transport and Controlled Release of Oxygen

    KAUST Repository

    Patil, Yogesh Raghunath


    Saturated fluorocarbons, their derivatives and emulsions are capable of dissolving anomalously high amounts of oxygen and other gases. The mechanistic aspects of this remarkable effect remain to be explored experimentally. Here, the synthesis of a library of amphiphilic fluorous block-copolymers incorporating different fluorinated monomers is described, and the capacity of these copolymers for oxygen transport in water is systematically investigated. The structure of the fluorous monomer employed was found to have a profound effect on both the oxygen-carrying capacity and the gas release kinetics of the polymer emulsions. Furthermore, the release of O2 from the polymer dispersions could be triggered by changing the pH of the solution. This is the first example of a polymer-based system for controlled release of a non-polar, non-covalently entrapped respiratory gas.

  1. Self-assembly of block copolymer-based ionic supramolecules based upon multi-tail amphiphiles

    DEFF Research Database (Denmark)

    Asad Ayoubi, M.; Almdal, Kristoffer; Zhu, K.


    Utilising simple acid-base titration chemistry, a new family of Linear-b-Amphiphilic Comb (L-b-AC) ionic supramolecules [Soft Matter 2013, 9, 1540-1555] featuring multi-tail side-chains have been synthesized and examined by synchrotron SAXS. To three different parent diblock copolymers of poly......(styrene)-b-poly(methacrylic acid) PS-b-PMAA multi-tail ammonium side-chains of (C8)2-, (C8)4- or (C12)2-type were attached at various side-chain grafting densities (X), making it possible to separate effects of the details of the AC-block architecture from effects of the overall volume fraction of the AC block. The micro...

  2. Formation of nanoscale networks: selectively swelling amphiphilic block copolymers with CO2-expanded liquids. (United States)

    Gong, Jianliang; Zhang, Aijuan; Bai, Hua; Zhang, Qingkun; Du, Can; Li, Lei; Hong, Yanzhen; Li, Jun


    Polymeric films with nanoscale networks were prepared by selectively swelling an amphiphilic diblock copolymer, polystyrene-block-poly(4-vinylpyridine) (PS-b-P4VP), with the CO(2)-expanded liquid (CXL), CO(2)-methanol. The phase behavior of the CO(2)-methanol system was investigated by both theoretical calculation and experiments, revealing that methanol can be expanded by CO(2), forming homogeneous CXL under the experimental conditions. When treated with the CO(2)-methanol system, the spin cast compact PS-b-P4VP film was transformed into a network with interconnected pores, in a pressure range of 12-20 MPa and a temperature range of 45-60 °C. The formation mechanism of the network, involving plasticization of PS and selective swelling of P4VP, was proposed. Because the diblock copolymer diffusion process is controlled by the activated hopping of individual block copolymer chains with the thermodynamic barrier for moving PVP segments from one to another, the formation of the network structures is achieved in a short time scale and shows "thermodynamically restricted" character. Furthermore, the resulting polymer networks were employed as templates, for the preparation of polypyrrole networks, by an electrochemical polymerization process. The prepared porous polypyrrole film was used to fabricate a chemoresistor-type gas sensor which showed high sensitivity towards ammonia.

  3. Synthesis of Fluorinated Amphiphilic Block Copolymers Based on PEGMA, HEMA, and MMA via ATRP and CuAAC Click Chemistry

    Directory of Open Access Journals (Sweden)

    Fatime Eren Erol


    Full Text Available Synthesis of fluorinated amphiphilic block copolymers via atom transfer radical polymerization (ATRP and Cu(I catalyzed Huisgen 1,3-dipolar cycloaddition (CuAAC was demonstrated. First, a PEGMA and MMA based block copolymer carrying multiple side-chain acetylene moieties on the hydrophobic segment for postfunctionalization was carried out. This involves the synthesis of a series of P(HEMA-co-MMA random copolymers to be employed as macroinitiators in the controlled synthesis of P(HEMA-co-MMA-block-PPEGMA block copolymers by using ATRP, followed by a modification step on the hydroxyl side groups of HEMA via Steglich esterification to afford propargyl side-functional polymer, alkyne-P(HEMA-co-MMA-block-PPEGMA. Finally, click coupling between side-chain acetylene functionalities and 2,3,4,5,6-pentafluorobenzyl azide yielded fluorinated amphiphilic block copolymers. The obtained polymers were structurally characterized by 1H-NMR, 19F-NMR, FT-IR, and GPC. Their thermal characterizations were performed using DSC and TGA.

  4. Synthesis of an amphiphilic dendrimer-like block copolymer and its application on drug delivery

    KAUST Repository

    Wang, Shuaipeng


    Dendrimer-like amphiphilic copolymer is a kind of three-dimensional spherical structure polymer. An amphiphilic dendrimer-like diblock copolymer, PEEGE-G2-b-PEO(OH)12, constituted of a hydrophobic poly(ethoxyethyl glycidol ether) inner core and a hydrophilic poly(ethylene oxide) outer layer, has been successfully synthesized by the living anionic ring-opening polymerization method. The intermediates and targeted products were characterized with 1H NMR spectroscopy and gel permeation chromatography. The application on drug delivery of dendrimer-like diblock copolymer PEEGE-G2-b-PEO(OH)12 using DOX as a model drug was also studied. The drug loading content and encapsulation efficiency were found at 13.07% and 45.75%, respectively. In vitro release experiment results indicated that the drug-loaded micelles exhibited a sustained release behavior under acidic media.

  5. Synthesis of biodegradable amphiphilic Y-shaped block co-polymers via ring-opening polymerization for drug delivery. (United States)

    Jia, Lin; Yan, Lifeng; Li, Yang


    A series of novel Y-shaped biodegradable block co-polymers of poly(ε-caprolactone) (PCL) and poly(ethyl ethylene phosphate) (PEEP) (PCL-(PEEP)2) were synthesized via ring-opening polymerization (ROP) of EEP with bis-hydroxy-functional ROP initiator (init-PCL-(OH)2). The init-PCL-(OH)2 was synthesized by ROP of CL using 4-hydroxybutyl acrylate (HBA) as initiator and L-tartaric acid as catalyst in bulk, and subsequently the resulting vinyl-terminated PCL was end-capped by acetyl chloride, followed by Michael addition using excess diethanolamine. The Y-shaped co-polymers and their intermediates were characterized by (1)H-, (13)C-, (31)P-NMR, FT-IR and gel-permeation chromatography. The results indicated that the molecular weight of the Y-shaped co-polymers increased with the increasing of the molar ratios of EEP to init-PCL-(OH)2 in the feed, while the PCL chain length was kept constant. The amphiphilic block co-polymers could self-assemble into micelles in aqueous solution, which was demonstrated by dynamic light scattering, (1)H-NMR and atomic force microscopy. A study of controlled release of indomethacin indicated that the amphiphilic block co-polymers could potentially provide novel vehicles for drug delivery.

  6. Compartmentalization Technologies via Self-Assembly and Cross-Linking of Amphiphilic Random Block Copolymers in Water. (United States)

    Matsumoto, Mayuko; Terashima, Takaya; Matsumoto, Kazuma; Takenaka, Mikihito; Sawamoto, Mitsuo


    Orthogonal self-assembly and intramolecular cross-linking of amphiphilic random block copolymers in water afforded an approach to tailor-make well-defined compartments and domains in single polymer chains and nanoaggregates. For a double compartment single-chain polymer, an amphiphilic random block copolymer bearing hydrophilic poly(ethylene glycol) (PEG) and hydrophobic dodecyl, benzyl, and olefin pendants was synthesized by living radical polymerization (LRP) and postfunctionalization; the dodecyl and benzyl units were incorporated into the different block segments, whereas PEG pendants were statistically attached along a chain. The copolymer self-folded via the orthogonal self-assembly of hydrophobic dodecyl and benzyl pendants in water, followed by intramolecular cross-linking, to form a single-chain polymer carrying double yet distinct hydrophobic nanocompartments. A single-chain cross-linked polymer with a chlorine terminal served as a globular macroinitiator for LRP to provide an amphiphilic tadpole macromolecule comprising a hydrophilic nanoparticle and a hydrophobic polymer tail; the tadpole thus self-assembled into multicompartment aggregates in water.

  7. Micro- and nanophase separations in hierarchical self-assembly of strongly amphiphilic block copolymer-based ionic supramolecules

    DEFF Research Database (Denmark)

    Ayoubi, Mehran Asad; Zhu, Kaizheng; Nyström, Bo


    By a selective complexation between different alkyltrimethylammonium amphiphiles (C8, C12 and C16) and three different diblock copolymer systems of poly(styrene)-b-poly(methacrylic acid) at various grafting densities X (X = number of alkyl chains per acidic group of the poly(methacrylic acid) PMAA...... block), a class of ionic supramolecules are successfully synthesized whose molecular architecture consists of a poly(styrene) PS block (Linear block) covalently connected to a strongly amphiphilic comb-like block (AmphComb block), i.e. Linear-b-AmphComb. In the melt state, these ionic supramolecules can...... show simultaneous microphase (between Linear and AmphComb blocks) and nanophase (within the AmphComb blocks) separations. This leads to the formation of various structure-in-structure two-scale hierarchical self-assemblies, including S-in-SLL, S-in-SBCC, S-in-C, S-in-L and C-in-L, where S, SLL, SBCC, C...

  8. Model Amphiphilic Block Copolymers with Tailored Molecular Weight and Composition in PDMS-Based Films to Limit Soft Biofouling

    Energy Technology Data Exchange (ETDEWEB)

    Wenning, Brandon M. [Dipartimento di Chimica e Chimica Industriale, Università di Pisa, Pisa 56124, Italy; Martinelli, Elisa [Dipartimento di Chimica e Chimica Industriale, Università di Pisa, Pisa 56124, Italy; Mieszkin, Sophie [School of Biosciences, The University of Birmingham, Edgbaston, Birmingham B15 5TT, U.K.; Finlay, John A. [School of Biosciences, The University of Birmingham, Edgbaston, Birmingham B15 5TT, U.K.; Fischer, Daniel [National Institute of Standards and Technology, Gaithersburg, Maryland 20899, United States; Callow, James A. [School of Biosciences, The University of Birmingham, Edgbaston, Birmingham B15 5TT, U.K.; Callow, Maureen E. [School of Biosciences, The University of Birmingham, Edgbaston, Birmingham B15 5TT, U.K.; Leonardi, Amanda K.; Ober, Christopher K.; Galli, Giancarlo [Dipartimento di Chimica e Chimica Industriale, Università di Pisa, Pisa 56124, Italy


    A set of controlled surface composition films was produced utilizing amphiphilic block copolymers dispersed in a cross-linked poly(dimethylsiloxane) network. These block copolymers contained oligo(ethylene glycol) (PEGMA) and fluoroalkyl (AF6) side chains in selected ratios and molecular weights to control surface chemistry including antifouling and fouling-release performance. Such properties were assessed by carrying out assays using two algae, the green macroalga Ulva linza (favors attachment to polar surfaces) and the unicellular diatom Navicula incerta (favors attachment to nonpolar surfaces). All films performed well against U. linza and exhibited high removal of attached sporelings (young plants) under an applied shear stress, with the lower molecular weight block copolymers being the best performing in the set. The composition ratios from 50:50 to 60:40 of the AF6/PEGMA side groups were shown to be more effective, with several films exhibiting spontaneous removal of the sporelings. The cells of N. incerta were also removed from several coating compositions. All films were characterized by surface techniques including captive bubble contact angle, atomic force microscopy, and near edge X-ray absorption fine structure spectroscopy to correlate surface chemistry and morphology with biological performance.

  9. Methotrexate-Loaded Four-Arm Star Amphiphilic Block Copolymer Elicits CD8+ T Cell Response against a Highly Aggressive and Metastatic Experimental Lymphoma. (United States)

    Hira, Sumit Kumar; Ramesh, Kalyan; Gupta, Uttam; Mitra, Kheyanath; Misra, Nira; Ray, Biswajit; Manna, Partha Pratim


    We have synthesized a well-defined four-arm star amphiphilic block copolymer [poly(DLLA)-b-poly(NVP)]4 [star-(PDLLA-b-PNVP)4] that consists of D,L-lactide (DLLA) and N-vinylpyrrolidone (NVP) via the combination of ring-opening polymerization (ROP) and xanthate-mediated reversible addition-fragmentation chain transfer (RAFT) polymerization. Synthesis of the polymer was verified by 1H NMR spectroscopy and gel permeation chromatography (GPC). The amphiphilic four-arm star block copolymer forms spherical micelles in water as demonstrated by transmission electron microscopy (TEM) and 1H NMR spectroscopy. Pyrene acts as a probe to ascertain the critical micellar concentration (cmc) by using fluorescence spectroscopy. Methotrexate (MTX)-loaded polymeric micelles of star-(PDLLA15-b-PNVP10)4 amphiphilic block copolymer were prepared and characterized by fluorescence and TEM studies. Star-(PDLLA15-b-PNVP10)4 copolymer was found to be significantly effective with respect to inhibition of proliferation and lysis of human and murine lymphoma cells. The amphiphilic block copolymer causes cell death in parental and MTX-resistant Dalton lymphoma (DL) and Raji cells. The formulation does not cause hemolysis in red blood cells and is tolerant to lymphocytes compared to free MTX. Therapy with MTX-loaded star-(PDLLA15-b-PNVP10)4 amphiphilic block copolymer micelles prolongs the life span of animals with neoplasia by reducing the tumor load, preventing metastasis and augmenting CD8+ T cell-mediated adaptive immune responses.

  10. Polystyrene-Poly(sodium methacrylate) Amphiphilic Block Copolymers by ATRP : Effect of Structure, pH, and Ionic Strength on Rheology of Aqueous Solutions

    NARCIS (Netherlands)

    Raffa, Patrizio; Brandenburg, Piter; Wever, Diego A. Z.; Broekhuis, Antonius A.; Picchioni, Francesco


    Three well-defined polystyrene-poly(sodium methacrylate) amphiphilic block copolymers characterized by different molecular architecture (diblock, triblock, and four-arm star) have been synthesized by ATRP. The rheology of their water solutions has been evaluated by measuring dynamic moduli and shear

  11. Self-Assembly of Charged Amphiphilic Diblock Copolymers with Insoluble Blocks of Decreasing Hydrophobicity: From Kinetically Frozen Colloids to Macrosurfactants

    Energy Technology Data Exchange (ETDEWEB)

    M Jacquin; P Muller; H Cottet; O Theodoly


    We have investigated the self-assembly properties in aqueous solution of amphiphilic diblock copolymers with insoluble blocks of different hydrophobicity and demonstrated that the condition to obtain dynamic micelles is to design samples with insoluble blocks of low enough hydrophobicity. We focus here on results with new water-soluble amphiphilic diblock copolymers poly(diethyleneglycol ethylether acrylate)-b-poly(acrylic acid), or PDEGA-b-PAA. The physical characteristics of PDEGA-b-PAA micelles at high ionization have been determined by small angle neutron scattering (SANS). We show that PDEGA-b-PAA samples form micelles at thermodynamic equilibrium. The critical micelle concentrations (CMCs) decrease strongly with ionic strength and temperature due to a solvent quality decrease for, respectively, the corona and the core. This behavior of reversible aggregation is remarkable as compared to the behavior of kinetically frozen aggregation that has been widely observed with samples of similar architecture and different hydrophobic blocks, for example, poly(styrene)-b-poly(acrylic acid), PS-b-PAA, and poly(butyl acrylate)-b-poly(acrylic acid), PBA-b-PAA. We have measured the interfacial tension between water and the homopolymers PDEGA and PBA at, respectively, 3 and 20 mN/m at room temperature, which permits one to estimate the energy cost to extract a unimer from a micelle. The results are consistent with a micelle association that is fast for PDEGA-b-PAA and kinetically frozen PBA-b-PAA. Hence, PDEGA-b-PAA samples form a new system of synthetic charged macrosurfactant with unique properties of fast dynamic association, tunable charge, and water solubility even at temperatures and NaCl concentrations as high as 65 C and 1 M.

  12. Preparation and self-assembly behavior of polystyrene-block-poly (dimethylaminoethyl methacrylate amphiphilic block copolymer using atom transfer radical polymerization

    Directory of Open Access Journals (Sweden)


    Full Text Available Asymmetric and semi-symmetric amphiphilic diblock copolymers polystyrene-block-poly (dimethylaminoethyl methacrylate (PS-b-PDMAEMA with the same PS block length of 62 repeat units and quite short (3 repeat units or equivalent (47 repeat units length of PDMAEMA have been prepared simply by varying the ratio of the bromine-terminated macroinitiator polystyrene (PS-Br to DMAEMA using atom transfer radical polymerization (ATRP. The chemical structures and compositions of the PS-b-PDMAEMA block copolymers are studied by nuclear magnetic resonance (NMR spectroscopy, gel permeation chromatography (GPC, and elementary analysis (EA. The self-assembly behaviors of copolymers in N,N-dimethyl formamide (DMF with different pH and dioxane/water binary solvent mixture by direct dissolution method (DD, are studied by transmission electron microscopy (TEM, electron diffracting analysis (EDA, and energy-dispersive analysis of X-rays (EDAX techniques. Transmission electron microscopy results suggest that asymmetric block copolymer PS62-b-PDMAEMA3 (the numbers in the form of footnotes represent repeated units of each monomer in the copolymer can form spherical core-shell micelles, large compound reverse micelles (LCRMs, hexagonal/rhombic phases, reverse hexagonal/rhombic phases, vesicles, reverse vesicles and necklace-like reverse micelles, controlled by common or selective solvent and pH, while most of the aggregates of semi-symmetric PS62-b-PDMAEMA47 are simply spherical, such as spherical core-shell micelles and reverse spherical core-shell micelles, besides hexagonal/rhombic phases. All above structures are controlled by three components of the free energy of aggregation: core-chain stretching, interfacial energy and intercoronal chain interaction.

  13. Interface interaction within nanopores in thin films of an amphiphilic block copolymer and CTAB. (United States)

    Wang, Chengyin; Wang, Deyan; Hu, Xiaoya; Wang, Guoxiu


    With water droplets as sacrificed templates at a particular humidity, micro-porous solid thin films were successfully fabricated by self-assembly using an amphiphilic block polymer, polystyrene-b-polyacrylic acid (PS-b-PAA). Interface interactions between the micro-porous thin film and a cationic surfactant, cetyltrimethylammonium bromide (CTAB), are investigated by in-situ AFM in aqueous solutions. An interesting phenomenon was observed in water and CTAB solution, which the dimensions of the micropores are remarkably larger than the dimensions of those in air. The solid thin films exhibit different surface morphologies in response to stimulus by different concentrations of CTAB. These observations were explained by positing that the PAA chains in the micropores stretch and contract with interface interactions between PAA and CTAB. A promising electrochemical application of this film is suggested. This study is aimed at strategies for the functionalization of stimulus-responsive micro-porous solid thin films with tunable surface morphologies, and exploring new smart materials. Copyright © 2010 Elsevier Inc. All rights reserved.

  14. Development and Characterization of Biocompatible Fullerene [C60]/Amphiphilic Block Copolymer Nanocomposite

    Directory of Open Access Journals (Sweden)

    Alok Chaurasia


    Full Text Available We report a supramolecular process for the synthesis of well-defined fullerene (C60/polymer colloid nanocomposites in an aqueous solution via complex formation. A biocompatible triblock poly(4-vinylpyridine-b-polyethylene-b-poly(4-vinylpyridine, P4VP8-b-PEO105-b-P4VP8, was synthesized by atom transfer radical polymerization. The block copolymer formed complexes with C60 in toluene and resulted in fullerene assembly in cluster form. Nanocomposite dispersion in an aqueous solution could be obtained using an aged solution of the polymer/C60/toluene solution by a solvent evaporation technique. The UV-Vis and FTIR spectroscopy confirmed the complex formation of fullerene with the polymer which plays a significant role in controlling the PDI and size of polymer/C60 micelles in the toluene solution. The particle size and morphology of P4VP8-b-PEO105-b-P4VP8 and P4VP8-b-PEO105-b-P4VP8/C60 mixture were studied by dynamic light scattering (DLS and transmission electron microscopy (TEM. In a cytotoxicity test, both pure polymer and the resulting polymer/C60 composite in water showed more than 90% cell viability at 1 mg/mL concentration.

  15. Amphiphilic star block copolymers as gene carrier Part I: Synthesis via ATRP using calix[4]resorcinarene-based initiators and characterization

    Energy Technology Data Exchange (ETDEWEB)

    Zheng, Anna; Xue, Yan; Wei, Dafu [Shanghai Key Laboratory of Advanced Polymeric Materials, Key Laboratory for Ultrafine Materials of Ministry of Education, School of Materials Science and Engineering, East China University of Science and Technology, Shanghai 200237 (China); Guan, Yong, E-mail: [Shanghai Key Laboratory of Advanced Polymeric Materials, Key Laboratory for Ultrafine Materials of Ministry of Education, School of Materials Science and Engineering, East China University of Science and Technology, Shanghai 200237 (China); Xiao, Huining [Department of Chemical Engineering, University of New Brunswick, Fredericton, New Brunswick, Canada E3B 5A3 (Canada)


    In this work, a cationic star polymer [poly(2-dimethylamino)ethyl methacrylate (PDMAEMA)] was prepared via atom transfer radical polymerization (ATRP), using brominated calix[4]resorcinarene as an initiator. Hydrophobic moieties, methyl methacrylate (MMA) and butyl acrylate (BA), were further incorporated via 'one-pot' method. Well-defined eight-armed star block copolymers bearing hydrophilic blocks inside and hydrophobic blocks outside were synthesized. The molecular weight, particle size, electrophoretic mobility and apparent charge density were determined by gel permeation chromatography (GPC), dynamic light scattering (DLS), phase analysis light scattering (PALS) and colloidal titration, respectively. The zeta potentials and apparent charge densities of the products exhibited the characteristics of polyelectrolyte. The incorporation of hydrophobic moieties generated electrostatic screening effect. The as-synthesized amphiphilic star copolymer is promising as a thermo-sensitive gene carrier for gene therapy. Highlights: Black-Right-Pointing-Pointer Amphiphilic cationic star block copolymers with well-controlled structures were prepared via ATRP. Black-Right-Pointing-Pointer The molecular structures and properties of the initiator and copolymers were systematically characterized. Black-Right-Pointing-Pointer The products exhibited the positive charged character, and hydrophobic moieties generated electrostatic screening effect.

  16. Linear-g-hyperbranched and cyclodextrin-based amphiphilic block copolymer as a multifunctional nanocarrier

    Directory of Open Access Journals (Sweden)

    Yamei Zhao


    Full Text Available In this paper, a novel, multifunctional polymer nanocarrier was designed to provide adequate volume for high drug loading, to afford a multiregion encapsulation ability, and to achieve controlled drug release. An amphiphilic, triblock polymer (ABC with hyperbranched polycarbonsilane (HBPCSi and β-cyclodextrin (β-CD moieties were first synthesized by the combination of a two-step reversible addition-fragmentation transfer polymerization into a pseudo-one-step hydrosilylation and quaternization reaction. The ABC then self-assembled into stable micelles with a core–shell structure in aqueous solution. These resulting micelles are multifunctional nanocarriers which possess higher drug loading capability due to the introduction of HBPCSi segments and β-CD moieties, and exhibit controlled drug release based on the diffusion release mechanism. The novel multifunctional nanocarrier may be applicable to produce highly efficient and specialized delivery systems for drugs, genes, and diagnostic agents.

  17. Synthesis and self-assembly behavior of amphiphilic diblock copolymer dextran-block-poly(ε-caprolactone (DEX-b-PCL in aqueous media

    Directory of Open Access Journals (Sweden)


    Full Text Available An amphiphilic diblock copolymer, dextran-block-poly(ε-caprolactone (DEX-b-PCL, with a series of welldefined chain lengths of each block was prepared by conjugating a dextran chain with a PCL block via aza-Michael addition reaction under mild conditions. For the dextran block, samples with relatively uniform molecular weight, 3.5 and 6.0 kDa, were used, and the PCL blocks were prepared via ring-opening polymerization at defined ratios of ε-caprolactone to initiator in order to give copolymers with mass fraction of dextran (fDEX ranging from 0.16 to 0.45. When these copolymers were allowed to self-assemble in aqueous solution, the morphology of assembled aggregates varied as a function of fDEX when characterized by transmission electron microscope (TEM, fluorescence microscope (FM and dynamic laser scattering (DLS. As fDEX decreases gradually from 0.45 to 0.16, the morphology of the copolymer assembly changes from spherical micelles to worm-like micelles and eventually to polymersomes, together with an increase in particle sizes.

  18. Non-surface activity and micellization behavior of cationic amphiphilic block copolymer synthesized by reversible addition-fragmentation chain transfer process. (United States)

    Ghosh, Arjun; Yusa, Shin-ichi; Matsuoka, Hideki; Saruwatari, Yoshiyuki


    Cationic amphiphilic diblock copolymers of poly(n-butylacrylate)-b-poly(3-(methacryloylamino)propyl)trimethylammonium chloride) (PBA-b-PMAPTAC) with various hydrophobic and hydrophilic chain lengths were synthesized by a reversible addition-fragmentation chain transfer (RAFT) process. Their molecular characteristics such as surface activity/nonactivity were investigated by surface tension measurements and foam formation observation. Their micelle formation behavior and micelle structure were investigated by fluorescence probe technique, static and dynamic light scattering (SLS and DLS), etc., as a function of hydrophilic and hydrophobic chain lengths. The block copolymers were found to be non-surface active because the surface tension of the aqueous solutions did not change with increasing polymer concentration. Critical micelle concentration (cmc) of the polymers could be determined by fluorescence and SLS measurements, which means that these polymers form micelles in bulk solution, although they were non-surface active. Above the cmc, the large blue shift of the emission maximum of N-phenyl-1-naphthylamine (NPN) probe and the low micropolarity value of the pyrene probe in polymer solution indicate the core of the micelle is nonpolar in nature. Also, the high value of the relative intensity of the NPN probe and the fluorescence anisotropy of the 1,6-diphenyl-1,3,5-hexatriene (DPH) probe indicated that the core of the micelle is highly viscous in nature. DLS was used to measure the average hydrodynamic radii and size distribution of the copolymer micelles. The copolymer with the longest PBA block had the poorest water solubility and consequently formed micelles with larger size while having a lower cmc. The "non-surface activity" was confirmed for cationic amphiphilic diblock copolymers in addition to anionic ones studied previously, indicating the universality of non-surface activity nature.

  19. The effect of hydrophilic and hydrophobic block length on the rheology of amphiphilic diblock Polystyrene-b-Poly(sodium methacrylate) copolymers prepared by ATRP. (United States)

    Raffa, Patrizio; Stuart, Marc C A; Broekhuis, Antonius A; Picchioni, Francesco


    Following our previous investigation on the effect of molecular architecture on the rheology of Polystyrene-b-Poly(sodium methacrylate) copolymers (PS-b-PMAA), we consider here diblock PS-b-PMAA copolymers characterized by a different length of either the hydrophilic or the hydrophobic block. Various copolymers characterized by different PS or PMAA block length have been prepared by ATRP (kinetics is also discussed) and studied from the point of view of their rheological behaviour in water. To the best of our knowledge, this is the first systematic investigation concerning the effect of block length on the rheology of diblock polyelectrolytes. We found that the hydrophobic block length has small influence on the rheology. Surprisingly, the polymers with shortest PMAA blocks yield the strongest gels at high concentration. A simple model based on the classical theories of self-assembly and percolation of amphiphilic polymers has been here developed in order to explain the observed data. Copyright © 2014 Elsevier Inc. All rights reserved.

  20. Core–Shell Structure and Aggregation Number of Micelles Composed of Amphiphilic Block Copolymers and Amphiphilic Heterografted Polymer Brushes Determined by Small-Angle X-ray Scattering

    Energy Technology Data Exchange (ETDEWEB)

    Szymusiak, Magdalena; Kalkowski, Joseph; Luo, Hanying; Donovan, Alexander J.; Zhang, Pin; Liu, Chang; Shang, Weifeng; Irving, Thomas; Herrera-Alonso, Margarita; Liu, Ying (JHU); (IIT); (UIC)


    A large group of functional nanomaterials employed in biomedical applications, including targeted drug delivery, relies on amphiphilic polymers to encapsulate therapeutic payloads via self-assembly processes. Knowledge of the micelle structures will provide critical insights into design of polymeric drug delivery systems. Core–shell micelles composed of linear diblock copolymers poly(ethylene glycol)-b-poly(caprolactone) (PEG-b-PCL), poly(ethylene oxide)-b-poly(lactic acid) (PEG-b-PLA), as well as a heterografted brush consisting of a poly(glycidyl methacrylate) backbone with PEG and PLA branches (PGMA-g-PEG/PLA) were characterized by dynamic light scattering (DLS) and small-angle X-ray scattering (SAXS) measurements to gain structural information regarding the particle morphology, core–shell size, and aggregation number. The structural information at this quasi-equilibrium state can also be used as a reference when studying the kinetics of polymer micellization.

  1. Core–Shell Structure and Aggregation Number of Micelles Composed of Amphiphilic Block Copolymers and Amphiphilic Heterografted Polymer Brushes Determined by Small-Angle X-ray Scattering

    Energy Technology Data Exchange (ETDEWEB)

    Szymusiak, Magdalena [Department; Kalkowski, Joseph [Department; Luo, Hanying [Department; Donovan, Alexander J. [Department; Zhang, Pin [Department; Liu, Chang [Department; Shang, Weifeng [Department; Irving, Thomas [Department; Herrera-Alonso, Margarita [Department; Liu, Ying [Department; Department


    A large group of functional nanomaterials employed in biomedical applications, including targeted drug delivery, relies on amphiphilic polymers to encapsulate therapeutic payloads via self-assembly processes. Knowledge of the micelle structures will provide critical insights into design of polymeric drug delivery systems. Core–shell micelles composed of linear diblock copolymers poly(ethylene glycol)-b-poly(caprolactone) (PEG-b-PCL), poly(ethylene oxide)-b-poly(lactic acid) (PEG-b-PLA), as well as a heterografted brush consisting of a poly(glycidyl methacrylate) backbone with PEG and PLA branches (PGMA-g-PEG/PLA) were characterized by dynamic light scattering (DLS) and small-angle X-ray scattering (SAXS) measurements to gain structural information regarding the particle morphology, core–shell size, and aggregation number. The structural information at this quasi-equilibrium state can also be used as a reference when studying the kinetics of polymer micellization.

  2. Sulfonated amphiphilic block copolymers : synthesis, self-assembly in water, and application as stabilizer in emulsion polymerization (United States)

    Jiguang Zhang; Matthew R. Dubay; Carl J. Houtman; Steven J. Severtson


    Described is the synthesis of diblock copolymers generated via sequential atom transfer radical polymerization (ATRP) of poly(n-butyl acrylate) (PnBA) followed by chain augmentation with either sulfonated poly(2-hydroxyethyl methacrylate) (PHEMA) or poly(2-hydroxyethyl acrylate) (PHEA) blocks. ATRP of PHEMA or PHEA from PnBA macroinitiator was conducted in acetone/...

  3. Amphiphilic copolymers for fouling-release coatings

    DEFF Research Database (Denmark)

    Noguer, Albert Camós; Olsen, Stefan Møller; Hvilsted, Søren

    of the coatings [9,10,11]. This work shows the effect of an amphiphilic copolymer that induces hydrophilicity on the surface of the silicone-based fouling release coatings. The behaviour of these copolymers within the coating upon immersion and the interaction of these surface-active additives with other...

  4. Microspheres for protein delivery prepared from amphiphilic multiblock copolymers. 1. influence of preparation techniques on particle characteristics and protein delivery

    NARCIS (Netherlands)

    Bezemer, J.M.; Radersma, R.; Grijpma, Dirk W.; Dijkstra, Pieter J.; van Blitterswijk, Clemens; Feijen, Jan


    The entrapment of lysozyme in amphiphilic multiblock copolymer microspheres by emulsification and subsequent solvent removal processes was studied. The copolymers are composed of hydrophilic poly(ethylene glycol) (PEG) blocks and hydrophobic poly(butylene terephthalate) (PBT) blocks. Direct solvent

  5. A study on amphiphilic fluorinated block copolymer in graphite exfoliation using supercritical CO2 for stable graphene dispersion. (United States)

    Kim, Young Hyun; Lee, Hyang Moo; Choi, Sung Wook; Cheong, In Woo


    In this study, poly(2,2,2-trifluoroethyl methacrylate)-block-poly(4-vinylpyridine) (PTFEMA-b-PVP) was synthesized by stepwise reversible addition-fragmentation chain transfer (RAFT) polymerization for the preparation of graphene by the exfoliation of graphite nanoplatelets (GPs) in supercritical CO 2 (SCCO 2 ). Two different block copolymers (low and high molecular weights) were prepared with the same block ratio and used at different concentrations in the SCCO 2 process. The amount of PTFEMA-b-PVP adsorbed on the GPs and the electrical conductivity of the SCCO 2 -treated GP samples were evaluated using thermogravimetric analysis (TGA) and four-point probe method, respectively. All GP samples treated with SCCO 2 were then dispersed in methanol and the dispersion stability was investigated using online turbidity measurements. The concentration and morphology of few-layer graphene stabilized with PTFEMA-b-PVP in the supernatant solution were investigated by gravimetry, scanning electron microscopy, and Raman spectroscopy. Destabilization study of the graphene dispersions revealed that the longer block copolymer exhibited better affinity for graphene, resulting in a higher yield of stable graphene with minimal defects. Copyright © 2017 Elsevier Inc. All rights reserved.

  6. Importance of crystallinity of anchoring block of semi-solid amphiphilic triblock copolymers in stabilization of silicone nanoemulsions. (United States)

    Le Kim, Trang Huyen; Jun, Hwiseok; Nam, Yoon Sung


    Polymer emulsifiers solidified at the interface between oil and water can provide exceptional dispersion stability to emulsions due to the formation of unique semi-solid interphase. Our recent works showed that the structural stability of paraffin-in-water emulsions highly depends on the oil wettability of hydrophobic block of methoxy poly(ethylene glycol)-block-poly(ε-caprolactone) (mPEG-b-PCL). Here we investigate the effects of the crystallinity of hydrophobic block of triblock copolymer-based emulsifiers, PCLL-b-PEG-b-PCLL, on the colloidal properties of silicone oil-in-water nanoemulsions. The increased ratio of l-lactide to ε-caprolactone decreases the crystallinity of the hydrophobic block, which in turn reduces the droplet size of silicone oil nanoemulsions due to the increased chain mobility at the interface. All of the prepared nanoemulsions are very stable for a month at 37°C. However, the exposure to repeated freeze-thaw cycles quickly destabilizes the nanoemulsions prepared using the polymer with the reduced crystallinity. This work demonstrates that the anchoring chain crystallization in the semi-solid interphase is critically important for the structural robustness of nanoemulsions under harsh physical stresses. Copyright © 2017 Elsevier Inc. All rights reserved.

  7. Continuous Preparation of Hollow Polymeric Nanocapsules Using Self-Assembly and a Photo-Crosslinking Process of an Amphiphilic Block Copolymer

    Directory of Open Access Journals (Sweden)

    Xuan Don Nguyen


    Full Text Available This paper presents a fabrication method of hollow polymeric nanocapsules (HPNCs. The HPNCs were examined to reduce light trapping in an organic light emitting diodes (OLED device by increasing the refractive index contrast. They were continuously fabricated by the sequential process of self-assembly and photo-crosslinking of an amphiphilic block copolymer of SBR-b-PEGMA, poly(styrene-r-butadiene-b-poly(poly(ethylene glycol methyl ether methacrylate in a flow-focusing microfluidic device. After the photo-crosslinking process, the produced HPNCs have a higher resistance to water and organic solvents, which is applicable to the fabrication process of optical devices. The morphology and hollow structure of the produced nanocapsules were determined by transmission electron microscopy (TEM, scanning electron microscopy (SEM, and atomic force microscopy (AFM. Also, their size control was examined by varying the ratio of inlet flow rates and the morphological difference was studied by changing the polymer concentration. The size was measured by dynamic light scattering (DLS. The refractive index of the layer with and without the HPNCs was measured, and a lower refractive index was obtained in the HPNCs-dispersed layer. In future work, the light extraction efficiency of the HPNCs-dispersed OLED will be examined.

  8. Synthesis of amphiphilic copolymers by ATRP initiated with a bifunctional initiator containing trichlomethyl groups

    Czech Academy of Sciences Publication Activity Database

    Ritz, Pavel; Látalová, Petra; Janata, Miroslav; Toman, Luděk; Kříž, Jaroslav; Genzer, J.; Vlček, Petr


    Roč. 67, č. 10 (2007), s. 1027-1039 ISSN 1381-5148 R&D Projects: GA MŠk 1P05ME753 Institutional research plan: CEZ:AV0Z40500505 Keywords : ATRP * block copolymer * polyhalogenated initiator * amphiphilic copolymer Subject RIV: CD - Macromolecular Chemistry Impact factor: 1.720, year: 2007

  9. Optoelectronics using block copolymers.

    Energy Technology Data Exchange (ETDEWEB)

    Botiz, I.; Darling, S. B.; Center for Nanoscale Materials


    Block copolymers, either as semiconductors themselves or as structure directors, are emerging as a promising class of materials for understanding and controlling processes associated with both photovoltaic energy conversion and light emitting devices.

  10. The effect of hydrophilic and hydrophobic block length on the rheology of amphiphilic diblock Polystyrene-b-Poly(sodium methacrylate) copolymers prepared by ATRP

    NARCIS (Netherlands)

    Raffa, Patrizio; Stuart, Marc C.A.; Broekhuis, Antonius A.; Picchioni, Francesco


    Following our previous investigation on the effect of molecular architecture on the rheology of Polystyrene-b-Poly(sodium methacrylate) copolymers (PS-b-PMAA), we consider here diblock PS-b-PMAA copolymers characterized by a different length of either the hydrophilic or the hydrophobic block.

  11. Micellization Thermodynamics of Pluronic P123 (EO20PO70EO20 Amphiphilic Block Copolymer in Aqueous Ethylammonium Nitrate (EAN Solutions

    Directory of Open Access Journals (Sweden)

    Zhiqi He


    Full Text Available Poly(ethylene oxide-poly(propylene oxide-poly(ethylene oxide (PEO-PPO-PEO block copolymers (commercially available as Pluronics or Poloxamers can self-assemble into various nanostructures in water and its mixtures with polar organic solvents. Ethylammonium nitrate (EAN is a well-known protic ionic liquid that is expected to affect amphiphile self-assembly due to its ionic nature and hydrogen bonding ability. By proper design of isothermal titration calorimetry (ITC experiments, we determined the enthalpy and other thermodynamic parameters of Pluronic P123 (EO20PO70EO20 micellization in aqueous solution at varied EAN concentration. Addition of EAN promoted micellization in a manner similar to increasing temperature, e.g., the addition of 1.75 M EAN lowered the critical micelle concentration (CMC to the same extent as a temperature increase from 20 to 24 °C. The presence of EAN disrupts the water solvation around the PEO-PPO-PEO molecules through electrostatic interactions and hydrogen bonding, which dehydrate PEO and promote micellization. At EAN concentrations lower than 1 M, the PEO-PPO-PEO micellization enthalpy and entropy increase with EAN concentration, while both decrease above 1 M EAN. Such a change can be attributed to the formation by EAN of semi-ordered nano-domains with water at higher EAN concentrations. Pyrene fluorescence suggests that the polarity of the mixed solvent decreased linearly with EAN addition, whereas the polarity of the micelle core remained unaltered. This work contributes to assessing intermolecular interactions in ionic liquid + polymer solutions, which are relevant to a number of applications, e.g., drug delivery, membrane separations, polymer electrolytes, biomass processing and nanomaterial synthesis.

  12. Amphiphilic building blocks for self-assembly: from amphiphiles to supra-amphiphiles. (United States)

    Wang, Chao; Wang, Zhiqiang; Zhang, Xi


    The process of self-assembly spontaneously creates well-defined structures from various chemical building blocks. Self-assembly can include different levels of complexity: it can be as simple as the dimerization of two small building blocks driven by hydrogen bonding or as complicated as a cell membrane, a remarkable supramolecular architecture created by a bilayer of phospholipids embedded with functional proteins. The study of self-assembly in simple systems provides a fundamental understanding of the driving forces and cooperativity behind these processes. Once the rules are understood, these guidelines can facilitate the research of highly complex self-assembly processes. Among the various components for self-assembly, an amphiphilic molecule, which contains both hydrophilic and hydrophobic parts, forms one of the most powerful building blocks. When amphiphiles are dispersed in water, the hydrophilic component of the amphiphile preferentially interacts with the aqueous phase while the hydrophobic portion tends to reside in the air or in the nonpolar solvent. Therefore, the amphiphiles aggregate to form different molecular assemblies based on the repelling and coordinating forces between the hydrophilic and hydrophobic parts of the component molecules and the surrounding medium. In contrast to conventional amphiphiles, supra-amphiphiles are constructed on the basis of noncovalent interactions or dynamic covalent bonds. In supra-amphiphiles, the functional groups can be attached to the amphiphiles by noncovalent synthesis, greatly speeding their construction. The building blocks for supra-amphiphiles can be either small organic molecules or polymers. Advances in the development of supra-amphiphiles will not only enrich the family of conventional amphiphiles that are based on covalent bonds but will also provide a new kind of building block for the preparation of complex self-assemblies. When polymers are used to construct supra-amphiphiles, the resulting

  13. Synthesis and pH- and salinity-controlled self-assembly of novel amphiphilic block-gradient copolymers of styrene and acrylic acid

    Czech Academy of Sciences Publication Activity Database

    Borisova, O.; Billon, L.; Zaremski, M.; Grassl, B.; Bakaeva, Zulfiya; Lapp, A.; Štěpánek, Petr; Borisov, O.


    Roč. 8, č. 29 (2012), s. 7649-7659 ISSN 1744-683X R&D Projects: GA ČR GAP208/10/1600 Institutional research plan: CEZ:AV0Z40500505 Keywords : block-gradient copolymers * light scattering * small-angle neutron scattering Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 3.909, year: 2012

  14. Poly(N-isopropyl acrylamide)-block-poly(n-butyl acrylate) thermoresponsive amphiphilic copolymers: synthesis, characterization and self-assembly behavior in aqueous solutions

    Czech Academy of Sciences Publication Activity Database

    Škvarla, J.; Zedník, J.; Šlouf, Miroslav; Pispas, S.; Štěpánek, M.


    Roč. 61, December (2014), s. 124-132 ISSN 0014-3057 R&D Projects: GA TA ČR TE01020118 Institutional support: RVO:61389013 Keywords : thermoresponsive block copolymers * poly(N-isopropyl acrylamide ) * light scattering Subject RIV: CD - Macromolecular Chemistry Impact factor: 3.005, year: 2014

  15. Micellar structure of amphiphilic poly(2-oxazoline) diblock copolymers

    DEFF Research Database (Denmark)

    Papadakis, C.M.; Ivanova, R.; Lüdtke, K.


    Amphiphilic diblock copolymers from poly(2-oxazoline)s in aqueous solution can form micelles. By means of small-angle neutron scattering, we have found that poly[(n-nonyl-2-oxazoline)-b-(methyl-2-oxazoline)] {P[(NOx)-b-(MOx)]} diblock copolymers in aqueous solution form micelles of core-shell typ...

  16. Amphiphilic copolymers based on PEG-acrylate as surface active water viscosifiers : Towards new potential systems for enhanced oil recovery

    NARCIS (Netherlands)

    Raffa, Patrizio; Broekhuis, Antonius A.; Picchioni, Francesco


    With the purpose of investigating new potential candidates for enhanced oil recovery (EOR), amphiphilic copolymers based on Poly(ethylene glycol) methyl ether acrylate (PEGA) have been prepared by Atom Transfer Radical Polymerization (ATRP). A P(PEGA) homopolymer, a block copolymer with styrene

  17. Synthesis, Characterization, and Aqueous Lubricating Properties of Amphiphilic Graft Copolymers Comprising 2-Methoxyethyl Acrylate

    DEFF Research Database (Denmark)

    Javakhishvili, Irakli; Røn, Troels; Jankova Atanasova, Katja


    Amphiphilic anionic and cationic graft copolymers possessing poly(2-hydroxyethyl methacrylate) (PHEMA) backbone and poly(methacrylic acid), poly(2-methoxyethyl acrylate-co-methacrylic acid), and poly(2-methoxyethyl acrylate-co-2-(dimethylamino)ethyl methacrylate) grafts are constructed by merging...... of the corresponding monomers followed by deblocking reaction leads to well-defined amphiphiles with narrow molecular weight distributions (PDI ≤ 1.29) and varying content of methacrylic acid. The graft copolymers showed effective surface adsorption and lubrication for self-mated poly(dimethylsiloxane) (PDMS) contacts...... in physiological salt concentration. This is indebted from “dilution” of the charges along the grafted chains by balancing neutral/charged repeating units to minimize the accumulated charge repulsion on neutral surface. Improved lubricating properties of the graft copolymers compared to the block copolymer...

  18. Solubilization of a polar oil used in nuclear industry by amphiphilic tri-block copolymers solutions. Relation between structure and behavior by proton nuclear magnetic resonance and small angle neutron scattering

    International Nuclear Information System (INIS)

    Causse, J.


    The first step in a decommissioning operation of a nuclear plant concerns the nuclear decontamination of various surfaces. More and more techniques developed for nuclear decontamination use soluble surfactants in aqueous solution with suitable chemical reagents. In most cases decontamination is based on the removal of a surface layer containing most of the activity (grease, organic deposits, paint, oxide layer...). The Tributylphosphate (TBP), a polar oil, is widely used as a complexing agent of Plutonium and Uranium in nuclear industry. This lipophilic compound, containing radioactive residues, strongly sticks on many surfaces. This organic layer is resistant to all classical treatments. Micellar systems proved to be efficient to pull TBP away and solubilize it so as to make easier its draining. In this study, Amphiphilic tri-block copolymers, referred to as Pluronics (polyethylene(oxide) - polypropylene(oxide) - polyethylene(oxide), (EO) n PO) m EO) n ) have been selected as polymeric amphiphiles so as to solubilize TBP in their supramolecular aggregates above the critical aggregation concentration. A first systematic study of the phase behavior of various three components systems (TBP-Water-Pluronic) by turbidity showed the particular behavior of one copolymer (the L64, (EO) 13 PO) 30 EO) 13 ), especially its very high TBP solubilization capacity. Consequently, the main part of this thesis has been devoted to the structural characterization of this micellar system (TBP-Water-L64) using 1 H NMR and SANS measurements. 1 H NMR gave information on the chemical environment of each component in the mixture and especially allowed hypothesis on the TBP location in the copolymer aggregates to be drawn. Direct structural information (size, shape, correlations) were obtained by SANS. Both experimental technique were proved to be very complementary and allowed a structural evolution of the aggregates following addition of TBP in the system to be evidenced. (author)

  19. Block copolymer investigations (United States)

    Yufa, Nataliya A.

    The research presented in this thesis deals with various aspects of block copolymers on the nanoscale: their behavior at a range of temperatures, their use as scaffolds, or for creation of chemically striped surfaces, as well as the behavior of metals on block copolymers under the influence of UV light, and the healing behavior of copolymers. Invented around the time of World War II, copolymers have been used for decades due to their macroscopic properties, such as their ability to be molded without vulcanization, and the fact that, unlike rubber, they can be recycled. In recent years, block copolymers (BCPs) have been used for lithography, as scaffolds for nano-objects, to create a magnetic hard drive, as well as in photonic and other applications. In this work we used primarily atomic force microscopy (AFM) and transmission electron microscopy (TEM), described in Chapter II, to conduct our studies. In Chapter III we demonstrate a new and general method for positioning nanoparticles within nanoscale grooves. This technique is suitable for nanodots, nanocrystals, as well as DNA. We use AFM and TEM to demonstrate selective decoration. In Chapters IV and V we use AFM and TEM to study the structure of polymer surfaces coated with metals and self-assembled monolayers. We describe how the surfaces were created, exhibit their structure on the nanoscale, and prove that their macroscopic wetting properties have been altered compared to the original polymer structures. Finally, Chapters VI and VII report out in-situ AFM studies of BCP at high temperatures, made possible only recently with the invention of air-tight high-temperature AFM imaging cells. We locate the transition between disordered films and cylinders during initial ordering. Fluctuations of existing domains leading to domain coarsening are also described, and are shown to be consistent with reptation and curvature minimization. Chapter VII deals with the healing of PS-b-PMMA following AFM-tip lithography or

  20. Hybrid, Nanoscale Phospholipid/Block Copolymer Vesicles

    Directory of Open Access Journals (Sweden)

    Bo Liedberg


    Full Text Available Hybrid phospholipid/block copolymer vesicles, in which the polymeric membrane is blended with phospholipids, display interesting self-assembly behavior, incorporating the robustness and chemical versatility of polymersomes with the softness and biocompatibility of liposomes. Such structures can be conveniently characterized by preparing giant unilamellar vesicles (GUVs via electroformation. Here, we are interested in exploring the self-assembly and properties of the analogous nanoscale hybrid vesicles (ca. 100 nm in diameter of the same composition prepared by film-hydration and extrusion. We show that the self-assembly and content-release behavior of nanoscale polybutadiene-b-poly(ethylene oxide (PB-PEO/1-palmitoyl-2-oleoyl-sn-glycero-3-phosphatidylcholine (POPC hybrid phospholipid/block copolymer vesicles can be tuned by the mixing ratio of the amphiphiles. In brief, these hybrids may provide alternative tools for drug delivery purposes and molecular imaging/sensing applications and clearly open up new avenues for further investigation.

  1. Synthesis and self-assembly of amphiphilic poly(acrylicacid)-poly(ɛ-caprolactone)-poly(acrylicacid) block copolymer as novel carrier for 7-ethyl-10-hydroxy camptothecin. (United States)

    Djurdjic, Beti; Dimchevska, Simona; Geskovski, Nikola; Petrusevska, Marija; Gancheva, Valerya; Georgiev, Georgi; Petrov, Petar; Goracinova, Katerina


    The process of molecular self-assembly plays a crucial role in formulation of polymeric nanoparticulated drug delivery carriers as it creates the possibility for enhanced drug encapsulation and carrier surface engineering. This study aimed to develop a novel self-assembled polymeric micelles for targeted delivery in tumor cells in order to overcome not only various drawbacks of 7-ethyl-10-hydroxy camptothecin (SN-38) but also various reported limitations of other drug delivery systems, especially low drug loading and premature release. Custom synthesized amphiphilic triblock copolymer poly(acrylic acid)-poly(ɛ-caprolactone)-poly(acrylic acid) (PAA(13)-PCL(35)-PAA(13)) was used to prepare kinetically stable micelles by nanoprecipitation and modified nanoprecipitation procedure. Core-shell micelles with diameter of 120-140 nm, negative zeta potential and satisfactory drug loading were produced. The prepared formulations were stable in pH range of 3-12 and in media with NaCl concentration calorimetry analyses confirmed the entrapment of the active substance into the micelles. The kinetic analysis of dissolution studies revealed that the main mechanism of drug release from the prepared formulations is Fickian diffusion. Growth inhibition studies as well as DNA fragmentation assay performed on SW-480 cell lines clearly demonstrated increased growth inhibition effect and presence of fragmented DNA in cells treated with loaded micelles compared to SN-38 solution. Altogether, these results point out to potential biomedical and clinical application of PAA-PCL-PAA systems in the future. © The Author(s) 2014 Reprints and permissions:

  2. Conjugates of Superoxide Dismutase 1 with Amphiphilic Poly(2-oxazoline) Block Copolymers for Enhanced Brain Delivery: Synthesis, Characterization and Evaluation in Vitro and in Vivo

    KAUST Repository

    Tong, Jing


    Superoxide dismutase 1 (SOD1) efficiently catalyzes dismutation of superoxide, but its poor delivery to the target sites in the body, such as brain, hinders its use as a therapeutic agent for superoxide-associated disorders. Here to enhance the delivery of SOD1 across the blood-brain barrier (BBB) and in neurons the enzyme was conjugated with poly(2-oxazoline) (POx) block copolymers, P(MeOx-b-BuOx) or P(EtOx-b-BuOx), composed of (1) hydrophilic 2-methyl-2-oxazoline (MeOx) or 2-ethyl-2-oxazoline (EtOx) and (2) hydrophobic 2-butyl-2-oxazoline (BuOx) repeating units. The conjugates contained from 2 to 3 POx chains joining the protein amino groups via cleavable -(ss)- or noncleavable -(cc)- linkers at the BuOx block terminus. They retained 30% to 50% of initial SOD1 activity, were conformationally and thermally stable, and assembled in 8 or 20 nm aggregates in aqueous solution. They had little if any toxicity to CATH.a neurons and displayed enhanced uptake in these neurons as compared to native or PEGylated SOD1. Of the two conjugates, SOD1-(cc)-P(MeOx-b-BuOx) and SOD1-(cc)-P(EtOx-b-BuOx), compared, the latter was entering cells 4 to 7 times faster and at 6 h colocalized predominantly with endoplasmic reticulum (41 ± 3%) and mitochondria (21 ± 2%). Colocalization with endocytosis markers and pathway inhibition assays suggested that it was internalized through lipid raft/caveolae, also employed by the P(EtOx-b-BuOx) copolymer. The SOD activity in cell lysates and ability to attenuate angiotensin II (Ang II)-induced superoxide in live cells were increased for this conjugate compared to SOD1 and PEG-SOD1. Studies in mice showed that SOD1-POx had ca. 1.75 times longer half-life in blood than native SOD1 (28.4 vs 15.9 min) and after iv administration penetrated the BBB significantly faster than albumin to accumulate in brain parenchyma. The conjugate maintained high stability both in serum and in brain (77% vs 84% at 1 h postinjection). Its amount taken up by the brain

  3. Synthesis and performance of amphiphilic copolymers for blood cell separation. (United States)

    Natori, Shizue Hayashi; Gomei, Yumiko; Higuchi, Akon


    Three types of amphiphilic copolymers using n-butylmethacrylate (BMA) as a hydrophobic monomer, and each of N,N'-dimethylacrylamide (DMA), N-acryloylmorpholine (AMO), and N-vinylpyrrolidone (VP) as hydrophilic comonomers were synthesized for coating filters used to remove leukocytes. The influence of the amphiphilic property of the resulting filters, which were composed of nonwoven fabrics coated with the above copolymers, on leukocyte removal and platelet permeation through the filters from whole blood was investigated. The platelet permeation ratio through hydrophobic noncoated filters was only 0.2%, because platelets in whole blood adhered easily to the hydrophobic filter material. However, filters coated with poly(AMO-co-BMA) of high AMO content showed a much higher platelet permeation ratio (nearly 90%). Further, the filters coated with poly(DMA-co-BMA) also showed high permeation ratios of platelets (more than 78%) over a broad range of DMA content in the copolymer. On the other hand, the coated filters showed slightly a higher permeation ratio of leukocytes than did the noncoated filters, resulting from the increase in hydrophilicity of the surface of the filters. Moreover, the coating of the amphiphilic copolymers on the surface of the nonwoven fabrics may have affected the pore size of the filters, affecting the permeation ratio of leukocytes more strongly than that of platelets. The coated filters effectively improved platelet permeation through the filters, with a slight increase in the permeation ratio of leukocytes.

  4. Amphiphilic copolymers reduce aggregation of unfolded lysozyme more effectively than polyethylene glycol (United States)

    Chin, Jaemin; Mustafi, Devkumar; Poellmann, Michael J.; Lee, Raphael C.


    Certain amphiphilic block copolymers are known to prevent aggregation of unfolded proteins. To better understand the mechanism of this effect, the optical properties of heat-denatured and dithiothreitol reduced lysozyme were evaluated with respect to controls using UV-Vis spectroscopy, transmission electron microscopy (TEM) and circular dichroism (CD) measurements. Then, the effects of adding Polyethylene Glycol (8000 Da), the triblock surfactant Poloxamer 188 (P188), and the tetrablock copolymer Tetronic 1107 (T1107) to the lysozyme solution were compared. Overall, T1107 was found to be more effective than P188 in inhibiting aggregation, while PEG exhibited no efficacy. TEM imaging of heat-denatured and reduced lysozymes revealed spherical aggregates with on average 250-450 nm diameter. Using CD, more soluble lysozyme was recovered with T1107 than P188 with β-sheet secondary structure. The greater effectiveness of the larger T1107 in preventing aggregation of unfolded lysozyme than the smaller P188 and PEG points to steric hindrance at play; signifying the importance of size match between the hydrophobic region of denatured protein and that of amphiphilic copolymers. Thus, our results corroborate that certain multi-block copolymers are effective in preventing heat-induced aggregation of reduced lysozymes and future studies warrant more detailed focus on specific applications of these copolymers.

  5. Functional Block Copolymers as Compatibilizers for Nanoclays in Polypropylene Nanocomposites

    DEFF Research Database (Denmark)

    Jankova Atanasova, Katja; Daugaard, Anders Egede; Stribeck, Norbert


    With the aim of creating tough nanocomposits (NC) [1] based on polypropylene (PP) and nanoclay (NCl) in the framework of the 7th EU program NANOTOUGH we have designed amphiphilic block copolymers utilizing Atom Transfer Radical Polymerization (ATRP) [2]. They consist of a hydrophobic block...... crystallites) is replaced by alien-reinforcement (of the MMT). Furthermore, the results from the impact strength and cyclic test of the prepared PP nanocomposites [3] are promicing....

  6. Block coordination copolymers

    Energy Technology Data Exchange (ETDEWEB)

    Koh, Kyoung Moo; Wong-Foy, Antek G.; Matzger, Adam J.; Benin, Annabelle I.; Willis, Richard R.


    The present invention provides compositions of crystalline coordination copolymers wherein multiple organic molecules are assembled to produce porous framework materials with layered or core-shell structures. These materials are synthesized by sequential growth techniques such as the seed growth technique. In addition, the invention provides a simple procedure for controlling functionality.

  7. Block coordination copolymers

    Energy Technology Data Exchange (ETDEWEB)

    Koh, Kyoung Moo; Wong-Foy, Antek G; Matzger, Adam J; Benin, Annabelle I; Willis, Richard R


    The present invention provides compositions of crystalline coordination copolymers wherein multiple organic molecules are assembled to produce porous framework materials with layered or core-shell structures. These materials are synthesized by sequential growth techniques such as the seed growth technique. In addition, the invention provides a simple procedure for controlling functionality.

  8. Block coordination copolymers

    Energy Technology Data Exchange (ETDEWEB)

    Koh, Kyoung Moo; Wong-Foy, Antek G; Matzger, Adam J; Benin, Annabelle I; Willis, Richard R


    The present invention provides compositions of crystalline coordination copolymers wherein multiple organic molecules are assembled to produce porous framework materials with layered or core-shell structures. These materials are synthesized by sequential growth techniques such as the seed growth technique. In addition, the invention provides a simple procedure for controlling functionality.

  9. Main-chain supramolecular block copolymers. (United States)

    Yang, Si Kyung; Ambade, Ashootosh V; Weck, Marcus


    Block copolymers are key building blocks for a variety of applications ranging from electronic devices to drug delivery. The material properties of block copolymers can be tuned and potentially improved by introducing noncovalent interactions in place of covalent linkages between polymeric blocks resulting in the formation of supramolecular block copolymers. Such materials combine the microphase separation behavior inherent to block copolymers with the responsiveness of supramolecular materials thereby affording dynamic and reversible materials. This tutorial review covers recent advances in main-chain supramolecular block copolymers and describes the design principles, synthetic approaches, advantages, and potential applications.

  10. Thermo-responsive block copolymers

    NARCIS (Netherlands)

    Mocan Cetintas, Merve


    Block copolymers (BCPs) are remarkable materials because of their self-assembly behavior into nano-sized regular structures and high tunable properties. BCPs are in used various applications such as surfactants, nanolithography, biomedicine and nanoporous membranes. In these thesis, we aimed to

  11. Micellization and Dynamics of a Block Copolymer

    DEFF Research Database (Denmark)

    Hvidt, Søren


    Triblock copolymers of the type EPE, where E and P denote ethylene oxide and propylene oxide blocks, respectively, are industrially important copolymers often called Pluronics or Poloxamers. EPE copolymers form micelles with a core of P blocks and different micellar shapes depending on block leng...

  12. Transiently responsive block copolymer micelles based on N-(2-hydroxypropyl)methacrylamide engineered with hydrolyzable ethylcarbonate side chains

    NARCIS (Netherlands)

    Kasmi, Sabah; Louage, Benoit; Nuhn, Lutz; Van Driessche, Alexandra; Van Deun, Jan; Karalic, Izet; Risseeuw, Martijn; Van Calenbergh, Serge; Hoogenboom, Richard; De Rycke, Riet; De Wever, Olivier; Hennink, Wim E.; de Geest, B.G.


    The lack of selectivity and low solubility of many chemotherapeutics impels the development of different biocompatible nanosized drug carriers. Amphiphilic block copolymers, composed of a hydrophilic and hydrophobic domain, show great potential because of their small size, large solubilizing power

  13. Formation and structural properties of multi-block copolymer vesicles (United States)

    Wang, Rong; Ma, Shiying


    Due to the unique structure, vesicles have attracted considerable attention for their potential applications, such as gene and drug delivery, microcapsules, nanoreactors, cell membrane mimetic, synthetic organelles, etc. By using dissipative particle dynamics, we studied the self-assembly of amphiphilic multi-block copolymer. The phase diagram was constructed by varying the interaction parameters and the composition of the block copolymers. The results show that the vesicles are stable in a large region which is different from the diblock copolymer or triblock copolymer. The structural properties of vesicles can be controlled by varying the interaction parameters and the length of the hydrophobic block. The relationship between the hydrophilic and hydrophobic block length vs the aqueous cavity size and vesicle size are revealed. The copolymers with shorter hydrophobic blocks length or the higher hydrophilicity are more likely to form vesicles with larger aqueous cavity size and vesicle size as well as thinner wall thickness. However, the increase in hydrophobic-block length results to form vesicles with smaller aqueous cavity size and larger vesicle size. Acknowledgments. This work has been supported by NNSFC (No. 21074053) and NBRPC (No. 2010CB923303).

  14. Adsorption and Aqueous Lubricating Properties of Charged and Neutral Amphiphilic Diblock Copolymers at a Compliant, Hydrophobic Interface

    DEFF Research Database (Denmark)

    Røn, Troels; Javakhishvili, Irakli; Jankova Atanasova, Katja


    We have investigated the adsorption and lubricating properties of neutral and charged amphiphilic diblock copolymers at a hydrophobic polydimethylsiloxane (PDMS) interface in an aqueous environment. The diblock copolymers consist of a hydrophilic block of either neutral poly(ethylene glycol) (PEG......) or negatively charged poly(acrylic acid) (PAA) and of a hydrophobic block of polystyrene (PS) or poly(2-methoxyethyl acrylate) (PMEA), thus generating PEG-b-X or PAA-b-X, where X block is either PS or PMEA. The molecular weight ratios were roughly 1:1 with each block ca. 5 kDa. Comparing the neutral PEG...... effective adsorption only when PMEA was employed as the anchoring block. For PAA-b-PS, the poor adsorption properties are chiefly attributed to micellization due to the high interfacial tension between the PS core and water. The poor lubricating properties of PAA-b-PS diblock copolymer for a PDMS...

  15. Anomalous Micellization of Pluronic Block Copolymers (United States)

    Leonardi, Amanda; Ryu, Chang Y.


    Poly(ethylene oxide) - poly(propylene oxide) - poly(ethylene oxide) (PEO-PPO-PEO) block copolymers, commercially known as Pluronics, are a unique family of amphiphilic triblock polymers, which self-assemble into micelles in aqueous solution. These copolymers have shown promise in therapeutic, biomedical, cosmetic, and nanotech applications. As-received samples of Pluronics contain low molecular weight impurities (introduced during the manufacturing and processing), that are ignored in most applications. It has been observed, however, that in semi-dilute aqueous solutions, at concentrations above 1 wt%, the temperature dependent micellization behavior of the Pluronics is altered. Anomalous behavior includes a shift of the critical micellization temperature and formation of large aggregates at intermediate temperatures before stable sized micelles form. We attribute this behavior to the low molecular weight impurities that are inherent to the Pluronics which interfere with the micellization process. Through the use of Dynamic Light Scattering and HPLC, we compared the anomalous behavior of different Pluronics of different impurity levels to their purified counterparts.

  16. Novel fluorinated block copolymer architectures fuelled by atom transfer radical polymerization

    DEFF Research Database (Denmark)

    Jankova, Katja; Hvilsted, Søren


    Block copolymers based on poly(pentafluorostyrene), PFS, in various numbers and of different lengths, and polystyrene are prepared by atom transfer radical polymerization (ATRP). Di- and triblock copolymers with varying amounts of PFS were synthesized employing either I phenylethylbromide or 1......,4-dibromoxylene as initiators for ATRP. Diverse bromo(ester) (macro)initiators were also devised and involved in the formulation of fluorinated pentablock as well as amphiphilic triblock copolymers with a central polyether segment. Amphiphilic star-shaped fluoropolymers, hydrophobic fluorinated nanoparticles...

  17. Synthesis and Characterization of Poly(ethylene glycol)-block-Poly(Nα-Boc-L-tryptophan) copolymers (United States)

    Voda, Andreea S.; Guo, Qipeng


    Amphiphilic diblock and triblock copolymers were synthesized from poly(ethylene glycol) (PEG) and Nα-Boc-L-tryptophan. A number of reaction conditions were investigated in order to achieve optimum yield and maximum chain extension for the newly formed block copolymers. Characterization of the novel copolymers was evaluated by means of 1D and 2D solution state nuclear magnetic resonance (NMR), infrared (IR) spectroscopy and size exclusion chromatography (SEC). The 2D NMR investigation of the block copolymers provided evidence to suggest that protonation of the nitrogen atoms present along the newly formed peptide back bone was occurring when the solvent environment was under acidic conditions.

  18. Block copolymer vesicles-using concepts from polymer chemistry to mimic biomembranes


    Kita-Tokarczyk, Katarzyna; Grumelard, Julie; Haefele, Thomas; Meier, Wolfgang


    A review. Owing to the increasing interest in self-assembled structures from block copolymer materials, we present here a review of recent literature concerning amphiphilic block copolymer vesicles. A vesicular morphol. is applicable not only in such fields like delivery-release and biomineralization, but also has been utilized for prepn. of nanoreactors and incorporation of biol. macromols. The organization of this paper is the following: we first provide the readers with the overview of the...

  19. Nanostructured Polysulfone-Based Block Copolymer Membranes

    KAUST Repository

    Xie, Yihui


    The aim of this work is to fabricate nanostructured membranes from polysulfone-based block copolymers through self-assembly and non-solvent induced phase separation. Block copolymers containing polysulfone are novel materials for this purpose providing better mechanical and thermal stability to membranes than polystyrene-based copolymers, which have been exclusively used now. Firstly, we synthesized a triblock copolymer, poly(tert-butyl acrylate)-b-polsulfone-b-poly(tert-butyl acrylate) through polycondensation and reversible addition-fragmentation chain-transfer polymerization. The obtained membrane has a highly porous interconnected skin layer composed of elongated micelles with a flower-like arrangement, on top of the graded finger-like macrovoids. Membrane surface hydrolysis was carried out in a combination with metal complexation to obtain metal-chelated membranes. The copper-containing membrane showed improved antibacterial capability. Secondly, a poly(acrylic acid)-b-polysulfone-b-poly(acrylic acid) triblock copolymer obtained by hydrolyzing poly(tert-butyl acrylate)-b-polsulfone-b-poly(tert-butyl acrylate) formed a thin film with cylindrical poly(acrylic acid) microdomains in polysulfone matrix through thermal annealing. A phase inversion membrane was prepared from the same polymer via self-assembly and chelation-assisted non-solvent induced phase separation. The spherical micelles pre-formed in a selective solvent mixture packed into an ordered lattice in aid of metal-poly(acrylic acid) complexation. The space between micelles was filled with poly(acrylic acid)-metal complexes acting as potential water channels. The silver0 nanoparticle-decorated membrane was obtained by surface reduction, having three distinct layers with different particle sizes. Other amphiphilic copolymers containing polysulfone and water-soluble segments such as poly(ethylene glycol) and poly(N-isopropylacrylamide) were also synthesized through coupling reaction and copper0-mediated

  20. Synthesis of amphiphilic diblock copolymer for surface modification of Ethylene-Norbornene copolymers

    DEFF Research Database (Denmark)

    Levinsen, Simon; Svendsen, Winnie Edith; Horsewell, Andy


    -norbornene copolymer TOPAS. Through matching of the radius of gyration for the model polymer and TOPAS the miscibility was achieved. The poly(ethylene-1-butene) polymer was synthesized from a hydrogenated anionic polymerized polybutadiene polymer. As hydrophilic block poly(ethylene oxide) was subsequently added also...... consisting of a bulk material compatible block and a hydrophilic block. To utilize the possibility of incorporating diblock copolymers into ethylenenorbornene copolymers, we have in this work developed a model poly(ethylene-1-butene) polymer compatible with the commercial available ethylene...

  1. Triblock Copolymers with Grafted Fluorine-Free Amphiphilic Non-Ionic Side Chains for Antifouling and Fouling-Release Applications

    Energy Technology Data Exchange (ETDEWEB)

    Y Cho; H Sundaram; C Weinman; M Paik; M Dimitriou; J Finlay; M Callow; J Callow; E Kramer; C Ober


    Fluorine-free, amphiphilic, nonionic surface active block copolymers (SABCs) were synthesized through chemical modification of a polystyrene-block-poly(ethylene-ran-butylene)-block-polyisoprene triblock copolymer precursor with selected amphiphilic nonionic Brij and other surfactants. Amphiphilicity was imparted by a hydrophobic aliphatic group combined with a hydrophilic poly(ethylene glycol) (PEG) group-containing moiety. The surfaces were characterized by dynamic water contact angle, atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS), and near edge X-ray absorption fine structure (NEXAFS) analysis. In biofouling assays, settlement (attachment) of both spores of the green alga Ulva and cells of the diatom Navicula on SABCs modified with Brij nonionic side chains was significantly reduced relative to a PDMS standard, with a nonionic surfactant combining a PEG group and an aliphatic moiety demonstrating the best performance. Additionally, a fouling-release assay using sporelings (young plants) of Ulva and Navicula suggested that the SABC derived from nonionic Brij side chains also out-performed PDMS as a fouling-release material. Good antifouling and fouling-release properties were not demonstrated for the other two amphiphilic surfaces derived from silicone and aromatic group containing nonionic surfactants included in this study. The results suggest that small differences in chemical surface functionality impart more significant changes with respect to the antifouling settlement and fouling-release performance of materials than overall wettability behavior.

  2. Efficient cytosolic delivery mediated by polymersomes facilely prepared from a degradable, amphiphilic, and amphoteric copolymer. (United States)

    Huang, Zhonghui; Teng, Wei; Liu, Longshan; Wang, Lichun; Wang, Qinmei; Dong, Yugang


    To solve problems in polymersome preparation caused by liposolubility of copolymers and to improve the cytosolic delivery efficiency of polymersomes to drugs, a lipopolysaccharide-amine (LPSA) copolymer with amphotericity and amphiphilicity is developed. LPSA contains two hydrophilic oppositely charged blocks (anionic oxidized alginate (OA), cationic polyethyleneimine (PEI 1.8 k)) and one hydrophobic block (cholesteryl), where OA is the backbone and cholesteryl-grafted PEI is the side chain. The two hydrophilic blocks first guarantee that LPSA will dissolve in water, and then help polymersome formation via electrostatic interactions to generate water insoluble interpolyelectrolyte complexes, which supplement the hydrophobic part to reach the right hydrophilicity/hydrophobicity ratio, and thus realize a one-step self-assembly of polymersomes in water. Our results show LPSA nanopolymersomes (LNPs) have low cytotoxicity and degradability, and an excellent ability to enter cells. TEM observation demonstrates that LNPs are entrapped in endosomes after endocytosis, and are then released to cytosols because of their strong endosomal escape capacity. As an example of cytosolic delivery to bioactive molecules, pDNA is delivered in mesenchymal stem cells, and more than 95% of cells express a large target protein, indicating that LNPs have high cytosolic delivery efficiency. Our study provides a novel, easy, and universal method to design copolymers for the preparation of polymersomes as efficient cytosolic delivery nanocarriers.

  3. Preparation of amphiphilic block copolymer containing triazene ...

    Indian Academy of Sciences (India)

    unlimited structural variability offered by the macro- molecular chemistry of these polymers should be mentioned.8–11 ... ing energy could greatly shorten the synthesis time and can induce enhanced reaction rates and yields ... with an oil bath) the energy is transferred, often via solvent, by thermal conduction. This methodo-.

  4. PEO-related block copolymer surfactants

    DEFF Research Database (Denmark)

    Mortensen, K.


    Non-ionic block copolymer systems based on hydrophilic poly(ethylene oxide) and more hydrophobic co-polymer blocks are used intensively in a variety of industrial and personal applications. A brief description on the applications is presented. The physical properties of more simple model systems ...

  5. Micellization and Characterization of Block Copolymer Detergents

    DEFF Research Database (Denmark)

    Hvidt, Søren

    Triblock copolymers of the type EPE, where E and P denote ethylene oxide and propylene oxide blocks, respectively, are used widely in industry as emulsifiers, anti-foaming agents, and in delayed drug release. EPE copolymers form micelles with a core of P blocks and different micellar shapes depen...

  6. Micelle formation of amphiphilic polystyrene-b-poly(N-vinylpyrrolidone) diblock copolymer in methanol and water-methanol binary mixtures. (United States)

    Hussain, H; Tan, B H; Gudipati, C S; He, C B; Liu, Y; Davis, Thomas P


    The micelle formation by the amphiphilic polystyrene-block-poly(N-vinylpyrrolidone) (PS48-b-PNVP99) copolymer is investigated in methanol and water-methanol binary mixtures of various compositions using 1H NMR, fluorescence spectroscopy, static/dynamic light scattering (SLS/DLS), and transmission electron microscopy (TEM). Critical micelle concentrations (cmc) are determined by employing fluorescence spectroscopy and DLS measurements. The cmc of the PS48-b-PNVP99 block copolymer increases with increasing methanol content in the water-methanol binary mixtures, suggesting that methanol is a better solvent for the PS48-b-PNVP99 block copolymer than water-methanol mixtures or pure water. The amphiphilic PS48-b-PNVP99 diblock copolymer forms spherical micelles of Rh approximately 16 nm in pure methanol solution as revealed by DLS measurements. In contrast, significantly larger micelles having higher aggregation numbers are formed in water-methanol binary mixtures. Temperature dependent data reveal an increase in aggregation number and radius of gyration (Rg) concomitantly with temperature (10-40 degrees C). In contrast, the overall size (Rh) of the micelles remains almost constant over the same temperature range. An explanation is tendered that PNVP coronas dehydrate/desolvate at higher temperatures counteracting the increase in micelle size (Rh) caused by increased aggregation numbers (Nagg).

  7. Fabrication of supramolecular star-shaped amphiphilic copolymers for ROS-triggered drug release. (United States)

    Zuo, Cai; Peng, Jinlei; Cong, Yong; Dai, Xianyin; Zhang, Xiaolong; Zhao, Sijie; Zhang, Xianshuo; Ma, Liwei; Wang, Baoyan; Wei, Hua


    Star-shaped copolymers with branched structures can form unimolecular micelles with better stability than the micelles self-assembled from conventional linear copolymers. However, the synthesis of star-shaped copolymers with precisely controlled degree of branching (DB) suffers from complicated sequential polymerizations and multi-step purification procedures, as well as repeated optimizations of polymer compositions. The use of a supramolecular host-guest pair as the block junction would significantly simplify the preparation. Moreover, the star-shaped copolymer-based unimolecular micelle provides an elegant solution to the tradeoff between extracellular stability and intracellular high therapeutic efficacy if the association/dissociation of the supramolecular host-guest joint can be triggered by the biologically relevant stimuli. For this purpose, in this study, a panel of supramolecular star-shaped amphiphilic block copolymers with 9, 12, and 18 arms were designed and fabricated by host-guest complexations between the ring-opening polymerization (ROP)-synthesized star-shaped poly(ε-caprolactone) (PCL) with 3, 4, and 6 arms end-capped with ferrocene (Fc) (PCL-Fc) and the atom transfer radical polymerization (ATRP)-produced 3-arm poly(oligo ethylene glycol) methacrylates (POEGMA) with different degrees of polymerization (DPs) of 24, 30, 47 initiated by β-cyclodextrin (β-CD) (3Br-β-CD-POEGMA). The effect of DB and polymer composition on the self-assembled properties of the five star-shaped copolymers was investigated by dynamic light scattering (DLS), transmission electron microscopy (TEM), and fluorescence spectrometery. Interestingly, the micelles self-assembled from 12-arm star-shaped copolymers exhibited greater stability than the 9- and 18-arm formulations. The potential of the resulting supramolecular star-shaped amphiphilic copolymers as drug carriers was evaluated by an in vitro drug release study, which confirmed the ROS-triggered accelerated drug

  8. Block copolymer self-assembly and co-assembly : shape function and application

    NARCIS (Netherlands)

    Li, F.


    Amphiphilic block copolymers can, in selective solvents such as water, assemble into various shapes and architectures. Among those, polymer vesicles, polymer micelles and polymer fibers are very popular structures in current nanotechnology. These objects each have their own particular properties and

  9. Star block-copolymers: Enzyme-inspired catalysts for oxidation of alcohols in water

    KAUST Repository

    Mugemana, Clement


    A number of fluorous amphiphilic star block-copolymers containing a tris(benzyltriazolylmethyl)amine motif have been prepared. These polymers assembled into well-defined nanostructures in water, and their mode of assembly could be controlled by changing the composition of the polymer. The polymers were used for enzyme-inspired catalysis of alcohol oxidation. This journal is © the Partner Organisations 2014.

  10. Block copolymer structures in nano-pores (United States)

    Pinna, Marco; Guo, Xiaohu; Zvelindovsky, Andrei


    We present results of coarse-grained computer modelling of block copolymer systems in cylindrical and spherical nanopores on Cell Dynamics Simulation. We study both cylindrical and spherical pores and systematically investigate structures formed by lamellar, cylinders and spherical block copolymer systems for various pore radii and affinity of block copolymer blocks to the pore walls. The obtained structures include: standing lamellae and cylinders, ``onions,'' cylinder ``knitting balls,'' ``golf-ball,'' layered spherical, ``virus''-like and mixed morphologies with T-junctions and U-type defects [1]. Kinetics of the structure formation and the differences with planar films are discussed. Our simulations suggest that novel porous nano-containers can be formed by confining block copolymers in pores of different geometries [1,2]. [4pt] [1] M. Pinna, X. Guo, A.V. Zvelindovsky, Polymer 49, 2797 (2008).[0pt] [2] M. Pinna, X. Guo, A.V. Zvelindovsky, J. Chem. Phys. 131, 214902 (2009).

  11. Block copolymer membranes for aqueous solution applications

    KAUST Repository

    Nunes, Suzana Pereira


    Block copolymers are known for their intricate morphology. We review the state of the art of block copolymer membranes and discuss perspectives in this field. The main focus is on pore morphology tuning with a short introduction on non-porous membranes. The two main strategies for pore formation in block copolymer membranes are (i) film casting and selective block sacrifice and (ii) self-assembly and non-solvent induced phase separation (SNIPS). Different fundamental aspects involved in the manufacture of block copolymer membranes are considered, including factors affecting the equilibrium morphology in solid films, self-assembly of copolymer in solutions and macrophase separation by solvent-non-solvent exchange. Different mechanisms are proposed for different depths of the SNIPS membrane. Block copolymer membranes can be prepared with much narrower pore size distribution than homopolymer membranes. Open questions and indications of what we consider the next development steps are finally discussed. They include the synthesis and application of new copolymers and specific functionalization, adding characteristics to respond to stimuli and chemical environment, polymerization-induced phase separation, and the manufacture of organic-inorganic hybrids.

  12. Effects of amphiphilic diblock copolymer on drug nanoparticle formation and stability (United States)

    Zhu, Zhengxi


    This study systematically compares the effects of amphiphilic diblock copolymer (di-BCP) on stabilizing hydrophobic drug nanoparticles formed by flash nanoprecipitation (FNP), and provides a guideline on choosing suitable di-BCPs. Four widely used di-BCPs, i.e., polystyrene-block-poly(ethylene glycol) (PS-b-PEG), polycaprolactone-block-poly(ethylene glycol) (PCL-b-PEG), polylactide-block-poly(ethylene glycol) (PLA-b-PEG), and poly(lactic-co-glycolic acid) (PLGA-b-PEG), and β-carotene as a model drug were used. The study showed that PLGA-b-PEG was the most suitable one, whose hydrophobic block was biodegradable and noncrystallizable as well as had relatively high glass transition temperature (Tg) and a right solubility parameter (δ). The molecular weight of PLGA block over the range from 5k to 15k showed an insignificant effect on controlling the particle size. Amorphous drug particles with a high drug loading of over 83 wt% can be achieved. Much remarkable evidence supported the nanoparticles with kinetically frozen and nonequilibrium packing structures of polymer chains rather than either the micelles or micellar nanoparticles with two well segregated polymer blocks. The thermodynamic effects of the drug and BCP on the particle stability, size and structures were discussed by using solubility parameters. PMID:24070569

  13. Block Copolymers: Synthesis and Applications in Nanotechnology (United States)

    Lou, Qin

    This study is focused on the synthesis and study of (block) copolymers using reversible deactivation radical polymerizations (RDRPs), including atom transfer radical polymerization (ATRP) and reversible addition-fragmentation chain transfer (RAFT) polymerization. In particular, two primary areas of study are undertaken: (1) a proof-of-concept application of lithographic block copolymers, and (2) the mechanistic study of the deposition of titania into block copolymer templates for the production of well-ordered titania nanostructures. Block copolymers have the ability to undergo microphase separation, with an average size of each microphase ranging from tens to hundreds of nanometers. As such, block copolymers have been widely considered for nanotechnological applications over the past two decades. The development of materials for various nanotechnologies has become an increasingly studied area as improvements in many applications, such as those found in the semiconductor and photovoltaic industries are constantly being sought. Significant growth in developments of new synthetic methods ( i.e. RDRPs) has allowed the production of block copolymers with molecular (and sometimes atomic) definition. In turn, this has greatly expanded the use of block copolymers in nanotechnology. Herein, we describe the synthesis of statistical and block copolymers of 193 nm photolithography methacrylate and acrylate resist monomers with norbornyl and adamantyl moieties using RAFT polymerization.. For these resist (block) copolymers, the phase separation behaviors were examined by atomic force microscopy (AFM). End groups were removed from the polymers to avoid complications during the photolithography since RAFT end groups absorb visible light. Poly(glycidyl methacrylate-block-polystyrene) (PGMA-b-PS) was synthesize by ATRP and demonstrated that this block copolymer acts as both a lithographic UV (365 nm) photoresist and a self-assembly material. The PGMA segments can undergo cationic

  14. Electrostatic control of block copolymer morphology (United States)

    Sing, Charles E.; Zwanikken, Jos W.; Olvera de La Cruz, Monica


    Energy storage is at present one of the foremost issues society faces. However, material challenges now serve as bottlenecks in technological progress. Lithium-ion batteries are the current gold standard to meet energy storage needs; however, they are limited owing to the inherent instability of liquid electrolytes. Block copolymers can self-assemble into nanostructures that simultaneously facilitate ion transport and provide mechanical stability. The ions themselves have a profound, yet previously unpredictable, effect on how these nanostructures assemble and thus the efficiency of ion transport. Here we demonstrate that varying the charge of a block copolymer is a powerful mechanism to predictably tune nanostructures. In particular, we demonstrate that highly asymmetric charge cohesion effects can induce the formation of nanostructures that are inaccessible to conventional uncharged block copolymers, including percolated phases desired for ion transport. This vastly expands the design space for block copolymer materials and is informative for the versatile design of battery electrolyte materials.

  15. Fabrication of platinum nanoparticles in aqueous solution and solid phase using amphiphilic PB-b-PEO copolymer nanoreactors

    International Nuclear Information System (INIS)

    Hoda, Numan; Budama, Leyla; Çakır, Burçin Acar; Topel, Önder; Ozisik, Rahmi


    Graphical abstract: TEM image of Pt nanoparticles produced by reducing by NaBH 4 within PB-b-PEO micelles in aqueous media (scale bar 1 nm). - Highlights: • Pt nanoparticles were synthesized within amphiphilic diblock copolymer micelles. • The effects of reducing agents and precursor dose on Pt np size were investigated. • The effect on fabrication of Pt np by reducing in aqueous and solid phases was compared. • The size of nanoparticles was about 1.4 nm for all doses and reducing agents types. - Abstract: Fabrication of Pt nanoparticles using an amphiphilic copolymer template in aqueous solution was achieved via polybutadiene-block-polyethyleneoxide copolymer micelles, which acted as nanoreactors. In addition, Pt nanoparticles were synthesized using hydrogen gas as the reducing agent in solid state for the first time to compare against solution synthesis. The influences of loaded precursor salt amount to micelles and the type of reducing agent on the size of nanoparticles were investigated through transmission electron microscopy. It was found that increasing the ratio of precursor salt to copolymer and using different type of reducing agent, even in solid phase reduction, did not affect the nanoparticle size. The average size of Pt nanoparticles was estimated to be 1.4 ± 0.1 nm. The reason for getting same sized nanoparticles was discussed in the light of nucleation, growth process, stabilization and diffusion of nanoparticles within micelles

  16. Fabrication of platinum nanoparticles in aqueous solution and solid phase using amphiphilic PB-b-PEO copolymer nanoreactors

    Energy Technology Data Exchange (ETDEWEB)

    Hoda, Numan, E-mail: [Department of Chemistry, Faculty of Sciences, Akdeniz University, 07058 Antalya (Turkey); Budama, Leyla; Çakır, Burçin Acar; Topel, Önder [Department of Chemistry, Faculty of Sciences, Akdeniz University, 07058 Antalya (Turkey); Ozisik, Rahmi [Department of Materials Science and Engineering and Renssleaer Nanotechnology Center, Rensselaer Polytechnic Institute, Troy, NY 12180 (United States)


    Graphical abstract: TEM image of Pt nanoparticles produced by reducing by NaBH{sub 4} within PB-b-PEO micelles in aqueous media (scale bar 1 nm). - Highlights: • Pt nanoparticles were synthesized within amphiphilic diblock copolymer micelles. • The effects of reducing agents and precursor dose on Pt np size were investigated. • The effect on fabrication of Pt np by reducing in aqueous and solid phases was compared. • The size of nanoparticles was about 1.4 nm for all doses and reducing agents types. - Abstract: Fabrication of Pt nanoparticles using an amphiphilic copolymer template in aqueous solution was achieved via polybutadiene-block-polyethyleneoxide copolymer micelles, which acted as nanoreactors. In addition, Pt nanoparticles were synthesized using hydrogen gas as the reducing agent in solid state for the first time to compare against solution synthesis. The influences of loaded precursor salt amount to micelles and the type of reducing agent on the size of nanoparticles were investigated through transmission electron microscopy. It was found that increasing the ratio of precursor salt to copolymer and using different type of reducing agent, even in solid phase reduction, did not affect the nanoparticle size. The average size of Pt nanoparticles was estimated to be 1.4 ± 0.1 nm. The reason for getting same sized nanoparticles was discussed in the light of nucleation, growth process, stabilization and diffusion of nanoparticles within micelles.

  17. Micellization of symmetric PEP-PEO block copolymers in water molecular weight dependence

    CERN Document Server

    Kaya, H; Allgaier, J; Stellbrink, J; Richter, D


    The micellar behaviour of the amphiphilic block copolymer poly-(ethylene-propylene)-poly-(ethylene oxide) (PEP-PEO) in aqueous solution has been studied with small-angle neutron scattering. The polymer was studied over a wide range of molecular weights, always keeping the volume of the blocks equal. The scattering behaviour of the solutions showed that a morphological transition takes place upon lowering the molecular weight. The high molecular weight block copolymers all build spherical, monodisperse micelles with large aggregation numbers. At low molecular weights, however, cylindrical micelles are formed. An interesting intermediate case is represented by the PEP2-PEO2 system, in which a morphological transition occurs upon dilution. (orig.)

  18. Rapid self-assembly of block copolymers to photonic crystals (United States)

    Xia, Yan; Sveinbjornsson, Benjamin R; Grubbs, Robert H; Weitekamp, Raymond; Miyake, Garret M; Atwater, Harry A; Piunova, Victoria; Daeffler, Christopher Scot; Hong, Sung Woo; Gu, Weiyin; Russell, Thomas P.


    The invention provides a class of copolymers having useful properties, including brush block copolymers, wedge-type block copolymers and hybrid wedge and polymer block copolymers. In an embodiment, for example, block copolymers of the invention incorporate chemically different blocks comprising polymer size chain groups and/or wedge groups that significantly inhibit chain entanglement, thereby enhancing molecular self-assembly processes for generating a range of supramolecular structures, such as periodic nanostructures and microstructures. The present invention also provides useful methods of making and using copolymers, including block copolymers.

  19. An amphiphilic graft copolymer-based nanoparticle platform for reduction-responsive anticancer and antimalarial drug delivery (United States)

    Najer, Adrian; Wu, Dalin; Nussbaumer, Martin G.; Schwertz, Geoffrey; Schwab, Anatol; Witschel, Matthias C.; Schäfer, Anja; Diederich, François; Rottmann, Matthias; Palivan, Cornelia G.; Beck, Hans-Peter; Meier, Wolfgang


    Medical applications of anticancer and antimalarial drugs often suffer from low aqueous solubility, high systemic toxicity, and metabolic instability. Smart nanocarrier-based drug delivery systems provide means of solving these problems at once. Herein, we present such a smart nanoparticle platform based on self-assembled, reduction-responsive amphiphilic graft copolymers, which were successfully synthesized through thiol-disulfide exchange reaction between thiolated hydrophilic block and pyridyl disulfide functionalized hydrophobic block. These amphiphilic graft copolymers self-assembled into nanoparticles with mean diameters of about 30-50 nm and readily incorporated hydrophobic guest molecules. Fluorescence correlation spectroscopy (FCS) was used to study nanoparticle stability and triggered release of a model compound in detail. Long-term colloidal stability and model compound retention within the nanoparticles was found when analyzed in cell media at body temperature. In contrast, rapid, complete reduction-triggered disassembly and model compound release was achieved within a physiological reducing environment. The synthesized copolymers revealed no intrinsic cellular toxicity up to 1 mg mL-1. Drug-loaded reduction-sensitive nanoparticles delivered a hydrophobic model anticancer drug (doxorubicin, DOX) to cancer cells (HeLa cells) and an experimental, metabolically unstable antimalarial drug (the serine hydroxymethyltransferase (SHMT) inhibitor (+/-)-1) to Plasmodium falciparum-infected red blood cells (iRBCs), with higher efficacy compared to similar, non-sensitive drug-loaded nanoparticles. These responsive copolymer-based nanoparticles represent a promising candidate as smart nanocarrier platform for various drugs to be applied to different diseases, due to the biocompatibility and biodegradability of the hydrophobic block, and the protein-repellent hydrophilic block.Medical applications of anticancer and antimalarial drugs often suffer from low aqueous

  20. Substrate tolerant direct block copolymer nanolithography

    DEFF Research Database (Denmark)

    Li, Tao; Wang, Zhongli; Schulte, Lars


    Block copolymer (BC) self-assembly constitutes a powerful platform for nanolithography. However, there is a need for a general approach to BC lithography that critically considers all the steps from substrate preparation to the final pattern transfer. We present a procedure that significantly...... plasma treatment enables formation of the oxidized PDMS hard mask, PS block removal and polymer or graphene substrate patterning....


    NARCIS (Netherlands)

    Hilberer, A; Gill, R.E; Herrema, J.K; Malliaras, G.G; Wildeman, J.; Hadziioannou, G

    In this article we review results obtained in our laboratory on the design and study of new light-emitting polymers. We are interested in the synthesis and characterisation of block copolymers with regularly alternating conjugated and non conjugated sequences. The blocks giving rise to luminescence

  2. Charge Transport in Conjugated Block Copolymers (United States)

    Smith, Brandon; Le, Thinh; Lee, Youngmin; Gomez, Enrique

    Interest in conjugated block copolymers for high performance organic photovoltaic applications has increased considerably in recent years. Polymer/fullerene mixtures for conventional bulk heterojunction devices, such as P3HT:PCBM, are severely limited in control over interfaces and domain length scales. In contrast, microphase separated block copolymers self-assemble to form lamellar morphologies with alternating electron donor and acceptor domains, thereby maximizing electronic coupling and local order at interfaces. Efficiencies as high as 3% have been reported in solar cells for one block copolymer, P3HT-PFTBT, but the details concerning charge transport within copolymers have not been explored. To fill this gap, we probed the transport characteristics with thin-film transistors. Excellent charge mobility values for electron transport have been observed on aluminum source and drain contacts in a bottom gate, bottom contact transistor configuration. Evidence of high mobility in ordered PFTBT phases has also been obtained following thermal annealing. The insights gleaned from our investigation serve as useful guideposts, revealing the significance of the interplay between charge mobility, interfacial order, and optimal domain size in organic block copolymer semiconductors.

  3. Biodegradable hyperbranched amphiphilic polyurethane multiblock copolymers consisting of poly(propylene glycol), poly(ethylene glycol), and polycaprolactone as in situ thermogels. (United States)

    Li, Zibiao; Zhang, Zhongxing; Liu, Kerh Li; Ni, Xiping; Li, Jun


    This paper reports the synthesis and characterization of new hyperbranched amphiphilic polyurethane multiblock copolymers consisting of poly(propylene glycol) (PPG), poly(ethylene glycol) (PEG), and polycaprolactone (PCL) segments as in situ thermogels. The hyperbranched poly(PPG/PEG/PCL urethane)s, termed as HBPEC copolymers, were synthesized from PPG-diol, PEG-diol, and PCL-triol by using 1,6-hexamethylene diisocyanate (HMDI) as a coupling agent. The compositions and structures of HBPEC copolymers were determined by GPC and 1H NMR spectroscopy. We carried out comparative studies of the new hyperbranched copolymers with their linear counterparts, the linear poly(PPG/PEG/PCL urethane) (LPEC) copolymer and Pluronic F127 PEG-PPG-PEG block copolymer, in terms of their self-assembly and aggregation behaviors and thermoresponsive properties. HBPEC copolymers were found to show thermoresponsive micelle formation and aggregation behaviors. Particularly, the lower critical solution temperature (LCST) of the copolymers was significantly affected by the copolymer architecture. HBPEC copolymers showed much lower LCST than LPEC, the linear counterpart. Our studies revealed that the effect of hyperbranch architecture was more prominent in the gelation of the copolymers. The aqueous solutions of HBPEC copolymers exhibited thermogelling behaviors at critical gelation concentrations (CGCs) ranging from 4.3 to 7.4 wt %. These values are much lower than those reported on other PCL-contained linear thermogelling copolymers and Pluronic F127 copolymer. In addition, the CGC of HBPEC copolymers is much lower than the control LPEC copolymer. More interestingly, at high temperatures, while LPEC and other linear thermogelling copolymers formed turbid sol, HBPEC formed a dehydrated gel. Our data suggest that these phenomena are caused by the hyperbranched structure of HBPEC copolymers, which could increase the interaction of copolymer branches and enhance the chain association through

  4. Periodic titania nanostructures using block copolymer templates. (United States)

    Chinthamanipeta, Pavan S; Lou, Qin; Shipp, Devon A


    The deposition of periodic titania nanostructures, templated by a polystyrene-block-poly(4-vinylpyridine) (PS-b-P4VP) block copolymer, is reported. When cast as a thin film (30-50 nm thick), the PS-b-P4VP forms a morphology that consists of P4VP cylinders that are orientated perpendicular to the substrate. The P4VP phase was lightly cross-linked by exposing the film to diiodobutane. When the block copolymer film was exposed to the sol-gel titania precursor, titanium(IV) bis(ammonium lactate) dihydroxide (TALH), titania was formed in the P4VP phase. The resulting titania structures were identical in size to the P4VP cylinders and only formed (under the deposition conditions used in this study) when the block copolymer film was present on the substrate, thus providing evidence that the block copolymer indeed acts as a template. The process works for both silicon and indium tin oxide substrates.

  5. Biodegradable glycopolymer-b-poly(ε-caprolactone) block copolymer micelles: Versatile construction, tailored lactose functionality, and hepatoma-targeted drug delivery

    NARCIS (Netherlands)

    Chen, Wei; Meng, Fenghua; Cheng, Ru; Deng, Chao; Feijen, Jan; Zhong, Zhiyuan


    Glycopolymer-b-poly(ε-caprolactone) (GP-PCL) block copolymer micelles (‘glycomicelles’) with tailored lactose functionalities were developed and investigated for hepatoma-targeted doxorubicin (DOX) delivery. Amphiphilic GP-PCL copolymers were readily prepared with controlled lactobionic acid (LBA)

  6. Chiral Block Copolymer Structures for Metamaterial Applications (United States)


    elt Institution : Rice University Mailing Address : Department of...information from the molecular level to the micro and macrodomain levels. This joint work3 was published in the Journal of the American Chemical...Chirality from Molecule to Phase in Self‐Assembled Chiral Block Copolymers,” Journal of the American Chemical Society, 134 (26), 10974 – 10986, (2012).

  7. Self-Assembly of Block and Graft Copolymers in Organic Solvents: An Overview of Recent Advances

    Directory of Open Access Journals (Sweden)

    Leonard Ionut Atanase


    Full Text Available This review is an attempt to update the recent advances in the self-assembly of amphiphilic block and graft copolymers. Their micellization behavior is highlighted for linear AB, ABC triblock terpolymers, and graft structures in non-aqueous selective polar and non-polar solvents, including solvent mixtures and ionic liquids. The micellar characteristics, such as particle size, aggregation number, and morphology, are examined as a function of the copolymers’ architecture and molecular characteristics.

  8. Transport of Water in Semicrystalline Block Copolymer Membranes (United States)

    Hallinan, Daniel; Oparaji, Onyekachi

    Poly(styrene)-block-poly(ethylene oxide) (PS- b-PEO) is a semicrystalline block copolymer (BCP) with interesting properties. It is mechanically tough, amphiphilic, and has a polar phase. The mechanical toughness is due to the crystallinity of PEO and the high glass transition temperature of PS, as well as the morphological structure of the BCP. The polymer has high CO2, water, and salt solubility that derive from the polar PEO component. Potential applications include CO2 separation, water purification, and lithium air batteries. In all of the aforementioned applications, water transport is an important parameter. The presence of water can also affect thermal and mechanical properties. Water transport and thermal and mechanical properties of a lamellar PS- b-PEO copolymer have been measured as a function of water activity. Water transport can be affected by the heterogeneous nature of a semicrystalline BCP. Therefore, Fourier transform infrared - attenuated total reflectance (FTIR-ATR) spectroscopy has been employed, because water transport and polymer swelling can be measured simultaneously. The effect of BCP structure on transport has been investigated by comparing water transport in PS- b-PEO to a PEO homopolymer. The crystalline content of the PEO and the presence of glassy PS lamellae will be used to explain the transport results.

  9. Rapid ordering of block copolymer thin films. (United States)

    Majewski, Pawel W; Yager, Kevin G


    Block-copolymers self-assemble into diverse morphologies, where nanoscale order can be finely tuned via block architecture and processing conditions. However, the ultimate usage of these materials in real-world applications may be hampered by the extremely long thermal annealing times-hours or days-required to achieve good order. Here, we provide an overview of the fundamentals of block-copolymer self-assembly kinetics, and review the techniques that have been demonstrated to influence, and enhance, these ordering kinetics. We discuss the inherent tradeoffs between oven annealing, solvent annealing, microwave annealing, zone annealing, and other directed self-assembly methods; including an assessment of spatial and temporal characteristics. We also review both real-space and reciprocal-space analysis techniques for quantifying order in these systems.

  10. Amphiphilic copolymers based on polyoxazoline and grape seed vegetable oil derivatives: self-assemblies and dynamic light scattering

    Energy Technology Data Exchange (ETDEWEB)

    Travelet, Christophe, E-mail: [Universite Joseph Fourier (UJF), Institut de Chimie Moleculaire de Grenoble (ICMG-FR 2607 CNRS), PolyNat Carnot institute, Arcane LabEx, domaine universitaire de Grenoble, Centre de Recherches sur les Macromolecules Vegetales - CERMAV-UPR 5301 CNRS (France); Stemmelen, Mylene; Lapinte, Vincent [Universite de Montpellier II, Institut Charles Gerhardt Montpellier (UMR 5253 CNRS-UM2-UM1-ENSCM), equipe ingenierie et architectures macromoleculaires (France); Dubreuil, Frederic [Universite Joseph Fourier (UJF), Institut de Chimie Moleculaire de Grenoble (ICMG-FR 2607 CNRS), PolyNat Carnot institute, Arcane LabEx, domaine universitaire de Grenoble, Centre de Recherches sur les Macromolecules Vegetales - CERMAV-UPR 5301 CNRS (France); Robin, Jean-Jacques [Universite de Montpellier II, Institut Charles Gerhardt Montpellier (UMR 5253 CNRS-UM2-UM1-ENSCM), equipe ingenierie et architectures macromoleculaires (France); and others


    The self-assembly in solution of original structures of amphiphilic partially natural copolymers based on polyoxazoline [more precisely poly(2-methyl-2-oxazoline) (POx)] and grape seed vegetable oil derivatives (linear, T-, and trident-structure) is investigated. The results show that such systems are found, using dynamic light scattering (DLS), to spontaneously self-organize into monomodal, narrow-size, and stable nanoparticles in aqueous medium. The obtained hydrodynamic diameters (D{sub h}) range from 8.6 to 32.5 nm. Specifically, such size increases strongly with increasing natural block (i.e., lipophilic species) length due to higher hydrophobic interactions (from 10.1 nm for C{sub 19} to 19.2 nm for C{sub 57}). Furthermore, increasing the polyoxazoline (i.e., hydrophilic block) length leads to a moderate linear increase of the D{sub h}-values. Therefore, the first-order size effect comes from the natural lipophilic block, whereas the characteristic size can be tuned more finely (i.e., in a second-order) by choosing appropriately the polyoxazoline length. The DLS results in terms of characteristic size are corroborated using nanoparticle tracking analysis (NTA), and also by atomic force microscopy (AFM) and transmission electron microscopy (TEM) imaging where well-defined spherical and individual nanoparticles exhibit a very good mechanical resistance upon drying. Moreover, changing the lipophilic block architecture from linear to T-shape, while keeping the same molar mass, generates a branching and thus a shrinking by a factor of 2 of the nanoparticle volume, as observed by DLS. In this paper, it is clearly shown that the self-assemblies of amphiphilic block copolymer obtained from grape seed vegetable oil derivatives (sustainable renewable resources) as well as their tunability are of great interest for biomass valorization at the nanoscale level [continuation of the article by Stemmelen et al. (Polym Chem 4:1445-1458, 2013)].Graphical AbstractAmphiphilic

  11. Effects of amphiphilic PCL-PEG-PCL copolymer addition on 5-fluorouracil release from biodegradable PCL films for stent application. (United States)

    Lu, Fei; Lei, Lei; Shen, Yuan-Yuan; Hou, Jing-Wen; Chen, Wei-Luan; Li, Yang-Gong; Guo, Sheng-Rong


    Biodegradable film-based stents emerged as a promising medical platform for drug delivery to resolve stenosis encountered in physiological conduits (e.g. blood vessels, biliary and urethral tracts). Drug release kinetics significantly affects the pharmacological effects of a stent, thus it is desirable for a stent to possess highly adjustable drug release kinetics. In this study, a series of amphiphilic poly(ɛ-caprolactone)-poly(ethylene glycol)-poly(ɛ-caprolactone) (PCL-PEG-PCL) copolymers were used as additives to adjust 5-fluorouracil (5-FU) release from PCL films. The effects of the copolymer addition on drug release behavior, drug permeability, crystalline states, and surface and internal morphologies of the films were investigated. It was found that, the addition of PCL-PEG-PCL could accelerate 5-FU release. The release rate of 5-FU increased with increasing content of PCL-PEG-PCL in the film, but it decreased with the ratio of PCL blocks in the PCL-PEG-PCL copolymer. The diffusion test results showed that 5-FU diffused through the film containing PCL-PEG-PCL faster than it permeated through the pure PCL film, indicating that the addition of PCL-PEG-PCL can improve the permeability of 5-FU in PCL film. The addition of PCL-PEG-PCL copolymer showed high drug-release-regulating ability in the 5-FU-loaded PCL films. Copyright © 2011 Elsevier B.V. All rights reserved.

  12. Synthesis and Characterization of Stimuli Responsive Block Copolymers, Self-Assembly Behavior and Applications

    Energy Technology Data Exchange (ETDEWEB)

    Determan, Michael Duane [Iowa State Univ., Ames, IA (United States)


    The central theme of this thesis work is to develop new block copolymer materials for biomedical applications. While there are many reports of stimuli-responsive amphiphilic [19-21] and crosslinked hydrogel materials [22], the development of an in situ gel forming, pH responsive pentablock copolymer is a novel contribution to the field, Figure 1.1 is a sketch of an ABCBA pentablock copolymer. The A blocks are cationic tertiary amine methacrylates blocked to a central Pluronic F127 triblock copolymer. In addition to the prerequisite synthetic and macromolecular characterization of these new materials, the self-assembled supramolecular structures formed by the pentablock were experimentally evaluated. This synthesis and characterization process serves to elucidate the important structure property relationships of these novel materials, The pH and temperature responsive behavior of the pentablock copolymer were explored especially with consideration towards injectable drug delivery applications. Future synthesis work will focus on enhancing and tuning the cell specific targeting of DNA/pentablock copolymer polyplexes. The specific goals of this research are: (1) Develop a synthetic route for gel forming pentablock block copolymers with pH and temperature sensitive properties. Synthesis of these novel copolymers is accomplished with ATRP, yielding low polydispersity and control of the block copolymer architecture. Well defined macromolecular characteristics are required to tailor the phase behavior of these materials. (2) Characterize relationship between the size and shape of pentablock copolymer micelles and gel structure and the pH and temperature of the copolymer solutions with SAXS, SANS and CryoTEM. (3) Evaluate the temperature and pH induced phase separation and macroscopic self-assembly phenomenon of the pentablock copolymer. (4) Utilize the knowledge gained from first three goals to design and formulate drug delivery formulations based on the multi

  13. Self-consistent field theoretic simulations of amphiphilic triblock copolymer solutions: Polymer concentration and chain length effects

    Directory of Open Access Journals (Sweden)

    X.-G. Han


    Full Text Available Using the self-consistent field lattice model, polymer concentration φP and chain length N (keeping the length ratio of hydrophobic to hydrophilic blocks constant the effects on temperature-dependent behavior of micelles are studied, in amphiphilic symmetric ABA triblock copolymer solutions. When chain length is increased, at fixed φP, micelles occur at higher temperature. The variations of average volume fraction of stickers φcos and the lattice site numbers Ncols at the micellar cores with temperature are dependent on N and φP, which demonstrates that the aggregation of micelles depends on N and φP. Moreover, when φP is increased, firstly a peak appears on the curve of specific heat CV for unimer-micelle transition, and then in addition a primary peak, the secondary peak, which results from the remicellization, is observed on the curve of CV. For a long chain, in intermediate and high concentration regimes, the shape of specific heat peak markedly changes, and the peak tends to be a more broad peak. Finally, the aggregation behavior of micelles is explained by the aggregation way of amphiphilic triblock copolymer. The obtained results are helpful in understanding the micellar aggregation process.

  14. Rheological Design of Sustainable Block Copolymers (United States)

    Mannion, Alexander M.

    Block copolymers are extremely versatile materials that microphase separate to give rise to a rich array of complex behavior, making them the ideal platform for the development of rheologically sophisticated soft matter. In line with growing environmental concerns of conventional plastics from petroleum feedstocks, this work focuses on the rheological design of sustainable block copolymers--those derived from renewable sources and are degradable--based on poly(lactide). Although commercially viable, poly(lactide) has a number of inherent deficiencies that result in a host of challenges that require both creative and practical solutions that are cost-effective and amenable to large-scale production. Specifically, this dissertation looks at applications in which both shear and extensional rheology dictate performance attributes, namely chewing gum, pressure-sensitive adhesives, and polymers for blown film extrusion. Structure-property relationships in the context of block polymer architecture, polymer composition, morphology, and branching are explored in depth. The basic principles and fundamental findings presented in this thesis are applicable to a broader range of substances that incorporate block copolymers for which rheology plays a pivotal role.

  15. Dynamics of Block Copolymer Nanocomposites

    Energy Technology Data Exchange (ETDEWEB)

    Mochrie, Simon G. J.


    A detailed study of the dynamics of cadmium sulfide nanoparticles suspended in polystyrene homopolymer matrices was carried out using X-ray photon correlation spectroscopy for temperatures between 120 and 180 °C. For low molecular weight polystyrene homopolymers, the observed dynamics show a crossover from diffusive to hyper-diffusive behavior with decreasing temperatures. For higher molecular weight polystyrene, the nanoparticle dynamics appear hyper-diffusive at all temperatures studied. The relaxation time and characteristic velocity determined from the measured hyper-diffusive dynamics reveal that the activation energy and underlying forces determined are on the order of 2.14 × 10-19 J and 87 pN, respectively. We also carried out a detailed X-ray scattering study of the static and dynamic behavior of a styrene– isoprene diblock copolymer melt with a styrene volume fraction of 0.3468. At 115 and 120 °C, we observe splitting of the principal Bragg peak, which we attribute to phase coexistence of hexagonal cylindrical and cubic double- gyroid structure. In the disordered phase, above 130 °C, we have characterized the dynamics of composition fluctuations via X-ray photon correlation spectroscopy. Near the peak of the static structure factor, these fluctuations show stretched-exponential relaxations, characterized by a stretching exponent of about 0.36 for a range of temperatures immediately above the MST. The corresponding characteristic relaxation times vary exponentially with temperature, changing by a factor of 2 for each 2 °C change in temperature. At low wavevectors, the measured relaxations are diffusive with relaxation times that change by a factor of 2 for each 8 °C change in temperature.

  16. Synthesis of Functional Block Copolymers Carrying One Poly( p -phenylenevinylene) and One Nonconjugated Block in a Facile One-Pot Procedure

    KAUST Repository

    Menk, Florian


    Block copolymers composed of a MEH-PPV block and a nonconjugated functional block (molecular weights between 5 and 90 kg/mol) were synthesized in a facile one-pot procedure via ROMP. This one-pot procedure permits the synthesis of numerous block copolymers with little effort. Amphiphilic block copolymers were obtained via incorporation of oxanorbornene carrying a PEG side chain as well as via postpolymerization modification of a reactive ester carrying norbornene derivative with methoxypoly(ethylene glycol)amine. These amphiphilic block copolymers can be self-assembled into micelles exhibiting different sizes (60-95 nm), morphologies (micelles or fused, caterpillar-like micelles), and optical properties depending on the polymer composition and the micellization procedure. Furthermore, the reactive ester carrying block copolymers enabled the introduction of anchor groups which facilitated the preparation of nanocomposites with CdSe/CdZnS core-shell QDs. The obtained composites were studied using time-resolved photoluminescence measurements. The results revealed an increased interaction based on an accelerated decay of the QD emission for composites as compared to the mixture of the QDs with unfunctionalized polymers. © 2016 American Chemical Society.

  17. SANS study of coated block copolymer micelles

    Czech Academy of Sciences Publication Activity Database

    Pleštil, Josef; Kříž, Jaroslav; Koňák, Čestmír; Pospíšil, Herman; Kadlec, Petr; Sedláková, Zdeňka; Grillo, I.; Cubitt, R.


    Roč. 206, č. 12 (2005), s. 1206-1215 ISSN 1022-1352 R&D Projects: GA ČR GA203/03/0600; GA AV ČR IAA1050201; GA AV ČR KSK4050111 Institutional research plan: CEZ:AV0Z40500505 Keywords : block copolymer micelles * core-shell polymers * nanoparticles Subject RIV: CD - Macromolecular Chemistry Impact factor: 2.111, year: 2005

  18. Protein Modification with Amphiphilic Block Copoly(2-oxazoline)s as a New Platform for Enhanced Cellular Delivery

    KAUST Repository

    Tong, Jing


    Several homopolymers, random copolymers and block copolymers based on poly(2-oxazoline)s (POx) were synthesized and conjugated to horseradish peroxidase (HRP) using biodegradable and nonbiodegradable linkers. These conjugates were characterized by amino group titration, polyacrylamide gel electrophoresis (PAGE), isoelectric focusing, enzymatic activity assay and conformation analysis. The conjugates contained on average from about one to two polymer chains per enzyme. From 70% to 90% of enzymatic activity was retained in most cases. Circular dichroism (CD) analysis revealed that HRP modification affected the secondary structure of the apoprotein but did not affect the tertiary structure and heme environment. Enhanced cellular uptake was found in the conjugates of two block copolymers using both MDCK cells and Caco-2 cells, but not in the conjugates of random copolymer and homopolymer. Conjugation with a block copolymer of 2-methyl-2-oxazoline and 2-butyl-2-oxazoline led to the highest cellular uptake as compared to other conjugates. Our data indicates that modification with amphiphilic POx has the potential to modulate and enhance cellular delivery of proteins.

  19. Helical cylinders or multicompartment cylinders through the solution assembly of charged block copolymers with multivalent organic counterions (United States)

    Pochan, Darrin; Zhong, Sheng; Cui, Honggang; Chen, Zhiyun; Wooley, Karen


    By manipulating the interaction of charged block copolymer hydrophilic corona blocks with multivalent organic counterions, and controlling the kinetics of block copolymer solution self-assembly, desired micelle geometries can be formed. Specifically, polyacrylic acid-b-polymethylacrylate-b-polystyrene amphiphilic triblock copolymers were studied in water/THF solvent mixtures with organic multiamines as counterions. By manipulating block copolymer and solvent composition, different micelle geometries were formed. However, by altering the chemical structure and/or concentration of the multiamine counterions, as well as the kinetic pathway through which the molecules are assembled, complex nanostructures were formed. An example of nanostructure from kinetic control includes spherical micelles that can be controllably assembled into 1-d multicompartment cylinders. Examples of nanostructure from control of the type and amount of multivalent organic counterion added are helical cylinder superstructures many micrometers in length. The system has been investigated by means of cryogenic transmission electron microscopy (cryo-TEM) and small angle neutron scattering (SANS).

  20. Self-Assembly of Amphiphilic Block Copolypeptoids with C 2 -C 5 Side Chains in Aqueous Solution

    KAUST Repository

    Fetsch, Corinna


    © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim. Nowadays, amphiphilic molecules play an important role in our life. In medical applications, amphiphilic block copolymers have attracted much attention as excipients in drug delivery systems. Here, the polymers are used as emulsifiers, micelles, or polymersomes with a hydrophilic corona block and a hydrophobic core or membrane. The aggregation behavior in aqueous solutions of a series of different amphiphilic block copolypeptoids comprising polysarcosine as a hydrophilic part is here reported. The formation of aggregates is investigated with 1H NMR spectroscopy and dynamic light scattering, and the determination of the critical micelle concentration (cmc) is performed using pyrene fluorescence spectroscopy. For the different block copolypeptoids cmc values ranging from 0.6 × 10-6 M to 0.1 × 10-3 M are found. The tendency to form micelles increases with increasing hydrophobicity at the nitrogen side chain in the hydrophobic moiety. Furthermore, in the case of the same hydrophobic side chain, a decreasing hydrophilic/lipophilic balance leads to the formation of larger aggregates. The aggregates formed in the buffer are able to solubilize the hydrophobic model compounds Reichardt\\'s dye and pyrene, and exhibit versatile microenvironments. Final investigations about the cytotoxicity reveal that the block copolypeptoids are well tolerated by mammalian cells up to high concentrations.

  1. Spontaneous Lipid Nanodisc Fomation by Amphiphilic Polymethacrylate Copolymers


    Yasuhara, Kazuma; Arakida, Jin; Ravula, Thirupathi; Ramadugu, Sudheer Kumar; Sahoo, Bikash; Kikuchi, Jun-ichi; Ramamoorthy, Ayyalusamy


    There is a growing interest in the use of lipid bilayer nanodiscs for various biochemical and biomedical applications. Among the different types of nanodiscs, the unique features of synthetic polymer-based nanodiscs have attracted additional interest. A styrene–maleic acid (SMA) copolymer demonstrated to form lipid nanodiscs has been used for structural biology related studies on membrane proteins. However, the application of SMA polymer based lipid nanodiscs is limited because of the strong ...

  2. In vitro evaluation of anticancer nanomedicines based on doxorubicin and amphiphilic Y-shaped copolymers

    Directory of Open Access Journals (Sweden)

    Li D


    Full Text Available Di Li,1,2,* Jian Xun Ding,1,3,* Zhao Hui Tang,1 Hai Sun,1 Xiu Li Zhuang,1 Jing Zhe Xu,2 Xue Si Chen1 1Key Laboratory of Polymer Ecomaterials, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun, 2Department of Chemistry, Yanbian University, Yanji, 3Graduate University of Chinese Academy of Sciences, Beijing, China *These authors contributed equally to this workAbstract: Four monomethoxy poly(ethylene glycol-poly(L-lactide-co-glycolide2 (mPEG-P(LA-co-GA2 copolymers were synthesized by ring-opening polymerization of L-lactide and glycolide with double hydroxyl functionalized mPEG (mPEG-(OH2 as macroinitiator and stannous octoate as catalyst. The copolymers self-assembled into nanoscale micellar/vesicular aggregations in phosphate buffer at pH 7.4. Doxorubicin (DOX, an anthracycline anticancer drug, was loaded into the micellar/vesicular nanoparticles, yielding micellar/vesicular nanomedicines. The in vitro release behaviors could be adjusted by content of hydrophobic polyester and pH of the release medium. In vitro cell experiments showed that the intracellular DOX release could be adjusted by content of P(LA-co-GA, and the nanomedicines displayed effective proliferation inhibition against Henrietta Lacks’s cells with different culture times. Hemolysis tests indicated that the copolymers were hemocompatible, and the presence of copolymers could reduce the hemolysis ratio of DOX significantly. These results suggested that the novel anticancer nanomedicines based on DOX and amphiphilic Y-shaped copolymers were attractive candidates as tumor tissular and intracellular targeting drug delivery systems in vivo, with enhanced stability during circulation and accelerated drug release at the target sites.Keywords: amphiphilic Y-shaped copolymer, anticancer nanomedicine, cellular proliferation inhibition, doxorubicin

  3. Physical tuning of cellulose-polymer interactions utilizing cationic block copolymers based on PCL and quaternized PDMAEMA. (United States)

    Utsel, Simon; Bruce, Carl; Pettersson, Torbjörn; Fogelström, Linda; Carlmark, Anna; Malmström, Eva; Wågberg, Lars


    In this work, the objective was to synthesize and evaluate the properties of a compatibilizer based on poly(ε-caprolactone) aimed at tuning the surface properties of cellulose fibers used in fiber-reinforced biocomposites. The compatibilizer is an amphiphilic block copolymer consisting of two different blocks which have different functions. One block is cationic, quaternized poly(2-(dimethylamino)ethyl methacrylate) (PDMAEMA) and can therefore electrostatically attach to anionic reinforcing materials such as cellulose-based fibers/fibrils under mild conditions in water. The other block consists of poly(ε-caprolactone) (PCL) which can decrease the surface energy of a cellulose surface and also has the ability to form physical entanglements with a PCL surface thereby improving the interfacial adhesion. Atom Transfer Radical Polymerization (ATRP) and Ring-Opening Polymerization (ROP) were used to synthesize three block copolymers with the same length of the cationic PDMAEMA block but with different lengths of the PCL blocks. The block copolymers form cationic micelles in water which can adsorb to anionic surfaces such as silicon oxide and cellulose-model surfaces. After heat treatment, the contact angles of water on the treated surfaces increased significantly, and contact angles close to those of pure PCL were obtained for the block copolymers with longer PCL blocks. AFM force measurements showed a clear entangling behavior between the block copolymers and a PCL surface at about 60 °C, which is important for the formation of an adhesive interface in the final biocomposites. This demonstrates that this type of amphiphilic block copolymer can be used to improve interactions in biocomposites between anionic reinforcing materials such as cellulose-based fibers/fibrils and less polar matrices such as PCL.

  4. Self-Assembly of Block Copolymer Chains To Promote the Dispersion of Nanoparticles in Polymer Nanocomposites. (United States)

    Liu, Jun; Wang, Zixuan; Zhang, Zhiyu; Shen, Jianxiang; Chen, Yulong; Zheng, Zijian; Zhang, Liqun; Lyulin, Alexey V


    In this paper we adopt molecular dynamics simulations to study the amphiphilic AB block copolymer (BCP) mediated nanoparticle (NP) dispersion in polymer nanocomposites (PNCs), with the A-block being compatible with the NPs and the B-block being miscible with the polymer matrix. The effects of the number and components of BCP, as well as the interaction strength between A-block and NPs on the spatial organization of NPs, are explored. We find that the increase of the fraction of the A-block brings different dispersion effect to NPs than that of B-block. We also find that the best dispersion state of the NPs occurs in the case of a moderate interaction strength between the A-block and the NPs. Meanwhile, the stress-strain behavior is probed. Our simulation results verify that adopting BCP is an effective way to adjust the dispersion of NPs in the polymer matrix, further to manipulate the mechanical properties.

  5. "Non-equilibrium" block copolymer micelles with glassy cores: a predictive approach based on theory of equilibrium micelles. (United States)

    Nagarajan, Ramanathan


    Micelles generated in water from most amphiphilic block copolymers are widely recognized to be non-equilibrium structures. Typically, the micelles are prepared by a kinetic process, first allowing molecular scale dissolution of the block copolymer in a common solvent that likes both the blocks and then gradually replacing the common solvent by water to promote the hydrophobic blocks to aggregate and create the micelles. The non-equilibrium nature of the micelle originates from the fact that dynamic exchange between the block copolymer molecules in the micelle and the singly dispersed block copolymer molecules in water is suppressed, because of the glassy nature of the core forming polymer block and/or its very large hydrophobicity. Although most amphiphilic block copolymers generate such non-equilibrium micelles, no theoretical approach to a priori predict the micelle characteristics currently exists. In this work, we propose a predictive approach for non-equilibrium micelles with glassy cores by applying the equilibrium theory of micelles in two steps. In the first, we calculate the properties of micelles formed in the mixed solvent while true equilibrium prevails, until the micelle core becomes glassy. In the second step, we freeze the micelle aggregation number at this glassy state and calculate the corona dimension from the equilibrium theory of micelles. The condition when the micelle core becomes glassy is independently determined from a statistical thermodynamic treatment of diluent effect on polymer glass transition temperature. The predictions based on this "non-equilibrium" model compare reasonably well with experimental data for polystyrene-polyethylene oxide diblock copolymer, which is the most extensively studied system in the literature. In contrast, the application of the equilibrium model to describe such a system significantly overpredicts the micelle core and corona dimensions and the aggregation number. The non-equilibrium model suggests ways to

  6. Nitroxide-mediated radical ring-opening copolymerization: chain-end investigation and block copolymer synthesis. (United States)

    Delplace, Vianney; Harrisson, Simon; Tardy, Antoine; Gigmes, Didier; Guillaneuf, Yohann; Nicolas, Julien


    Well-defined, degradable copolymers are successfully prepared by nitroxide-mediated radical ring opening polymerization (NMrROP) of oligo(ethylene glycol) methyl ether methacrylate (OEGMA) or methyl methacrylate (MMA), a small amount of acrylonitrile (AN) and cyclic ketene acetals (CKAs) of different structures. Phosphorous nuclear magnetic resonance allows in-depth chain-end characterization and gives crucial insights into the nature of the copoly-mer terminal sequences and the living chain fractions. By using a small library of P(OEGMA-co-AN-co-CKA) and P(MMA-co-AN-co-CKA) as macroinitiators, chain extensions with styrene are performed to furnish (amphiphilic) block copolymers comprising a degradable segment. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  7. Microspheres for protein delivery prepared from amphiphilic multiblock copolymers. 1. Influence of preparation techniques on particle characteristics and protein delivery. (United States)

    Bezemer, J M; Radersma, R; Grijpma, D W; Dijkstra, P J; van Blitterswijk, C A; Feijen, J


    The entrapment of lysozyme in amphiphilic multiblock copolymer microspheres by emulsification and subsequent solvent removal processes was studied. The copolymers are composed of hydrophilic poly(ethylene glycol) (PEG) blocks and hydrophobic poly(butylene terephthalate) (PBT) blocks. Direct solvent extraction from a water-in-oil (w/o) emulsion in ethanol or methanol did not result in the formation of microspheres, due to massive polymer precipitation caused by rapid solvent extraction in these non-solvents. In a second process, microspheres were first prepared by a water-in-oil-in-water (w/o/w) emulsion system with 4% poly(vinyl alcohol) (PVA) as stabilizer in the external phase, followed by extraction of the remaining solvent. As non-solvents ethanol, methanol and mixtures of methanol and water were employed. However, the use of alcohols in the extraction medium resulted in microspheres which gave an incomplete lysozyme release at a non-constant rate. Complete lysozyme release was obtained from microspheres prepared by an emulsification-solvent evaporation method in PBS containing poly(vinyl pyrrolidone) (PVP) or PVA as stabilizer. PVA was most effective in stabilizing the w/o/w emulsion. Perfectly spherical microspheres were produced, with high protein entrapment efficiencies. These microspheres released lysozyme at an almost constant rate for approximately 28 days. The reproducibility of the w/o/w emulsion process was demonstrated by comparing particle characteristics and release profiles of three batches, prepared under similar conditions.

  8. Spontaneous Lipid Nanodisc Fomation by Amphiphilic Polymethacrylate Copolymers. (United States)

    Yasuhara, Kazuma; Arakida, Jin; Ravula, Thirupathi; Ramadugu, Sudheer Kumar; Sahoo, Bikash; Kikuchi, Jun-Ichi; Ramamoorthy, Ayyalusamy


    There is a growing interest in the use of lipid bilayer nanodiscs for various biochemical and biomedical applications. Among the different types of nanodiscs, the unique features of synthetic polymer-based nanodiscs have attracted additional interest. A styrene-maleic acid (SMA) copolymer demonstrated to form lipid nanodiscs has been used for structural biology related studies on membrane proteins. However, the application of SMA polymer based lipid nanodiscs is limited because of the strong absorption of the aromatic group interfering with various experimental measurements. Thus, there is considerable interest in the development of other molecular frameworks for the formation of polymer-based lipid nanodiscs. In this study, we report the first synthesis and characterization of a library of polymethacrylate random copolymers as alternatives to SMA polymer. In addition, we experimentally demonstrate the ability of these polymers to form lipid bilayer nanodiscs through the fragmentation of lipid vesicles by means of light scattering, electron microscopy, differential scanning calorimetry, and solution and solid-state NMR experiments. We further demonstrate a unique application of the newly developed polymer for kinetics and structural characterization of the aggregation of human islet amyloid polypeptide (also known as amylin) within the lipid bilayer of the polymer nanodiscs using thioflavin-T-based fluorescence and circular dichroism experiments. Our results demonstrate that the reported new styrene-free polymers can be used in high-throughput biophysical experiments. Therefore, we expect that the new polymer nanodiscs will be valuable in the structural studies of amyloid proteins and membrane proteins by various biophysical techniques.

  9. In vitro evaluation of anticancer nanomedicines based on doxorubicin and amphiphilic Y-shaped copolymers (United States)

    Li, Di; Ding, Jian Xun; Tang, Zhao Hui; Sun, Hai; Zhuang, Xiu Li; Xu, Jing Zhe; Chen, Xue Si


    Four monomethoxy poly(ethylene glycol)-poly(L-lactide-co-glycolide)2 (mPEG-P( LA-co-GA)2) copolymers were synthesized by ring-opening polymerization of L-lactide and glycolide with double hydroxyl functionalized mPEG (mPEG-(OH)2) as macroinitiator and stannous octoate as catalyst. The copolymers self-assembled into nanoscale micellar/vesicular aggregations in phosphate buffer at pH 7.4. Doxorubicin (DOX), an anthracycline anticancer drug, was loaded into the micellar/vesicular nanoparticles, yielding micellar/vesicular nanomedicines. The in vitro release behaviors could be adjusted by content of hydrophobic polyester and pH of the release medium. In vitro cell experiments showed that the intracellular DOX release could be adjusted by content of P(LA-co-GA), and the nanomedicines displayed effective proliferation inhibition against Henrietta Lacks’s cells with different culture times. Hemolysis tests indicated that the copolymers were hemocompatible, and the presence of copolymers could reduce the hemolysis ratio of DOX significantly. These results suggested that the novel anticancer nanomedicines based on DOX and amphiphilic Y-shaped copolymers were attractive candidates as tumor tissular and intracellular targeting drug delivery systems in vivo, with enhanced stability during circulation and accelerated drug release at the target sites. PMID:22701317

  10. Synthesis and studies of polypeptide materials: Self-assembled block copolypeptide amphiphiles, DNA-condensing block copolypeptides and membrane-interactive random copolypeptides (United States)

    Wyrsta, Michael Dmytro

    A new class of transition metal initiators for the controlled polymerization of alpha-aminoacid-N-carboxyanhydrides (alpha-NCAs), has been developed by Deming et al. This discovery has allowed for the synthesis of well-defined "protein-like" polymers. Using this chemistry we have made distinct block/random copolypeptides for biomedical applications. Drug delivery, gene delivery, and antimicrobial polymers were the focus of our research efforts. The motivation for the synthesis and study of synthetic polypeptide based materials comes from proteins. Natural proteins are able to adopt a staggeringly large amount of uniquely well-defined folded structures. These structures account for the diversity in properties of proteins. As catalysts (enzymes) natural proteins perform some of the most difficult chemistry with ease and precision at ambient pressures and temperatures. They also exhibit incredible structural properties that directly result from formation of complex hierarchical assemblies. Self-assembling block copolymers were synthesized with various compositions and architectures. In general, di- and tri-block amphiphiles were studied for their self-assembling properties. Both spherical and tubular vesicles were found to assemble from di- and tri-block amphiphiles, respectively. In addition to self-assembly, pH responsiveness was engineered into these amphiphiles by the incorporation of basic residues (lysine) into the hydrophobic block. Another form of self-assembly studied was the condensation of DNA using cationic block copolymers. It was found that cationic block copolymers could condense DNA into compact, ordered, water-soluble aggregates on the nanoscale. These aggregates sufficiently protected DNA from nucleases and yet were susceptible to proteases. These studies form the basis of a gene delivery platform. The ease with which NCAs are polymerized renders them completely amenable to parallel synthetic methods. We have employed this technique to discover new

  11. Amphiphilic copolymer derived from tamarind gum and poly (methyl methacrylate) via ATRP towards selective removal of toxic dyes. (United States)

    Pal, Aniruddha; Pal, Sagar


    Herein an amphiphilic graft copolymer has been synthesized from tamarind gum and poly (methyl methacrylate) (g-TKP/pMMA) using atom transfer radical polymerization (ATRP) in presence of CuBr/bpy catalyst. Structural and surface properties of the copolymer have been investigated using 1 H NMR and FTIR spectra, DLS, TGA and FESEM analyses. The controlled and living nature of polymerization reaction has been explored using GPC analysis, while the gel characteristics of the copolymer has been analysed by rheological study. Finally, the copolymer demonstrates excellent pH triggered selective adsorption efficacy towards removal of toxic cationic/anionic dyes. Copyright © 2016 Elsevier Ltd. All rights reserved.

  12. High-concentration graphene dispersion stabilized by block copolymers in ethanol. (United States)

    Perumal, Suguna; Lee, Hyang Moo; Cheong, In Woo


    This article describes a comprehensive study for the preparation of graphene dispersions by liquid-phase exfoliation using amphiphilic diblock copolymers; poly(ethylene oxide)-block-poly(styrene) (PEO-b-PS), poly(ethylene oxide)-block-poly(4-vinylpyridine) (PEO-b-PVP), and poly(ethylene oxide)-block-poly(pyrenemethyl methacrylate) (PEO-b-PPy) with similar block lengths. Block copolymers were prepared from PEO using the Steglich coupling reaction followed by reversible addition-fragmentation chain transfer (RAFT) polymerization. Graphite platelets (G) and reduced graphene oxide (rGO) were used as graphene sources. The dispersion stability of graphene in ethanol was comparatively investigated by on-line turbidity, and the graphene concentration in the dispersions was determined gravimetrically. Our results revealed that the graphene dispersions with PEO-b-PVP were much more stable and included graphene with fewer defects than that with PEO-b-PS or PEO-b-PPy, as confirmed by turbidity and Raman analyses. Gravimetry confirmed that graphene concentrations up to 1.7 and 1.8mg/mL could be obtained from G and rGO dispersions, respectively, using PEO-b-PVP after one week. Distinctions in adhesion forces of PS, VP, PPy block units with graphene surface and the variation in solubility of the block copolymers in ethanol medium significantly affected the stability of the graphene dispersion. Copyright © 2017 Elsevier Inc. All rights reserved.

  13. Modification of nanofibrillated cellulose using amphiphilic block-structured galactoglucomannans. (United States)

    Lozhechnikova, Alina; Dax, Daniel; Vartiainen, Jari; Willför, Stefan; Xu, Chunlin; Österberg, Monika


    Nanofibrillated cellulose (NFC) and hemicelluloses have shown to be highly promising renewable components both as barrier materials and in novel biocomposites. However, the hydrophilic nature of these materials restricts their use in some applications. In this work, the usability of modified O-acetyl galactoglucomannan (GGM) for modification of NFC surface properties was studied. Four GGM-block-structured, amphiphilic derivatives were synthesized using either fatty acids or polydimethylsiloxane as hydrophobic tails. The adsorption of these GGM derivatives was consecutively examined in aqueous solution using a quartz crystal microbalance with dissipation monitoring (QCM-D). It was found that the hydrophobic tails did not hinder adsorption of the GGM derivatives to cellulose, which was concluded to be due to the presence of the native GGM-block with high affinity to cellulose. The layer properties of the adsorbed block-co-polymers were discussed and evaluated. Self-standing NFC films were further prepared and coated with the GGM derivatives and the effect of the surface modification on wetting properties and oxygen permeability (OP) of the modified films was assessed. Copyright © 2014 Elsevier Ltd. All rights reserved.

  14. Self-assemblies of magnetic nanoparticles and di-block copolymers: Magnetic micelles and vesicles

    International Nuclear Information System (INIS)

    Lecommandoux, S.; Sandre, O.; Checot, F.; Rodriguez-Hernandez, J.; Perzynski, R.


    Magnetic nanocomposites are obtained by the self-assembly in water of polypeptide-based di-block copolymers polybutadiene-b-poly(glutamic acid) combined with hydrophobic γ-Fe 2 O 3 nanoparticles. These hybrid supramolecular objects are either-(3D) spherical micelles filled with a hydrophobic ferrofluid at a concentration as high as 45 vol% or-hollow vesicles with a (2D) magnetic membrane. In this last case, the organic amphiphile copolymers are able to confine the hydrophobic nanoparticles within the thin layer of polybutadiene blocks. We probe these objects by atomic force microscopy, by small-angle neutron scattering (SANS) and by light scattering. Furthermore, anisotropic SANS data bring the experimental evidence of the capability to modify the shape of the mineralized membranes in response to a magnetic field intensity as low as 290 G

  15. Antimicrobial films obtained from latex particles functionalized with quaternized block copolymers. (United States)

    Alvarez-Paino, Marta; Juan-Rodríguez, Rafael; Cuervo-Rodríguez, Rocío; Tejero, Rubén; López, Daniel; López-Fabal, Fátima; Gómez-Garcés, José L; Muñoz-Bonilla, Alexandra; Fernández-García, Marta


    New amphiphilic block copolymers with antimicrobial properties were obtained by atom transfer radical polymerization (ATRP) and copper catalyzed cycloaddition following two approaches, a simultaneous strategy or a two-step synthesis, which were proven to be very effective methods. These copolymers were subsequently quaternized using two alkyl chains, methyl and butyl, to amplify their antimicrobial properties and to investigate the effect of alkyl length. Antimicrobial experiments in solution were performed with three types of bacteria, two gram-positive and one gram-negative, and a fungus. Those copolymers quaternized with methyl iodide showed better selectivities on gram-positive bacteria, Staphylococcus aureus and Staphylococcus epidermidis, against red blood cells, demonstrating the importance of the quaternizing agent chosen. Once the solution studies were performed, we prepared poly(butyl methacrylate) latex particles functionalized with the antimicrobial copolymers by emulsion polymerization of butyl methacrylate using such copolymers as surfactants. The characterization by various techniques served to test their effectiveness as surfactants. Finally, films were prepared from these emulsions, and their antimicrobial activity was studied against the gram-positive bacteria. The results indicate that the antimicrobial efficiency of the films depends not only on the copolymer activity but also on other factors such as the surface segregation of the antimicrobial agent to the interface. Copyright © 2015 Elsevier B.V. All rights reserved.

  16. Tough and Sustainable Graft Block Copolymer Thermoplastics

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Jiuyang; Li, Tuoqi; Mannion, Alexander M.; Schneiderman, Deborah K.; Hillmyer, Marc A.; Bates, Frank S. (UMM)


    Fully sustainable poly[HPMC-g-(PMVL-b-PLLA)] graft block copolymer thermoplastics were prepared from hydroxypropyl methylcellulose (HPMC), β-methyl-δ-valerolactone (MVL), and l-lactide (LLA) using a facile two-step sequential addition approach. In these materials, rubbery PMVL functions as a bridge between the semirigid HPMC backbone and the hard PLLA end blocks. This specific arrangement facilitates PLLA crystallization, which induces microphase separation and physical cross-linking. By changing the backbone molar mass or side chain composition, these thermoplastic materials can be easily tailored to access either plastic or elastomeric behavior. Moreover, the graft block architecture can be utilized to overcome the processing limitations inherent to linear block polymers. Good control over molar mass and composition enables the deliberate design of HPMC-g-(PMVL-b-PLLA) samples that are incapable of microphase separation in the melt state. These materials are characterized by relatively low zero shear viscosities in the melt state, an indication of easy processability. The simple and scalable synthetic procedure, use of inexpensive and renewable precursors, and exceptional rheological and mechanical properties make HPMC-g-(PMVL-b-PLLA) polymers attractive for a broad range of applications.

  17. Patchy micelles based on coassembly of block copolymer chains and block copolymer brushes on silica particles. (United States)

    Zhu, Shuzhe; Li, Zhan-Wei; Zhao, Hanying


    Patchy particles are a type of colloidal particles with one or more well-defined patches on the surfaces. The patchy particles with multiple compositions and functionalities have found wide applications from the fundamental studies to practical uses. In this research patchy micelles with thiol groups in the patches were prepared based on coassembly of free block copolymer chains and block copolymer brushes on silica particles. Thiol-terminated and cyanoisopropyl-capped polystyrene-block-poly(N-isopropylacrylamide) block copolymers (PS-b-PNIPAM-SH and PS-b-PNIPAM-CIP) were synthesized by reversible addition-fragmentation chain transfer polymerization and chemical modifications. Pyridyl disulfide-functionalized silica particles (SiO2-SS-Py) were prepared by four-step surface chemical reactions. PS-b-PNIPAM brushes on silica particles were prepared by thiol-disulfide exchange reaction between PS-b-PNIPAM-SH and SiO2-SS-Py. Surface micelles on silica particles were prepared by coassembly of PS-b-PNIPAM-CIP and block copolymer brushes. Upon cleavage of the surface micelles from silica particles, patchy micelles with thiol groups in the patches were obtained. Dynamic light scattering, transmission electron microscopy, and zeta-potential measurements demonstrate the preparation of patchy micelles. Gold nanoparticles can be anchored onto the patchy micelles through S-Au bonds, and asymmetric hybrid structures are formed. The thiol groups can be oxidized to disulfides, which results in directional assembly of the patchy micelles. The self-assembly behavior of the patchy micelles was studied experimentally and by computer simulation.

  18. Tunable Nanocarrier Morphologies from Glycopolypeptide-based Amphiphilic Biocompatible Star Copolymers and Their Carbohydrate Specific Intracellular Delivery

    KAUST Repository

    Pati, Debasis


    Nano-carriers with carbohydrates on the surface represent a very interesting class of drug delivery vehicles since carbohydrates are involved in bio-molecular recognition events in vivo. We have synthesized biocompatible miktoarm star copolymers comprising glycopolypeptide and poly(ε-caprolactone) chains, using ring opening polymerization and ‘click chemistry’. The amphiphilic copolymers were self-assembled in water into morphologies such as nanorods, polymersomes and micelles with carbohydrates displayed on the surface. We demonstrate that, the formation of nanostructure could be tuned by chain length of the blocks and was not affected by the type of sugar residue. These nanostructures were characterized in detail using a variety of techniques such as TEM, AFM, cryogenic electron microscopy, spectrally resolved fluorescence imaging and dye encapsulation techniques. We show that it is possible to sequester both hydrophobic as well as hydrophilic dyes within the nanostructures. Finally, we show that these non-cytotoxic manno-sylated rods and polymersomes were selectively and efficiently taken up by MDA-MB-231 breast cancer cells demonstrating their potential as nanocarriers for drug delivery.

  19. The effects of ethylene oxide containing lipopolymers and tri-block copolymers on lipid bilayers of dipalmitoylphosphatidylcholine

    DEFF Research Database (Denmark)

    Baekmark, T. R.; Pedersen, S.; Jorgensen, K.


    oxide moity, anchored to the bilayer by a 1,2-dioctadecanoyl-s,n-glycero-3-phosphoethanolamine (DC18PE) lipid. The second type, which is a novel type of membrane-spanning object, is an amphiphilic tri-block copolymer composed of two hydrophilic stretches of polyethylene oxide separated by a hydrophobic...... stretch of polystyrene. Hence the tri-block copolymer may act as a membrane-spanning macromolecule mimicking an amphiphilic protein or polypeptide. Differential scanning calorimetry is used to determine a partial phase diagram for the lipopolymer systems and to assess the amount of lipopolymer that can...... be loaded into DC16PC lipid bilayers before micellization takes place. Unilamellar and micellar phase structures are investigated by fluorescence quenching using bilayer permeating dithionite. The chain length-dependent critical lipopolymer concentration, denoting the lamellar-to-micellar phase transition...

  20. Restructuring in block copolymer thin films

    DEFF Research Database (Denmark)

    Posselt, Dorthe; Zhang, Jianqi; Smilgies, Detlef-M.


    Block copolymer (BCP) thin films have been proposed for a number of nanotechnology applications, such as nanolithography and as nanotemplates, nanoporous membranes and sensors. Solvent vapor annealing (SVA) has emerged as a powerful technique for manipulating and controlling the structure of BCP...... thin films, e.g., by healing defects, by altering the orientation of the microdomains and by changing the morphology. Due to high time resolution and compatibility with SVA environments, grazing-incidence small-angle X-ray scattering (GISAXS) is an indispensable technique for studying the SVA process......, providing information of the BCP thin film structure both laterally and along the film normal. Especially, state-of-the-art combined GISAXS/SVA setups at synchrotron sources have facilitated in situ and real-time studies of the SVA process with a time resolution of a few seconds, giving important insight...

  1. Coating of reverse osmosis membranes with amphiphilic copolymers for biofouling control

    KAUST Repository

    Bucs, Szilard


    Surface coating of membranes may be a promising option to control biofilm development and biofouling impact on membrane performance of spiral-wound reverse osmosis (RO) systems. The objective of this study was to investigate the impact of an amphiphilic copolymer coating on biofilm formation and biofouling control. The coating was composed of both hydrophilic and hydrophobic monomers hydroxyethyl methacrylate (HEMA) and perfluorodecyl acrylate (PFA), respectively. Commercial RO membranes were coated with HEMA-PFA copolymer film. Long and short term biofouling studies with coated and uncoated membranes and feed spacer were performed using membrane fouling simulators (MFSs) operated in parallel, fed with water containing nutrients. For the long-term studies pressure drop development in time was monitored and after eight days the MFSs were opened and the accumulated biofilm on the membrane and spacer sheets was quantified and characterized. The presence of the membrane coating was determined using X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectroscopy (FTIR). Results showed that the amphiphilic coating (i) delayed biofouling (a lower pressure drop increase by a factor of 3 and a lower accumulated active biomass amount by a factor of 6), (ii) influenced the biofilm composition (23% lower polysaccharides and 132% higher protein content) and (iii) was still completely present on the membrane at the end of the biofouling study, showing that the coating was strongly attached to the membrane surface. Using coated membranes and feed spacers in combination with advanced cleaning strategies may be a suitable way to control biofouling.

  2. Block Copolymer Metastability: Scientific Nightmare or Engineering Dream? (United States)

    Bates, Frank S.


    Most experimental studies and almost all theories that deal with block copolymers, or mixtures of block copolymers and homopolymers, have been designed from an equilibrium perspective. Yet a myriad of factors conspire to retard approach to equilibrium in these systems, including: subtle features in the free energy surface that are controlled by ordered state symmetry; a coupling between microphase separation and entanglement dynamics; complex molecular architectures such as multiblock, starblock, and miktoarm. Even unentangled low molecular weight diblock copolymers, the simplest and dynamically least encumbered materials, exhibit long-lived metastable states that confound attempts to validate equilibrium theories. However, this apparent dilemma can be exploited through clever processing strategies. This lecture will address two opposing consequences of block copolymer metastability. The first is a potential nightmare: Can we ever establish universal block copolymer phase diagrams? The second is the stuff of dreams: Self-assembled thermoset nanocomposites.

  3. Block copolymer micelles with near infrared metal phthalocyanine dyes for laser induced writing. (United States)

    Acharya, Himadri; Yoon, Bokyung; Park, Youn Jung; Bae, Insung; Park, Cheolmin


    A route has been developed to disperse metal-containing phthalocyanine dyes in a non-polar medium based on amphiphilic block copolymer micelles of poly[styrene-block-(4-vinylpyridine)] (PS-b-P4VP) and poly[styrene-block-(acrylic acid)] (PS-b-PAA) copolymers. Polar P4VP and PAA efficiently encapsulate cobalt(II), manganese(II), and nickel(II) phthalocyanine dyes by axial coordination of nitrogen and µ-oxo bridged dimerization with the transition metals, respectively. Good dispersion of the dyes is confirmed by the linear enhancement of Q-bands in UV-vis absorption spectra with dye concentration. A thin monolayered PS-b-P4VP micelle film that contained a nickel(II) phthalocyanine dye which efficiently adsorbs a laser beam on a localized area to generate a local heat higher than the glass transition temperatures of both blocks. One-dimensional laser writing on the dye-containing film allows the fabrication of a few submicrometer wide line patterns in which the self-assembled nanostructure of the block copolymer is modified by the directional heat arising from laser scanning. Copyright © 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  4. Aggregation behavior or amphiphilic poly(2-alkyl-2-oxazoline) diblock copolymers in aqueous solution studied by fluorescence correlation spectroscopy

    Czech Academy of Sciences Publication Activity Database

    Bonné, T. B.; Lüdtke, K.; Jordan, R.; Štěpánek, Petr; Papadakis, C. M.


    Roč. 282, č. 12 (2004), s. 833-843 ISSN 0303-402X R&D Projects: GA AV ČR IAA4050403 Keywords : self-diffusion * fluorescence correlation spectroscopy * amphiphilic diblock copolymers Subject RIV: CD - Macromolecular Chemistry Impact factor: 1.110, year: 2004

  5. Morphological studies on block copolymer modified PA 6 blends (United States)

    Poindl, M.; Bonten, C.


    Recent studies show that compounding polyamide 6 (PA 6) with a PA 6 polyether block copolymers made by reaction injection molding (RIM) or continuous anionic polymerization in a reactive extrusion process (REX) result in blends with high impact strength and high stiffness compared to conventional rubber blends. In this paper, different high impact PA 6 blends were prepared using a twin screw extruder. The different impact modifiers were an ethylene propylene copolymer, a PA PA 6 polyether block copolymer made by reaction injection molding and one made by reactive extrusion. To ensure good particle matrix bonding, the ethylene propylene copolymer was grafted with maleic anhydride (EPR-g-MA). Due to the molecular structure of the two block copolymers, a coupling agent was not necessary. The block copolymers are semi-crystalline and partially cross-linked in contrast to commonly used amorphous rubbers which are usually uncured. The combination of different analysis methods like atomic force microscopy (AFM), transmission electron microscopy (TEM) and scanning electron microscopy (SEM) gave a detailed view in the structure of the blends. Due to the partial cross-linking, the particles of the block copolymers in the blends are not spherical like the ones of ethylene propylene copolymer. The differences in molecular structure, miscibility and grafting of the impact modifiers result in different mechanical properties and different blend morphologies.

  6. Mixed micellization between natural and synthetic block copolymers: β-casein and Lutrol F-127. (United States)

    Portnaya, Irina; Khalfin, Rafail; Kesselman, Ellina; Ramon, Ory; Cogan, Uri; Danino, Dganit


    Amphiphilic block copolymers and mixtures of amphiphiles find broad applications in numerous technologies, including pharma, food, cosmetic and detergency. Here we report on the interactions between a biological charged diblock copolymer, β-casein, and a synthetic uncharged triblock copolymer, Lutrol F-127 (EO(101)PO(56)EO(101)), on their mixed micellization characteristics and the micelles' structure and morphology. Isothermal titration calorimetry (ITC) experiments indicate that mixed micelles form when Lutrol is added to monomeric as well as to assembled β-casein. The main driving force for the mixed micellization is the hydrophobic interactions. Above β-casein CMC, strong perturbations caused by penetration of the hydrophobic oxypropylene sections of Lutrol into the protein micellar core lead to disintegration of the micelles and reformation of mixed Lutrol/β-casein micelles. The negative enthalpy of micelle formation (ΔH) and cooperativity increase with raising β-casein concentration in solution. ζ-potential measurements show that Lutrol interacts with the protein micelles to form mixed micelles even below its critical micellization temperature (CMT). They further indicate that Lutrol effectively masks the protein charges, probably by forming a coating layer of the ethyleneoxide rich chains. Small-angle X-ray scattering (SAXS) and cryogenic-transmission electron microscopy (cryo-TEM) indicate relatively small changes in the oblate micellar shape, but do show swelling along the small axis of β-casein micelles in the presence of Lutrol, thereby confirming the formation of mixed micelles.

  7. Electrochemically controlled self-assembly of block copolymer nanostructures (United States)

    Eitouni, Hany Basam

    Organometallic block copolymers, wherein one block is composed of alternating ferrocene and dialkylsilane units in the main chain, undergo self-assembly to form microphase-separated ordered structures similarly to typical organic block copolymers. The 1,1'-dimethylsilylferrocenophane monomer was synthesized and polymerized anionically with other monomers to make a variety of different organometallic block copolymers. The phase behavior and thermodynamic interactions of anionically synthesized poly(styrene-block-ferrocenyldimethylsilane) (SF) and poly(isoprene-block-ferrocenyldimethylsilane) (IF) copolymers were examined using depolarized light scattering, small angle x-ray and neutron scattering (SAXS and SANS), and transmission electron microscopy. The temperature-dependence of the Flory-Huggins parameter, chi, and the statistical segment lengths of SF and IF copolymers were determined by SAXS and SANS using the random phase approximation. The thermodynamic interactions in poly(ferrocenyldimethylsilane) diblock copolymers were systematically adjusted by oxidizing the ferrocene moieties with silver salts and examined using SAXS and depolarized light scattering. The polymers retained microphase separated ordered structures upon oxidation and showed systematic changes in the location of the order-disorder transition as a function of extent of oxidation. By controlling the redox properties of the ferrocene moiety in the backbone of the polymer, we present a method for controlling the self-assembled microstructure and hence bulk material properties. Using electrochemical techniques, a novel means of controlling the order-disorder transition of block copolymers was discovered. By applying very small electrical potentials to disordered solutions of organometallic block copolymers, oriented ordered grains were formed near one electrode, the result of electrochemical reactions. After reversing the electrical bias on the system, the ordered grains disappeared and new

  8. Colloidal ionic assembly between anionic native cellulose nanofibrils and cationic block copolymer micelles into biomimetic nanocomposites. (United States)

    Wang, Miao; Olszewska, Anna; Walther, Andreas; Malho, Jani-Markus; Schacher, Felix H; Ruokolainen, Janne; Ankerfors, Mikael; Laine, Janne; Berglund, Lars A; Osterberg, Monika; Ikkala, Olli


    We present a facile ionic assembly between fibrillar and spherical colloidal objects toward biomimetic nanocomposites with majority hard and minority soft domains based on anionic reinforcing native cellulose nanofibrils and cationic amphiphilic block copolymer micelles with rubbery core. The concept is based on ionic complexation of carboxymethylated nanofibrillated cellulose (NFC, or also denoted as microfibrillated cellulose, MFC) and micelles formed by aqueous self-assembly of quaternized poly(1,2-butadiene)-block-poly(dimethylaminoethyl methacrylate) with high fraction of the NFC reinforcement. The adsorption of block copolymer micelles onto nanocellulose is shown by quartz crystal microbalance measurements, atomic force microscopy imaging, and fluorescent optical microscopy. The physical properties are elucidated using electron microscopy, thermal analysis, and mechanical testing. The cationic part of the block copolymer serves as a binder to NFC, whereas the hydrophobic rubbery micellar cores are designed to facilitate energy dissipation and nanoscale lubrication between the NFC domains under deformation. We show that the mechanical properties do not follow the rule of mixtures, and synergistic effects are observed with promoted work of fracture in one composition. As the concept allows wide possibilities for tuning, the work suggests pathways for nanocellulose-based biomimetic nanocomposites combining high toughness with stiffness and strength.

  9. Radiation crosslinked block copolymer blends with improved impact resistance

    International Nuclear Information System (INIS)

    Saunders, F.L.; Pelletier, R.R.


    Polymer blends having high impact resistance after mechanical working are produced by blending together a non-elastomeric monovinylidene aromatic polymer such as polystyrene with an elastomeric copolymer, such as a block copolymer of styrene and butadiene, in the form of crosslinked, colloidal size particles

  10. Tensile properties of segmented block copolymers with monodisperse hard segments

    NARCIS (Netherlands)

    Biemond, G.J.E.; Feijen, Jan; Gaymans, R.J.


    The tensile properties of segmented block copolymers with mono-disperse hard segments were studied with respect to the hard segment content (16–44 wt.%) and the temperature (20–110 °C). The copolymers were comprised of poly(tetramethylene oxide) segments with the molecular weights of 650–2,900 Da

  11. Functional Block Copolymers via Anionic Polymerization for Electroactive Membranes


    Schultz, Alison


           Ion-containing block copolymers blend ionic liquid properties with well-defined polymer architectures. This provides conductive materials with robust mechanical stability, efficient processability, and tunable macromolecular design. Conventional free radical polymerization and anion exchange achieved copolymers containing n-butyl acrylate and phosphonium ionic liquids. These compositions incorporated vinylbenzyl triphenyl phosphonium and vinylbenzyl tricyclohexyl phosphonium cations be...

  12. Graphene oxide-enhanced sol-gel transition sensitivity and drug release performance of an amphiphilic copolymer-based nanocomposite (United States)

    Hu, Huawen; Wang, Xiaowen; Lee, Ka I; Ma, Kaikai; Hu, Hong; Xin, John H.


    We report the fabrication of a highly sensitive amphiphilic copolymer-based nanocomposite incorporating with graphene oxide (GO), which exhibited a low-intensity UV light-triggered sol-gel transition. Non-cytotoxicity was observed for the composite gels after the GO incorporation. Of particular interest were the microchannels that were formed spontaneously within the GO-incorporated UV-gel, which expedited sustained drug release. Therefore, the present highly UV-sensitive, non-cytotoxic amphiphilic copolymer-based composites is expected to provide enhanced photothermal therapy and chemotherapy by means of GO’s unique photothermal properties, as well as through efficient passive targeting resulting from the sol-gel transition characteristic of the copolymer-based system with improved sensitivity, which thus promises the enhanced treatment of patients with cancer and other diseases. PMID:27539298

  13. Synthesis and Characterization of Smart Block Copolymers for Biomineralization and Biomedical Applications

    Energy Technology Data Exchange (ETDEWEB)

    Kanapathipillai, Mathumai [Iowa State Univ., Ames, IA (United States)


    Self-assembly is a powerful tool in forming structures with nanoscale dimensions. Self-assembly of macromolecules provides an efficient and rapid pathway for the formation of structures from the nanometer to micrometer range that are difficult, if not impossible to obtain by conventional lithographic techniques [1]. Depending on the morphologies obtained (size, shape, periodicity, etc.) these self-assembled systems have already been applied or shown to be useful for a number of applications in nanotechnology [2], biomineralization [3, 4], drug delivery [5, 6] and gene therapy [7]. In this respect, amphiphilic block copolymers that self-organize in solution have been found to be very versatile [1]. In recent years, polymer-micellar systems have been designed that are adaptable to their environment and able to respond in a controlled manner to external stimuli. In short, synthesis of 'nanoscale objects' that exhibit 'stimulus-responsive' properties is a topic gathering momentum, because their behavior is reminiscent of that exhibited by proteins [8]. By integrating environmentally sensitive homopolymers into amphiphilic block copolymers, smart block copolymers with self assembled supramolecular structures that exhibit stimuli or environmentally responsive properties can be obtained [1]. Several synthetic polymers are known to have environmentally responsive properties. Changes in the physical, chemical or biochemical environment of these polymers results in modulation of the solubility or chain conformation of the polymer [9]. There are many common schemes of engineering stimuli responsive properties into materials [8, 9]. Polymers exhibiting lower critical solution temperature (LCST) are soluble in solvent below a specific temperature and phase separate from solvent above that temperature while polymers exhibiting upper critical solution temperatures (UCST) phase separate below a certain temperature. The solubility of polymers with ionizable

  14. Microbial production of polyhydroxyalkanoate block copolymer by recombinant Pseudomonas putida. (United States)

    Li, Shi Yan; Dong, Cui Ling; Wang, Shen Yu; Ye, Hai Mu; Chen, Guo-Qiang


    Polyhydroxyalkanoate (PHA) synthesis genes phaPCJ(Ac) cloned from Aeromonas caviae were transformed into Pseudomonas putida KTOY06ΔC, a mutant of P. putida KT2442, resulting in the ability of the recombinant P. putida KTOY06ΔC (phaPCJ(A.c)) to produce a short-chain-length and medium-chain-length PHA block copolymer consisting of poly-3-hydroxybutyrate (PHB) as one block and random copolymer of 3-hydroxyvalerate (3HV) and 3-hydroxyheptanoate (3HHp) as another block. The novel block polymer was studied by differential scanning calorimetry (DSC), nuclear magnetic resonance, and rheology measurements. DSC studies showed the polymer to possess two glass transition temperatures (T(g)), one melting temperature (T(m)) and one cool crystallization temperature (T(c)). Rheology studies clearly indicated a polymer chain re-arrangement in the copolymer; these studies confirmed the polymer to be a block copolymer, with over 70 mol% homopolymer (PHB) of 3-hydroxybutyrate (3HB) as one block and around 30 mol% random copolymers of 3HV and 3HHp as the second block. The block copolymer was shown to have the highest tensile strength and Young's modulus compared with a random copolymer with similar ratio and a blend of homopolymers PHB and PHVHHp with similar ratio. Compared with other commercially available PHA including PHB, PHBV, PHBHHx, and P3HB4HB, the short-chain- and medium-chain-length block copolymer PHB-b-PHVHHp showed differences in terms of mechanical properties and should draw more attentions from the PHA research community. © Springer-Verlag 2010

  15. Synthesis of Amylose-b-P2 VP Block Copolymers. (United States)

    Kumar, Kamlesh; Woortman, Albert J J; Loos, Katja


    A new class of rod-coil block copolymers is synthesized by chemoenzymatic polymerization. In the first step, maltoheptaose, which acts as a primer for the synthesis of amylose, is attached to poly(2-vinyl pyridine) (P2 VP). The enzymatic polymerization of maltoheptaose is carried out by phosphorylase to obtain amylose-b-P2 VP block copolymers. The block copolymer is characterized by Fourier transform infrared spectroscopy, nuclear magnetic resonance, gel permeation chromatography, and wide-angle X-ray scattering techniques. The designed molecules combine the inclusion complexation ability of amylose with the supramolecular complexation ability of P2 VP and therefore this kind of rod-coil block copolymers can be used to generate well-organized novel self-assembled structures. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  16. Ionic Block Copolymers for Anion Exchange Membranes (United States)

    Tsai, Tsung-Han; Herbst, Dan; Giffin, Guinevere A.; di Noto, Vito; Witten, Tom; Coughlin, E. Bryan


    Anion exchange membrane (AEM) fuel cells have regained interest because it allows the use of non-noble metal catalysts. Until now, most of the studies on AEM were based on random polyelectrolytes. In this work, Poly(vinylbenzyltrimethylammonium bromide)-b- (methylbutylene) ([PVBTMA][Br]-b-PMB) was studied by SAXS, TEM and dielectric spectroscopy to understand the fundamental structure-conductivity relationship of ion transport mechanisms within well-ordered block copolymers. The ionic conductivity and the formation of order structure were dependent on the casting solvent. Higher ion exchange capacity (IEC) of the membranes showed higher conductivity at as IEC values below 1.8mmol/g, as above this, the ionic conductivity decreases due to more water uptake leading to dilution of charge density. The humidity dependence of morphology exhibited the shifting of d-spacing to higher value and the alteration in higher characteristic peak of SAXS plot as the humidity increase from the dry to wet state. This phenomenon can be further explained by a newly developed polymer brush theory. Three ionic conduction pathways with different conduction mechanism within the membranes can be confirmed by broadband electric spectroscopy. US Army MURI (W911NF1010520)

  17. Comb-like amphiphilic polypeptide-based copolymer nanomicelles for co-delivery of doxorubicin and P-gp siRNA into MCF-7 cells

    Energy Technology Data Exchange (ETDEWEB)

    Suo, Aili, E-mail: [Department of Oncology, The First Affiliated Hospital of Xi' an Jiaotong University, Xi' an 710061 (China); Qian, Junmin, E-mail: [State Key Laboratory for Mechanical Behavior of Materials, Xi' an Jiaotong University, Xi' an 710049 (China); Zhang, Yaping; Liu, Rongrong; Xu, Weijun [State Key Laboratory for Mechanical Behavior of Materials, Xi' an Jiaotong University, Xi' an 710049 (China); Wang, Hejing [Department of Oncology, The First Affiliated Hospital of Xi' an Jiaotong University, Xi' an 710061 (China)


    A comb-like amphiphilic copolymer methoxypolyethylene glycol-graft-poly(L-lysine)-block-poly(L-phenylalanine) (mPEG-g-PLL-b-Phe) was successfully synthesized. To synthesize mPEG-g-PLL-b-Phe, diblock copolymer PLL-b-Phe was first synthesized by successive ring-opening polymerization of α-amino acid N-carboxyanhydrides followed by the removal of benzyloxycarbonyl protecting groups, and then mPEG was grafted onto PLL-b-Phe by reductive amination via Schiff's base formation. The chemical structures of the copolymers were identified by {sup 1}H NMR. mPEG-g-PLL-b-Phe copolymer had a critical micelle concentration of 6.0 mg/L and could self-assemble in an aqueous solution into multicompartment nanomicelles with a mean diameter of approximately 78 nm. The nanomicelles could encapsulate doxorubicin (DOX) through hydrophobic and π–π stacking interactions between DOX molecules and Phe blocks and simultaneously complex P-gp siRNA with cationic PLL blocks via electrostatic interactions. The DOX/P-gp siRNA-loaded nanomicelles showed spherical morphology, possessed narrow particle size distribution and had a mean particle size of 120 nm. The DOX/P-gp siRNA-loaded nanomicelles exhibited pH-responsive release behaviors and displayed accelerated release under acidic conditions. The DOX/P-gp siRNA-loaded nanomicelles were efficiently internalized into MCF-7 cells, and DOX released could successfully reach nuclei. In vitro cytotoxicity assay demonstrated that the DOX/P-gp siRNA-loaded nanomicelles showed a much higher cytotoxicity in MCF-7 cells than DOX-loaded nanomicelles due to their synergistic killing effect and that the blank nanomicelles had good biocompatibility. Thus, the novel comb-like mPEG-g-PLL-b-Phe nanomicelles could be a promising vehicle for co-delivery of chemotherapeutic drug and genetic material. - Highlights: • Comb-like amphiphilic copolymer mPEG-g-PLL-b-Phe was successfully synthesized. • Polypeptide-based copolymer could self-assemble into

  18. Micellar aggregates of amylose-block-polystyrene rod-coil block copolymers in water and THF

    NARCIS (Netherlands)

    Loos, Katja; Böker, Alexander; Zettl, Heiko; Zhang, Mingfu; Krausch, Georg; Müller, Axel H.E.; Boker, A.; Zhang, A.F.


    Amylose-block-polystyrenes with various block copolymer compositions were investigated in water and in THF solution. Fluorescence correlation spectroscopy, dynamic light, scattering (DLS), and asymmetric flow field-flow fractionation with multiangle light scattering detection indicate the presence

  19. Amphiphilic block copolymer micelles with hydrophobically modified shells

    Czech Academy of Sciences Publication Activity Database

    Jelínek, K.; Uhlík, F.; Limpouchová, Z.; Matějíček, P.; Humpolíčková, J.; Procházka, K.; Tuzar, Zdeněk; Špírková, Milena; Hof, Martin


    Roč. 29, 10-11 (2003), s. 655-660 ISSN 0892-7022 R&D Projects: GA AV ČR KSK4050111 Institutional research plan: CEZ:AV0Z4050913 Keywords : micelles * conformation * NRET Subject RIV: CD - Macromolecular Chemistry Impact factor: 0.721, year: 2003

  20. Linoleic acid functionalized amphiphilic block copolymers application in waterborne coatings

    NARCIS (Netherlands)

    Tan, B.H.


    Conventional organic solvent coating systems are a major concern in terms of safety, health and the environment and are therefore being replaced by waterborne coating systems. In the formulation of waterborne coating systems, surfactants play an important role, especially during the latex

  1. Biocompatible Soft Nanoparticles with Multiple Morphologies Obtained from Nanoprecipitation of Amphiphilic Graft Copolymers in a Backbone-Selective Solvent. (United States)

    Le Fer, Gaëlle; Le Cœur, Clémence; Guigner, Jean-Michel; Amiel, Catherine; Volet, Gisèle


    Stealth nanocarriers are a promising technology for the treatment of diseases. However, the preparation and characterization of well-defined soft nanoparticulate systems remain challenging. Here we describe a platform of amphiphilic graft copolymers leading to nanoparticles with multiple morphologies and the role of the hydrophilic backbone in their interaction with a model protein. The amphiphilic graft copolymers platform was composed of hydrophilic backbone poly(2-methyl-2-oxazoline-co-2-pentyl-2-oxazoline) (P(MeOx-co-PentOx)), prepared via cationic ring-opening polymerization. Hydrophobic poly(d,l-lactide) (PLA) chains were grafted on the backbone via Huisgen 1,3-dipolar cycloaddition. The "click" copper-catalyzed cycloaddition reactions of azides with alkynes (CuAAC) were successfully carried out, and a series of amphiphilic copolymers were prepared containing a backbone with a number-average molecular weight of 14.2 × 10 3 g mol -1 and different hydrophobic PLA grafts with various molecular weights (2.8 × 10 3 -12.4 × 10 3 g mol -1 ). These original architectures of copolymers, when nanoprecipitated in water, the backbone-selective solvent, allowed us to obtain various structures of nanoparticles with a hydrodynamic diameter in the range of 65-99 nm. More interestingly, a plurality of morphologies going from unilamellar, multilamellar, and large compound vesicles to core-shell nanoparticles and depending on the PLA molecular weights were evidenced by combining cryo-transmission electron microscopy (cryo-TEM) and small-angle neutron scattering (SANS) studies. A first evaluation of their stealthiness by studying the stability and the interaction of these nano-objects with a model protein revealed the role played by the P(MeOx-co-PentOx) in these interactions, demonstrating the utility of this amphiphilic graft copolymers platform with well-defined architectures for the design of nanocarriers in drug delivery applications.

  2. Design, synthesis, morphology and properties of semiconducting block copolymers for photonic applications

    Energy Technology Data Exchange (ETDEWEB)

    De Boer, B.


    morphology can be obtained. Morphological observations of the solid films can provide information on the local order of polymers and the influence of order on the device performance. Ultimately, this should lead to the establishment of relationships between thin-film structure/ordering and opto-electronic properties. Chapter 2 describes the design and synthesis of a series of novel diblock copolymers, in which one block is PPV and the other is a C60-functionalized polystyrene. During casting of soluble, semiconducting polymers, both the temperature and the quality of the solvent are strongly affected due to rapid evaporation of the solvent and the increasing concentration of the semiconducting polymer. The influence of the solvent temperature and the solvent quality on the chain conformation and the aggregation of semiconducting block copolymers is described in Chapter 3. In Chapter 4 the thermotropic properties and the solid-state morphology of PPV-based block copolymers are studied. As demonstrated in Chapter 5, the covalent incorporation of C60 in the PPV-based block copolymer results in a strong quenching of the photoluminescence from the PPV block, which is indicative of an efficient electron transfer at the donor-acceptor interface. Furthermore, photovoltaic devices based on thin films of donor and acceptor moieties, either a blend of donor and acceptor homopolymers or a donor-acceptor block copolymer, were prepared. In Chapter 6, the formation of highly ordered honeycomb structures upon dropcasting a solution of PPV-b-PS in CS{sub 2} is described. Chapter 7 describes a novel method to modify the surface properties of inorganic substrates by chemically grafting an initiator for Iiving free radical photopolymerizations. The design, synthesis, characterization and properties of regioregular, amphiphilic polythiophenes is described in Chapter 8. refs.

  3. Nanospheres and nanocapsules of amphiphilic copolymers constituted by methoxypolyethylene glycol cyanoacrylate and hexadecyl cyanoacrylate units

    Directory of Open Access Journals (Sweden)

    J. Puiggali


    Full Text Available Nanospheres and nanocapsules of an amphiphilic copolymer having methylated polyethylene glycol and hexadecyl lateral groups were prepared by the solvent displacement method and using confined impinging jet mixers. Degradation, thermal properties and crystalline structure were investigated. Interestingly, pegylated chains hydrolyzed through ester bond cleavage, whereas the more hydrophobic hexadecyl ester groups were resistant to degradation in aqueous media. The copolymer crystallized from the melt, giving rise to spherulites with a negative birefringence and domains corresponding to crystallization of the different lateral groups. Size distribution and morphology of nanoparticles were mainly evaluated by electron microscopy. Nanocapsules were characterized by a stable membrane with a thickness close to 5 nm that allowed efficient encapsulation of a triglyceride oil. Triclosan was selected as an example of a hydrophobic drug to be loaded in both nanospheres and nanocapsules. The release behavior of these dosage forms was clearly different. Thus, the Burst effect was practically suppressed when using nanocapsules; in addition, these showed a sustained, controlled release over a greater time period. Antimicrobial activity of triclosan loaded nanospheres and nanocapsules was evaluated using Gram-negative and Gram-positive bacteria. The former were highly sensitive to the released triclosan whereas the latter strongly depended on the number of particles in the culture medium.

  4. Long circulating micelles of an amphiphilic random copolymer bearing cell outer membrane phosphorylcholine zwitterions. (United States)

    Zhao, Jing; Chai, Yu-Dong; Zhang, Jing; Huang, Peng-Fei; Nakashima, Kenichi; Gong, Yong-Kuan


    Polymeric micelles with cell outer membrane mimetic structure were prepared in water from amphiphilic random copolymers bearing both the hydrophilic phosphorylcholine zwitterions and hydrophobic octadecyl side chains of cell outer membrane. The polymeric micelles showed sizes ranging from 80 nm to 120 nm in hydrodynamic diameter and zeta-potentials from -6.4 mV to -2.4 mV by dynamic light scattering measurements. The micelles loaded with 6-coumarin as a fluorescence probe were stable to investigate their blood circulation and biodistribution. The in vitro phagocytosis results using murine peritoneal macrophages showed 10-fold reduction compared with a reference micelle. The in vivo blood circulation half-life of the polymeric micelles following intravenous administration in New Zealand Rabbits was increased from 0.55 h to 90.5h. More interestingly, tissue distribution results showed that the concentration of the micelles in the kidney is 4-fold higher than that in the liver and other organs 48 h after administration. The results of this work show great promise for designing more effective stealth drug carriers that can minimize reticuloendothelial system clearance and circulate for long time to reach target by using simple cell membrane mimetic random copolymer micelles. Copyright © 2015 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

  5. Self-assembly of block copolymer micelles: synthesis via reversible addition-fragmentation chain transfer polymerization and aqueous solution properties. (United States)

    Mya, Khine Y; Lin, Esther M J; Gudipati, Chakravarthy S; Gose, Halima B A S; He, Chaobin


    Poly(hexafluorobutyl methacrylate) (PHFBMA) homopolymer was synthesized by reversible addition-fragmentation chain transfer (RAFT)-mediated living radical polymerization in the presence of cyano-2-propyl dithiobenzoate (CPDB) RAFT agent. A block copolymer of PHFBMA-poly(propylene glycol acrylate) (PHFBMA-b-PPGA) with dangling poly(propylene glycol) (PPG) side chains was then synthesized by using CPDB-terminated PHFBMA as a macro-RAFT agent. The amphiphilic properties and self-assembly of PHFBMA-b-PPGA block copolymer in aqueous solution were investigated by dynamic and static light scattering (DLS and SLS) studies, in combination with fluorescence spectroscopy and transmission electron microscopy (TEM). Although PPG shows moderately hydrophilic character, the formation of nanosize polymeric micelles was confirmed by fluorescence and TEM studies. The low value of the critical aggregation concentration exhibited that the tendency for the formation of copolymer aggregates in aqueous solution was very high due to the strong hydrophobicity of the PHFBMA(145)-b-PPGA(33) block copolymer. The combination of DLS and SLS measurements revealed the existence of micellar aggregates in aqueous solution with an association number of approximately 40 +/- 7 for block copolymer micelles. It was also found in TEM observation that there are 40-50 micelles accumulated into one aggregate and these micelles are loosely packed inside the aggregate.

  6. The plumber's nightmare: a new morphology in block copolymer-ceramic nanocomposites and mesoporous aluminosilicates. (United States)

    Finnefrock, Adam C; Ulrich, Ralph; Toombes, Gilman E S; Gruner, Sol M; Wiesner, Ulrich


    A novel cubic bicontinuous morphology is found in polymer-ceramic nanocomposites and mesoporous aluminosilicates that are derived by an amphiphilic diblock copolymer, poly(isoprene-b-ethylene oxide) (PI-b-PEO), used as a structure-directing agent for an inorganic aluminosilicate. Small-angle X-ray scattering (SAXS) was employed to unambiguously identify the Im(-)3m crystallographic symmetry of the materials by fitting individual Bragg peak positions in the two-dimensional X-ray images. Structure factor calculations, in conjunction with results from transmission electron microscopy, were used to narrow the range of possible structures consistent with the symmetry and showed the plumber's nightmare morphology to be consistent with the data. The samples are made by deposition onto a substrate that imposes a strain field, generating a lattice distortion. This distortion is quantitatively analyzed and shown to have resulted in shrinkage of the crystallites by approximately one-third in a direction perpendicular to the substrate, in both as-made composites and calcined ceramic materials. Finally, the observation of the bicontinuous block-copolymer-derived hybrid morphology is discussed in the context of a pseudo-ternary morphology diagram and compared to existing studies of ternary phase diagrams of amphiphiles in a mixture of two solvents. The calcined mesoporous materials have potential applications in the fields of catalysis, separation technology, and microelectronics.

  7. Near-infrared light-triggered dissociation of block copolymer micelles for controlled drug release (United States)

    Cao, Jie; Huang, Shanshan; Chen, Yuqi; Li, Siwen; Achilefu, Samuel; Qian, Zhiyu; Gu, Yueqing


    In this manuscript, a new near-infrared (NIR) light-breakable amphiphilic block copolymer containing light-sensitive triggering group on the hydrophobic block was developed. By encapsulating NIR dye cypate inside micelles of poly (N-succinyl-N'-4- (2-nitrobenzyloxy)-succinyl chitosan) and exposing the micellar solution to 765.9 nm light, the photo-cleavage reaction was activated and leading to the dissociation of micelles and release of co-loaded hydrophobic species. The UV-vis absorption spectra, fourier transform infrared (FTIR) spectra and 1H nuclear magnetic resonance (1H NMR) spectra of micelles were characterized. Triggered burst release of the payload upon NIR irradiation and subsequent degradation of the micelles were observed by transmission electron microscopy (TEM). This system represents a general and efficient method to circumvent the need for UV or visible light excitation that is a common drawback for light-responsive polymeric systems developed for potential biomedical applications.

  8. Desalination membranes from functional block copolymer via non-solvent induced phase inversion (United States)

    Sung, Hyemin; Poelma, Justin; Leibfarth, Frank; Hawker, Craig; Bang, Joona


    Commercially available reverse osmosis (RO) and forward osmosis (FO) membranes are most commonly derived from materials such as polysulfone, polyimide, and cellulose acetate. While these membranes have improved the efficiency of the desalination process, they suffer from mechanical and chemical stability, fouling issues, and low fluxes. In this study, we combine a well-established membrane formation method, non-solvent-induced phase separation, with the self-assembly of a functional amphiphilic block copolymersAn amine and acid functional polystyrene-block-poly(ethylene oxide-co-allyl glycidyl ether) were chosen for the membranes. Membranes were formed by casting a concentrated polymer solution (12 to 25 wt% polymer) on PET fabric followed by immersion in a non-solvent bath. Scanning electron microscopy revealed an asymmetric porous structure consisting of a dense skin layer on top of a highly porous layer. Membrane performance was investigating using an FO test cell under the seawater condition.

  9. From Block Copolymers to Nano-porous Materials

    DEFF Research Database (Denmark)

    Vigild, Martin Etchells; Ndoni, Sokol; Berg, Rolf Henrik


    Quantitative etching of the polydimethylsiloxane block in a series of polystyrene-polydimethylsiloxane (PS-PDMS) block copolymers is reported. Reacting the block copolymer with anhydrous hydrogen fluoride (HF) renders a nanoporous material with the remaining PS maintaining the original morphology...... in the bulk. The method is very accurate for analytical determination of the PDMS content in the samples. Several morphologies (BCC, HEX and Gyroid) are conserved in the resulting glassy PS-matrix, as ascertained by small angle X-ray scattering. Especially, films of mm thickness containing secluded spherical...... nm wide holes of BCC symmetry are produced by this procedure....

  10. Synthesis and characterization of ferrocene containing block copolymers

    DEFF Research Database (Denmark)

    Chernyy, Sergey; Wang, Zhongli; Kirkensgaard, Jacob Judas Kain


    Narrowly dispersed diblock copolymers containing poly(methyl methacrylate) [PMMA] or poly(nonafluorohexyl methacrylate) [PF9MA] as the first block and poly(ferrocenylmethyl methacrylate) [PFMMA] as the second block, were prepared by anionic polymerization for the first time. Disordered bulk morph...... of the solvent and without the need for preliminary surface modification, for example by means of grafted brush layer....

  11. Side-chain amino-acid-based pH-responsive self-assembled block copolymers for drug delivery and gene transfer. (United States)

    Kumar, Sonu; Acharya, Rituparna; Chatterji, Urmi; De, Priyadarsi


    Developing safe and effective nanocarriers for multitype of delivery system is advantageous for several kinds of successful biomedicinal therapy with the same carrier. In the present study, we have designed amino acid biomolecules derived hybrid block copolymers which can act as a promising vehicle for both drug delivery and gene transfer. Two representative natural chiral amino acid-containing (l-phenylalanine and l-alanine) vinyl monomers were polymerized via reversible addition-fragmentation chain transfer (RAFT) process in the presence of monomethoxy poly(ethylene glycol) based macro-chain transfer agents (mPEGn-CTA) for the synthesis of well-defined side-chain amino-acid-based amphiphilic block copolymers, monomethoxy poly(ethylene glycol)-b-poly(Boc-amino acid methacryloyloxyethyl ester) (mPEGn-b-P(Boc-AA-EMA)). The self-assembled micellar aggregation of these amphiphilic block copolymers were studied by fluorescence spectroscopy, atomic force microscopy (AFM) and scanning electron microscopy (SEM). Potential applications of these hybrid polymers as drug carrier have been demonstrated in vitro by encapsulation of nile red dye or doxorubicin drug into the core of the micellar nanoaggregates. Deprotection of side-chain Boc- groups in the amphiphilic block copolymers subsequently transformed them into double hydrophilic pH-responsive cationic block copolymers having primary amino groups in the side-chain terminal. The DNA binding ability of these cationic block copolymers were further investigated by using agarose gel retardation assay and AFM. The in vitro cytotoxicity assay demonstrated their biocompatible nature and these polymers can serve as "smart" materials for promising bioapplications.

  12. Pressure induced structure formation in Langmuir monolayers of amphiphilic metallocene diblock copolymers. (United States)

    Kraska, Martin; Gallei, Markus; Stühn, Bernd; Rehahn, Matthias


    We present in situ structural investigations of a metal-containing diblock copolymer on a water surface. Monolayers of poly(vinylferrocene-b-(2-vinylpyridine)) (PVFc-b-P2VP) block copolymers are studied in a wide range of compositions by varying molar masses of P2VP with two different molecular weights of PVFc. We focus on the role of the respective block partners, PVFc and P2VP, when compressing the layer on the water surface. Compression isotherms are presented and interpreted in terms of the classical gaseous, expanded, and condensed phases. We calculate isothermal compressibilities, which reveal a minimum value independent of the molar masses of the respective block partners. We find the isotherms to be dominated by P2VP while PVFc barely contribute to the compression behavior due to its rather compact coil structure. We consider the diblock copolymer monolayers as a two-dimensional model system, which is reflected by two-dimensional scaling behavior in the semi dilute and condensed regime. By X-ray reflectometry (XR), we monitor in situ the monolayer structure change with increasing surface pressure Π and observe the PVFc-b-P2VP separation at high Π.

  13. Fast & scalable pattern transfer via block copolymer nanolithography

    DEFF Research Database (Denmark)

    Li, Tao; Wang, Zhongli; Schulte, Lars


    A fully scalable and efficient pattern transfer process based on block copolymer (BCP) self-assembling directly on various substrates is demonstrated. PS-rich and PDMS-rich poly(styrene-b-dimethylsiloxane) (PS-b-PDMS) copolymers are used to give monolayer sphere morphology after spin-casting of s...... on long range lateral order, including fabrication of substrates for catalysis, solar cells, sensors, ultrafiltration membranes and templating of semiconductors or metals....

  14. Highly conductive side chain block copolymer anion exchange membranes. (United States)

    Wang, Lizhu; Hickner, Michael A


    Block copolymers based on poly(styrene) having pendent trimethyl styrenylbutyl ammonium (with four carbon ring-ionic group alkyl linkers) or benzyltrimethyl ammonium groups with a methylene bridge between the ring and ionic group were synthesized by reversible addition-fragmentation radical (RAFT) polymerization as anion exchange membranes (AEMs). The C4 side chain polymer showed a 17% increase in Cl(-) conductivity of 33.7 mS cm(-1) compared to the benzyltrimethyl ammonium sample (28.9 mS cm(-1)) under the same conditions (IEC = 3.20 meq. g(-1), hydration number, λ = ∼7.0, cast from DMF/1-propanol (v/v = 3 : 1), relative humidity = 95%). As confirmed by small angle X-ray scattering (SAXS), the side chain block copolymers with tethered ammonium cations showed well-defined lamellar morphologies and a significant reduction in interdomain spacing compared to benzyltrimethyl ammonium containing block copolymers. The chemical stabilities of the block copolymers were evaluated under severe, accelerated conditions, and degradation was observed by (1)H NMR. The block copolymer with C4 side chain trimethyl styrenylbutyl ammonium motifs displayed slightly improved stability compared to that of a benzyltrimethyl ammonium-based AEM at 80 °C in 1 M NaOD aqueous solution for 30 days.

  15. Method of forming oriented block copolymer line patterns, block copolymer line patterns formed thereby, and their use to form patterned articles

    Energy Technology Data Exchange (ETDEWEB)

    Russell, Thomas P.; Hong, Sung Woo; Lee, Dong Hyun; Park, Soojin; Xu, Ting


    A block copolymer film having a line pattern with a high degree of long-range order is formed by a method that includes forming a block copolymer film on a substrate surface with parallel facets, and annealing the block copolymer film to form an annealed block copolymer film having linear microdomains parallel to the substrate surface and orthogonal to the parallel facets of the substrate. The line-patterned block copolymer films are useful for the fabrication of magnetic storage media, polarizing devices, and arrays of nanowires.

  16. Cationic, amphiphilic copolymer micelles as nucleic acid carriers for enhanced transfection in rat spinal cord. (United States)

    Gwak, So-Jung; Nice, Justin; Zhang, Jeremy; Green, Benjamin; Macks, Christian; Bae, Sooneon; Webb, Ken; Lee, Jeoung Soo


    Spinal cord injury commonly leads to permanent motor and sensory deficits due to the limited regenerative capacity of the adult central nervous system (CNS). Nucleic acid-based therapy is a promising strategy to deliver bioactive molecules capable of promoting axonal regeneration. Branched polyethylenimine (bPEI: 25kDa) is one of the most widely studied nonviral vectors, but its clinical application has been limited due to its cytotoxicity and low transfection efficiency in the presence of serum proteins. In this study, we synthesized cationic amphiphilic copolymers, poly (lactide-co-glycolide)-graft-polyethylenimine (PgP), by grafting low molecular weight PLGA (4kDa) to bPEI (25kDa) at approximately a 3:1 ratio as an efficient nonviral vector. We show that PgP micelle is capable of efficiently transfecting plasmid DNA (pDNA) and siRNA in the presence of 10% serum in neuroglioma (C6) cells, neuroblastoma (B35) cells, and primary E8 chick forebrain neurons (CFN) with pDNA transfection efficiencies of 58.8%, 75.1%, and 8.1%, respectively. We also show that PgP provides high-level transgene expression in the rat spinal cord in vivo that is substantially greater than that attained with bPEI. The combination of improved transfection and reduced cytotoxicity in vitro in the presence of serum and in vivo transfection of neural cells relative to conventional bPEI suggests that PgP may be a promising nonviral vector for therapeutic nucleic acid delivery for neural regeneration. Gene therapy is a promising strategy to overcome barriers to axonal regeneration in the injured central nervous system. Branched polyethylenimine (bPEI: 25kDa) is one of the most widely studied nonviral vectors, but its clinical application has been limited due to cytotoxicity and low transfection efficiency in the presence of serum proteins. Here, we report cationic amphiphilic copolymers, poly (lactide-co-glycolide)-graft-polyethylenimine (PgP) that are capable of efficiently transfecting reporter

  17. Block copolymer/homopolymer dual-layer hollow fiber membranes

    KAUST Repository

    Hilke, Roland


    We manufactured the first time block copolymer dual-layer hollow fiber membranes and dual layer flat sheet membranes manufactured by double solution casting and phase inversion in water. The support porous layer was based on polystyrene and the selective layer with isopores was formed by micelle assembly of polystyrene-. b-poly-4-vinyl pyridine. The dual layers had an excellent interfacial adhesion and pore interconnectivity. The dual membranes showed pH response behavior like single layer block copolymer membranes with a low flux for pH values less than 3, a fast increase between pH4 and pH6 and a constant high flux level for pH values above 7. The dry/wet spinning process was optimized to produce dual layer hollow fiber membranes with polystyrene internal support layer and a shell block copolymer selective layer.

  18. Characterization of Lithium Polysulfide Salts in Homopolymers and Block Copolymers (United States)

    Wang, Dunyang; Wujcik, Kevin; Balsara, Nitash

    Ion-conducting polymers are important for solid-state batteries due to the promise of better safety and the potential to produce higher energy density batteries. Nanostructured block copolymer electrolytes can provide high ionic conductivity and mechanical strength through microphase separation. One of the potential use of block copolymer electrolytes is in lithium-sulfur batteries, a system that has high theoretical energy density wherein the reduction of sulfur leads to the formation of lithium polysulfide intermediates. In this study we investigate the effect of block copolymer morphology on the speciation and transport properties of the polysulfides. The morphology and conductivities of polystyrene-b-poly(ethylene oxide) (SEO) containing lithium polysulfides were studies using small-angle X-ray scattering and ac impedance spectroscopy. UV-vis spectroscopy is being used to determine nature of the polysulfide species in poly(ethylene oxide) and SEO. Department of Energy, Soft Matter Electron Microscopy Program and Battery Materials Research Program.

  19. SANS and SAXS study of block copolymer/homopolymer mixtures

    International Nuclear Information System (INIS)

    Hasegawa, Hirokazu; Tanaka, Hideaki; Hashimoto, Takeji; Han, C.C.


    The lateral and vertical components of the radius of gyration for a single block copolymer chain and those of a single homopolymer chain in the lamellar microdomain space formed by a mixture of diblock copolymers and homopolymers were investigated by means of small-angle neutron scattering (SANS) and the microdomain structures by small-angle X-ray scattering (SAXS). The homopolymers whose molecular weights are much smaller than that of the corresponding chains of the block copolymers were used so that the homopolymers were uniformly solubilized in the corresponding microdomains. The SANS result suggests that the homopolymer chains in the microdomain space as well as the block copolymer chains are more compressed in the direction parallel to the interface and more stretched in the direction perpendicular to the interface than the corresponding unperturbed polymer chains with the same molecular weight. On increasing the volume fraction of the homopolymers the thickness of the lamellar microdomains increases. The block copolymer chains were found to undergo an isochoric affine deformation on addition of the homopolymers or with the change of the thickness of the lamellar microdomains. (orig.)

  20. Controlling block copolymer phase behavior using ionic surfactant

    Energy Technology Data Exchange (ETDEWEB)

    Ray, D.; Aswal, V. K. [Solid State Physics Division, Bhabha Atomic Research Centre, Mumbai 400 085, India E-mail: (India)


    The phase behavior of poly(ethylene oxide)-poly(propylene oxide-poly(ethylene oxide) PEO-PPO-PEO triblock copolymer [P85 (EO{sub 26}PO{sub 39}EO{sub 26})] in presence of anionic surfactant sodium dodecyl sulfate (SDS) in aqueous solution as a function of temperature has been studied using dynamic light scattering (DLS) and small-angle neutron scattering (SANS). The measurements have been carried out for fixed concentrations (1 wt%) of block copolymer and surfactants. Each of the individual components (block copolymer and surfactant) and the nanoparticle–surfactant mixed system have been examined at varying temperature. The block copolymer P85 forms spherical micelles at room temperature whereas shows sphere-to-rod like micelle transition at higher temperatures. On the other hand, SDS surfactant forms ellipsoidal micelles over a wide temperature range. Interestingly, it is found that phase behavior of mixed micellar system (P85 + SDS) as a function of temperature is drastically different from that of P85, giving the control over the temperature-dependent phase behavior of block copolymers.

  1. Design of block copolymer membranes using segregation strength trend lines

    KAUST Repository

    Sutisna, Burhannudin


    Block copolymer self-assembly and non-solvent induced phase separation are now being combined to fabricate membranes with narrow pore size distribution and high porosity. The method has the potential to be used with a broad range of tailor-made block copolymers to control functionality and selectivity for specific separations. However, the extension of this process to any new copolymer is challenging and time consuming, due to the complex interplay of influencing parameters, such as solvent composition, polymer molecular weights, casting solution concentration, and evaporation time. We propose here an effective method for designing new block copolymer membranes. The method consists of predetermining a trend line for the preparation of isoporous membranes, obtained by computing solvent properties, interactions and copolymer block sizes for a set of successful systems and using it as a guide to select the preparation conditions for new membranes. We applied the method to membranes based on poly(styrene-b-ethylene oxide) diblocks and extended it to newly synthesized poly(styrene-b-2-vinyl pyridine-b-ethylene oxide) (PS-b-P2VP-b-PEO) terpolymers. The trend line method can be generally applied to other new systems and is expected to dramatically shorten the path of isoporous membrane manufacture. The PS-b-P2VP-b-PEO membrane formation was investigated by in situ Grazing Incident Small Angle X-ray Scattering (GISAXS), which revealed a hexagonal micelle order with domain spacing clearly correlated to the membrane interpore distances.

  2. Structure-directing star-shaped block copolymers: supramolecular vesicles for the delivery of anticancer drugs. (United States)

    Yang, Chuan; Liu, Shao Qiong; Venkataraman, Shrinivas; Gao, Shu Jun; Ke, Xiyu; Chia, Xin Tian; Hedrick, James L; Yang, Yi Yan


    Amphiphilic polycarbonate/PEG copolymer with a star-like architecture was designed to facilitate a unique supramolecular transformation of micelles to vesicles in aqueous solution for the efficient delivery of anticancer drugs. The star-shaped amphipilic block copolymer was synthesized by initiating the ring-opening polymerization of trimethylene carbonate (TMC) from methyl cholate through a combination of metal-free organo-catalytic living ring-opening polymerization and post-polymerization chain-end derivatization strategies. Subsequently, the self-assembly of the star-like polymer in aqueous solution into nanosized vesicles for anti-cancer drug delivery was studied. DOX was physically encapsulated into vesicles by dialysis and drug loading level was significant (22.5% in weight) for DOX. Importantly, DOX-loaded nanoparticles self-assembled from the star-like copolymer exhibited greater kinetic stability and higher DOX loading capacity than micelles prepared from cholesterol-initiated diblock analogue. The advantageous disparity is believed to be due to the transformation of micelles (diblock copolymer) to vesicles (star-like block copolymer) that possess greater core space for drug loading as well as the ability of such supramolecular structures to encapsulate DOX. DOX-loaded vesicles effectively inhibited the proliferation of 4T1, MDA-MB-231 and BT-474 cells, with IC50 values of 10, 1.5 and 1.0mg/L, respectively. DOX-loaded vesicles injected into 4T1 tumor-bearing mice exhibited enhanced accumulation in tumor tissue due to the enhanced permeation and retention (EPR) effect. Importantly, DOX-loaded vesicles demonstrated greater tumor growth inhibition than free DOX without causing significant body weight loss or cardiotoxicity. The unique ability of the star-like copolymer emanating from the methyl cholate core provided the requisite modification in the block copolymer interfacial curvature to generate vesicles of high loading capacity for DOX with significant

  3. Self-Assembly of Block Copolymer Chains To Promote the Dispersion of Nanoparticles in Polymer Nanocomposites (United States)


    In this paper we adopt molecular dynamics simulations to study the amphiphilic AB block copolymer (BCP) mediated nanoparticle (NP) dispersion in polymer nanocomposites (PNCs), with the A-block being compatible with the NPs and the B-block being miscible with the polymer matrix. The effects of the number and components of BCP, as well as the interaction strength between A-block and NPs on the spatial organization of NPs, are explored. We find that the increase of the fraction of the A-block brings different dispersion effect to NPs than that of B-block. We also find that the best dispersion state of the NPs occurs in the case of a moderate interaction strength between the A-block and the NPs. Meanwhile, the stress–strain behavior is probed. Our simulation results verify that adopting BCP is an effective way to adjust the dispersion of NPs in the polymer matrix, further to manipulate the mechanical properties. PMID:28892620

  4. Stabilization and controlled association of superparamagnetic nanoparticles using block copolymers

    International Nuclear Information System (INIS)

    Frka-Petesic, Bruno; Fresnais, Jerome; Berret, Jean-Francois; Dupuis, Vincent; Perzynski, Regine; Sandre, Olivier


    Mixing in aqueous solutions polyelectrolyte-neutral block copolymers with oppositely charged species, spontaneously forms stable core-shell complexes, which are electrostatically driven. We report here on the structural and orientational properties of such mixed magnetic nanoclusters made of magnetic iron oxide nanoparticles (MNPs) and polyelectrolyte-neutral block copolymers. Small angle neutron scattering and transmission electron microscopy experiments allows to probe the inner-core nanoparticle organization, leading to an average interparticle distance and confirming the hierarchical internal structure of the clusters. Thanks to the MNP optical anisotropy, we also probe the under-magnetic field orientational properties of the core-shell clusters and their dynamical rotational relaxation

  5. Development of Fully Degradable Phosphonium-Functionalized Amphiphilic Diblock Copolymers for Nucleic Acids Delivery. (United States)

    Borguet, Yannick P; Khan, Sarosh; Noel, Amandine; Gunsten, Sean P; Brody, Steven L; Elsabahy, Mahmoud; Wooley, Karen L


    To expand the range of functional polymer materials to include fully hydrolytically degradable systems that bear bioinspired phosphorus-containing linkages both along the backbone and as cationic side chain moieties for packaging and delivery of nucleic acids, phosphonium-functionalized polyphosphoester- block-poly(l-lactide) copolymers of various compositions were synthesized, fully characterized, and their self-assembly into nanoparticles were studied. First, an alkyne-functionalized polyphosphoester- block-poly(l-lactide) copolymer was synthesized via a one pot sequential ring opening polymerization of an alkyne-functionalized phospholane monomer, followed by the addition of l-lactide to grow the second block. Second, the alkynyl side groups of the polyphosphoester block were functionalized via photoinitiated thiol-yne radical addition of a phosphonium-functionalized free thiol. The polymers of varying phosphonium substitution degrees were self-assembled in aqueous buffers to afford formation of well-defined core-shell assemblies with an average size ranging between 30 and 50 nm, as determined by dynamic light scattering. Intracellular delivery of the nanoparticles and their effects on cell viability and capability at enhancing transfection efficiency of nucleic acids (e.g., siRNA) were investigated. Cell viability assays demonstrated limited toxicity of the assembly to RAW 264.7 mouse macrophages, except at high polymer concentrations, where the polymer of high degree of phosphonium functionalization induced relatively higher cytotoxicity. Transfection efficiency was strongly affected by the phosphonium-to-phosphate (P + /P - ) ratios of the polymers and siRNA, respectively. The AllStars Hs Cell Death siRNA complexed to the various copolymers at a P + /P - ratio of 10:1 induced comparable cell death to Lipofectamine. These fully degradable nanoparticles might provide biocompatible nanocarriers for therapeutic nucleic acid delivery.

  6. Protective effects of nonionic tri-block copolymers on bile acid-mediated epithelial barrier disruption.

    Energy Technology Data Exchange (ETDEWEB)

    Edelstein, A.; Fink, D.; Musch, M.; Valuckaite, V.; Zabornia, O.; Grubjesic, S.; Firestone, M. A.; Matthews, J. B.; Alverdy, J. C. (Materials Science Division); (Univ. of Chicago)


    Translocation of bacteria and other luminal factors from the intestine following surgical injury can be a major driver of critical illness. Bile acids have been shown to play a key role in the loss of intestinal epithelial barrier function during states of host stress. Experiments to study the ability of nonionic block copolymers to abrogate barrier failure in response to bile acid exposure are described. In vitro experiments were performed with the bile salt sodium deoxycholate on Caco-2 enterocyte monolayers using transepithelial electrical resistance to assay barrier function. A bisphenol A coupled triblock polyethylene glycol (PEG), PEG 15-20, was shown to prevent sodium deoxycholate-induced barrier failure. Enzyme-linked immunosorbent assay, lactate dehydrogenase, and caspase 3-based cell death detection assays demonstrated that bile acid-induced apoptosis and necrosis were prevented with PEG 15-20. Immunofluorescence microscopic visualization of the tight junctional protein zonula occludens 1 (ZO-1) demonstrated that PEG 15-20 prevented significant changes in tight junction organization induced by bile acid exposure. Preliminary transepithelial electrical resistance-based studies examining structure-function correlates of polymer protection against bile acid damage were performed with a small library of PEG-based copolymers. Polymer properties associated with optimal protection against bile acid-induced barrier disruption were PEG-based compounds with a molecular weight greater than 10 kd and amphiphilicity. The data demonstrate that PEG-based copolymer architecture is an important determinant that confers protection against bile acid injury of intestinal epithelia.

  7. Synthesis and Characterization of Star-Shaped Block Copolymer sPCL-b-PEG-GA

    Directory of Open Access Journals (Sweden)

    Yi Zhang


    Full Text Available Compared to linear polymers with the same molecular weight, star-shaped polymers have the superiority of drug loading and delivery. The glycyrrhetinic acid (GA from licorice is remarkably characteristic of liver distribution and liver cells targetability. In this paper, four-armed star-shaped polycaprolactone was synthesized and amino polyethylene glycol was modified by glycyrrhetinic acid (NH2-PEG-GA. Then the condensation reaction between the two above polymers finally produced four-armed star-shaped poly(ethylene glycol-b-poly(ε-caprolactone block copolymer (sPCL-b-PEG-GA. The structures of the intermediates and product were characterized by 1H NMR. The results indicated that the structure and molecular weight of sPCL-b-PEG-GA can be controlled by the varied ratios of pentaerythritol (PTOL to ε-caprolactone (ε-CL in the presence of stannous octoate (Sn(Oct2, and the amphiphilic copolymer sPCL-b-PEG-GA consists of PTOL as core, PCL as inner hydrophobic segments, PEG as external hydrophilic segments, and terminal glycyrrhetic acid as targeting ligand. The work explored a new synthesis route of star poly(ethylene glycol-b-poly(ε-caprolactone copolymer with liver targetability. The star-shaped polymer is expected to be an efficient drug carrier.

  8. Self-assembly behavior of well-defined polymethylene-block-poly(ethylene glycol) copolymers in aqueous solution

    KAUST Repository

    Alkayal, Nazeeha


    A series of well-defined amphiphilic polymethylene-b-poly(ethylene glycol) (PM-b-PEG) diblock copolymers, with different hydrophobic chain length, were synthesized by combining Diels-Alder reaction with polyhomologation. The successful synthetic procedure was confirmed by size-exclusion chromatography (SEC) and 1H NMR spectroscopy. These block copolymers self-assembled into spherical micelles in aqueous solutions and exhibit low critical micelle concentration (CMC) of 2–4 mg/mL, as determined by fluorescence spectroscopy using pyrene as a probe. Measurements of the micelle hydrodynamic diameters, performed by dynamic light scattering (DLS), cryo-transmission electron microscopy (cryo-TEM) and atomic force microscopy (AFM), revealed a direct dependence of the micelle size from the polymethylene block length.

  9. Preparation and Performance of Amphiphilic Random Copolymer Noncovalently Modified MWCNTs/Epoxy Composite

    Directory of Open Access Journals (Sweden)

    MA Qiang


    Full Text Available An amphiphilic random copolymer of polyglycidyl methacrylate-co-N-vinyl carbazole P(GMA-co-NVC was synthesized by free radical polymerization and was used to noncovalently modify multi-walled carbon nanotubes (MWCNTs. The obtained P(GMA-co-NVC/MWCNTs was mixed with epoxy resin and used to reinforce epoxy resin. Polymer modified carbon nanotubes/epoxy resin composites were prepared by a casting molding method. Tensile test, electrical resistivity test and differential scanning calorimeter(DSC analysis were used to study the effect of polymer modified carbon nanotubes on the mechanical, electrical, and thermal properties of epoxy resin. The results show that the epoxy composite reinforced with P(GMA-co-NVC/MWCNTs shows a remarkable enhancement in both tensile strength and elongation at break compared to either the pure epoxy or the pristine MWCNTs/epoxy composites. In addition, the electrical conductivity of epoxy is significantly improved and the volume resistivity decreases from 1014Ω·m to 106Ω·m with 0.25% mass fraction loading of P(GMA-co-NVC/MWCNTs. Moreover, glass transition temperature of the epoxy composite also increases from 144℃ to 149℃.

  10. Synthesis and Characterization of Silicate Ester Prodrugs and Poly(ethylene glycol)-b-poly(lactic-co-glycolic acid) Block Copolymers for Formulation into Prodrug-Loaded Nanoparticles (United States)

    Wohl, Adam Richard

    Fine control of the physical and chemical properties of customized materials is a field that is rapidly advancing. This is especially critical in pursuits to develop and optimize novel nanoparticle drug delivery. Specifically, I aim to apply chemistry concepts to test the hypothesis "Silicate ester prodrugs of paclitaxel, customized to have the proper hydrophobicity and hydrolytic lability, can be formulated with well-defined, biocompatible, amphiphilic block copolymers into nanoparticles that are effective drugs." Chapter 1 briefly describes the context and motivation of the scientific pursuits described in this thesis. In Chapter 2, a family of model silicate esters is synthesized, the hydrolysis rate of each compound is benchmarked, and trends are established based upon the steric bulk and leaving group ability of the silicate substituents. These trends are then applied to the synthesis of labile silicate ester prodrugs in Chapter 3. The bulk of this chapter focuses on the synthesis, hydrolysis, and cytotoxicity of prodrugs based on paclitaxel, a widely used chemotherapeutic agent. In Chapter 4, a new methodology for the synthesis of narrowly dispersed, "random" poly(lactic-co-glycolic acid) polymers by a constant infusion of the glycolide monomer is detailed. Using poly(ethylene glycol) as a macroinitiator, amphiphilic block copolymers were synthesized. Co-formulating a paclitaxel silicate and an amphiphilic block copolymer via flash nanoprecipitation led to highly prodrug-loaded, kinetically trapped nanoparticles. Studies to determine the structure, morphology, behavior, and efficacy of these nanoparticles are described in Chapter 5. Efforts to develop a general strategy for the selective end-functionalization of the polyether block of these amphiphilic block copolymers are discussed in Chapter 6. Examples of this strategy include functionalization of the polyether with an azide or a maleimide. Finally, Chapter 7 provides an outlook for future development of

  11. Funding initiates production of tunable nano-porous block copolymer membranes

    KAUST Repository

    Peinemann, Klaus-Viktor


    Researchers in Saudi Arabia at King Abdullah University of Science & Technology have created a membrane comprising a thin layer of densely packed, highly ordered cylindrical channels with uniform pore sizes - oriented perpendicular to its surface - on top of a non-ordered sponge-like layer. It is fabricated in a fast, one-step process by combining the self-assembly of an amphiphilic block copolymer (PS- b-P4VP) with non-solvent-induced phase separation. The university\\'s "Seed Fund" has helped the researchers to start manufacturing this membrane, which is particularly suited to size-selective and charge-based separation of bio-molecules. © 2013 Elsevier Ltd.

  12. Synthesis, Characterization and Bulk Properties of Amphiphilic Copolymers Containing Fluorinated Methacrylates from Sequential Copper-Mediated Radical Polymerization

    DEFF Research Database (Denmark)

    Hansen, Natanya Majbritt Louie; Gerstenberg, Michael; Haddleton, David M.


    ABSTRACT: The partly fluorinated monomers, 2,2,2-trifluoroethyl methacrylate (3FM), 2,2,3,3,4,4,5,5-octafluoropentyl methacrylate (8FM), and 1,1,2,2-tetrahydroperfluorodecyl methacrylate (17FM) have been used in the preparation of block copolymers with methyl methacrylate (MMA), 2-methoxyethyl...... acrylate (MEA), and poly(ethylene glycol) methyl ether methacrylate (PEGMA) by Atom Transfer Radical Polymerization. A kinetic study of the 3FM homopolymerization initiated with ethyl bromoisobutyrate and Cu(I)Br/N-(n-propyl)-2-pyridylmethanimine reveals a living/ controlled polymerization in the range 80......-110 °C, with apparent rate constants of 1.6 . 10-4 S-l to 2.9 . 10-4 S-l. Various 3FM containing block copolymers with MMA are prepared by sequential monomer addition or from a PMMA macroinitiator in all cases with controlled characteristics. Block copolymers of 3FM and PEGMA resulted in block copolymers...

  13. Solution Self-Assemblies of Sequence-Defined Ionic Peptoid Block Copolymers. (United States)

    Sternhagen, Garrett L; Gupta, Sudipta; Zhang, Yueheng; John, Vijay; Schneider, Gerald J; Zhang, Donghui


    A series of amphiphilic ionic peptoid block copolymers where the total number (1 or 3) and position of ionic monomers along the polymer chain are precisely controlled have been synthesized by the submonomer method. Upon dissolution in water at pH = 9, the amphiphilic peptoids self-assemble into small spherical micelles having hydrodynamic radius in ∼5-10 nm range and critical micellar concentration (CMC) in the 0.034-0.094 mg/mL range. Small-angle neutron scattering (SANS) analysis of the micellar solutions revealed unprecedented dependence of the micellar structure on the number and position of ionic monomers along the chain. It was found that the micellar aggregation number ( N agg ) and the micellar radius ( R m ) both increase as the ionic monomer is positioned progressively away from the junction of the hydrophilic and hydrophobic segments along the polymer chain. By defining an ionic monomer position number ( n) as the number of monomers between the junction and the ionic monomer, N agg exhibited a power law dependence on n with an exponent of ∼1/3 and ∼3/10 for the respective singly and triply charged series. By contrast, R m exhibited a weaker dependence on the ionic monomer position by a power law relationship with an exponent of ∼1/10 and ∼1/20 for the respective singly and triply charged series. Furthermore, R m was found to scale with N agg in a power-law relationship with an exponent of 0.32 for the singly charged series, consistent with a weakly charged ionic star-like polymer model in the unscreened regime. This study demonstrated a unique method to precisely tailor the structure of small spherical micelles based on ionic block copolymers by controlling the sequence and position of the ionic monomer.

  14. Kinetics of block-copolymer aggregation in supercritical CO2

    Czech Academy of Sciences Publication Activity Database

    Triolo, A.; Lo Celso, F.; Triolo, F.; Amenitsch, H.; Steinhart, Miloš; Thiyagarajan, P.; Wells, S.; DeSimone, J. M.; Triolo, R.


    Roč. 307, - (2002), s. 725-730 ISSN 0022-3093 R&D Projects: GA AV ČR KSK4050111 Keywords : block copolymers * X-ray scattering * small-angle Subject RIV: CD - Macromolecular Chemistry Impact factor: 1.435, year: 2002

  15. A Block Copolymer for Functionalisation of Polymersome Surfaces

    NARCIS (Netherlands)

    van Dongen, Stijn; Nallani, Madhavan; Schoffelen, S.; Cornelissen, Jeroen Johannes Lambertus Maria; Nolte, Roeland; van Hest, Jan


    A block copolymer was designed to functionalise the surface of polystyrene-based polymersomes via coaggregation. An α,ω-diacetylene-functionalised poly(ethylene glycol) (PEG) was coupled to an azide-terminated polystyrene via a Cu(I)-catalysed cycloaddition to produce a PS-b-PEG polymer with an

  16. Asymmetric block copolymers confined in a thin film

    NARCIS (Netherlands)

    Huinink, HP; Brokken-Zijp, JCM; van Dijk, MA; Sevink, GJA


    We have used a dynamic density functional theory (DDFT) for polymeric systems, to simulate the formation of micro phases in a melt of an asymmetric block copolymer, A(n)B(m)(f(A) = 1/3), both in the bulk and in a thin film. In the DDFT model a polymer is represented as a chain of springs and beads.

  17. Sprayable Elastic Conductors Based on Block Copolymer Silver Nanoparticle Composites


    Vural, Mert; Behrens, Adam M.; Ayyub, Omar B.; Ayoub, Joseph J.; Kofinas, Peter


    Block copolymer silver nanoparticle composite elastic conductors were fabricated through solution blow spinning and subsequent nanoparticle nucleation. The reported technique allows for conformal deposition onto nonplanar substrates. We additionally demonstrated the ability to tune the strain dependence of the electrical properties by adjusting nanoparticle precursor concentration or localized nanoparticle nucleation. The stretchable fiber mats were able to display electrical conductivity val...

  18. Hydrophilic segmented block copolymers based on poly(ethylene oxide)

    NARCIS (Netherlands)

    Husken, D.


    Segmented block copolymers consist of alternating flexible segments and crystallisable rigid segments. The flexible segments have a low glass transition temperature and are used to obtain flexible materials. The rigid segments can crystallise and act as thermal-reversible physical crosslinks, giving

  19. Mesoscale Modelling of Block Copolymers under External Fields.

    NARCIS (Netherlands)

    Lyakhova, Kateryna S.


    A remarkable feature of block copolymer systems is their ability to self-assemble into a variety of ordered structures with domain sizes in the mesoscale range. One of the open questions is the dynamics of structure formation, which can be highly dependent on external fields often present in

  20. Polystyrene-b-polyethylene oxide block copolymer membranes, methods of making, and methods of use

    KAUST Repository

    Peinemann, Klaus-Viktor


    Embodiments of the present disclosure provide for polystyrene-b-polyethylene oxide (PS-b-PEO) block copolymer nanoporous membranes, methods of making a PS-b-PEO block copolymer nanoporous membrane, methods of using PS-b-PEO block copolymer nanoporous membranes, and the like.

  1. Novel multiarm star block copolymer ionomers as proton conductive membranes


    Demirel, Adem Levent; Erdoğan, Tuba; Bilir, Çiğdem; Ünveren, Elif; Tunca, Ümit


    A series of well-defined novel multiarm star block copolymer ionomers with an average of 6, 11 and 15 arms, sulfonated polystyrene-block-poly(2,2,3,3,3-pentafluoropropyl methacrylate) (SPS-b-PFPMA), were prepared via a combination of atom transfer radical polymerization (ATRP), Diels–Alder click reaction and postsulfonation reaction. First, multiarm star polymer with anthracene functionality as reactive periphery groups was prepared by a cross-linking reaction of divinyl benzene using ?-anthr...

  2. Self-assembled biodegradable amphiphilic PEG-PCL-lPEI triblock copolymers at the borderline between micelles and nanoparticles designed for drug and gene delivery. (United States)

    Endres, Thomas K; Beck-Broichsitter, Moritz; Samsonova, Olga; Renette, Thomas; Kissel, Thomas H


    Amphiphilic PEG-PCL-PEI triblock copolymers self-assemble into nano-scaled, positively charged, multifunctional carriers, suitable for drug and gene delivery. A set of block copolymers with varying hydrophilic/hydrophobic ratio (systematically altered at the borderline of micelle and particle forming polymers) was synthesized, characterized and assembled into carriers. A detailed structural characterization in the liquid state of these assemblies was carried out: carrier size was determined using dynamic light scattering, cryogenic scanning electron microscopy and atomic force microscopy. Nuclear magnetic resonance analyses elucidated carrier's core-shell structure. ζ-potential and thickness of the hydrophilic outer polymer shell were determined by laser Doppler anemometry. Subsequently the impact of carrier's structure on its features (stability and toxicity) was investigated. Polymers hydrophilic in nature formed small (polymers aggregated to larger particle-like assemblies (>100 nm). Monitoring carrier size as a function of initial polymer concentration clarified different assembly mechanisms. Shell thickness, colloidal stability and toxicity were found to depend on the length of the hydrophilic polymer block. Due to controllable size, charge, stability and toxicity, this class of novel carriers is a promising candidate for prospective co-delivery of drugs and nucleic acids. Copyright © 2011 Elsevier Ltd. All rights reserved.

  3. Dynamic photoinduced realignment processes in photoresponsive block copolymer films: effects of the chain length and block copolymer architecture. (United States)

    Sano, Masami; Shan, Feng; Hara, Mitsuo; Nagano, Shusaku; Shinohara, Yuya; Amemiya, Yoshiyuki; Seki, Takahiro


    A series of block copolymers composed of an amorphous poly(butyl methacrylate) (PBMA) block connected with an azobenzene (Az)-containing liquid crystalline (PAz) block were synthesized by changing the chain length and polymer architecture. With these block copolymer films, the dynamic realignment process of microphase separated (MPS) cylinder arrays of PBMA in the PAz matrix induced by irradiation with linearly polarized light was studied by UV-visible absorption spectroscopy, and time-resolved grazing incidence small angle X-ray scattering (GI-SAXS) measurements using a synchrotron beam. Unexpectedly, the change in the chain length hardly affected the realignment rate. In contrast, the architecture of the AB-type diblock or the ABA-type triblock essentially altered the realignment feature. The strongly cooperative motion with an induction period before realignment was characteristic only for the diblock copolymer series, and the LPL-induced alignment change immediately started for triblock copolymers and the PAz homopolymer. Additionally, a marked acceleration in the photoinduced dynamic motions was unveiled in comparison with a thermal randomization process.

  4. Polymers and block copolymers of fluorostyrenes by ATRP

    DEFF Research Database (Denmark)

    Hvilsted, Søren; Borkar, Sachin; Abildgaard, Lillian


    Fully or partly fluorinated polymers have many desirable and intriguing properties. In the framework of a larger program on design and control of new functional block copolymers we recently employed the Atom Transfer Radical Polymerization (ATRP) protocol on 2,3,4,5,6-pentafluorostyrene (FS). We...... materials based on 2,3,5,6-tetrafiuoro-4-methoxy-styrene (TFMS). TFMS homopolymers as well as diblock copolymers with FS are produced by ATRP. Both types of novel polymers were subsequently demethylated and different side chains introduced on the resulting hydroxy sites....

  5. Block copolymer-nanoparticle hybrid self-assembly

    KAUST Repository

    Hoheisel, Tobias N.


    © 2014 Published by Elsevier Ltd. Polymer-inorganic hybrid materials provide exciting opportunities as they may display favorable properties from both constituents that are desired in applications including catalysis and energy conversion and storage. For the preparation of hybrid materials with well-defined morphologies, block copolymer-directed nanoparticle hybrids present a particularly promising approach. As will be described in this review, once the fundamental characteristics for successful nanostructure formation at or close to the thermodynamic equilibrium of these nanocomposites are identified, the approach can be generalized to various materials classes. In addition to the discussion of recent materials developments based on the use of AB diblock copolymers as well as ABC triblock terpolymers, this review will therefore emphasize progress in the fundamental understanding of the underlying formation mechanisms of such hybrid materials. To this end, critical experiments for, as well as theoretical progress in the description of these nanostructured block copolymer-based hybrid materials will be discussed. Rather than providing a comprehensive overview, the review will emphasize work by the Wiesner group at Cornell University, US, on block copolymer-directed nanoparticle assemblies as well as their use in first potential application areas. The results provide powerful design criteria for wet-chemical synthesis methodologies for the generation of functional nanomaterials for applications ranging from microelectronics to catalysis to energy conversion and storage.

  6. Low molecular weight block copolymers as plasticizers for polystyrene

    DEFF Research Database (Denmark)

    Hansen, Kristoffer Karsten; Nielsen, Charlotte Juel; Hvilsted, Søren


    Polystyrene-b-alkyl, polystyrene-b-polybutadiene-b-polystyrene, and polystyrene-b-poly(propylene glycol)monotridecyl ether were synthesized using macro initiators and atom transfer radical polymerization or by esterifications of homopolymers. The aim was a maximum molecular weight of 4 kg....../mol and minimum polystyrene content of 50 w/w%, which by us is predicted as the limits for solubility of polystyrene-b-alkyl in polystyrene. DSC showed polystyrene was plasticized, as seen by a reduction in glass transition temperature, by block copolymers consisting of a polystyrene block with molecular weight...... for polystyrene-b-polyisoprene-b-polystyrene (SIS) block copolymers. The end use properties of SIS plasticized with polystyrene-b-alkyl, measured as tensile strength, is higher than for SIS plasticized with dioctyl adipate. The polystyrene-b-polybutadiene-b-polystyrene and polystyrene-bpoly(propylene glycol...

  7. Nanostructured anion conducting block copolymer electrolyte thin films (United States)

    Arges, Christopher; Kambe, Yu; Nealey, Paul

    Lamellae forming block copolymer electrolyte (BCE) thin-films with perpendicular aligned orientation were registered with high fidelity over large areas via a self-assembly process followed by a novel chemical vapor infiltration reaction (CVIR) technique. In this scheme, poly(styrene- b-2-vinyl pyridine) (PS bP2VP) block copolymers were self-assembled with perpendicular orientations on neutral chemical brushes using solvent vapor annealing. The ionic groups were selectively introduced into the P2VP block via a Menshutkin reaction that converted the nitrogen in the pyridine to n-methylpyridinium - anion carrier groups. FTIR-ATR and XPS tools confirmed the formation of the aforementioned ionic moieties post CVIR process and structure imaging tools (e.g., SEM and AFM imaging, GI-SAXS and RSOXs) established that incorporation of the ionic groups did not alter the self-assembled nanostructured films nor did subsequent ion-exchange processes. Electrochemical impedance spectroscopy determined the in-plane ion conductivity of different counteranions in the BCE thin films and alteration to the symmetry of the block copolymer film substantially improved (or hindered) BCE ion conductivity if the P2VP block's volume fraction was slightly greater than (or less than) 0.5. U.S. Department of Energy, Office of Science under Contract No. DE-AC02-06CH11357.

  8. Amphiphilic triblock copolymers with PEGylated hydrocarbon structures as environmentally friendly marine antifouling and fouling-release coatings. (United States)

    Zhou, Zhaoli; Calabrese, David R; Taylor, Warren; Finlay, John A; Callow, Maureen E; Callow, James A; Fischer, Daniel; Kramer, Edward J; Ober, Christopher K


    The ideal marine antifouling (AF)/fouling-release (FR) coating should be non-toxic, while effectively either resisting the attachment of marine organisms (AF) or significantly reducing their strength of attachment (FR). Many recent studies have shown that amphiphilic polymeric materials provide a promising solution to producing such coatings due to their surface dual functionality. In this work, poly(ethylene glycol) (PEG) of different molecular weights (Mw = 350, 550) was coupled to a saturated difunctional alkyl alcohol to generate amphiphilic surfactants (PEG-hydrocarbon-OH). The resulting macromolecules were then used as side chains to covalently modify a pre-synthesized PS8 K-b-P(E/B)25 K-b-PI10 K (SEBI or K3) triblock copolymer, and the final polymers were applied to glass substrata through an established multilayer surface coating technique to prepare fouling resistant coatings. The coated surfaces were characterized with AFM, XPS and NEXAFS, and evaluated in laboratory assays with two important fouling algae, Ulva linza (a green macroalga) and Navicula incerta, a biofilm-forming diatom. The results suggest that these polymer-coated surfaces undergo surface reconstruction upon changing the contact medium (polymer/air vs polymer/water), due to the preferential interfacial aggregation of the PEG segment on the surface in water. The amphiphilic polymer-coated surfaces showed promising results as both AF and FR coatings. The sample with longer PEG chain lengths (Mw = 550 g mol(-1)) exhibited excellent properties against both algae, highlighting the importance of the chemical structures on ultimate biological performance. Besides reporting synthesis and characterization of this new type of amphiphilic surface material, this work also provides insight into the nature of PEG/hydrocarbon amphiphilic coatings, and this understanding may help in the design of future generations of fluorine-free, environmentally friendly AF/FR polymeric coatings.

  9. Self-Assembly of Discrete Metal Complexes in Aqueous Solution via Block Copolypeptide Amphiphiles

    Directory of Open Access Journals (Sweden)

    Timothy J. Deming


    Full Text Available The integration of discrete metal complexes has been attracting significant interest due to the potential of these materials for soft metal-metal interactions and supramolecular assembly. Additionally, block copolypeptide amphiphiles have been investigated concerning their capacity for self-assembly into structures such as nanoparticles, nanosheets and nanofibers. In this study, we combined these two concepts by investigating the self-assembly of discrete metal complexes in aqueous solution using block copolypeptides. Normally, discrete metal complexes such as [Au(CN2]−, when molecularly dispersed in water, cannot interact with one another. Our results demonstrated, however, that the addition of block copolypeptide amphiphiles such as K183L19 to [Au(CN2]− solutions induced one-dimensional integration of the discrete metal complex, resulting in photoluminescence originating from multinuclear complexes with metal-metal interactions. Transmission electron microscopy (TEM showed a fibrous nanostructure with lengths and widths of approximately 100 and 20 nm, respectively, which grew to form advanced nanoarchitectures, including those resembling the weave patterns of Waraji (traditional Japanese straw sandals. This concept of combining block copolypeptide amphiphiles with discrete coordination compounds allows the design of flexible and functional supramolecular coordination systems in water.

  10. Morphology evolution of PS-b-PDMS block copolymer and its hierarchical directed self-assembly on block copolymer templates

    DEFF Research Database (Denmark)

    Rasappa, Sozaraj; Schulte, Lars; Borah, Dipu


    Cylinder-forming polystyrene-block-polydimethylsiloxane (PS-b-PDMS, 27.2k-b-11.7k, SD39) block copolymer having a total molecular weight of 39 kg mol−1 was exploited to achieve in-plane morphologies of lines, dots and antidots. Brush-free self-assembly of the SD39 on silicon substrates was invest...... substrates provides a simplified method for surface nanopatterning, templated growth of nanomaterials and nanofabrication....... the pattern into the underlying substrate. Directed self-assembly and hierarchical directed self-assembly on block copolymer templates for confinement of dots was successfully demonstrated. The strategy for achieving multiple morphologies using one BCP by mere choice of the annealing solvents on unmodified...

  11. Hydrogen Bond Induces Hierarchical Self-Assembly in Liquid-Crystalline Block Copolymers. (United States)

    Huang, Shuai; Pang, Linlin; Chen, Yuxuan; Zhou, Liming; Fang, Shaoming; Yu, Haifeng


    Microphase-separated structures of block copolymers (BCs) with a size of sub-10 nm are usually obtained by hydrogen-bond-induced self-assembly of BCs through doping with small molecules as functional additives. Here, fabrication of hierarchically self-assembled sub-10 nm structures upon microphase separation of amphiphilic liquid-crystalline BCs (LCBCs) at the existence of hydrogen bonds but without any dopants is reported. The newly introduced urethane groups in the side chain of the hydrophobic block of LCBCs interact with the ether groups of the hydrophilic poly(ethylene oxide) (PEO) block, leading to imperfect crystallization of the PEO blocks. Both crystalline and amorphous domains coexist in the separated PEO phase, enabling a lamellar structure to appear inside the PEO nanocylinders. This provides an elegant method to fabricate controllable sub-10 nm microstructures in well-defined polymer systems without the introduction of any dopants. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  12. Boundary layers of aqueous surfactant and block copolymer solutions against hydrophobic and hydrophilic solid surfaces

    International Nuclear Information System (INIS)

    Steitz, Roland; Schemmel, Sebastian; Shi Hongwei; Findenegg, Gerhard H


    The boundary layer of aqueous surfactants and amphiphilic triblock copolymers against flat solid surfaces of different degrees of hydrophobicity was investigated by neutron reflectometry (NR), grazing incidence small angle neutron scattering (GISANS) and atomic force microscopy (AFM). Solid substrates of different hydrophobicities were prepared by appropriate surface treatment or by coating silicon wafers with polymer films of different chemical natures. For substrates coated with thin films (20-30 nm) of deuterated poly(styrene) (water contact angle θ w ∼ 90), neutron reflectivity measurements on the polymer/water interface revealed a water depleted liquid boundary layer of 2-3 nm thickness and a density about 90% of the bulk water density. No pronounced depletion layer was found at the interface of water against a less hydrophobic polyelectrolyte coating (θ w ∼ 63). It is believed that the observed depletion layer at the hydrophobic polymer/water interface is a precursor of the nanobubbles which have been observed by AFM at this interface. Decoration of the polymer coatings by adsorbed layers of nonionic C m E n surfactants improves their wettability by the aqueous phase at surfactant concentrations well below the critical micellar concentration (CMC) of the surfactant. Here, GISANS experiments conducted on the system SiO 2 /C 8 E 4 /D 2 O reveal that there is no preferred lateral organization of the C 8 E 4 adsorption layers. For amphiphilic triblock copolymers (PEO-PPO-PEO) it is found that under equilibrium conditions they form solvent-swollen brushes both at the air/water and the solid/water interface. In the latter case, the brushes transform to uniform, dense layers after extensive rinsing with water and subsequent solvent evaporation. The primary adsorption layers maintain properties of the precursor brushes. In particular, their thickness scales with the number of ethylene oxide units (EO) of the block copolymer. In the case of dip-coating without

  13. Synthesis and characterization of novel amphiphilic copolymer stearic acid-coupled F127 nanoparticles for nano-technology based drug delivery system. (United States)

    Gao, Qihe; Liang, Qing; Yu, Fei; Xu, Jian; Zhao, Qihua; Sun, Baiwang


    Pluronic, F127, amphiphilic block copolymers, are used for several applications, including drug delivery systems. The critical micelle concentration (CMC) of F127 is about 0.26-0.8 wt% so that the utility of F127 in nano-technology based drug delivery system is limited since the nano-sized micelles could dissociate upon dilution. Herein, stearic acid (SA) was simply coupled to F127 between the carboxyl group of SA and the hydroxyl group of F127, which formed a novel copolymer named as SA-coupled F127, with significantly lower CMC. Above the CMC 6.9 × 10(-5)wt%, SA-coupled F127 self-assembled stable nanoparticles with Zeta potential -36 mV. Doxorubicin (DOX)-loaded nanoparticles were made, with drug loading (DL) 5.7 wt% and Zeta potential -36 to -39 mV, and the nanoparticles exhibited distinct shape with the size distribution from 20 to 50 nm. DOX-loaded nanoparticles were relatively stable and exhibited DOX dependant cytotoxicity toward MCF-7 cells in vitro. These results suggest that SA-coupled F127 potentially could be applied as a nano-technology based drug delivery method. Copyright © 2011 Elsevier B.V. All rights reserved.

  14. Magnetic Alignment of Block Copolymer Microdomains by Intrinsic Chain Anisotropy. (United States)

    Rokhlenko, Yekaterina; Gopinadhan, Manesh; Osuji, Chinedum O; Zhang, Kai; O'Hern, Corey S; Larson, Steven R; Gopalan, Padma; Majewski, Paweł W; Yager, Kevin G


    We examine the role of intrinsic chain susceptibility anisotropy in magnetic field directed self-assembly of a block copolymer using in situ x-ray scattering. Alignment of a lamellar mesophase is observed on cooling across the disorder-order transition with the resulting orientational order inversely proportional to the cooling rate. We discuss the origin of the susceptibility anisotropy, Δχ, that drives alignment and calculate its magnitude using coarse-grained molecular dynamics to sample conformations of surface-tethered chains, finding Δχ≈2×10^{-8}. From field-dependent scattering data, we estimate that grains of ≈1.2  μm are present during alignment. These results demonstrate that intrinsic anisotropy is sufficient to support strong field-induced mesophase alignment and suggest a versatile strategy for field control of orientational order in block copolymers.

  15. Novel block, graft and random copolymers for biomedical applications

    DEFF Research Database (Denmark)

    Javakhishvili, Irakli; Jankova Atanasova, Katja; Tanaka, Masaru

    Despite the simple structure, poly(2-methoxyethyl acrylate) (PMEA) shows excellent blood compatibility [1]. Both the freezing-bound water (intermediate water: preventing the biocomponents from directly contacting the polymer surface) and non-freezing water on the polymer surface play important ro...... copolymers with MMA [4] utilizing ATRP. Here we present other block, graft and random copolymers of MEA intended for biomedical applications. These macromolecular architectures have been constructed by employing controlled radical polymerization methods such as RAFT and ATRP....... roles for this [2]. An artificial lung (oxygenator), already in use, is coated with high MW PMEA prepared by radical polymerization with AIBN [2]. To broaden the possibilities for designing biomedical devices [3] and inspired from these findings we first prepared homo polymers of MEA and their block...

  16. Characterization of nanoparticles based on block copolymer micelles

    Czech Academy of Sciences Publication Activity Database

    Pleštil, Josef; Pospíšil, Herman; Kříž, Jaroslav; Kadlec, Petr; Tuzar, Zdeněk; Cubitt, R.


    Roč. 17, č. 21 (2001), s. 6699-6704 ISSN 0743-7463 R&D Projects: GA AV ČR KSK4050111; GA ČR GA203/00/1317; GA ČR GA203/01/0536 Institutional research plan: CEZ:AV0Z4050913 Keywords : block copolymer micelles * nanoparticles * small - angle neutron scattering Subject RIV: CD - Macromolecular Chemistry Impact factor: 2.963, year: 2001

  17. Diffusion of surface-active amphiphiles in silicone-based fouling-release coatings

    DEFF Research Database (Denmark)

    Noguer, Albert Camós; Olsen, S. M.; Hvilsted, Søren


    Amphiphiles (i.e. amphiphilic molecules such as surfactants, block copolymers and similar compounds) are used in small amounts to modify the surface properties of polymeric materials. In silicone fouling-release coatings, PEG-based amphiphiles are added to provide biofouling-resistance. The success...... of the amphiphiles shows a weak dependency on their molecular weight, although this dependency is much less pronounced than for other rubbery polymeric materials. The biofouling-resistance properties in fouling-release coatings were also studied for these amphiphiles. It was found that the diffusion coefficient does...... not have any influence on the biofouling-resistance results for the studied compounds. Instead, the chemistry of the hydrophobic block of the amphiphiles is much more significant, with PEG-PDMS block copolymers showing the best properties among the studied compounds....

  18. Application of Bottlebrush Block Copolymers as Photonic Crystals. (United States)

    Liberman-Martin, Allegra L; Chu, Crystal K; Grubbs, Robert H


    Brush block copolymers are a class of comb polymers that feature polymeric side chains densely grafted to a linear backbone. These polymers display interesting properties due to their dense functionality, low entanglement, and ability to rapidly self-assemble to highly ordered nanostructures. The ability to prepare brush polymers with precise structures has been enabled by advancements in controlled polymerization techniques. This Feature Article highlights the development of brush block copolymers as photonic crystals that can reflect visible to near-infrared wavelengths of light. Fabrication of these materials relies on polymer self-assembly processes to achieve nanoscale ordering, which allows for the rapid preparation of photonic crystals from common organic chemical feedstocks. The characteristic physical properties of brush block copolymers are discussed, along with methods for their preparation. Strategies to induce self-assembly at ambient temperatures and the use of blending techniques to tune photonic properties are emphasized. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  19. Donor-Acceptor Block Copolymers: Synthesis and Solar Cell Applications

    Directory of Open Access Journals (Sweden)

    Kazuhiro Nakabayashi


    Full Text Available Fullerene derivatives have been widely used for conventional acceptor materials in organic photovoltaics (OPVs because of their high electron mobility. However, there are also considerable drawbacks for use in OPVs, such as negligible light absorption in the visible-near-IR regions, less compatibility with donor polymeric materials and high cost for synthesis and purification. Therefore, the investigation of non-fullerene acceptor materials that can potentially replace fullerene derivatives in OPVs is increasingly necessary, which gives rise to the possibility of fabricating all-polymer (polymer/polymer solar cells that can deliver higher performance and that are potentially cheaper than fullerene-based OPVs. Recently, considerable attention has been paid to donor-acceptor (D-A block copolymers, because of their promising applications as fullerene alternative materials in all-polymer solar cells. However, the synthesis of D-A block copolymers is still a challenge, and therefore, the establishment of an efficient synthetic method is now essential. This review highlights the recent advances in D-A block copolymers synthesis and their applications in all-polymer solar cells.

  20. Electrically Tunable Soft-Solid Block Copolymer Structural Color. (United States)

    Park, Tae Joon; Hwang, Sun Kak; Park, Sungmin; Cho, Sung Hwan; Park, Tae Hyun; Jeong, Beomjin; Kang, Han Sol; Ryu, Du Yeol; Huh, June; Thomas, Edwin L; Park, Cheolmin


    One-dimensional photonic crystals based on the periodic stacking of two different dielectric layers have been widely studied, but the fabrication of mechanically flexible polymer structural color (SC) films, with electro-active color switching, remains challenging. Here, we demonstrate free-standing electric field tunable ionic liquid (IL) swollen block copolymer (BCP) films. Placement of a polymer/ionic liquid film-reservoir adjacent to a self-assembled poly(styrene-block-quaternized 2-vinylpyridine) (PS-b-QP2VP) copolymer SC film allowed the development of red (R), green (G), and blue (B) full-color SC block copolymer films by swelling of the QP2VP domains by the ionic liquid associated with water molecules. The IL-polymer/BCP SC film is mechanically flexible with excellent color stability over several days at ambient conditions. The selective swelling of the QP2VP domains could be controlled by both the ratio of the IL to a polymer in the gel-like IL reservoir layer and by an applied voltage in the range of -3 to +6 V using a metal/IL reservoir/SC film/IL reservoir/metal capacitor type device.

  1. Stabilization of nano-TiO2 aqueous dispersions with poly(ethylene glycol)-b-poly(4-vinyl pyridine) block copolymer and their incorporation in photocatalytic acrylic varnishes


    Monteiro, S.; Angela Dias; Mendes, A.; Mendes, J.; Serra, A.; Rocha, N.; Coelho, J.; Magalhães, F.


    In this work, TiO2 nanoparticles were dispersed and stabilized in water using a novel type of dispersant based on tailor-made amphiphilic block copolymers of poly(ethylene glycol)-block-poly(4-vinyl pyridine) (mPEG-b-P4VP) prepared by atom transfer radical polymerization (ATRP). The performance of this new block copolymer as dispersant was compared to a polyelectrolyte dispersant commonly used for TiO2, sodium salt of polyacrylic acid (Na-PAA). The effect of dispersion technique and type and ...

  2. Lamellar Microdomains of Block-Copolymer-Based Ionic Supramolecules Exhibiting a Hierarchical Self-Assembly

    DEFF Research Database (Denmark)

    Ayoubi, Mehran Asad; Almdal, Kristoffer; Zhu, Kaizheng


    (Cn; n = 8, 12, and 16) trimethylammonium counterions (i.e., side chains) at various ion (pair) fractions X [i.e., counterion/side-chain grafting density; X = number of alkyl counterions (i.e., side chains) per acidic group of the parent PMAA block] these L-b-AC ionic supramolecules exhibit...... a spherical-in-lamellar hierarchical self-assembly. For these systems, (1) the effective Flory-Huggins interaction parameter between L- and AC-blocks chi'(Cn/x) was extracted, and (2) analysis of the lamellar microdomains showed that when there is an increase in X, alkyl counterion (i.e., side chain) length l......Based on a parent diblock copolymer of poly(styrene)-b-poly(methacrylic acid), PS-b-PMAA, linear-b-amphiphilic comb (L-b-AC) ionic supramolecules [Soft Matter 2013, 9, 1540-1555] are synthesized in which the poly(methacrylate) backbone of the ionic supramolecular AC-block is neutralized by alkyl...

  3. Responsive block copolymer photonics triggered by protein-polyelectrolyte coacervation. (United States)

    Fan, Yin; Tang, Shengchang; Thomas, Edwin L; Olsen, Bradley D


    Ionic interactions between proteins and polyelectrolytes are demonstrated as a method to trigger responsive transitions in block copolymer (BCP) photonic gels containing one neutral hydrophobic block and one cationic hydrophilic block. Poly(2-vinylpyridine) (P2VP) blocks in lamellar poly(styrene-b-2-vinylpyridine) block copolymer thin films are quaternized with primary bromides to yield swollen gels that show strong reflectivity peaks in the visible range; exposure to aqueous solutions of various proteins alters the swelling ratios of the quaternized P2VP (QP2VP) gel layers in the PS-QP2VP materials due to the ionic interactions between proteins and the polyelectrolyte. Parameters such as charge density, hydrophobicity, and cross-link density of the QP2VP gel layers as well as the charge and size of the proteins play significant roles on the photonic responses of the BCP gels. Differences in the size and pH-dependent charge of proteins provide a basis for fingerprinting proteins based on their temporal and equilibrium photonic response. The results demonstrate that the BCP gels and their photonic effect provide a robust and visually interpretable method to differentiate different proteins.

  4. Coarse-grained modeling of hybrid block copolymer system (United States)

    Su, Yongrui

    This thesis is comprised of three major projects of my research. In the first project, I proposed a nanoparticle model and combined it with the Theoretically Informed Coarse Grained (TICG) model for pure polymer systems and the grand canonical slip springs model developed in our group to build a new model for entangled nanocomposites. With Molecule Dynamics(MD) simulation, I studied the mechanic properties of the nanocomposites, for example the influence of nanoparticles size and volume fraction on entanglements, the diffusion of polymers and nanoparticles, and the influence of nanoparticles size and volume fraction on viscosity et al.. We found that the addition of small-size nanoparticles reduces the viscosity of the nanocomposites, which is in contrary to what Einstein predicted a century ago. However, when particle increases its size to micrometers the Einstein predictions is recovered. From our simulation, we believe that small-size nanoparticles can more effectively decrease the entanglements of nanocomposites than larger particles. The free volume effect introduced by small-size nanoparticles also helps decrease the viscosity of the whole system. In the second project, I combined the Ohta-Kawasaki (OK) model [3] and the Covariance Matrix Adaptation Evolutionary Strategy(CMA-ES) to optimize the block copolymer blends self-assembly in the hole-shrink process. The aim is to predict the optimal composition and the optimal surface energy to direct the block copolymer blends self-assembly process in the confined hole. After optimization in the OK model, we calibrated the optimal results by the more reliable TICG model and got the same morphology. By comparing different optimization process, we found that the homopolymers which are comprised of the same monomers as either block of the block copolymer can form a perfect perforated hole and might have better performance than the pure block copolymer. While homopolymers which are comprised of a third-party monomers

  5. Synthesis of segmented (pb(ps-block-pb)(n)) and (pb(san-block- pb)(n)) block-copolymers via polymeric thermal iniferters

    NARCIS (Netherlands)

    Kroeze, E; ten Brinke, G.; Hadziioannou, G


    A technique is described for the synthesis of segmented poly(butadiene-block-styrene) block copolymers and segmented poly(butadiene-block-(styrene-co-acrylonitrile)) block copolymers through polybutadiene-based thermal iniferters. Dihydroxy- and dicarboxy-terminated polybutadienes were transformed

  6. Thermosensitive Self-Assembling Block Copolymers as Drug Delivery Systems

    Directory of Open Access Journals (Sweden)

    Giovanni Filippo Palmieri


    Full Text Available Self-assembling block copolymers (poloxamers, PEG/PLA and PEG/PLGA diblock and triblock copolymers, PEG/polycaprolactone, polyether modified poly(Acrylic Acid with large solubility difference between hydrophilic and hydrophobic moieties have the property of forming temperature dependent micellar aggregates and, after a further temperature increase, of gellifying due to micelle aggregation or packing. This property enables drugs to be mixed in the sol state at room temperature then the solution can be injected into a target tissue, forming a gel depot in-situ at body temperature with the goal of providing drug release control. The presence of micellar structures that give rise to thermoreversible gels, characterized by low toxicity and mucomimetic properties, makes this delivery system capable of solubilizing water-insoluble or poorly soluble drugs and of protecting labile molecules such as proteins and peptide drugs.

  7. Bicomponent Block Copolymers Derived from One or More Random Copolymers as an Alternative Route to Controllable Phase Behavior

    Energy Technology Data Exchange (ETDEWEB)

    Ashraf, Arman R. [Corporate Research and Development, The Procter and Gamble Company, Cincinnati OH 45224 USA; Ryan, Justin J. [Department of Materials Science and Engineering, North Carolina State University, Raleigh NC 27695 USA; Satkowski, Michael M. [Corporate Research and Development, The Procter and Gamble Company, Cincinnati OH 45224 USA; Lee, Byeongdu [Advanced Photon Source, Argonne National Laboratory, Argonne IL 60439 USA; Smith, Steven D. [Corporate Research and Development, The Procter and Gamble Company, Cincinnati OH 45224 USA; Spontak, Richard J. [Department of Materials Science and Engineering, North Carolina State University, Raleigh NC 27695 USA; Department of Chemical and Biomolecular Engineering, North Carolina State University, Raleigh NC 27695 USA


    Block copolymers have been extensively studied due to their ability to spontaneously self-organize into a wide variety of morphologies that are valuable in energy-, medical- and conservation-related (nano)technologies. While the phase behavior of bicomponent diblock and triblock copolymers is conventionally governed by temperature and individual block masses, we demonstrate that their phase behavior can alternatively be controlled through the use of blocks with random monomer sequencing. Block random copolymers (BRCs), i.e., diblock copolymers wherein one or both blocks is a random copolymer comprised of A and B repeat units, have been synthesized, and their phase behavior, expressed in terms of the order-disorder transition (ODT), has been investigated. Our results establish that, depending on the block composition contrast and molecular weight, BRCs can microphase-separate. We also report that the predicted ODT can be generated at relatively constant molecular weight and temperature with these new soft materials. This sequence-controlled synthetic strategy is extended to thermoplastic elastomeric triblock copolymers differing in chemistry and possessing a random-copolymer midblock.

  8. Microtome Sliced Block Copolymers and Nanoporous Polymers as Masks for Nanolithography

    DEFF Research Database (Denmark)

    Shvets, Violetta; Schulte, Lars; Ndoni, Sokol


    Introduction. Block copolymers self-assembling properties are commonly used for creation of very fine nanostructures [1]. Goal of our project is to test new methods of the block-copolymer lithography mask preparation: macroscopic pieces of block-copolymers or nanoporous polymers with cross...... PDMS can be chemically etched from the PB matrix by tetrabutylammonium fluoride in tetrahydrofuran and macroscopic nanoporous PB piece is obtained. Both block-copolymer piece and nanoporous polymer piece were sliced with cryomicrotome perpendicular to the axis of cylinder alignment and flakes...... of etching patterns appear only under the certain parts of thick flakes and are not continuous. Although flakes from block copolymer are thinner and more uniform in thickness than flakes from nanoporous polymer, quality of patterns under nanoporous flakes appeared to be better than under block copolymer...

  9. Improving dielectric permittivity by incorporating PDMS-PEG block copolymer into PDMS network

    DEFF Research Database (Denmark)

    A Razak, Aliff Hisyam; Szabo, Peter; Skov, Anne Ladegaard

    .Combination of both polymers as a block copolymer depicts a possibility for substantial improvement of properties such as high permittivity and non-conductivity – if carefully designed 2. The objective of my research is to synthesize PDMS-PEG block copolymer assembling into different morphologies such as lamellae...... introduces different properties in terms of contact angles, dielectric permittivity and rheological behaviour. All morphologies of PDMS-PEG block copolymer in this study exhibit high storage permittivity; at the same time the loss permittivity is even higher which implies that the synthesized PDMS-PEG block...... copolymers are conductive. By incorporating conductive PDMS-PEG block copolymer into commercial PDMS elastomer from Wacker Chemie,the storage permittivity is significantly enhanced by 38% with 20% of PDMS-PEG block copolymer incorporated in pure PDMS network as depicted in Fig. 2....

  10. Self-assembled structures of PMAA-PMMA block copolymers: Synthesis, characterization, and self-consistent field computations

    NARCIS (Netherlands)

    Li, F.; Schellekens, J.; Bont, de J.A.M.; Peters, R.; Overbeek, A.; Leermakers, F.A.M.; Tuinier, R.


    Block copolymers composed of methacrylic acid (MAA) and methyl methacrylate (MMA) blocks are interesting candidates for replacing surfactants in emulsion polymerization methods. Here the synthesis and experimental characterization of well-defined PMAA–PMMA block copolymers made via RAFT

  11. Self-Assembled Structures of PMAA-PMMA Block Copolymers : Synthesis, Characterization, and Self-Consistent Field Computations

    NARCIS (Netherlands)

    Li, Feng; Schellekens, Mike; de Bont, Jens; Peters, Ron; Overbeek, Ad; Leermakers, Frans A. M.; Tuinier, Remco


    Block copolymers composed of methacrylic acid (MAA) and methyl methacrylate (MMA) blocks are interesting candidates for replacing surfactants in emulsion polymerization methods. Here the synthesis and experimental characterization of well-defined PMAA-PMMA block copolymers made via RAFT

  12. Compatibilization efficiency of styrene-butadiene block copolymers as a function of their block number

    Czech Academy of Sciences Publication Activity Database

    Vranješ, N.; Lednický, František; Kotek, Jiří; Baldrian, Josef; Rek, V.; Fortelný, Ivan; Horák, Zdeněk


    Roč. 108, č. 1 (2008), s. 466-472 ISSN 0021-8995 R&D Projects: GA ČR GA106/06/0729 Institutional research plan: CEZ:AV0Z40500505 Keywords : blends * block copolymer * compatibility Subject RIV: CD - Macromolecular Chemistry Impact factor: 1.187, year: 2008

  13. Regulation of Aquaporin Z osmotic permeability in ABA tri-block copolymer

    Directory of Open Access Journals (Sweden)

    Wenyuan Xie


    Full Text Available Aquaporins are transmembrane water channel proteins present in biological plasma membranes that aid in biological water filtration processes by transporting water molecules through at high speeds, while selectively blocking out other kinds of solutes. Aquaporin Z incorporated biomimetic membranes are envisaged to overcome the problem of high pressure needed, and holds great potential for use in water purification processes, giving high flux while keeping energy consumption low. The functionality of aquaporin Z in terms of osmotic permeability might be regulated by factors such as pH, temperature, crosslinking and hydrophobic thickness of the reconstituted bilayers. Hence, we reconstituted aquaporin Z into vesicles that are made from a series of amphiphilic block copolymers PMOXA-PDMS-PMOXAs with various hydrophobic molecular weights. The osmotic permeability of aquaporin Z in these vesicles was determined through a stopped-flow spectroscopy. In addition, the temperature and pH value of the vesicle solutions were adjusted within wide ranges to investigate the regulation of osmotic permeability of aquaporin Z through external conditions. Our results show that aquaporin Z permeability was enhanced by hydrophobic mismatch. In addition, the water filtration mechanism of aquaporin Z is significantly affected by the concentration of H+ and OH- ions.

  14. Designing block copolymer architectures for targeted membrane performance

    KAUST Repository

    Dorin, Rachel Mika


    Using a combination of block copolymer self-assembly and non-solvent induced phase separation, isoporous ultrafiltration membranes were fabricated from four poly(isoprene-b-styrene-b-4-vinylpyridine) triblock terpolymers with similar block volume fractions but varying in total molar mass from 43 kg/mol to 115 kg/mol to systematically study the effect of polymer size on membrane structure. Small-angle X-ray scattering was used to probe terpolymer solution structure in the dope. All four triblocks displayed solution scattering patterns consistent with a body-centered cubic morphology. After membrane formation, structures were characterized using a combination of scanning electron microscopy and filtration performance tests. Membrane pore densities that ranged from 4.53 × 1014 to 1.48 × 1015 pores/m 2 were observed, which are the highest pore densities yet reported for membranes using self-assembly and non-solvent induced phase separation. Hydraulic permeabilities ranging from 24 to 850 L m-2 h-1 bar-1 and pore diameters ranging from 7 to 36 nm were determined from permeation and rejection experiments. Both the hydraulic permeability and pore size increased with increasing molar mass of the parent terpolymer. The combination of polymer characterization and membrane transport tests described here demonstrates the ability to rationally design macromolecular structures to target specific performance characteristics in block copolymer derived ultrafiltration membranes. © 2013 Elsevier Ltd. All rights reserved.

  15. Insertion Mechanism of a Poly(ethylene oxide)-poly(butylene oxide) Block Copolymer into a DPPC Monolayer

    Energy Technology Data Exchange (ETDEWEB)

    Leiske, Danielle L.; Meckes, Brian; Miller, Chad E.; Wu, Cynthia; Walker, Travis W.; Lin, Binhua; Meron, Mati; Ketelson, Howard A.; Toney, Michael F.; Fuller, Gerald G. (Stanford); (SLAC); (UC); (Alcan)


    Interactions between amphiphilic block copolymers and lipids are of medical interest for applications such as drug delivery and the restoration of damaged cell membranes. A series of monodisperse poly(ethylene oxide)-poly(butylene oxide) (EOBO) block copolymers were obtained with two ratios of hydrophilic/hydrophobic block lengths. We have explored the surface activity of EOBO at a clean interface and under 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) monolayers as a simple cell membrane model. At the same subphase concentration, EOBO achieved higher equilibrium surface pressures under DPPC compared to a bare interface, and the surface activity was improved with longer poly(butylene oxide) blocks. Further investigation of the DPPC/EOBO monolayers showed that combined films exhibited similar surface rheology compared to pure DPPC at the same surface pressures. DPPC/EOBO phase separation was observed in fluorescently doped monolayers, and within the liquid-expanded liquid-condensed coexistence region for DPPC, EOBO did not drastically alter the liquid-condensed domain shapes. Grazing incidence X-ray diffraction (GIXD) and X-ray reflectivity (XRR) quantitatively confirmed that the lattice spacings and tilt of DPPC in lipid-rich regions of the monolayer were nearly equivalent to those of a pure DPPC monolayer at the same surface pressures.

  16. Functional materials derived from block copolymer self-assembly

    DEFF Research Database (Denmark)

    Li, Tao

    surface energy, including polymers, silicon and graphene, thus bypassing the laborious and delicate substrate chemical pre-modification. To push the boundary even further for minimal lithography steps, a scalable ultra-fast block copolymer lithography procedure is developed. Using selective solvent spin....... We believe this project opens up for a number of strategies aiming at the creation of high-performance functional materials on the length scale of sub-20 nanometers that cannot be manufactured in an easy fashion by conventional top-down lithography methods....

  17. Study on reactive extrusion processes of block copolymer

    International Nuclear Information System (INIS)

    Wu Lili; Jia Yuxi; Sun Sheng; Zhang Guofang; Zhao Guoqun; An Lijia


    The anionic copolymerization process of styrene-butadiene (S/B) block copolymer in a closely intermeshing co-rotating twin screw extruder with butyl-lithium initiator was studied. According to the anionic copolymerization mechanism and the reactive extrusion characteristics, the mathematical models of monomer conversion, average molecular weight and fluid viscosity during the anionic copolymerization of S/B were constructed, and then the reactive extrusion process was simulated by means of the finite volume method and the uncoupled semi-implicit iterative algorithm. Finally, the influence of the feeding mixture composition on conversion was discussed. The simulated results were nearly in agreement with the experimental results

  18. Self-assembly in casting solutions of block copolymer membranes

    KAUST Repository

    Marques, Debora S.


    Membranes with exceptional pore regularity and high porosity were obtained from block copolymer solutions. We demonstrate by small-angle X-ray scattering that the order which gives rise to the pore morphology is already incipient in the casting solution. Hexagonal order was confirmed in PS-b-P4VP 175k-b-65k solutions in DMF/THF/dioxane with concentrations as high as 24 wt%, while lamellar structures were obtained in more concentrated solutions in DMF or DMF/dioxane. The change in order has been understood with the support of dissipative particle dynamic modeling. © 2013 The Royal Society of Chemistry.

  19. Low molecular weight block copolymers as plasticizers for polystyrene

    DEFF Research Database (Denmark)

    Hansen, Kristoffer Karsten; Nielsen, Charlotte Juel; Hvilsted, Søren


    Polystyrene-b-alkyl, polystyrene-b-polybutadiene-b-polystyrene, and polystyrene-b-poly(propylene glycol)monotridecyl ether were synthesized using macro initiators and atom transfer radical polymerization or by esterifications of homopolymers. The aim was a maximum molecular weight of 4 kg...... for polystyrene-b-polyisoprene-b-polystyrene (SIS) block copolymers. The end use properties of SIS plasticized with polystyrene-b-alkyl, measured as tensile strength, is higher than for SIS plasticized with dioctyl adipate. The polystyrene-b-polybutadiene-b-polystyrene and polystyrene-bpoly(propylene glycol...

  20. Cooperative catalysis with block copolymer micelles: A combinatorial approach

    KAUST Repository

    Bukhryakov, Konstantin V.


    A rapid approach to identifying complementary catalytic groups using combinations of functional polymers is presented. Amphiphilic polymers with "clickable" hydrophobic blocks were used to create a library of functional polymers, each bearing a single functionality. The polymers were combined in water, yielding mixed micelles. As the functional groups were colocalized in the hydrophobic microphase, they could act cooperatively, giving rise to new modes of catalysis. The multipolymer "clumps" were screened for catalytic activity, both in the presence and absence of metal ions. A number of catalyst candidates were identified across a wide range of model reaction types. One of the catalytic systems discovered was used to perform a number of preparative-scale syntheses. Our approach provides easy access to a range of enzyme-inspired cooperative catalysts.

  1. Fabrication of block copolymer templated mesoporous metal oxide composites for energy storage applications (United States)

    Bhaway, Sarang M.

    Block copolymer templated mesoporous (2 nm-50 nm) metal oxides are considered promising electrode materials for energy storage devices such as electrochemical capacitors or lithium/sodium ion batteries. The mesoporous electrode morphology offers several advantages: (1) high surface area and porosity facilitate charge transfer across the electrolyte-electrode interface, (2) nanoscale-dimension of the oxide framework minimizes the solid state ion diffusion paths, and (3) interconnected porous morphology enables rapid electrolyte transport through the electrodes, leading to overall enhancement in charge storage capabilities. This research attempts to study the effect of mesoporosity and mesopore geometry on charge storage capabilities and cycling stability of ordered mesoporous metal oxide electrodes in energy storage devices. The first part of this dissertation focuses on fabrication of ordered mesoporous metal oxide composites utilizing the Evaporation Induced Self-Assembly (EISA) and the Block Copolymer Micelle Templating (BCMT) strategy. Firstly, we demonstrate fabrication of ordered mesoporous carbon-vanadium oxide composites utilizing EISA of phenolic resin oligomer (resol), VOCl3 and an amphiphilic triblock. We illustrate that carbon yield from resol carbonization can prevent break-out crystallization of vanadia during calcination and help maintain an ordered mesostructure. The mesoporous carbon-vanadia mesostructured thin films exhibit specific capacitance 7 times higher than their non-porous analog at high scan rates when tested as electrode in aqueous supercapacitor. The second part of this thesis focuses on BCMT technique to fabricate ordered mesoporous mixed-metal oxide electrodes for battery applications. Ordered mesoporous NixCo(3-x)O4 thin films with varying chemical composition are fabricated using a metal nitrate-citric acid complex and an amphiphilic PEGMA-b-PBA block copolymer template. This templating strategy is further extended to fabricate

  2. Polymerization Induced Self-Assembly of Alginate Based Amphiphilic Graft Copolymers Synthesized by Single Electron Transfer Living Radical Polymerization. (United States)

    Kapishon, Vitaliy; Whitney, Ralph A; Champagne, Pascale; Cunningham, Michael F; Neufeld, Ronald J


    Alginate-based amphiphilic graft copolymers were synthesized by single electron transfer living radical polymerization (SET-LRP), forming stable micelles during polymerization induced self-assembly (PISA). First, alginate macroinitiator was prepared by partial depolymerization of native alginate, solubility modification and attachment of initiator. Depolymerized low molecular weight alginate (∼12 000 g/mol) was modified with tetrabutylammonium, enabling miscibility in anhydrous organic solvents, followed by initiator attachment via esterification yielding a macroinitiator with a degree of substitution of 0.02, or 1-2 initiator groups per alginate chain. Then, methyl methacrylate was polymerized from the alginate macroinitiator in mixtures of water and methanol, forming poly(methyl methacrylate) grafts, prior to self-assembly, of ∼75 000 g/mol and polydispersity of 1.2. PISA of the amphiphilic graft-copolymer resulted in the formation of micelles with diameters of 50-300 nm characterized by light scattering and electron microscopy. As the first reported case of LRP from alginate, this work introduces a synthetic route to a preparation of alginate-based hybrid polymers with a precise macromolecular architecture and desired functionalities. The intended application is the preparation of micelles for drug delivery; however, LRP from alginate can also be applied in the field of biomaterials to the improvement of alginate-based hydrogel systems such as nano- and microhydrogel particles, islet encapsulation materials, hydrogel implants, and topical applications. Such modified alginates can also improve the function and application of native alginates in food and agricultural applications.

  3. Silver-enhanced block copolymer membranes with biocidal activity

    KAUST Repository

    Madhavan, Poornima


    Silver nanoparticles were deposited on the surface and pore walls of block copolymer membranes with highly ordered pore structure. Pyridine blocks constitute the pore surfaces, complexing silver ions and promoting a homogeneous distribution. Nanoparticles were then formed by reduction with sodium borohydride. The morphology varied with the preparation conditions (pH and silver ion concentration), as confirmed by field emission scanning and transmission electron microscopy. Silver has a strong biocide activity, which for membranes can bring the advantage of minimizing the growth of bacteria and formation of biofilm. The membranes with nanoparticles prepared under different pH values and ion concentrations were incubated with Pseudomonas aeruginosa and compared with the control. The strongest biocidal activity was achieved with membranes containing membranes prepared under pH 9. Under these conditions, the best distribution with small particle size was observed by microscopy.

  4. Hollow ZIF-8 Nanoworms from Block Copolymer Templates (United States)

    Yu, Haizhou; Qiu, Xiaoyan; Neelakanda, Pradeep; Deng, Lin; Khashab, Niveen M.; Nunes, Suzana P.; Peinemann, Klaus-Viktor


    Recently two quite different types of “nano-containers” have been recognized as attractive potential drug carriers; these are wormlike filamenteous micelles (“filomicelles”) on the one hand and metal organic frameworks on the other hand. In this work we combine these two concepts. We report for the first time the manufacturing of metal organic framework nanotubes with a hollow core. These worm-like tubes are about 200 nm thick and several μm long. The preparation is simple: we first produce long and flexible filament-shaped micelles by block copolymer self-assembly. These filomicelles serve as templates to grow a very thin layer of interconnected ZIF-8 crystals on their surface. Finally the block copolymer is removed by solvent extraction and the hollow ZIF-8 nanotubes remain. These ZIF-NTs are surprisingly stable and withstand purification by centrifugation. The synthesis method is straightforward and can easily be applied for other metal organic framework materials. The ZIF-8 NTs exhibit high loading capacity for the model anti cancer drug doxorubicin (DOX) with a pH-triggered release. Hence, a prolonged circulation in the blood stream and a targeted drug release behavior can be expected.

  5. Hollow ZIF-8 Nanoworms from Block Copolymer Templates

    KAUST Repository

    Yu, Haizhou


    Recently two quite different types of “nano-containers” have been recognized as attractive potential drug carriers; these are wormlike filamenteous micelles (“filomicelles”) on the one hand and metal organic frameworks on the other hand. In this work we combine these two concepts. We report for the first time the manufacturing of metal organic framework nanotubes with a hollow core. These worm-like tubes are about 200 nm thick and several μm long. The preparation is simple: we first produce long and flexible filament-shaped micelles by block copolymer self-assembly. These filomicelles serve as templates to grow a very thin layer of interconnected ZIF-8 crystals on their surface. Finally the block copolymer is removed by solvent extraction and the hollow ZIF-8 nanotubes remain. These ZIF-NTs are surprisingly stable and withstand purification by centrifugation. The synthesis method is straightforward and can easily be applied for other metal organic framework materials. The ZIF-8 NTs exhibit high loading capacity for the model anti cancer drug doxorubicin (DOX) with a pH-triggered release. Hence, a prolonged circulation in the blood stream and a targeted drug release behavior can be expected.

  6. Topology and Shape Control for Assemblies of Block Copolymer Blends in Solution

    KAUST Repository

    Moreno Chaparro, Nicolas


    We study binary blends of asymmetric diblock copolymers (AB/AC) in selective solvents with a mesoscale model. We investigate the morphological transitions induced by the concentration of the AC block copolymer and the difference in molecular weight between the AB and AC copolymers, when segments B and C exhibit hydrogen-bonding interactions. To the best of our knowledge, this is the first work modeling mixtures of block copolymers with large differences in molecular weight. The coassembly mechanism localizes the AC molecules at the interface of A and B domains and induces the swelling of the B-rich domains. The coil size of the large molecular weight block copolymer depends only on the concentration of the short block copolymer (AC or AB), regardless of the B–C interactions. However, the B–C interactions control the morphological transitions that occur in these blends.

  7. Block and graft copolymers and NanoGel copolymer networks for DNA delivery into cell. (United States)

    Lemieux, P; Vinogradov, S V; Gebhart, C L; Guérin, N; Paradis, G; Nguyen, H K; Ochietti, B; Suzdaltseva, Y G; Bartakova, E V; Bronich, T K; St-Pierre, Y; Alakhov, V Y; Kabanov, A V


    Self-assembling complexes from nucleic acids and synthetic polymers are evaluated for plasmid and oligonucleotide (oligo) delivery. Polycations having linear, branched, dendritic. block- or graft copolymer architectures are used in these studies. All these molecules bind to nucleic acids due to formation of cooperative systems of salt bonds between the cationic groups of the polycation and phosphate groups of the DNA. To improve solubility of the DNA/polycation complexes, cationic block and graft copolymers containing segments from polycations and non-ionic soluble polymers, for example, poly(ethylene oxide) (PEO) were developed. Binding of these copolymers with short DNA chains, such as oligos, results in formation of species containing hydrophobic sites from neutralized DNA polycation complex and hydrophilic sites from PEO. These species spontaneously associate into polyion complex micelles with a hydrophobic core from neutralized polyions and a hydrophilic shell from PEO. Such complexes are very small (10-40 nm) and stable in solution despite complete neutralization of charge. They reveal significant activity with oligos in vitro and in vivo. Binding of cationic copolymers to plasmid DNA forms larger (70-200 nm) complexes. which are practically inactive in cell transfection studies. It is likely that PEO prevents binding of these complexes with the cell membranes ("stealth effect"). However attaching specific ligands to the PEO-corona can produce complexes, which are both stable in solution and bind to target cells. The most efficient complexes were obtained when PEO in the cationic copolymer was replaced with membrane-active PEO-b-poly(propylene oxide)-b-PEO molecules (Pluronic 123). Such complexes exhibited elevated levels of transgene expression in liver following systemic administration in mice. To increase stability of the complexes, NanoGel carriers were developed that represent small hydrogel particles synthesized by cross-linking of PEI with double end

  8. Mechanical properties of weakly segregated block copolymers : 1. Synergism on tensile properties of poly(styrene-b-n-butylmethacrylate) diblock copolymers

    NARCIS (Netherlands)

    Weidisch, R.; Michler, G.H.; Fischer, H.; Arnold, M.; Hofmann, S.; Stamm, M.


    Mechanical properties of poly(styrene-b-n-butylmethacrylate) diblock copolymers, PS-b-PBMA, with different lengths of the polystyrene block were investigated. The copolymers display a composition range where the tensile strength of the block copolymers exceeds the values of the corresponding

  9. Structure-property relations of segmented block copolymers with liquid liquid demixed morphologies

    NARCIS (Netherlands)

    van der Schuur, J.M.; van der Heide, Evert; Feijen, Jan; Gaymans, R.J.


    Poly(propylene oxide) based polyether(ester-amide)s (PEEA) with non-crystallisable amide segments were synthesized and their structure–property relations studied. These model segmented block copolymers were used to gain insight in the structure–property relations of block copolymers with

  10. Light scattering from block copolymer melts near the order-disorder transition

    Czech Academy of Sciences Publication Activity Database

    Štěpánek, Petr; Lodge, T. P.; Bates, F. S.


    Roč. 2, - (1994), s. 110 ISSN 0009-2347. [Symposium Block Copolymer Dynamics, Chain Dynamics of Block Copolymers: Dynamics near the Ordering Transition. San Diego, 13.03.1994-18.03.1994] R&D Projects: GA AV ČR IA45023 Impact factor: 0.331, year: 1994

  11. Polarizability of DNA Block Copolymer Nanoparticles Observed by Electrostatic Force Microscopy

    NARCIS (Netherlands)

    Sowwan, Mukhles; Faroun, Maryam; Mentovich, Elad; Ibrahim, Imad; Haboush, Shayma; Alemdaroglu, Fikri Emrah; Kwak, Minseok; Richter, Shachar; Herrmann, Andreas


    In this study, DNA block copolymer (DBC) micelles with a polystyrene (PS) core and a single-stranded (ss) DNA shell were doped with ferrocene (Fc) molecules. Tapping mode atomic force microscopy (AFM) was used to study the morphology of the doped and undoped block copolymer aggregates. We show that

  12. Synthesis and solution self-assembly of side-chain cobaltocenium-containing block copolymers. (United States)

    Ren, Lixia; Hardy, Christopher G; Tang, Chuanbing


    The synthesis of side-chain cobaltocenium-containing block copolymers and their self-assembly in solution was studied. Highly pure monocarboxycobaltocenium was prepared and subsequently attached to side chains of poly(tert-butyl acrylate)-block-poly(2-hydroxyethyl acrylate), yielding poly(tert-butyl acrylate)-block-poly(2-acryloyloxyethyl cobaltoceniumcarboxylate). The cobaltocenium block copolymers exhibited vesicle morphology in the mixture of acetone and water, while micelles of nanotubes were formed in the mixture of acetone and chloroform.

  13. Fabrication of gold nanoparticle arrays by block copolymer

    International Nuclear Information System (INIS)

    Chen, Xiao Ling


    Gold nanoparticle is one of the widely research objects in various fields including catalysis and biotechnology. Precise control of gold nanoparticles placement and their integration is essential to take full advantage of these unique properties for applications. An approach to self-assembling of gold nanoparticles (AuNPs) from reconstructed block copolymer was introduced. Highly ordered polystyrene-block-poly(2-vinylpyridine)(PS-b-P2VP) micellar arrays were obtained by solvent annealing. Subsequent immersion of the films in a preferential solvent for P2VP caused a reorganization of the film to generate a porous structure upon drying. PEG-coated AuNPs were spin-coated onto this reconstruction PS-b-P2VP template. When such films were exposed to toluene vapor-which is non-selective solvent for PEO and P2VP, AuNPs were drawn into those porous to form ordered arrays. Gold nanospheres with size 12±1.8 nm were synthesized by reducing HAuCl 4 via sodium citrate. Gold nanorods (aspect ratio about 6) were prepared from seed-mediated surfactant capping wet chemical method and the aspect ratio is tunable by changing surfactant amount. PEG ligand is used to modify gold nanoparticle surface by removing the original surfactant (sodium citrate -gold nanospheres: CTAB-gold nanorods), which have affinity with certain block copolymer component. Once gold nanoparticle is modified with PEG thiol, they were spin coated onto PS-b-P2VP template, which was prepared by solvent annealing and surface reconstruction process. So gold nanoparticle array was fabricated by this self-assembling process. The same idea can be applied on other nanoparticles

  14. Self-assembled Block Copolymers with Various Architectures Designed by ATRP

    DEFF Research Database (Denmark)

    Jankova Atanasova, Katja

    of the macromolecular building blocks they self assemble in attractive morphologies and exhibit interesting rheology. The designed at the Danish Polymer Centre by ATRP self-assembling block copolymers will be demonstrated by several examples: i. Diblock copolymers of PMMA with side chain liquid crystalline (LC......Exploring Atom Transfer Radical Polymerization, ATRP, and using the basic concepts to construct a particular advanced material, a number of novel block copolymers has been designed (1-3). Additionally the properties of new macromolecular architectures have been utilized (4-5). Below are presented...... the principal block copolymer architectures based on pentafluorostyrene (FS), synthesized from us (1, 4). They can be applied for any other monomers polymerizing under ATRP conditions too. Block copolymers display a very interesting phase behavior. Depending on the chemical nature and the size...

  15. Synthesis of polyisobutylene-polycaprolactone block copolymers using enzyme catalysis

    Directory of Open Access Journals (Sweden)

    M. Castano


    Full Text Available The synthesis of poly(isobutylene-b-ε-caprolactone diblock and poly(ε-caprolactone-b-isobutylene-b-ε-caprolactone triblock copolymers was accomplished using a combination of living carbocationic polymerization of isobutylene (IB with the ring-opening polymerization (ROP of ε-caprolactone (ε-CL. OH-PIB-allyl was prepared by living carbocationic polymerization of IB initiated with 1,2-propylene oxide/TiCl4 followed by termination with allyltrimethylsilane. Hydroxyl telechelic HO-PIB-OH was obtained by living IB polymerization initiated by 2,4,4,6-tetramethyl-heptane-2,6-diol/TiCl4, termination with allyltrimethylsilane and subsequent thiol-ene click reaction with mercaptoethanol. The structure of the hydroxyl PIBs was confirmed by 1H NMR (proton Nuclear Magnetic Resonance spectroscopy. OH-PIB-allyl and HO-PIB-OH were then successfully used as macroinitiators for the polymerization of ε-CL catalyzed by Candida antarctica Lipase B (CALB, yielding poly(ε-caprolactone-b-isobutylene diblock and poly(ε-caprolactone-b-isobutylene-b-ε-caprolactone triblock copolymers, respectively. Differential Scanning Calorimetry (DSC, Transition Electron Microscopy (TEM and Atomic Force Microscopy (AFM demonstrated that the amorphous PIB and the semicrystalline PCL block segments phase separated, creating nanostructured phase morphology.

  16. Orientationally Ordered Lamellar Block Copolymer Films for Electrostatic Capacitor Applications (United States)

    Grabowski, Christopher; Samant, Saumil; Karim, Alamgir; Durstock, Michael


    Improving the maximum operating voltage of an electrostatic capacitor requires materials that can better suppress breakdown initiation and/or forestall breakdown propagation. Progress has been made in developing layered architectures through polymer co-extrusion and inorganic nanolaminates, which create tortuous pathways to the applied electric field, resulting in increased breakdown strength. Block copolymer films provide another route to achieve such layered structures, while allowing more control over orientation, domain size, and morphology. We report the dielectric performance of micron-thick linear diblock copolymer films consisting of polystyrene-b-poly-2-vinylpyridine and polystyrene-b-poly methyl methacrylate, focusing on molecular weight ratios that yield lamellar and spherical morphologies. Specialized techniques such as cold-zone soft shear annealing allow for the precise control of lamellae orientation (layering parallel or perpendicular to the applied electric field). Our results indicate dielectric breakdown performance for parallel ordered lamellae is greater than comparable perpendicular lamellae and as-cast films with no induced microphase separation, which we attribute to the presence of interfacial layers that act as barriers to the applied field.

  17. Role of Synthetic and Dimensional Synthetic Organic Chemistry in Block Copolymer Micelle Nanosensor Engineering

    DEFF Research Database (Denmark)

    Ek, Pramod Kumar

    or comicellisation strategy. In this approach, the amphiphilic triblock copolymers synthesized by ATRP were further modified, and conjugated with targeting ligands and fluorophores. The co-micellisation of this functionalized amphiphilic triblock copolymers resulted in functionalized mixed micelle nanosensors. Post......-shellcorona micelle based ratiometric fluorescence pH nanosensor fabrications. Two synthetic strategies such as post micelle modification and mixed micellisation (co-micellisation) were employed for pH nanosensor synthesis. In the post micelle modification strategy, dimensional synthetic modifications on polymer...... synthesized with sensitivity ranges that were appropriate for pH measurements in living cells. The sensitivity ranges of the nanosensors were simply altered by changing the fluorophores conjugated to the shell region. Nanosensors having targeting capabilities were synthesized by mixed micellisation...

  18. Aligned nanowires and nanodots by directed block copolymer assembly (United States)

    Xiao, Shuaigang; Yang, XiaoMin; Lee, Kim Y.; ver der Veerdonk, Rene J. M.; Kuo, David; Russell, Thomas P.


    The directed self-assembly of block copolymers (BCPs) is a promising route to generate highly ordered arrays of sub-10 nm features. Ultradense arrays of a monolayer of spherical microdomains or cylindrical microdomains oriented parallel to the surface have been produced where the lateral ordering is guided by surface patterning and the lattice defined by the patterning can be commensurate or incommensurate with the natural period of the BCP. Commensurability between the two can be used to elegantly manipulate the lateral ordering and orientation of the BCP microdomains so as to form well-aligned arrays of 1D nanowires or 2D addressable nanodots. No modification of the substrate surface, aside from the patterning, was used, making the influence of lattice mismatch and pattern amplification on the size, shape and pitch of the BCP microdomains more transparent. A skew angle between incommensurate lattices, defining a stretching or compression of the BCP chains to compensate for the lattice mismatch, is presented.

  19. Sprayable elastic conductors based on block copolymer silver nanoparticle composites. (United States)

    Vural, Mert; Behrens, Adam M; Ayyub, Omar B; Ayoub, Joseph J; Kofinas, Peter


    Block copolymer silver nanoparticle composite elastic conductors were fabricated through solution blow spinning and subsequent nanoparticle nucleation. The reported technique allows for conformal deposition onto nonplanar substrates. We additionally demonstrated the ability to tune the strain dependence of the electrical properties by adjusting nanoparticle precursor concentration or localized nanoparticle nucleation. The stretchable fiber mats were able to display electrical conductivity values as high as 2000 ± 200 S/cm with only a 12% increase in resistance after 400 cycles of 150% strain. Stretchable elastic conductors with similar and higher bulk conductivity have not achieved comparable stability of electrical properties. These unique electromechanical characteristics are primarily the result of structural changes during mechanical deformation. The versatility of this approach was demonstrated by constructing a stretchable light emitting diode circuit and a strain sensor on planar and nonplanar substrates.

  20. Intradomain Textures in Block Copolymers: Multizone Alignment and Biaxiality (United States)

    Prasad, Ishan; Seo, Youngmi; Hall, Lisa M.; Grason, Gregory M.


    Block copolymer (BCP) melt assembly has been studied for decades, focusing largely on self-organized spatial patterns of periodically ordered segment density. Here, we demonstrate that underlying the well-known composition profiles (i.e., ordered lamella, cylinders, spheres, and networks) are generic and heterogeneous patterns of segment orientation that couple strongly to morphology, even in the absence of specific factors that promote intra or interchain segment alignment. We employ both self-consistent field theory and coarse-grained simulation methods to measure polar and nematic order parameters of segments in a freely jointed chain model of diblock melts. We show that BCP morphologies have a multizone texture, with segments predominantly aligned normal and parallel to interdomain interfaces in the respective brush and interfacial regions of the microdomain. Further, morphologies with anisotropically curved interfaces (i.e., cylinders and networks) exhibit biaxial order that is aligned to the principal curvature axes of the interface.

  1. Influence of solvent on micellar morphologies of semifluorinated block copolymers. (United States)

    Lee, Min Young; Kim, Sang Jae; Jeong, Yeon Tae; Kim, Joo Hyun; Gal, Yeong-Soon; Lim, Kwon Taek


    The influence of solvents on micellar architectures of block copolymers composed of poly(1H,1H-dihydroperfluorooctyl methacrylate) and poly(ethylene oxide) was investigated. In this study, binary solvents with desired proportions were chosen, which had remarkable influence on the morphology of the resulting micelles. With simple adjusting the composition of the binary solvent of chloroform and trichlorofluoromethane, interesting shapes of micelle-like aggregates, such as core-shell, cylinder, worm-like and inverted micelles were formed with sizes of 15, 70, 30 and 250 nm, respectively. In the case of methanol/water system, core-shell spheres and vesicles were produced by varying the proportion of the contents. The morphologies were also tuned to honeycomb-like and bowl-shaped micelles as well as large planar lamellae with holes in DMF and water binary solvent.

  2. Ultraporous films with uniform nanochannels by block copolymer micelles assembly

    KAUST Repository

    Nunes, Suzana Pereira


    Films with high pore density and regularity that are easy to manufacture by conventional large-scale technology are key components aimed for fabrication of new generations of magnetic arrays for storage media, medical scaffolds, and artificial membranes. However, potential manufacture strategies like the self-assembly of block copolymers, which lead to amazing regular patterns, could be hardly reproduced up to now using commercially feasible methods. Here we report a unique production method of nanoporous films based on the self-assembly of copper(II) ion-polystyrene-b-poly(4-vinylpyridine) complexes and nonsolvent induced phase separation. Extremely high pore densities and uniformity were achieved. Water fluxes of 890 L m-2 h-1 bar-1 were obtained, which are at least 1 order of magnitude higher than those of commercially available membranes with comparable pore size. The pores are also stimuli (pH)-responsive. © 2010 American Chemical Society.

  3. Block Copolymer Micellization as a Protection Strategy for DNA Origami. (United States)

    Agarwal, Nayan P; Matthies, Michael; Gür, Fatih N; Osada, Kensuke; Schmidt, Thorsten L


    DNA nanotechnology enables the synthesis of nanometer-sized objects that can be site-specifically functionalized with a large variety of materials. For these reasons, DNA-based devices such as DNA origami are being considered for applications in molecular biology and nanomedicine. However, many DNA structures need a higher ionic strength than that of common cell culture buffers or bodily fluids to maintain their integrity and can be degraded quickly by nucleases. To overcome these deficiencies, we coated several different DNA origami structures with a cationic poly(ethylene glycol)-polylysine block copolymer, which electrostatically covered the DNA nanostructures to form DNA origami polyplex micelles (DOPMs). This straightforward, cost-effective, and robust route to protect DNA-based structures could therefore enable applications in biology and nanomedicine where unprotected DNA origami would be degraded. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  4. The effect of heat treatment on the internal structure of nanostructured block copolymer films

    DEFF Research Database (Denmark)

    Sepe, Alessandro; Hoppe, E T; Jaksch, S


    We report on the temperature dependence of the nanostructure of thin block copolymer films, as studied using in situ grazing-incidence small-angle x-ray scattering (GISAXS). We focus on spin-coated poly(styrene-b-butadiene) diblock copolymer thin films featuring lamellae perpendicular to the subs......We report on the temperature dependence of the nanostructure of thin block copolymer films, as studied using in situ grazing-incidence small-angle x-ray scattering (GISAXS). We focus on spin-coated poly(styrene-b-butadiene) diblock copolymer thin films featuring lamellae perpendicular...

  5. Thermodynamics of Surfactants, Block Copolymers and Their Mixtures in Water: The Role of the Isothermal Calorimetry (United States)

    De Lisi, Rosario; Milioto, Stefania; Muratore, Nicola


    The thermodynamics of conventional surfactants, block copolymers and their mixtures in water was described to the light of the enthalpy function. The two methodologies, i.e. the van’t Hoff approach and the isothermal calorimetry, used to determine the enthalpy of micellization of pure surfactants and block copolymers were described. The van’t Hoff method was critically discussed. The aqueous copolymer+surfactant mixtures were analyzed by means of the isothermal titration calorimetry and the enthalpy of transfer of the copolymer from the water to the aqueous surfactant solutions. Thermodynamic models were presented to show the procedure to extract straightforward molecular insights from the bulk properties. PMID:19742173

  6. Fluorinated polyphenylenevinylene (PPV) block co-polymers for nanophotonics (United States)

    Sun, Sam-Shajing; Nguyen, Thuong; Brooks, Jaleesa


    Polymer based optoelectronic materials and thin film devices exhibit great potential in future space applications due to their flexibility, light weight, large light absorption coefficient, and promising radiation tolerance in space environment as compared to their inorganic semiconductor counterparts. Since carbon-fluorine (C-F) chemical bonds are much stronger than the carbon-hydrogen (C-H) bonds, fluorinated polymer films offer great potential for space applications due their expected resistance to oxidation, thermal stability, excellent wear properties, and low coefficients of friction. Their use in a space environment is extremely attractive since they are expected to retain their lubricating characteristics in vacuum, unlike many solid lubricants. Current existing polymer photovoltaic materials and devices suffer low photoelectric power conversion efficiencies due to a number factors including poor morphologies at nano scale that hinder the charge separation and transport. This paper reports our recent work on a fluorinated DBfA type block copolymer system where the donor (D) block contains a donor substituted and hydrocarbon based polyphenylenevinylene (PPV), acceptor (fA) block contains a fluorinated and a sulfone acceptor substituted polyphenylenevinylene (f-PPV), and B is a non-conjugated and flexible bridge unit. Preliminary studies reveal DBfA exhibits better nano phase morphologies and over 100 times more efficient optoelectronic conversion efficiencies as compared to D/fA blend.

  7. Poly(Lactic Acid) Hemodialysis Membranes with Poly(Lactic Acid)-block-Poly(2-Hydroxyethyl Methacrylate) Copolymer As Additive: Preparation, Characterization, and Performance. (United States)

    Zhu, Lijing; Liu, Fu; Yu, Xuemin; Xue, Lixin


    Poly(lactic acid) (PLA) hemodialysis membranes with enhanced antifouling capability and hemocompatibility were developed using poly(lactic acid)-block-poly(2-hydroxyethyl methacrylate) (PLA-PHEMA) copolymers as the blending additive. PLA-PHEMA block copolymers were synthesized via reversible addition-fragmentation (RAFT) polymerization from aminolyzed PLA. Gel permeation chromatography (GPC) and (1)H-nuclear magnetic resonance ((1)H NMR) were applied to characterize the synthesized products. By blending PLA with the amphiphilic block copolymer, PLA/PLA-PHEMA membranes were prepared by nonsolvent induced phase separation (NIPS) method. Their chemistry and structure were characterized with X-ray photoelectron spectroscopy (XPS), scanning electron microscope (SEM) and atomic force microscopy (AFM). The results revealed that PLA/PLA-PHEMA membranes with high PLA-PHEMA contents exhibited enhanced hydrophilicity, water permeability, antifouling and hemocompatibility. Especially, when the PLA-PHEMA concentration was 15 wt %, the water flux of the modified membrane was about 236 L m(-2) h(-1). Its urea and creatinine clearance was more than 0.70 mL/min, lysozyme clearance was about 0.50 mL/min, BSA clearance was as less as 0.31 mL/min. All the results suggest that PLA-PHEMA copolymers had served as effective agents for optimizing the property of PLA-based membrane for hemodialysis applications.

  8. Kinetic assembly of block copolymers in solution helical cylindrical micelles and patchy nanoparticles (United States)

    Zhong, Sheng

    There is always an interest to understand how molecules behave under different conditions. One application of this knowledge is to self-assemble molecules into increasingly complex structures in a simple fashion. Self-assembly of amphiphilic block copolymer in solution has produced a large variety of nanostructures through the manipulation in polymer chemistry, assembly environment, and additives. Moreover, some reports suggest the formation of many polymeric assemblies is driven by kinetic process. The goal of this dissertation is to study the influence of kinetics on the assembly of block copolymer. The study shows kinetic control can be a very effective way to make novel polymeric nanostructures. Two examples discussed here are helical cylindrical micelles and patchy nanoparticles. Helical cylindrical micelles are made from the co-assembly of amphiphilic triblock copolymer poly(acrylic acid)-block-poly(methyl acrylate)- block-polystyrene and organoamine molecules in a mixture of tetrahydrofuran (THF) and water (H2O). This system has already shown promise of achieving many assembled structures. The unique aspects about this system are the use of amine molecules to complex with acid groups and the existence of cosolvent system. Application of amine molecules offers a convenient control over assembled morphology and the introduction of PMA-PS selective solvent, THF, promotes the mobility of the polymer chains. In this study, multivalent organoamine molecules, such as diethylenetriamine and triethylenetetramine, are used to interact with block copolymer in THF/water mixture. As expected, the assembled morphologies are dependent on the polymer architecture, selection and quantity of the organoamine molecules, and solution composition. Under the right conditions, unprecedented, multimicrometer-long, supramolecular helical cylindrical micelles are formed. Both single-stranded and double-stranded helices are found in the same system. These helical structures share

  9. PCL-PEG graft copolymers with tunable amphiphilicity as efficient drug delivery systems

    Czech Academy of Sciences Publication Activity Database

    Al Samad, A.; Bethry, A.; Koziolová, Eva; Netopilík, Miloš; Etrych, Tomáš; Bakkour, Y.; Coudane, J.; El Omar, F.; Nottelet, B.


    Roč. 4, č. 37 (2016), s. 6228-6239 ISSN 2050-750X R&D Projects: GA MŠk(CZ) LO1507; GA ČR(CZ) GA15-02986S Institutional support: RVO:61389013 Keywords : HPMA copolymer * tumor * micelle Subject RIV: CD - Macromolecular Chemistry Impact factor: 4.543, year: 2016

  10. pH-triggered reversible sol–gel transition in aqueous solutions of amphiphilic gradient copolymers

    Czech Academy of Sciences Publication Activity Database

    Borisova, O.; Billon, L.; Zaremski, M.; Grassl, B.; Bakaeva, Zulfiya; Lapp, A.; Štěpánek, Petr; Borisov, O.


    Roč. 7, č. 22 (2011), s. 10824-10833 ISSN 1744-683X R&D Projects: GA ČR GAP208/10/1600 Institutional research plan: CEZ:AV0Z40500505 Keywords : small angle neutron scattering * triblock copolymer * self-organized structure Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 4.390, year: 2011

  11. Fluorosilicone multi-block copolymers tethering quaternary ammonium salt groups for antimicrobial purpose

    International Nuclear Information System (INIS)

    Zhou, Fang; Qin, Xiaoshuai; Li, Yancai; Ren, Lixia; Zhao, Yunhui; Yuan, Xiaoyan


    Highlights: • QAS-containing fluorosilicone multi-block copolymers were synthesized. • The block length of PHFBMA in the copolymers was tailored via RAFT polymerization. • Surface roughness of the copolymers decreased with the increased PHFBMA content. • A certain length of PHFBMA block enhanced C−N + percentage on the surface. - Abstract: Symmetrically structured fluorosilicone multi-block copolymers containing poly(2-(dimethylamino)ethyl methacrylate) (PDMAEMA) and poly(hexafluorobutyl methacrylate) (PHFBMA) were sequentially synthesized via reversible addition–fragmentation chain transfer polymerization, using a polydimethylsiloxane (PDMS) chain transfer agent with dithiocarbonate groups at both ends. Then, the CBABC-type block copolymers were quaternized with n-octyliodide to tether quaternary ammonium salt (QAS) groups in the PDMAEMA blocks for the antimicrobial use. The obtained fluorosilicone copolymers showed clear variations in the C-N + composition and surface morphology on their films depending on the content of the PHFBMA blocks, which were characterized by X-ray photoelectron spectroscopy and atomic force microscopy, respectively. The results indicated that the symmetrical CBABC structure favored PDMS and QAS tethered blocks migrating to the film surface. With the mass percentage of the PHFBMA increased from 0 to 32.5%, the surface roughness of the copolymer film decreased gradually with a tendency to form a smooth surface. Owing to the surface properties, fluorosilicone multi-block copolymers containing a certain amount of PHFBMA with higher C-N + content and relatively smooth morphology demonstrated obvious antimicrobial activity against Gram-positive bacteria, Bacillus subtilis and Gram-negative bacteria, Escherichia coli. The functionalized multi-block copolymers based on fluorosilicone and QAS groups would have potential applications in antimicrobial coatings

  12. Fluorosilicone multi-block copolymers tethering quaternary ammonium salt groups for antimicrobial purpose

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, Fang; Qin, Xiaoshuai; Li, Yancai; Ren, Lixia; Zhao, Yunhui, E-mail:; Yuan, Xiaoyan


    Highlights: • QAS-containing fluorosilicone multi-block copolymers were synthesized. • The block length of PHFBMA in the copolymers was tailored via RAFT polymerization. • Surface roughness of the copolymers decreased with the increased PHFBMA content. • A certain length of PHFBMA block enhanced C−N{sup +} percentage on the surface. - Abstract: Symmetrically structured fluorosilicone multi-block copolymers containing poly(2-(dimethylamino)ethyl methacrylate) (PDMAEMA) and poly(hexafluorobutyl methacrylate) (PHFBMA) were sequentially synthesized via reversible addition–fragmentation chain transfer polymerization, using a polydimethylsiloxane (PDMS) chain transfer agent with dithiocarbonate groups at both ends. Then, the CBABC-type block copolymers were quaternized with n-octyliodide to tether quaternary ammonium salt (QAS) groups in the PDMAEMA blocks for the antimicrobial use. The obtained fluorosilicone copolymers showed clear variations in the C-N{sup +} composition and surface morphology on their films depending on the content of the PHFBMA blocks, which were characterized by X-ray photoelectron spectroscopy and atomic force microscopy, respectively. The results indicated that the symmetrical CBABC structure favored PDMS and QAS tethered blocks migrating to the film surface. With the mass percentage of the PHFBMA increased from 0 to 32.5%, the surface roughness of the copolymer film decreased gradually with a tendency to form a smooth surface. Owing to the surface properties, fluorosilicone multi-block copolymers containing a certain amount of PHFBMA with higher C-N{sup +} content and relatively smooth morphology demonstrated obvious antimicrobial activity against Gram-positive bacteria, Bacillus subtilis and Gram-negative bacteria, Escherichia coli. The functionalized multi-block copolymers based on fluorosilicone and QAS groups would have potential applications in antimicrobial coatings.

  13. Investigating self-assembly and metal nanoclusters in aqueous di-block copolymers solutions

    CERN Document Server

    Lo Celso, F; Triolo, R; Triolo, A; Strunz, P; Bronstein, L; Zwanziger, J; Lin, J S


    Self-assembling properties of di-block copolymers/ surfactant hybrids in aqueous solution can be exploited to obtain metal nanoparticles stable dispersion. Results will be presented here for polystyrene-block-poly(ethylene oxide) solutions. A SANS structural investigation has been performed over different molecular weights of both hydrophilic and hydrophobic block, by varying temperature and concentration of the copolymer. A SAXS characterization of micellar systems containing Pt nanoparticles is reported. (orig.)

  14. Fabrication of Bioactive Surfaces by Functionalization of Electroactive and Surface-Active Block Copolymers

    Directory of Open Access Journals (Sweden)

    Omotunde Olubi


    Full Text Available Biofunctional block copolymers are becoming increasingly attractive materials as active components in biosensors and other nanoscale electronic devices. We have described two different classes of block copolymers with biofuctional properties. Biofunctionality for block copolymers is achieved through functionalization with appropriate biospecific ligands. We have synthesized block copolymers of electroactive poly(3-decylthiophene and 2-hydroxyethyl methacrylate by atom transfer radical polymerization. The block copolymers were functionalized with the dinitrophenyl (DNP groups, which are capable of binding to Immunoglobulin E (IgE on cell surfaces. The block copolymers were shown to be redox active. Additionally, the triblock copolymer of α, ω-bi-biotin (poly(ethylene oxide-b-poly (styrene-b-poly(ethylene oxide was also synthesized to study their capacity to bind fluorescently tagged avidin. The surface-active property of the poly(ethylene oxide block improved the availability of the biotin functional groups on the polymer surfaces. Fluorescence microscopy observations confirm the specific binding of biotin with avidin.

  15. How to Place Block Copolymer Molecules at the Interface of a Binary Blend (United States)

    Chen, Zhong-Ren; Xu, Yuci; Zhong, Shuo


    Block copolymers have been used to reduce the domain size of immiscible polymer blends and thus improve the mechanical and other properties. The effectiveness of this method, however, depends on the percentage of these polymeric surfactants residing at the interface of the blend. In fact, theoretical as well as experimental work indicate that a large percentage of block copolymers form micelles in the bulk of one or both of the component polymers. These micelles may serve as weak spots initiating crack propagation. Previous work have been focused on the design of molecular architecture and synthesis of new block copolymers to address this problem. In this presentation, a simple mixing strategy is applied to make each block copolymer molecule stay at the interface. As one example, when this strategy is used to mix natural rubber (NR) with butadiene rubber (BR), a small amount of low molecular weight block copolymer (LIR) improves both processing characteristics such as melt viscosity and mechanical properties of cured samples, such as crack resistance. AFM micrographs show the much smaller domain size; and an original real-time monitoring system reveals the lowest crack growth rate. Using a model A/B/A-B binary blend, we have witnessed by microscopy that all block copolymer molecules form micelles at the first mixing step, and all of these micelles are disappeared and all block copolymer molecules stay at the interface after the second mixing step.

  16. Improved synthesis of polystyrene-poly(ethylene oxide)-heparin block copolymers

    NARCIS (Netherlands)

    Vulic, I.; Loman, A.J.B.; Feijen, Jan; Okano, T.; Kim, S.W.


    A novel procedure for the synthesis of block copolymers composed of a hydrophobic block of polystyrene, a hydrophilic block of poly(ethylene oxide) and a bioactive block of nitrous acid-degraded heparin was developed. Amino-semitelechelic polystyrene was prepared by anionic polymerization of styrene

  17. Synthesis and characterization of polystyrene-poly(ethylene oxide)-heparin block copolymers

    NARCIS (Netherlands)

    Vulić, I.; Okano, T.; Kim, S.W.; Feijen, Jan


    A procedure for the preparation of new block copolymers composed of a hydrophobic block of polystyrene, a hydrophilic spacer-block of poly(ethylene oxide) and a bioactive block of heparin was investigated. Polystyrene with one amino group per chain was synthesized by free radical oligomerization of

  18. Block Copolymer Directed Biomimetic Mineral Formation for Polymer Nanocomposites (United States)

    Gleeson, Sarah; Yu, Tony; Chen, Xi; Marcolongo, Michele; Li, Christopher

    Bone is a hierarchically structured biocomposite comprised of mineralized collagen fibrils. The mechanical properties of bone can be precisely tuned by the structure and morphology of the mineral nanocrystals as well as the organic collagen fibrils. Synthetic materials that can mimic the nanostructure of natural bone show promise to replicate bone's structural function, yet little is known about the mechanism of mineral formation. We previously have shown that hierarchically ordered polymer fibers control the distribution and orientation of hydroxyapatite, enhancing mechanical properties and biocompatibility. We demonstrate a new method for mineralization by forming block copolymer single crystal films of polycaprolactone-block-poly(acrylic acid) (PCL- b-PAA) so that lamellar anionic PAA nanodomains recruit mineral ions and provide one-dimensional confinement to induce orientation. The effect of the anionic domain dimensions on mineral content, orientation, and structure within the polymer matrix is shown. The mechanical properties of the nanocomposite are evaluated to determine the role of mineral orientation and crystallinity in composite strength. These results can be used to tailor the physical mineralization environment to create a more biomimetic bone material.

  19. Block Copolymer Micelles for Photonic Fluids and Crystals. (United States)

    Poutanen, Mikko; Guidetti, Giulia; Gröschel, Tina I; Borisov, Oleg V; Vignolini, Silvia; Ikkala, Olli; Gröschel, Andre H


    Block copolymer micelles (BCMs) are self-assembled nanoparticles in solution with a collapsed core and a brush-like stabilizing corona typically in the size range of tens of nanometers. Despite being widely studied in various fields of science and technology, their ability to form structural colors at visible wavelength has not received attention, mainly due to the stringent length requirements of photonic lattices. Here, we describe the precision assembly of BCMs with superstretched corona, yet with narrow size distribution to qualify as building blocks for tunable and reversible micellar photonic fluids (MPFs) and micellar photonic crystals (MPCs). The BCMs form free-flowing MPFs with an average interparticle distance of 150-300 nm as defined by electrosteric repulsion arising from the highly charged and stretched corona. Under quiescent conditions, millimeter-sized MPCs with classical FCC lattice grow within the photonic fluid-medium upon refinement of the positional order of the BCMs. We discuss the generic properties of MPCs with special emphasis on surprisingly narrow reflected wavelengths with full width at half-maximum (fwhm) as small as 1 nm. We expect this concept to open a generic and facile way for self-assembled tunable micellar photonic structures.

  20. Effects of Morphology on Dynamics of Block Copolymer Systems (United States)

    Shen, Kuan-Hsuan; Hall, Lisa

    It is well known that block copolymers can microphase separate into ordered structures such as lamellae, hexagonally packed cylinders, or the bicontinuous double gyroid phase. Understanding the dynamics of the chains themselves and of added selective small molecule penetrants is relevant to the design of polymeric systems for transport applications. We expect that chain and penetrant dynamics are strongly dependent on morphology, while chain dynamics are also significantly impacted by individual polymer conformations within the morphology. For instance, in prior work on tapered polymers with a midblock of various concentration profiles, chains that fold back and forth across the lamellar interface were shown to have significantly decreased diffusion. Here we use coarse-grained molecular dynamics simulations to study how chain and penetrant dynamics depend on domain spacing, polymer conformations, and microphase morphology. We initialize systems of various fractions of A monomers in lamellar, cylinder, or gyroid microphases by growing polymers in a constrained random walk such that the two blocks are placed on opposite sides of the interface. We include, for comparison, systems with the same fraction of A that are initialized (and kinetically trapped) in different microphases, and show how this impacts polymer relaxation. How the dependence of penetrant diffusion on morphology relates to that of polymer chains will also be discussed. This material is based upon work supported by the National Science Foundation under Grant 1454343.

  1. Novel multi-responsive P2VP-block-PNIPAAm block copolymers via nitroxide-mediated radical polymerization

    Directory of Open Access Journals (Sweden)

    Cathrin Corten


    Full Text Available Linear soluble multi-responsive block copolymers are able to form so called schizophrenic micelles in aqueous solution. Here, such polymers are prepared via nitroxide-mediated radical polymerization (NMRP. In a first step nitroxide-terminated poly(2-vinylpyridine (P2VP was prepared with different molecular weights and narrow molecular weight distributions. The best reaction conditions, optimized by kinetic studies, were bulk polymerization at 110 °C. Using P2VP as a macroinitiator, the synthesis of new soluble linear block copolymers of P2VP and poly(N-isopropylacrylamide (PNIPAAm (P2VP-block-PNIPAAm was possible. The nitroxide terminated polymers were characterized by nuclear magnetic resonance (NMR spectroscopy, size exclusion chromatography (SEC and matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS. Thermal properties were investigated by the differential scanning calorimetry (DSC. Block copolymers showed pH- and temperature-responsive solubility in aqueous media. By increasing the P2VP content, the phase transition temperature shifted to lower temperatures (e.g. 26 °C for P2VP114-block-PNIPAAm180. Depending on the resulting block length, temperature and pH value of aqueous solution, the block copolymers form so called schizophrenic micelles. The hydrodynamic radius Rh of these micelles associated with pH values and temperature was analyzed by dynamic light scattering (DLS. Such kind of block copolymers has potential for many applications, such as controlled drug delivery systems.

  2. Rheological characterization of nanostructured material based on Polystyrene-b-poly(ethylene-butylene)-b-polystyrene (SEBS) block copolymer: Effect of block copolymer composition and nanoparticle geometry


    Hasanabadi, Noushin; Nazockdast, Hossein; Balog, Sandor; Lattuada, Marco


    Block copolymer (BCP) nanocomposite systems are of broad interest; however, reports on the role of nanoparticles on microphase separation behavior are rare. The goal of present study is to investigate the preparation of composite nanostructured materials containing Multi-Walled Carbon Nanotubes (MWCNTs) or graphene nanoplates. BCP nanocomposites based on the linear triblock copolymer, Polystyrene-b-poly(ethylene-butylene)-b-polystyrene (SEBS), with different morphological structure were...

  3. Novel blue emitters based on {pi}-conjugated block copolymers

    Energy Technology Data Exchange (ETDEWEB)

    Peres, L.O. [Universidade Federal de Sao Paulo - Campus Diadema, Rua Prof. Artur Riedel, 275, Cep 09972-270 - Jd Eldorado - Diadema - SP (Brazil)], E-mail:; Wang, S.H. [Departamento de Engenharia Metalurgica e de Materiais, Escola Politecnica, Universidade de Sao Paulo, Av. Prof. Mello Moraes 2463, 05508-900 Sao Paulo, SP (Brazil)], E-mail:; Wery, J.; Froyer, G. [Institut des Materiaux Jean Rouxel, 2 Rue de la Houssiniere, BP 32229, 44322 Nantes Cedex 03 (France); Faulques, E. [Institut des Materiaux Jean Rouxel, 2 Rue de la Houssiniere, BP 32229, 44322 Nantes Cedex 03 (France)], E-mail:


    A series of new phenyl-based conjugated copolymers has been synthesized and investigated by vibrational and photoluminescence spectroscopy (PL). The materials are: poly(1,4-phenylene-alt-3,6-pyridazine) (COP-PIR), poly(9,9-dioctylfluorene)-co-quaterphenylene (COP-PPP) and poly[(1,4-phenylene-alt-3,6-pyridazine)-co-(1,4-phenylene-alt-9, 9-dioctylfluorene)] (COP-PIR-FLUOR), with 3.5% of fluorene. COP-PPP and COP-PIR-FLUOR have high fluorescence quantum yields in solution. Infrared and Raman spectra were used to check the chemical structure of the compounds. The copolymers exhibit blue emission ranging from 2.8 to 3.6 eV when excited at E{sub exc} = 4.13 eV. Stokes-shift values were estimated on pristine samples in their condensed state from steady-state PL-emission and PL-excitation spectra. They suggest a difference in the torsional angle between the molecular configuration of the polymer blocks at the absorption and PL transitions and also in the photoexcitation diffusion. Additionally, the time-resolved PL of these materials has been investigated by using 100 fs laser pulses at E{sub exc} = 4.64 eV and a streak camera. Results show very fast biexponential kinetics for the two fluorene-based polymers with decay times below 300 ps indicating both intramolecular, fast radiative recombination and migration of photogenerated electron-hole pairs. By contrast, the PL of COP-PIR is less intense and longer lived, indicating that excitons are confined to the chains in this polymer.

  4. Non-immunogenic, hydrophilic/cationic block copolymers and uses thereof (United States)

    Scales, Charles W.; Huang, Faqing; McCormick, Charles L.


    The present invention provides novel non-immunogenic, hydrophilic/cationic block copolymers comprising a neutral-hydrophilic polymer and a cationic polymer, wherein both polymers have well-defined chain-end functionality. A representative example of such a block copolymer comprises poly(N-(2-hydroxypropyl)methacrylamide) (PHPMA) and poly(N-[3-(dimethylamino)propyl]methacrylamide) (PDMAPMA). Also provided is a synthesis method thereof in aqueous media via reversible addition fragmentation chain transfer (RAFT) polymerization. Further provided are uses of these block copolymers as drug delivery vehicles and protection agents.

  5. The effect of salt on the morphologies of compositionally asymmetric block copolymer electrolytes (United States)

    Loo, Whitney; Maslyn, Jacqueline; Oh, Hee Jeung; Balsara, Nitash

    Block copolymer electrolytes are promising for applications in lithium metal solid-state batteries. Due to their ability to microphase separate into distinct morphologies, their ion transport and mechanical properties can be decoupled. The addition of lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) salt to poly(styrene)-block-poly(ethylene oxide) (SEO) has been shown to increase microphase separation in symmetric block copolymer systems due to an increase in the effective interaction parameter (χeff) ; however the effect of block copolymer compositional asymmetry is not well-understood. The effect of compositional asymmetry on polymer morphology was investigated through small and wide angle X-ray scattering (SAXS/WAXS). The effective Flory-Huggins interaction parameter was extracted from the scattering profiles in order to construct a phase diagram to demonstrate the effect of salt and compositional asymmetry on block copolymer morphology.

  6. Amphiphilic PEO-b-PBLG diblock and PBLG-b-PEO-b-PBLG triblock copolymer based nanoparticles: doxorubicin loading and in vitro evaluation. (United States)

    Kakkar, Dipti; Mazzaferro, Silvia; Thevenot, Julie; Schatz, Christophe; Bhatt, Anant; Dwarakanath, Bilikere S; Singh, Harpal; Mishra, Anil K; Lecommandoux, Sebastien


    Huisgen's 1,3-dipolar cycloaddition ("Click Chemestry") has been used to prepare amphiphilic PEO-b-PBLG diblock and PBLG-b-PEO-b-PBLG triblock copolymers as potential carriers of anticancer drugs. Spherical and flower shaped micelles (D ≈ 100 nm) were obtained from diblock and triblock copolymers respectively. DOX was effectively encapsulated up to 18 wt.% and 50-60% of it was steadily released from the micelles over a period of 7 d. Flow cytometry and fluorescence microscopy confirmed the effective intracellular uptake as well as the sustained release of DOX from micelles. These results suggest that the diblock as well as triblock copolymers are promising carriers for intra-cellular drug delivery. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  7. Nano-sized micelles of block copolymers of methoxy poly(ethylene glycol)-poly(epsilon-caprolactone)-graft-2-hydroxyethyl cellulose for doxorubicin delivery. (United States)

    Hsieh, Ming-Fa; Cuong, Nguyen Van; Chen, Chao-Hsuan; Chen, Yung Tsung; Yeh, Jui-Ming


    The amphiphilic block copolymers methoxy poly(ethylene glycol)-poly(epsilon-caprolactone) was grafted to 2-hydroxyethyl cellulose to produce the water-soluble copolymers. Doxorubicin loaded nanoparticles were prepared by dialysis method and the sizes of nanoparticles were determined by dynamic light scattering in solution and atomic force microscopes. As results the sizes were detected in a range of 197.4 to 340.7 nm. The in-vitro release of Dox was studied in phosphate and acetate buffered solution at 37 degrees C. The results showed that 43 and 53% of Dox remained after an incubation period of 7 days. The cytotoxicity of Dox loaded micelles was investigated in two different human MCF-7/wild type and MCF-7/Adriamycin drug resistant cells lines. The Dox-loaded micelles showed reduced cytotoxicity compared to free Dox in MCF-7/wild type and MCF-7/Adriamycin drug resistant cells.

  8. A Cationic Amphiphilic Random Copolymer with pH-Responsive Activity against Methicillin-Resistant Staphylococcus aureus. (United States)

    Hong, Sungyoup; Takahashi, Haruko; Nadres, Enrico T; Mortazavian, Hamid; Caputo, Gregory A; Younger, John G; Kuroda, Kenichi


    In this report, we demonstrate the pH-dependent, in vitro antimicrobial activity of a cationic, amphiphilic random copolymer against clinical isolates of drug-resistant Staphylococcus aureus. The polymer was developed toward a long-term goal of potential utility in the treatment of skin infections. The proposed mechanism of action of the polymer is through selectively binding to bacterial membranes and subsequent disruption of the membrane structure/integrity, ultimately resulting in bacterial cell death. The polymer showed bactericidal activity against clinical isolates of methicillin-resistant or vancomycin-intermediate S. aureus. The polymer was effective in killing S. aureus at neutral pH, but inactive under acidic conditions (pH 5.5). The polymer did not exhibit any significant hemolytic activity against human red blood cells or display cytotoxicity to human dermal fibroblasts over a range of pH values (5.5-7.4). These results indicate that the polymer activity was selective against bacteria over human cells. Using this polymer, we propose a new potential strategy for treatment of skin infections using the pH-sensitive antimicrobial polymer agent that would selectively target infections at pH-neutral wound sites, but not the acidic, healthy skin.

  9. Preparation of Al Fe{sub 2}O{sub 3} Core-Shell Composites Using Amphiphilic Graft Copolymer Template

    Energy Technology Data Exchange (ETDEWEB)

    Patel, Rajkumar; Kim, Sang Jin; Kim, Jin Kyu; Kim, Jong Hak [Yonsei University, Seoul (Korea, Republic of); Park, Jung Su [Agency for Defense and Development (ADD), Daejeon (Korea, Republic of)


    A graft copolymer of poly(vinyl chloride)-g-poly(oxyethylene methacrylate) (PVC-g-POEM) was synthesized via atom transfer radical polymerization (ATRP) and used as a structure-directing agent to prepare Al Fe{sub 2}O{sub 3} core-shell nanocomposites through a sol-gel process. The amphiphilic property of PVC-g-POEM allows for good dispersion of Al particles and leads to specific interaction with iron ethoxide, a precursor of Fe{sub 2}O{sub 3}. Secondary bonding interaction in the sol-gel composites was characterized by Fourier transform-infrared (FT-IR) spectroscopy. The well-organized morphology of Al Fe{sub 2}O{sub 3} core-shell nanocomposites was observed using scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Energy dispersive X-ray (EDX) and X-ray diffraction (XRD) were used to analyze the elemental composition and crystallization structure of the composites.

  10. Templated Self-Assembly of Block Copolymers: Effect on Substrate Topography

    NARCIS (Netherlands)

    Cheng, Joy Y.; Ross, C.A.; Thomas, Edwin L.; Smith, Henry I.; Vancso, Gyula J.


    Topographical confinement is used to template the formation of nanoscale domains in a self-assembled block copolymer film. The topographical template controls the row spacings and feature dimensions of the copolymer and can deliberately introduce defects in the arrays (see Figure). For example, a

  11. Stereocomplex mediated gelation of PEG-(PLA)2 and PEG(PLA)8 block copolymers

    NARCIS (Netherlands)

    Hiemstra, C.; Zhong, Zhiyuan; Dijkstra, Pieter J.; Feijen, Jan


    Stereocomplex mediated hydrogels have been prepared by mixing solutions of polymers of opposite chirality of either PEG-(PLA)2 triblock copolymers or PEG-(PLA)8 star block copolymers. The critical gel concentrations of the mixed enantiomer solutions were considerably lower compared to polymer

  12. Gas-permeation properties of poly(ethylene oxide) poly(butylene terephthalate block copolymers

    NARCIS (Netherlands)

    Metz, S.J.; Mulder, M.H.V.; Wessling, Matthias


    This paper reports the gas-permeation properties of poly(ethylene oxide) (PEO) poly(butylene terephthalate) (PBT) segmented multiblock copolymers. These block copolymers allow a precise structural modification by the amount of PBT and the PEO segment length, enabling a systematic study of the

  13. Preparation of pH-sensitive amphiphilic block star polymers, their self-assembling characteristics and release behavior on encapsulated molecules

    KAUST Repository

    Song, Xiaowan


    Poly(ethylene glycol) (PEG), a polymer with excellent biocompatibility, was widely used to form nanoparticles for drug delivery applications. In this paper, based on PEG, a series of pH-sensitive amphiphilic block star polymers of poly(ethylene glycol)-block-poly(ethoxy ethyl glycidyl ether) (PEG-b-PEEGE) with different hydrophobic length were synthesized by living anionic ring-opening polymerization method. The products were characterized using 1H NMR and gel permeation chromatography. These copolymers could self-assemble in aqueous solution to form micellar structure with controlled morphologies. Transmission electron microscopy showed that the nanoparticles are spherical or rodlike with different hydrophilic mass fractions. The pH response of polymeric aggregates from PEG-b-PEEGE was detected by fluorescence probe technique at different pH. A pH-dependent release behavior was observed and pH-responsiveness of PEG-b-PEEGE was affected by the hydrophobic block length. These results demonstrated that star-shaped polymers (PEG-b-PEEGE) are attractive candidates as anticancer drug delivery carriers. © 2016 Springer-Verlag Berlin Heidelberg

  14. Modulated self-organization in complex amphiphilic systems

    NARCIS (Netherlands)

    Sevink, A; Zvelindovsky, A; Fraaije, H


    We discuss novel simulation methods for 3D pattern formation in complex amphiphilic systems. The focus is on the supra-molecular or mesoscopic level. The building blocks consist of sequences of dissimilar monomers, connected in copolymer chain molecules. Internal factors such as composition and

  15. Modulated self-organization in complex amphiphilic systems

    NARCIS (Netherlands)

    Fraaije, JGEM; Zvelindovsky, AV; Sevink, GJA; Maurits, NM


    We discuss novel simulation methods for 3D pattern formation in complex amphiphilic systems. The focus is on the supra-molecular or mesoscopic level. The building blocks consist of sequences of dissimilar monomers. connected in copolymer chain molecules. Internal factors such as composition and

  16. Facile synthesis of main-chain degradable block copolymers for performance enhanced dismantlable adhesion. (United States)

    Sato, Eriko; Hagihara, Takashi; Matsumoto, Akikazu


    Block copolymers consisting of readily degradable polyperoxides and non-degradable vinyl polymers as the block segments were successfully synthesized by reversible chain transfer catalyzed polymerization, which is one of living radical polymerization techniques. The block copolymers showed characteristic morphology and wettability being different from the polymer blends. When block copolymers containing polyperoxide and polymethacrylate blocks were heated below 150 °C, the polyperoxide blocks were completely degraded and the polymethacrylate blocks were recovered without degradation. Block copolymers containing a poly(2-ethylhexyl methacrylate) block were then investigated as a dismantlable adhesion material, which requires adequate bonding strength during use and easy debonding on demand. Among the several block copolymers, the one consisting of poly(2-ethylhexyl methacrylate) and polyperoxide from methyl sorbate (PPMS) (M(n) = 4900) exhibited good performance as a pressure-sensitive adhesive (PSA). After heating the test specimens in a temperature range from 60 to 100 °C, PSA performance, which was evaluated by 180° peel strength and shear holding power measurements, was significantly diminished. Especially, after heating at 100 °C for 1 h, spontaneous debonding of some test specimens was observed because of the evolution of volatile acetaldehyde from PPMS.

  17. On the Use of Self-Assembling Block Copolymers to Toughen A Model Epoxy (United States)

    Chen, Yilin

    Block copolymers have been receiving considerable attention in toughening epoxy due to their ability to form a wide variety of nanostructures. This study focuses on using both triblock and diblock copolymers to improve the fracture toughness of an aromatic-amine cured epoxy system. The curing system consisted of 1,3- phenylenediamine (mPDA) as curing agent and aniline as a chain extender. Three triblock copolymers and three diblock copolymers were incorporated in the same lightly crosslinked model epoxy system, which was chosen to mimic an underfill material in flip-chip packaging for the microelectronics industry. In this research, rubber particles were formed in situ using self-assembling block copolymers. Mechanical, thermal and microscopic studies were conducted with the main goal to study the relationship between the block parameters and the final morphologies and their effects on static and dynamic mechanical properties of the toughened resin, especially fracture toughness. In these block-copolymer-modified epoxies, spherical micelles and wormlike micelles were obtained by varying block lengths, molecular weight, polarities and compositions. It was found that miscibility of the epoxy-miscible block played a crucial role in the formation of different types of morphologies. At a low loading level, diblock copolymers were able to toughen the model epoxy as effectively as triblock copolymers. The fracture toughness was improved to almost three times with respect to that of the neat resin with addition of 10 phr AM*-27. At the same time, other mechanical properties, such as yield strength and modulus, were well retained. Incorporation of block copolymers did not have a significant effect on glass transition temperature but caused an increase in coefficient of thermal expansion (CTE) of the modified epoxy. Particle cavitation and matrix void growth were proved to be the toughening mechanisms for SBM-Modified epoxies. However, these typical toughening mechanisms for

  18. Phase Separation and Elastic Properties of Poly(Trimethylene Terephthalate-block-poly(Ethylene Oxide Copolymers

    Directory of Open Access Journals (Sweden)

    Elżbieta Piesowicz


    Full Text Available A series of poly(trimethylene terephthalate-block-poly(ethylene oxide (PTT-b-PEOT copolymers with different compositions of rigid PTT and flexible PEOT segments were synthesized via condensation in the melt. The influence of the block length and the block ratio on the micro-separated phase structure and elastic properties of the synthesized multiblock copolymers was studied. The PEOT segments in these copolymers were kept constant at 1130, 2130 or 3130 g/mol, whereas the PTT content varied from 30 up to 50 wt %. The phase separation was assessed using differential scanning calorimetry (DSC and dynamic mechanical thermal analysis (DMTA. The crystal structure of the synthesised block copolymers and their microstructure on the manometer scale was evaluated by using WAXS and SAXS analysis. Depending on the PTT/PEOT ratio, but also on the rigid and flexible segment length in PTT-b-PEO copolymers, four different domains were observed i.e.,: a crystalline PTT phase, a crystalline PEO phase (which exists for the whole series based on three types of PEOT segments, an amorphous PTT phase (only at 50 wt % content of PTT rigid segments and an amorphous PEO phase. Moreover, the elastic deformability and reversibility of PTT-b-PEOT block copolymers were studied during a cyclic tensile test. Determined values of permanent set resultant from maximum attained stain (100% and 200% for copolymers were used to evaluate their elastic properties.

  19. Effect of Perfluoroalkyl Endgroups on the Interactions of Tri-Block Copolymers with Monofluorinated F-DPPC Monolayers

    Directory of Open Access Journals (Sweden)

    Syed W. H. Shah


    Full Text Available We studied the interaction of amphiphilic and triphilic polymers with monolayers prepared from F-DPPC (1-palmitoyl-2-(16-fluoropalmitoyl-sn-glycero-3-phosphocholine, a phospholipid with a single fluorine atom at the terminus of the sn-2 chain, an analogue of dipalmitoyl-phosphatidylcholine (DPPC. The amphiphilic block copolymers contained a hydrophobic poly(propylene oxide block flanked by hydrophilic poly(glycerol monomethacrylate blocks (GP. F-GP was derived from GP by capping both termini with perfluoro-n-nonyl segments. We first studied the adsorption of GP and F-GP to lipid monolayers of F-DPPC. F-GP was inserted into the monolayer up to a surface pressure Π of 42.4 mN m−1, much higher than GP (32.5 mN m−1. We then studied isotherms of lipid-polymer mixtures co-spread at the air-water interface. With increasing polymer content in the mixture a continuous shift of the onset of the liquid-expanded (LE to liquid-condensed (LC transition towards higher molecular and higher area per lipid molecule was observed. F-GP had a larger effect than GP indicating that it needed more space. At a Π-value of 32 mN m−1, GP was excluded from the mixed monolayer, whereas F-GP stayed in F-DPPC monolayers up to 42 mN m−1. F-GP is thus more stably anchored in the monolayer up to higher surface pressures. Images of mixed monolayers were acquired using different fluorescent probes and showed the presence of perfluorinated segments of F-GP at LE-LC domain boundaries.

  20. Identifying the nature of surface chemical modification for directed self-assembly of block copolymers

    Directory of Open Access Journals (Sweden)

    Laura Evangelio


    Full Text Available In recent years, block copolymer lithography has emerged as a viable alternative technology for advanced lithography. In chemical-epitaxy-directed self-assembly, the interfacial energy between the substrate and each block copolymer domain plays a key role on the final ordering. Here, we focus on the experimental characterization of the chemical interactions that occur at the interface built between different chemical guiding patterns and the domains of the block copolymers. We have chosen hard X-ray high kinetic energy photoelectron spectroscopy as an exploration technique because it provides information on the electronic structure of buried interfaces. The outcome of the characterization sheds light onto key aspects of directed self-assembly: grafted brush layer, chemical pattern creation and brush/block co-polymer interface.

  1. Photoinduced optical anisotropy in azobenzene methacrylate block copolymers: Influence of molecular weight and irradiation conditions

    DEFF Research Database (Denmark)

    Gimeno, Sofia; Forcen, Patricia; Oriol, Luis


    The photoinduced anisotropy in a series of azomethacrylate block copolymers with different Molecular weights and azo contents has been investigated under several irradiation conditions. Depending on molecular weight and composition, different microstructures (disordered, lamellar, spherical) appe...

  2. A Versatile Route to Functionalized Block Copolymers by Nitroxide Mediated 'Living' Free Radical Polymerization

    National Research Council Canada - National Science Library

    Benoit, Didler


    ... compatability approaching that of ATRP based systems. The ability of these new alkoxyamines, such as 1, to mediate the homopolymerization of a wide variety of monomers should permit a much greater range of well defined random, block, and star copolymers...

  3. Experimental investigation of the behaviour and fate of block copolymers in fouling-release coatings

    DEFF Research Database (Denmark)

    Noguer, Albert Camós

    exposed to seawater for up to 5 years were analysed and the results exhibited a large scatter in the data, mainly attributed to differences in the coatings compositions. However, some comparable formulations suggest that seawater temperature has an important effect on the loss of copolymer from PDMS...... the distribution and behaviour of PEG-b-PDMS-b-PEG copolymers in PDMS coatings by fluorescence means. Chapter 5 investigates the degradation of PDMS-PEG-based copolymers in FRC immersed in seawater. Chapter 6 consists of a long-term field study regarding the release/loss of these block copolymers from fouling...... to the interfaces of the PDMS film could be observed by following the fluorescence intensity at different depths over time. The chemical stability of PDMS-PEG-based copolymers in PDMS coatings immersed for up to 30 months in seawater in Singapore was also investigated. The copolymer remaining in the coatings after...

  4. Bioinert membranes prepared from amphiphilic poly(vinyl chloride)-g-poly(oxyethylene methacrylate) graft copolymers

    Energy Technology Data Exchange (ETDEWEB)

    Patel, Rajkumar [Department of Chemical and Biomolecular Engineering, Yonsei University, 262 Seongsanno, Seodaemun-gu, Seoul 120-749 (Korea, Republic of); Patel, Madhumita [Department of Life Science, Dongguk University-Seoul, 3–26 Phil-dong, Chung-gu, Seoul 100-715 (Korea, Republic of); Ahn, Sung Hoon [Department of Chemical and Biomolecular Engineering, Yonsei University, 262 Seongsanno, Seodaemun-gu, Seoul 120-749 (Korea, Republic of); Sung, Yong Kiel [ReSEAT Program, Korea Institute of Science and Technology Information, 206-9 Cheongyangni-dong, Dongdaemun-gu, Seoul 130-742 (Korea, Republic of); Lee, Hyung-Keun [Korea Institute of Energy Research, 71-2 Jang-dong, Yuseong-gu, Dae-jeon 305-343 (Korea, Republic of); Kim, Jong Hak, E-mail: [Department of Chemical and Biomolecular Engineering, Yonsei University, 262 Seongsanno, Seodaemun-gu, Seoul 120-749 (Korea, Republic of); Sung, Jung-Suk, E-mail: [Department of Life Science, Dongguk University-Seoul, 3–26 Phil-dong, Chung-gu, Seoul 100-715 (Korea, Republic of)


    Poly(vinyl chloride) (PVC) membrane was hydrophilically modified by grafting with poly(oxyethylene methacrylate) (POEM) using atom transfer radical polymerization (ATRP). The successful grafting of PVC main chain by POEM was characterized by Fourier transform infrared spectroscopy (FT-IR). The molecular weight and hydrophilicity of membranes increased with the amount of POEM grafting, as characterized by gel permeation chromatography (GPC) and contact angle measurement, respectively. Transmission electron microscope (TEM) and small angle X-ray scattering (SAXS) analysis revealed the microphase-separated structure of PVC-g-POEM and the domain spacing increased from 59.3 to 86.1 nm with increasing grafting degree. Scanning electron microscopy (SEM) was used for the direct visualization of the mouse embryonic fibroblast (MEF) cell and bacteria adhesion on the membrane surface. Protein adsorption and eukaryotic and prokaryotic cell adhesion tests showed that the bioinert properties of membranes were significantly increased with POEM content. Highlights: ► TEM and SAXS analysis revealed the microphase-separated structure of graft copolymer membranes. ► Protein adsorption and eukaryotic and prokaryotic cell adhesion tests were performed on graft copolymer membranes. ► Boinert properties of membranes were significantly increased with POEM content.

  5. Investigating Block-Copolymer Micelle Dynamics for Tunable Cargo Delivery (United States)

    Li, Xiuli; Kidd, Bryce; Cooksey, Tyler; Robertson, Megan; Madsen, Louis

    Block-copolymer micelles (BCPMs) can carry molecular cargo in a nanoscopic package that is tunable using polymer structure in combination with cargo properties, as well as with external stimuli such as temperature or pH. For example, BCPMs can be used in targeted anticancer drug delivery due to their biocompatibility, in vivo degradability and prolonged circulation time. We are using NMR spectroscopy and diffusometry as well as SANS to investigate BCPMs. Here we study a diblock poly(ethylene oxide)-b-(caprolactone) (PEO-PCL) that forms spherical micelles at 1% (w/v) in the mixed solvent D2O/THF-d8. We quantify the populations and diffusion coefficients of coexisting micelles and free unimers over a range of temperatures and solvent compositions. We use temperature as a stimulus to enhance unimer exchange and hence trigger cargo release, in some cases at a few degrees above body temperature. We present evidence for dominance of the insertion-expulsion mechanism of unimer exchange in these systems, and we map phase diagrams versus temperature and solvent composition. This study sheds light on how intermolecular interactions fundamentally affect cargo release, unimer exchange, and overall micelle tunability.

  6. Printable and Rewritable Full Block Copolymer Structural Color. (United States)

    Kang, Han Sol; Lee, Jinseong; Cho, Suk Man; Park, Tae Hyun; Kim, Min Ju; Park, Chanho; Lee, Seung Won; Kim, Kang Lib; Ryu, Du Yeol; Huh, June; Thomas, Edwin L; Park, Cheolmin


    Structural colors (SCs) of photonic crystals (PCs) arise from selective constructive interference of incident light. Here, an ink-jet printable and rewritable block copolymer (BCP) SC display is demonstrated, which can be quickly written and erased over 50 times with resolution nearly equivalent to that obtained with a commercial office ink-jet printer. Moreover, the writing process employs an easily modified printer for position- and concentration-controlled deposition of a single, colorless, water-based ink containing a reversible crosslinking agent, ammonium persulfate. Deposition of the ink onto a self-assembled BCP PC film comprising a 1D stack of alternating layers enables differential swelling of the written BCP film and produces a full-colored SC display of characters and images. Furthermore, the information can be readily erased and the system can be reset by application of hydrogen bromide. Subsequently, new information can be rewritten, resulting in a chemically rewritable BCP SC display. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  7. Direct Immersion Annealing of Block Copolymer Thin Films (United States)

    Karim, Alamgir

    We demonstrate ordering of thin block copolymer (BCP) films via direct immersion annealing (DIA) at enhanced rate leading to stable morphologies. The BCP films are immersed in carefully selected mixtures of good and marginal solvents that can impart enhanced polymer mobility, while inhibiting film dissolution. DIA is compatible with roll-to-roll assembly manufacturing and has distinct advantages over conventional thermal annealing and batch processing solvent-vapor annealing methods. We identify three solvent composition-dependent BCP film ordering regimes in DIA for the weakly interacting polystyrene -poly(methyl methacrylate) (PS -PMMA) system: rapid short range order, optimal long-range order, and a film instability regime. Kinetic studies in the ``optimal long-range order'' processing regime as a function of temperature indicate a significant reduction of activation energy for BCP grain growth compared to oven annealing at conventional temperatures. An attractive feature of DIA is its robustness to ordering other BCP (e.g. PS-P2VP) and PS-PMMA systems exhibiting spherical, lamellar and cylindrical ordering. Inclusion of nanoparticles in these films at high concentrations and fast ordering kinetics study with neutron reflectivity and SANS will be discussed. This is (late) Contributed Talk Abstract for Dillon Medal Symposium at DPOLY - discussed with DPOLY Chair Dvora Perahia.

  8. Complexation-tailored morphology of asymmetric block copolymer membranes

    KAUST Repository

    Madhavan, Poornima


    Hydrogen-bond formation between polystyrene-b-poly (4-vinylpyridine) (PS-b-P4VP) block copolymer (BCP) and -OH/-COOH functionalized organic molecules was used to tune morphology of asymmetric nanoporous membranes prepared by simultaneous self-assembly and nonsolvent induced phase separation. The morphologies were characterized by field emmision scanning electron microscopy (FESEM) and atomic force microscopy (AFM). Hydrogen bonds were confirmed by infrared (IR), and the results were correlated to rheology characterization. The OH-functionalized organic molecules direct the morphology into hexagonal order. COOH-functionalized molecules led to both lamellar and hexagonal structures. Micelle formation in solutions and their sizes were determined using dynamic light scattering (DLS) measurements and water fluxes of 600-3200 L/m 2·h·bar were obtained. The pore size of the plain BCP membrane was smaller than with additives. The following series of additives led to pores with hexagonal order with increasing pore size: terephthalic acid (COOH-bifunctionalized) < rutin (OH-multifunctionalized) < 9-anthracenemethanol (OH-monofunctionalized) < 3,5-dihydroxybenzyl alcohol (OH-trifunctionalized). © 2013 American Chemical Society.

  9. SANS and SAXS Study of Block and Graft Copolymers Containing Natural and Synthetic Rubbers (United States)

    Hasegawa, H.


    Small-angle neutron scattering (SANS) and small-angle X-ray scattering (SAXS) are excellent techniques to study nano-scale concentration fluctuations in the two-component polymer systems such as block and graft copolymers and polymer blends. The miscibility, phase transitions, microphase-separated structures and interface thicknesses were investigated by SANS and SAXS for the block and graft copolymers, which at least contain natural or synthetic rubber as one component.

  10. Nanoscale battery materials based on the self-assembly of block copolymers (United States)

    Bullock, Steven E.; Kofinas, Peter

    An ionically conducting block copolymer was used as a template for the synthesis and confinement of lithium manganese oxide nanoparticles. The block copolymer functions as a polyelectrolyte and as a composite anode in a lithium battery system. Impedance spectroscopy and galvanostatic testing, X-ray diffraction and transmission electron microscopy were used to characterize the anode and polyelectrolyte. Galvanostatic testing indicates 300 or more cycles were possible without appreciable capacity fade.

  11. Block-Copolymer-Assisted Solubilization of Carbon Nanotubes and Exfoliation Monitoring Through Viscosity

    NARCIS (Netherlands)

    Cotiuga, Irina; Picchioni, Francesco; Agarwal, Uday S.; Wouters, Daan; Loos, Joachim; Lemstra, Piet J.


    The use of the block copolymers polystyrene-block-poly(ethylene oxide) and poly(methyl methacrylate)-block-poly(ethylene oxide) is described to assist the direct solubilization of single-walled carbon nanotubes (SWNTs) into water under ultrasonic irradiation. As compared to surfactants and

  12. Poly(vinylidene fluoride)/nickel nanocomposites from semicrystalline block copolymer precursors

    NARCIS (Netherlands)

    Voet, Vincent S. D.; Tichelaar, Martijn; Tanase, Stefania; Mittelmeijer-Hazeleger, Marjo C.; ten Brinke, Gerrit; Loos, Katja


    The fabrication of nanoporous poly(vinylidene fluoride) (PVDF) and PVDF/nickel nanocomposites from semicrystalline block copolymer precursors is reported. Polystyrene-block-poly(vinylidene fluoride)-block-polystyrene (PS-b-PVDF-b-PS) is prepared through functional benzoyl peroxide initiated

  13. Ionic Liquids As Self-Assembly Guide for the Formation of Nanostructured Block Copolymer Membranes

    KAUST Repository

    Madhavan, Poornima


    Nanostructured block copolymer membranes were manufactured by water induced phase inversion, using ionic liquids (ILs) as cosolvents. The effect of ionic liquids on the morphology was investigated, by using polystyrene-b-poly(4-vinyl pyridine) (PS-b-PV4P) diblock as membrane copolymer matrix and imidazolium and pyridinium based ILs. The effect of IL concentration and chemical composition was evident with particular interaction with P4VP blocks. The order of block copolymer/ILs solutions previous to the membrane casting was confirmed by cryo scanning electron microscopy and the morphologies of the manufactured nanostructured membranes were characterized by transmission and scanning electron microscopy. Non-protic ionic liquids facilitate the formation of hexagonal nanoporous block copolymer structure, while protic ILs led to a lamella-structured membrane. The rheology of the IL/block copolymer solutions was investigated, evaluating the storage and loss moduli. Most membranes prepared with ionic liquid had higher water flux than pure block copolymer membranes without additives.

  14. Field-theoretic simulations of block copolymer nanocomposites in a constant interfacial tension ensemble (United States)

    Koski, Jason P.; Riggleman, Robert A.


    Block copolymers, due to their ability to self-assemble into periodic structures with long range order, are appealing candidates to control the ordering of functionalized nanoparticles where it is well-accepted that the spatial distribution of nanoparticles in a polymer matrix dictates the resulting material properties. The large parameter space associated with block copolymer nanocomposites makes theory and simulation tools appealing to guide experiments and effectively isolate parameters of interest. We demonstrate a method for performing field-theoretic simulations in a constant volume-constant interfacial tension ensemble (n V γ T ) that enables the determination of the equilibrium properties of block copolymer nanocomposites, including when the composites are placed under tensile or compressive loads. Our approach is compatible with the complex Langevin simulation framework, which allows us to go beyond the mean-field approximation. We validate our approach by comparing our n V γ T approach with free energy calculations to determine the ideal domain spacing and modulus of a symmetric block copolymer melt. We analyze the effect of numerical and thermodynamic parameters on the efficiency of the n V γ T ensemble and subsequently use our method to investigate the ideal domain spacing, modulus, and nanoparticle distribution of a lamellar forming block copolymer nanocomposite. We find that the nanoparticle distribution is directly linked to the resultant domain spacing and is dependent on polymer chain density, nanoparticle size, and nanoparticle chemistry. Furthermore, placing the system under tension or compression can qualitatively alter the nanoparticle distribution within the block copolymer.

  15. Field-theoretic simulations of block copolymer nanocomposites in a constant interfacial tension ensemble. (United States)

    Koski, Jason P; Riggleman, Robert A


    Block copolymers, due to their ability to self-assemble into periodic structures with long range order, are appealing candidates to control the ordering of functionalized nanoparticles where it is well-accepted that the spatial distribution of nanoparticles in a polymer matrix dictates the resulting material properties. The large parameter space associated with block copolymer nanocomposites makes theory and simulation tools appealing to guide experiments and effectively isolate parameters of interest. We demonstrate a method for performing field-theoretic simulations in a constant volume-constant interfacial tension ensemble (nVγT) that enables the determination of the equilibrium properties of block copolymer nanocomposites, including when the composites are placed under tensile or compressive loads. Our approach is compatible with the complex Langevin simulation framework, which allows us to go beyond the mean-field approximation. We validate our approach by comparing our nVγT approach with free energy calculations to determine the ideal domain spacing and modulus of a symmetric block copolymer melt. We analyze the effect of numerical and thermodynamic parameters on the efficiency of the nVγT ensemble and subsequently use our method to investigate the ideal domain spacing, modulus, and nanoparticle distribution of a lamellar forming block copolymer nanocomposite. We find that the nanoparticle distribution is directly linked to the resultant domain spacing and is dependent on polymer chain density, nanoparticle size, and nanoparticle chemistry. Furthermore, placing the system under tension or compression can qualitatively alter the nanoparticle distribution within the block copolymer.

  16. Effect of Systematic Hydrogenation on the Phase Behavior and Nanostructural Dimensions of Block Copolymers. (United States)

    Ashraf, Arman R; Ryan, Justin J; Satkowski, Michael M; Smith, Steven D; Spontak, Richard J


    Unsaturated polydienes are frequently hydrogenated to yield polyolefins that are more chemically stable. Here, the effects of partial hydrogenation on the phase behavior and nanostructure of polyisoprene-containing block copolymers are investigated. To ensure access to the order-disorder transition temperature (T ODT ) over a wide temperature range, we examine copolymers with at least one random block. Dynamic rheological and scattering measurements indicate that T ODT increases linearly with increasing hydrogenation. Small-angle scattering reveals that the temperature-dependence of the Flory-Huggins parameter changes and the microdomain period increases, while the interfacial thickness decreases. The influence of hydrogenation becomes less pronounced in more constrained multiblock copolymers.

  17. Antimicrobial activity of poly(acrylic acid) block copolymers

    International Nuclear Information System (INIS)

    Gratzl, Günther; Paulik, Christian; Hild, Sabine; Guggenbichler, Josef P.; Lackner, Maximilian


    The increasing number of antibiotic-resistant bacterial strains has developed into a major health problem. In particular, biofilms are the main reason for hospital-acquired infections and diseases. Once formed, biofilms are difficult to remove as they have specific defense mechanisms against antimicrobial agents. Antimicrobial surfaces must therefore kill or repel bacteria before they can settle to form a biofilm. In this study, we describe that poly(acrylic acid) (PAA) containing diblock copolymers can kill bacteria and prevent from biofilm formation. The PAA diblock copolymers with poly(styrene) and poly(methyl methacrylate) were synthesized via anionic polymerization of tert-butyl acrylate with styrene or methyl methacrylate and subsequent acid-catalyzed hydrolysis of the tert-butyl ester. The copolymers were characterized via nuclear magnetic resonance spectroscopy (NMR), size-exclusion chromatography (SEC), Fourier transform infrared spectroscopy (FTIR), elemental analysis, and acid–base titrations. Copolymer films with a variety of acrylic acid contents were produced by solvent casting, characterized by atomic force microscopy (AFM) and tested for their antimicrobial activity against Staphylococcus aureus, Escherichia coli, and Pseudomonas aeruginosa. The antimicrobial activity of the acidic diblock copolymers increased with increasing acrylic acid content, independent of the copolymer-partner, the chain length and the nanostructure. - Highlights: • Acrylic acid diblock copolymers are antimicrobially active. • The antimicrobial activity depends on the acrylic acid content in the copolymer. • No salts, metals or other antimicrobial agents are needed

  18. Antimicrobial activity of poly(acrylic acid) block copolymers

    Energy Technology Data Exchange (ETDEWEB)

    Gratzl, Günther, E-mail: [Johannes Kepler University Linz, Institute for Chemical Technology of Organic Materials, Altenberger Str. 69, 4040 Linz (Austria); Paulik, Christian [Johannes Kepler University Linz, Institute for Chemical Technology of Organic Materials, Altenberger Str. 69, 4040 Linz (Austria); Hild, Sabine [Johannes Kepler University Linz, Institute of Polymer Science, Altenberger Str. 69, 4040 Linz (Austria); Guggenbichler, Josef P.; Lackner, Maximilian [AMiSTec GmbH and Co. KG, Leitweg 13, 6345 Kössen, Tirol (Austria)


    The increasing number of antibiotic-resistant bacterial strains has developed into a major health problem. In particular, biofilms are the main reason for hospital-acquired infections and diseases. Once formed, biofilms are difficult to remove as they have specific defense mechanisms against antimicrobial agents. Antimicrobial surfaces must therefore kill or repel bacteria before they can settle to form a biofilm. In this study, we describe that poly(acrylic acid) (PAA) containing diblock copolymers can kill bacteria and prevent from biofilm formation. The PAA diblock copolymers with poly(styrene) and poly(methyl methacrylate) were synthesized via anionic polymerization of tert-butyl acrylate with styrene or methyl methacrylate and subsequent acid-catalyzed hydrolysis of the tert-butyl ester. The copolymers were characterized via nuclear magnetic resonance spectroscopy (NMR), size-exclusion chromatography (SEC), Fourier transform infrared spectroscopy (FTIR), elemental analysis, and acid–base titrations. Copolymer films with a variety of acrylic acid contents were produced by solvent casting, characterized by atomic force microscopy (AFM) and tested for their antimicrobial activity against Staphylococcus aureus, Escherichia coli, and Pseudomonas aeruginosa. The antimicrobial activity of the acidic diblock copolymers increased with increasing acrylic acid content, independent of the copolymer-partner, the chain length and the nanostructure. - Highlights: • Acrylic acid diblock copolymers are antimicrobially active. • The antimicrobial activity depends on the acrylic acid content in the copolymer. • No salts, metals or other antimicrobial agents are needed.

  19. Surfactant-Free RAFT Emulsion Polymerization of Styrene Using Thermoresponsive macroRAFT Agents: Towards Smart Well-Defined Block Copolymers with High Molecular Weights

    Directory of Open Access Journals (Sweden)

    Steffen Eggers


    Full Text Available The combination of reversible addition–fragmentation chain transfer (RAFT and emulsion polymerization has recently attracted much attention as a synthetic tool for high-molecular-weight block copolymers and their micellar nano-objects. Up to recently, though, the use of thermoresponsive polymers as both macroRAFT agents and latex stabilizers was impossible in aqueous media due to their hydrophobicity at the usually high polymerization temperatures. In this work, we present a straightforward surfactant-free RAFT emulsion polymerization to obtain thermoresponsive styrenic block copolymers with molecular weights of around 100 kDa and their well-defined latexes. The stability of the aqueous latexes is achieved by adding 20 vol % of the cosolvent 1,4-dioxane (DOX, increasing the phase transition temperature (PTT of the used thermoresponsive poly(N-acryloylpyrrolidine (PAPy macroRAFT agents above the polymerization temperature. Furthermore, this cosolvent approach is combined with the use of poly(N,N-dimethylacrylamide-block-poly(N-acryloylpiperidine-co-N-acryloylpyrrolidine (PDMA-b-P(APi-co-APy as the macroRAFT agent owning a short stabilizing PDMA end block and a widely adjustable PTT of the P(APi-co-APy block in between 4 and 47 °C. The temperature-induced collapse of the latter under emulsion polymerization conditions leads to the formation of RAFT nanoreactors, which allows for a very fast chain growth of the polystyrene (PS block. In dynamic light scattering (DLS, as well as cryo-transmission electron microscopy (cryoTEM, moreover, all created latexes indeed reveal a high (temperature stability and a reversible collapse of the thermoresponsive coronal block upon heating. Hence, this paper pioneers a versatile way towards amphiphilic thermoresponsive high-molecular-weight block copolymers and their nano-objects with tailored corona switchability.

  20. Kinetics of free radical decay reactions in butadiene-styrene block copolymers

    International Nuclear Information System (INIS)

    Basheer, R.; Dole, M.


    The radiation chemistry of copolymers of butadiene and styrene is of considerable interest in the rubber and other industries. In no radiation chemical studies have any kinetic data been obtained of free radical decay reaction which could be interpreted in terms of the kinetic equation developed by us. The purpose of the present research was to obtain such data and also to compare, if possible, the protective effect toward radiation induced reactions exerted by the styrene segments in the block as compared to random copolymers. Furthermore, no one has hitherto studied the catalytic effect of hydrogen gas on the free radical decay in block copolymers. In the case of polyethylene, hydrogen has been shown to exert a pronounced catalytic effect. We also wished to investigate a possible catalytic effect of hydrogen in the case of the block copolymers. Experimental details are given. Results are reported and discussed. (author)

  1. Self-consistent field theory of block copolymers on a general curved surface. (United States)

    Li, Jianfeng; Zhang, Hongdong; Qiu, Feng


    In this work, we propose a theoretical framework based on the self-consistent field theory (SCFT) for the study of self-assembling block copolymers on a general curved surface. Relevant numerical algorithms are also developed. To demonstrate the power of the approach, we calculate the self-assembled patterns of diblock copolymers on three distinct curved surfaces with different genus. We specially study the geometrical effects of curved surfaces on the conformation of polymer chains as well as on the pattern formation of block copolymers. By carefully examining the diffusion equation of the propagator on curved surfaces, it is predicted that Gaussian chains are completely unaware of the extrinsic curvature but that they will respond to the intrinsic curvature of the surface. This theoretical assertion is consistent with our SCFT simulations of block copolymers on general curved surfaces.

  2. Morphology-properties relationship on nanocomposite films based on poly(styrene-block-diene-block-styrene copolymers and silver nanoparticles

    Directory of Open Access Journals (Sweden)


    Full Text Available A comparative study on the self-assembled nanostructured morphology and the rheological and mechanical properties of four different triblock copolymers, based on poly(styrene-block-diene-block-styrene and poly(styrene-block-diene-block-styrene matrices, and of their respective nanocomposites with 1 wt% silver nanoparticles, is reported in this work. In order to obtain well-dispersed nanoparticles in the block copolymer matrix, dodecanethiol was used as surfactant, showing good affinity with both nanoparticles and the polystyrene phase of the matrices as predicted by the solubility parameters calculated based on Hoftyzer and Van Krevelen theory. The block copolymer with the highest PS content shows the highest tensile modulus and tensile strength, but also the smallest elongation at break. When silver nanoparticles treated with surfactant were added to the block copolymer matrices, each system studied shows higher mechanical properties due to the good dispersion and the good interface of Ag nanoparticles in the matrices. Furthermore, it has been shown that semiempirical models such as Guth and Gold equation and Halpin-Tsai model can be used to predict the tensile modulus of the analyzed nanocomposites.

  3. Mechanism of titania deposition into cylindrical poly(styrene-block-4 vinyl pyridine) block copolymer templates. (United States)

    Lou, Qin; Chinthamanipeta, Pavan S; Shipp, Devon A


    A simple and effective way for TiO(2) to be deposited on silicon or indium tin oxide (ITO) substrates has been achieved by using a poly(styrene-block-4-vinyl pyridine) (PS-b-P4VP) block copolymer template. In particular, a mechanism for the formation of TiO(2) within the P4VP phase was developed. Within this model, the TiO(2) deposition occurs by swelling of the protonated P4VP segments followed by transport of Ti precursor, probably protonated Ti(OH)(4) given the low pH conditions used, into the swollen P4VP followed by condensation into TiO(2) during the heating/plasma etch processes. TiO(2) nanostructure morphology is affected by pH and deposition temperatures, because these parameters affect the degree of protonation of P4VP segments and diffusion of the titanium(IV) bis(ammonium lactato)dihydroxide (TALH) precursor into the film. A pH range of 2.1-2.5 for silicon substrates and pH = 2.1 for ITO substrates gave the narrower TiO(2) nanostructures distributions, and deposition at 70 °C gave TiO(2) nanostructures with more regular arrangements and smoother surface than those deposited at room temperature. The use of 1,4-diiodobutane as a P4VP cross-linking compound is demonstrated to be a critical parameter for maintaining good cylindrical surface morphology for both the block copolymer template and the TiO(2) nanostructures. © 2011 American Chemical Society

  4. Dielectric Characterization of Poly(styrene-b-methyl methacrylate) Block Copolymer Films (United States)

    Grabowski, Christopher; Durstock, Michael; Vaia, Richard


    Polymer films that incorporate nanoscale features have been previously investigated for their suitability as dielectric insulating materials, such as mixtures of high dielectric strength polymers with high permittivity nanoparticles. Block copolymers, due to their highly customizable molecular-scale morphologies, may exhibit useful energy storage properties. Spherical, cylindrical, or lamellar morphologies can all be generated by altering block size ratio. We report the dielectric study of thin, substrate supported poly(styrene-b-methyl methacrylate) linear block copolymer films. Energy storage capabilities will be determined through dielectric strength and permittivity measurements. As both polymer blocks have similar permittivity, field enhancement effects that typically occur in inorganic nanoparticle/polymer composites are limited. Our experiments with block copolymers will more directly test how dielectric breakdown is influenced by interfacial interactions. We thank AFOSR and AFRL for their financial support.

  5. Multicompartment micellar aggregates of linear ABC amphiphiles in solvents selective for the C block: A Monte Carlo simulation

    KAUST Repository

    Zhu, Yutian


    In the current study, we applied the Monte Carlo method to study the self-assembly of linear ABC amphiphiles composed of two solvophobic A and B blocks and a solvophilic C block. A great number of multicompartment micelles are discovered from the simulations and the detailed phase diagrams for the ABC amphiphiles with different block lengths are obtained. The simulation results reveal that the micellar structure is largely controlled by block length, solvent quality, and incompatibility between the different block types. When the B block is longer than or as same as the terminal A block, a rich variety of micellar structures can be formed from ABC amphiphiles. By adjusting the solvent quality or incompatibility between the different block types, multiple morphological transitions are observed. These morphological sequences are well explained and consistent with all the previous experimental and theoretical studies. Despite the complexity of the micellar structures and morphological transitions observed for the self-assembly of ABC amphiphiles, two important common features of the phase behavior are obtained. In general, the micellar structures obtained in the current study can be divided into zero-dimensional (sphere-like structures, including bumpy-surfaced spheres and sphere-on-sphere structures), one-dimensional (cylinder-like structures, including rod and ring structures), two-dimensional (layer-like structures, including disk, lamella and worm-like and hamburger structures) and three-dimensional (vesicle) structures. It is found that the micellar structures transform from low- to high- dimensional structures when the solvent quality for the solvophobic blocks is decreased. In contrast, the micellar structures transform from high- to low-dimensional structures as the incompatibility between different block types increases. Furthermore, several novel micellar structures, such as the CBABC five-layer vesicle, hamburger, CBA three-layer ring, wormlike shape with

  6. Nanostructure in block copolymer solutions: Rheology and small-angle neutron scattering

    International Nuclear Information System (INIS)

    Habas, Jean-Pierre; Pavie, Emmanuel; Perreur, Christelle; Lapp, Alain; Peyrelasse, Jean


    Triblock copolymers composed of poly(ethylene oxide) (PEO) and poly(propylene oxide) (PPO) present an amphiphilic character in aqueous solutions. Since PPO is less hydrophilic than PEO and since their solubilities decrease when the temperature increases, the copolymers self-assemble spontaneously, forming micelles at moderate temperatures. For higher temperatures or concentrations, the copolymers or the micelles are ordered because of repulsive interactions and form lyotropic liquid crystalline phases. These are phases of very great viscosity with the aspect of gels, and transitions between different crystalline phases can occur at fixed concentration during an increase of temperature. We studied solutions of three different copolymers. The first two have a star structure. They are both composed of four branches (EO) x (PO) y fixed on an ethylene diamine, but differ by the values of x and y. Their commercial name is Tetronic 908 (x=114, y=21) and Tetronic 704 (x=16, y=18). The third copolymer (EO) 37 (PO) 56 (EO) 37 is linear and is known under the name of Pluronic P105. The measurements of the shear complex elastic modulus according to the temperature is used to determine the temperatures of the different transitions. Then, small-angle neutron scattering on samples under flow and true crystallographic arguments make it possible to identify the nature of the crystalline phases. For the systems studied, we show that the branched copolymers form only one type of liquid crystalline phase, which is bcc for the T908 and lamellar for the T704. For the linear copolymer, it is possible to identify three transitions: micellar solution to hexagonal phase, hexagonal phase to body-centered cubic phase, and finally body-centered cubic phase to lamellar phase

  7. Synthesis, Thermodynamics and Processing of Block Copolymer Based Nanocomposites

    National Research Council Canada - National Science Library

    Bates, Frank


    Two sets of model diblock copolymers were synthesized using anionic polymerization and heterogeneous catalytic hydrogenation: Poly(ethylene)-poly(ethylenepropylene) (PE-PEP) and poly(ethyleneoxide)-poly(alkane) (PEO-PA...

  8. Opto-electronic devices from block copolymers and their oligomers.

    NARCIS (Netherlands)

    Hadziioannou, G


    This paper presents research activities towards the development of polymer materials and devices for optoelectronics, An approach to controlling the conjugation length and transferring the luminescence properties of organic molecules to polymers through black copolymers containing well-defined

  9. Correlating self-assembly of block copolymers for their application in synthesis of gold nanoparticles. (United States)

    Ray, Debes; Aswall, Vinod Kumar; Srivastava, Dinesh


    We report the role of self-assembly of polyethylene oxide-polypropylene oxide-polyethylene oxide (PEO-PPO-PEO) block copolymers for the synthesis of gold nanoparticles from hydrogen tetrachloroaureate (III) hydrate (HAuCl4 x 3H2O) in aqueous solution. The synthesis has been carried out using three different block copolymers P85 [EO26PO39EO26], F88 [EO103PO39EO103] and P105 [EO37PO56EO37], which not only have varying molecular weight but also differ in hydrophobicity to hydrophilicity ratio. The formation of gold nanoparticles is confirmed by the UV-Visible Spectroscopy. Transmission electron microscopy (TEM) provides the sizes of the nanoparticles formed in these systems. Small-Angle Neutron Scattering (SANS) and Dynamic Light Scattering (DLS) techniques are used to correlate the self-assembly of block copolymer to their propensity to form gold nanoparticles. The yield is found to be in the order P105 > P85 > F88 and is related to the higher tendency of block copolymer to self-assemble to give greater yield of gold nanoparticles. For all the block copolymers, SANS and DLS results suggests that the yield in the synthesis does not always increases with the salt concentration and is limited due to the fact that most of the block copolymers remain unassociated with the gold nanoparticles. By making use of these unassociated block copolymers, we propose two methods (i) step addition method and (ii) additional reductant method, where the synthesis yield of gold nanoparticles can be enhanced by manifold.

  10. Antimicrobial activity of poly(acrylic acid) block copolymers. (United States)

    Gratzl, Günther; Paulik, Christian; Hild, Sabine; Guggenbichler, Josef P; Lackner, Maximilian


    The increasing number of antibiotic-resistant bacterial strains has developed into a major health problem. In particular, biofilms are the main reason for hospital-acquired infections and diseases. Once formed, biofilms are difficult to remove as they have specific defense mechanisms against antimicrobial agents. Antimicrobial surfaces must therefore kill or repel bacteria before they can settle to form a biofilm. In this study, we describe that poly(acrylic acid) (PAA) containing diblock copolymers can kill bacteria and prevent from biofilm formation. The PAA diblock copolymers with poly(styrene) and poly(methyl methacrylate) were synthesized via anionic polymerization of tert-butyl acrylate with styrene or methyl methacrylate and subsequent acid-catalyzed hydrolysis of the tert-butyl ester. The copolymers were characterized via nuclear magnetic resonance spectroscopy (NMR), size-exclusion chromatography (SEC), Fourier transform infrared spectroscopy (FTIR), elemental analysis, and acid-base titrations. Copolymer films with a variety of acrylic acid contents were produced by solvent casting, characterized by atomic force microscopy (AFM) and tested for their antimicrobial activity against Staphylococcus aureus, Escherichia coli, and Pseudomonas aeruginosa. The antimicrobial activity of the acidic diblock copolymers increased with increasing acrylic acid content, independent of the copolymer-partner, the chain length and the nanostructure. Copyright © 2014 Elsevier B.V. All rights reserved.

  11. Influence of polydispersity on the phase behavior of statistical multiblock copolymers with Schultz-Zimm block molecular weight distributions

    NARCIS (Netherlands)

    Angerman, H.J.; Brinke, G. ten; Slot, J.J.M.


    In this paper we investigate in a systematic way the influence of polydispersity in the block lengths on the phase behavior of AB-multiblock copolymer melts. As model system we take a polydisperse multiblock copolymer for which both the A-blocks and the B-blocks satisfy a Schultz-Zimm distribution.

  12. Enhanced Photophysical Properties of Nanopatterned Titania Nanodots/Nanowires upon Hybridization with Silica via Block Copolymer Templated Sol-Gel Process

    Directory of Open Access Journals (Sweden)

    Dinakaran Kannaiyan


    Full Text Available We fabricated titanium dioxide (TiO2-silica (SiO2 nanocomposite structures with controlled morphology by a simple synthetic approach using cooperative sol-gel chemistry and block copolymer (BCP self-assembly. Mixed TiO2-SiO2 sol-gel precursors were blended with amphiphilic poly(styrene-block-ethylene oxide (PS-b-PEO BCPs where the precursors were selectively incorporated into the hydrophilic PEO domains. Changing the volumetric ratio of TiO2-SiO2 sol-gel precursor from 5% to 20%, a stepwise structural inversion occurred from nanodot arrays to discrete nanowires. Template free hybrid inorganic nanostructures were produced after the removal of PS-b-PEO by irradiation of UV light. The morphological evolution and photophysical properties were investigated by microscopic studies, UV-visible absorption and photocatalytic properties.

  13. Lithium-Salt-Containing High-Molecular-Weight Polystyrene-block-Polyethylene Oxide Block Copolymer Films. (United States)

    Metwalli, Ezzeldin; Rasool, Majid; Brunner, Simon; Müller-Buschbaum, Peter


    Ionic conductivity in relation to the morphology of lithium-doped high-molecular-weight polystyrene-block-polyethylene oxide (PS-b-PEO) diblock copolymer films was investigated as solid-state membranes for lithium-ion batteries. The tendency of the polyethylene (PEO) block to crystallize was highly suppressed by increasing both the salt-doping level and the temperature. The PEO crystallites completely vanished at a salt-doping ratio of Li/EO>0.08, at which the PEO segments were hindered from entering the crystalline unit of the PEO chain. A kinetically trapped lamella morphology of PS-b-PEO was observed, due to PEO crystallization. The increase in the lamella spacing with increasing salt concentration was attributed to the conformation of the PEO chain rather than the volume contribution of the salt or the previously reported increase in the effective interaction parameter. Upon loading the salt, the PEO chains changed from a compact/highly folded conformation to an amorphous/expanded-like conformation. The ionic conductivity was enhanced by amorphization of PEO and thereby the mobility of the PEO blocks increased upon increasing the salt-doping level. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  14. Improved conductivity in dye-sensitised solar cells through block-copolymer confined TiO 2 crystallisation

    KAUST Repository

    Guldin, Stefan


    Anatase TiO2 is typically a central component in high performance dye-sensitised solar cells (DSCs). This study demonstrates the benefits of high temperature synthesised mesoporous titania for the performance of solid-state DSCs. In contrast to earlier methods, the high temperature stability of mesoporous titania is enabled by the self-assembly of the amphiphilic block copolymer polyisoprene-block-polyethylene oxide (PI-b -PEO) which compartmentalises TiO2 crystallisation, preventing the collapse of porosity at temperatures up to 700 °C. The systematic study of the temperature dependence on DSC performance reveals a parameter trade-off: high temperature annealed anatase consisted of larger crystallites and had a higher conductivity, but this came at the expense of a reduced specific surface area. While the reduction in specific surface areas was found to be detrimental for liquid-electrolyte DSC performance, solid-state DSCs benefitted from the increased anatase conductivity and exhibited a performance increase by a factor of three. © 2011 The Royal Society of Chemistry.

  15. The synthesis and protein resistance of amphiphilic PDMS-b-(PDMS-g-cysteine) copolymers (United States)

    Lei, Yufeng; Lin, Yaling; Zhang, Anqiang


    Zwitterionic polymers have been used to cope with nonspecific protein adsorption and bio-fouling problems for a wide range of materials, including biomedical devices, marine coatings and membrane separation. However, direct surface modification with highly water-soluble zwitterionic polymers is rather difficult due to their poor attachment to hydrophobic solid surfaces. In this work, we utilize the hydrophobic interaction to anchor zwitterionic polysiloxanes grafted with cysteine onto surfaces by adding an hydrophobic block of polydimethylsiloxanes, referred as PDMS-b-(PDMS-g-Cys)s. The synthesis involves only three steps of reactions, and the structures of each product were characterized using GPC, FT-IR and 1H NMR. The adsorption and protein resistance of PDMS-b-(PDMS-g-Cys)s on a gold surface are investigated with QCM-D. The results show that the hydrophobic interaction moieties of the additional PDMS blocks help the hydrophilic cysteine-grafted blocks stably attach and then function on the sensor. These findings suggest that the addition of hydrophobic moieties provides an effective approach to construct anti-fouling interfaces with zwitterionic polymers in aqueous solution.

  16. Synthesis, and Micro-Phase Separation of Hybrid Organic-Inorganic Polyhedral Oligomeric Silsesquioxane Block Copolymers (United States)

    Intasanta, Narupol; Russell, Thomas P.; Coughlin, E. Bryan


    Hybrid organic-inorganic di- and triblock copolymers containing Polyhedral Oligomeric Silsesquioxane (POSS) nanoparticles have been synthesized using Atom Transfer Radical Polymerization (ATRP). Chemical compositions and molecular weight distributions were determined by 1H NMR, and GPC, thermal properties were obtained by Differential Scanning Calorimetry (DSC) and Thermal Gravimetric Analysis (TGA). The block copolymers include either Methyl methacrylate (MMA), Styrene, or n-Butyl Acrylate (nBuA) as the organic block. Bulk morphologies and order-disorder transition phenomenon have been studied using Small Angle X-ray Scattering (SAXS). Thin film morphologies and interfacial interactions were investigated utilizing Atomic Force Microscopy (AFM). Fundamental studies on the dynamics of the polymers with, and without, applied external field have also been conducted. For PMMA containing block copolymers, the MMA blocks have been selectively degraded using UV irradiation and consequentially transformed into glass-like nano-patterned array utilizing oxygen plasma oxidation.

  17. Hemocompatibility of styrenic block copolymers for use in prosthetic heart valves. (United States)

    Brubert, Jacob; Krajewski, Stefanie; Wendel, Hans Peter; Nair, Sukumaran; Stasiak, Joanna; Moggridge, Geoff D


    Certain styrenic thermoplastic block copolymer elastomers can be processed to exhibit anisotropic mechanical properties which may be desirable for imitating biological tissues. The ex-vivo hemocompatibility of four triblock (hard-soft-hard) copolymers with polystyrene hard blocks and polyethylene, polypropylene, polyisoprene, polybutadiene or polyisobutylene soft blocks are tested using the modified Chandler loop method using fresh human blood and direct contact cell proliferation of fibroblasts upon the materials. The hemocompatibility and durability performance of a heparin coating is also evaluated. Measures of platelet and coagulation cascade activation indicate that the test materials are superior to polyester but inferior to expanded polytetrafluoroethylene and bovine pericardium reference materials. Against inflammatory measures the test materials are superior to polyester and bovine pericardium. The addition of a heparin coating results in reduced protein adsorption and ex-vivo hemocompatibility performance superior to all reference materials, in all measures. The tested styrenic thermoplastic block copolymers demonstrate adequate performance for blood contacting applications.

  18. The Organization of Nanoporous Structure Using Controlled Micelle Size from MPEG-b-PDLLA Block Copolymers

    International Nuclear Information System (INIS)

    Chang, Jeong Ho; Kim, Kyung Ja; Shin, Young Kook


    Selected MPEG-b-PDLLA block copolymers have been synthesized by ring-opening polymerization with systematic variation of the chain lengths of the resident hydrophilic and hydrophobic blocks. The size and shape of the micelles that spontaneously form in solution are then controlled by the characteristics of the block copolymer template. All the materials prepared in this study showed the tunable pore size of 20-80 A with the increase of hydrophobic chain lengths and up to 660 m 2 /g of specific surface area. The formation mechanism of these nanoporous structures obtained by controlling the micelle size has been confirmed using both liquid and solid state 13 C and 29 Si NMR techniques. This work verifies the formation mechanism of nanoporous structures in which the pore size and wall thickness are closely dependent on the size of hydrophobic cores and hydrophilic shells of the block copolymer templates

  19. Block copolymers of styrene, isoprene, and ethylene oxide prepared by anionic polymerization. I. Synthesis and characterization

    NARCIS (Netherlands)

    Koetsier, D.W.; Bantjes, A.; Feijen, Jan


    Anionic polymerization has been used as a technique for the synthesis of five-block copolymers of polystyrene (PS), polyisoprene (PI), and poly(ethylene oxide) (PEO). Two types of such polymers, PEO-PI-PS-PI-PEO and PEO-PS-PI-PS-PEO with varying PEO block length, have been prepared, using potassium

  20. Synthesis and properties of lyotropic poly(amide-block-aramid) copolymers

    NARCIS (Netherlands)

    De Ruijter, C.


    This thesis describes the synthesis and properties of liquid crystalline block copolymers comprised of alternating rigid and flexible blocks for the preparation of self-reinforcing materials. The incentive for this work was the expectation that the rigid segments would phase separate on a

  1. Multi-block sulfonated poly(phenylene) copolymer proton exchange membranes (United States)

    Fujimoto, Cy H [Albuquerque, NM; Hibbs, Michael [Albuquerque, NM; Ambrosini, Andrea [Albuquerque, NM


    Improved multi-block sulfonated poly(phenylene) copolymer compositions, methods of making the same, and their use as proton exchange membranes (PEM) in hydrogen fuel cells, direct methanol fuel cells, in electrode casting solutions and electrodes. The multi-block architecture has defined, controllable hydrophobic and hydrophilic segments. These improved membranes have better ion transport (proton conductivity) and water swelling properties.

  2. 125l-Labeled PEO/PLA block copolymer: biodistribution studies in rats

    Czech Academy of Sciences Publication Activity Database

    Nováková, K.; Lázníček, M.; Rypáček, František; Machová, Luďka


    Roč. 17, č. 4 (2002), s. 285-296 ISSN 0883-9115 R&D Projects: GA AV ČR KSK4055109 Institutional research plan: CEZ:AV0Z4050913 Keywords : block copolymer micelles * poly(D,L-lactide-block-ethylene oxide) * biodistribution Subject RIV: CC - Organic Chemistry Impact factor: 0.525, year: 2002

  3. Nanoporous materials from stable and metastable structures of 1,2-PB-b-PDMS block copolymers

    DEFF Research Database (Denmark)

    Schulte, Lars; Grydgaard, Anne; Jakobsen, Mathilde R.


    Experimental procedures used at the preparation and characterization stages of nanoporous materials (NPM) from 1,2-polybutadiene-b-polydimethylsiloxane (1,2-PB-b-PDMS) block copolymers are presented. The NPM were obtained from self-assembled block copolymers after firstly cross-linking 1,2-PB (the...... matrix component) and secondly degrading PDMS (the expendable component). Depending on the temperature of the cross-linking reaction different morphologies can be ‘frozen’ from the same block copolymer. Starting with a block copolymer precursor of lamellar morphology at room temperature, the gyroid...

  4. Ellipsometry measurements of glass transition breadth in bulk films of random, block, and gradient copolymers. (United States)

    Mok, M M; Kim, J; Marrou, S R; Torkelson, J M


    Bulk films of random, block and gradient copolymer systems were studied using ellipsometry to demonstrate the applicability of the numerical differentiation technique pioneered by Kawana and Jones for studying the glass transition temperature (T (g)) behavior and thermal expansivities of copolymers possessing different architectures and different levels of nanoheterogeneity. In a series of styrene/n -butyl methacrylate (S/nBMA) random copolymers, T (g) breadths were observed to increase from approximately 17( degrees ) C in styrene-rich cases to almost 30( degrees ) C in nBMA-rich cases, reflecting previous observations of significant nanoheterogeneity in PnBMA homopolymers. The derivative technique also revealed for the first time a substantial increase in glassy-state expansivity with increasing nBMA content in S/nBMA random copolymers, from 1.4x10(-4) K-1 in PS to 3.5x10(-4) K-1 in PnBMA. The first characterization of block copolymer T (g) 's and T (g) breadths by ellipsometry is given, examining the impact of nanophase-segregated copolymer structure on ellipsometric measurements of glass transition. The results show that, while the technique is effective in detecting the two T (g) 's expected in certain block copolymer systems, the details of the glass transition can become suppressed in ellipsometry measurements of a rubbery minor phase under conditions where the matrix is glassy; meanwhile, both transitions are easily discernible by differential scanning calorimetry. Finally, broad glass transition regions were measured in gradient copolymers, yielding in some cases extraordinary T (g) breadths of 69- 71( degrees ) C , factors of 4-5 larger than the T (g) breadths of related homopolymers and random copolymers. Surprisingly, one gradient copolymer demonstrated a slightly narrower T (g) breadth than the S/nBMA random copolymers with the highest nBMA content. This highlights the fact that nanoheterogeneity relevant to the glass transition response in selected

  5. Synthesis of manganese oxide supported on mesoporous titanium oxide: Influence of the block copolymer

    Energy Technology Data Exchange (ETDEWEB)

    Schmit, F. [Laboratoire des Multimatériaux et Interfaces, UMR CNRS 5615, Bât. Berthollet, Université Claude Bernard—Lyon 1, 43 Bd 11 novembre 1918, 69622 Villeurbanne (France); IRCELYON, Institut de recherches sur la catalyse et l’environnement de Lyon (UMR 5256 CNRS/Université Lyon 1), Lyon (France); Bois, L., E-mail: [Laboratoire des Multimatériaux et Interfaces, UMR CNRS 5615, Bât. Berthollet, Université Claude Bernard—Lyon 1, 43 Bd 11 novembre 1918, 69622 Villeurbanne (France); Chiriac, R.; Toche, F.; Chassagneux, F. [Laboratoire des Multimatériaux et Interfaces, UMR CNRS 5615, Bât. Berthollet, Université Claude Bernard—Lyon 1, 43 Bd 11 novembre 1918, 69622 Villeurbanne (France); Besson, M.; Descorme, C. [IRCELYON, Institut de recherches sur la catalyse et l’environnement de Lyon (UMR 5256 CNRS/Université Lyon 1), Lyon (France); Khrouz, L. [ENS LYON Laboratoire de Chimie (LR6, site Monod), 46, allée d’Italie, 69364 Lyon Cedex 07 (France)


    Manganese oxides supported on mesoporous titanium oxides were synthesized via a sol–gel route using block copolymer self-assembly. The oxides were characterized by X-ray diffraction, infrared spectroscopy, thermal analyses, nitrogen adsorption/desorption, electron microscopy and electronic paramagnetic resonance. A mesoporous anatase containing amorphous manganese oxide particles could be obtained with a 0.2 Mn:Ti molar ratio. At higher manganese loading (0.5 Mn:Ti molar ratio), segregation of crystalline manganese oxide occurred. The influence of block copolymer and manganese salt on the oxide structure was discussed. The evolution of the textural and structural characteristics of the materials upon hydrothermal treatment was also investigated. - Graphical abstract: One-pot amorphous MnO{sub 2} supported on mesoporous anataseTiO{sub 2}. - Highlights: • Mesoporous manganese titanium oxides were synthesized using block copolymer. • Block copolymers form complexes with Mn{sup 2+} from MnCl{sub 2}. • With block copolymer, manganese oxide can be dispersed around the titania crystallites. • With Mn(acac){sub 2}, manganese is dispersed inside titania. • MnOOH crystallizes outside mesoporous titania during hydrothermal treatment.

  6. Polydimethylsiloxane-polymethacrylate block copolymers tethering quaternary ammonium salt groups for antimicrobial coating

    Energy Technology Data Exchange (ETDEWEB)

    Qin, Xiaoshuai; Li, Yancai; Zhou, Fang; Ren, Lixia; Zhao, Yunhui, E-mail:; Yuan, Xiaoyan


    Highlights: • A series of PDMS-b-QPDMAEMA block copolymers were synthesized via RAFT polymerization. • The composition and morphology of the copolymer films strongly depended on the content of QPDMAEMA. • Migration of QPDMAEMA blocks toward surface was promoted when contacting with water. • Heterogeneous film surfaces with higher N{sup +} content exhibited more obvious antimicrobial activity. - Abstract: Block copolymers PDMS-b-PDMAEMA were synthesized via reversible addition-fragmentation chain transfer (RAFT) polymerization involving N,N-dimethylaminoethyl methacrylate (DMAEMA) by using poly(dimethylsiloxane) (PDMS) macro-chain transfer agent. And, the tertiary amino groups in PDMAEMA were quaternized with n-octyliodide to provide quaternary ammonium salts (QPDMAEMA). The well-defined copolymers generated composition variation and morphology evolvement on film surfaces, which were characterized by X-ray photoelectron spectroscopy, atomic force microscopy, and contact angle measurements. The results indicated that the enrichment of QPDMAEMA brought about lower elemental ratios of Si/N on the film surfaces. The surface morphologies evolved with the variations of QPDMAEMA content, and the variation trend of film roughness was exactly opposite to that of water contact angle hysteresis. With regard to structure-antimicrobial relationships, the copolymer films had more evident antimicrobial activity against Gram-positive, Bacillus subtilis, and the surfaces with heterogeneous morphology and higher N{sup +} content presented better antimicrobial activity. The functionalized copolymers based PDMS and quaternary ammonium salts materials have the potential applications as antimicrobial coatings.

  7. Studies on microphase-separated structures of block copolymers by neutron reflectivity measurement

    International Nuclear Information System (INIS)

    Torikai, Naoya; Noda, Ichiro; Matsushita, Yushu; Karim, A.; Satija, S.K.; Han, C.C.; Ebisawa, Toru.


    Segmental distributions of block copolymer chains in lamellar microphase-separated structure and those of homopolymers in block copolymer/homopolymer blends also with lamellar structures were studied by neutron reflectivity measurements. It was revealed that polystyrene and poly(2-vinylpyridine) lamellae were alternately stacked within the thin films of pure block copolymers spin-coated on silicon wafers, and they were preferentially oriented along the direction parallel to film surface. Polystyrene lamella appeared at air surfaces of the films, while poly(2-vinylpyridine) lamella did on silicon surfaces. Segment distribution at lamellar interface was well described by an error function, and the width of the lamellar interface, defined by a full-width half-maximum value of interfacial profile, was estimated to be about 4.5 nm. Segments of block chains adjacent to the chemical junction points connecting different block chains were strongly localized near the lamellar interfaces, while those on the free ends of block chains were distributed all over the lamellar microdomains with their distribution maxima at the centers of lamellae. On the other hand, it was clarified that homopolymers dissolved in the corresponding lamellar microdomains of block copolymers were also distributed throughout the microdomains with their concentration maxima at the centers of the lamellae. (author)

  8. Structure and ionic conductivity of block copolymer electrolytes over a wide salt concentration range (United States)

    Chintapalli, Mahati; Le, Thao; Venkatesan, Naveen; Thelen, Jacob; Rojas, Adriana; Balsara, Nitash

    Block copolymer electrolytes are promising materials for safe, long-lasting lithium batteries because of their favorable mechanical and ion transport properties. The morphology, phase behavior, and ionic conductivity of a block copolymer electrolyte, SEO mixed with LiTFSI was studied over a wide, previously unexplored salt concentration range using small angle X-ray scattering, differential scanning calorimetry and ac impedance spectroscopy, respectively. SEO exhibits a maximum in ionic conductivity at twice the salt concentration that PEO, the homopolymer analog of the ion-containing block, does. This finding is contrary to prior studies that examined a more limited range of salt concentrations. In SEO, the phase behavior of the PEO block and LiTFSI closely resembles the phase behavior of homopolymer PEO and LiTFSI. The grain size of the block copolymer morphology was found to decrease with increasing salt concentration, and the ionic conductivity of SEO correlates with decreasing grain size. Structural effects impact the ionic conductivity-salt concentration relationship in block copolymer electrolytes. SEO: polystyrene-block-poly(ethylene oxide); also PS-PEO LiTFSI: lithium bis(trifluoromethanesulfonyl imide

  9. Order-Disorder Transitions in Cross-Linked Block Copolymer Solids

    Energy Technology Data Exchange (ETDEWEB)

    Das, J.


    With a view toward creating solid block copolymers wherein the order-disorder transition can be accessed many times they investigated the nature of order-disorder transitions in cross-linked diblock copolymer melts using synergistic theory and experiment. A mean-field theory based on a coarse grained free-energy and the Random Phase Approximation (RPA) is developed for the system of interest. The quenched distribution of cross-links is averaged using the replica method. The phase behavior of a particular A-B block copolymer melt with a randomly cross-linked B-Block is determined as a function of the Florry-Huggins interaction parameter ({chi}) and the average number of cross-links per chain N{sub c}. They find for a cross-link density greater than N*{sub c} the B monomers are localized within a region of size {zeta} {approx} (N{sub c} - N*{sub c}){sup -1/2}. The cross-links strongly oppose ordering in the system as {zeta} becomes comparable to the radius of gyration of the block copolymer chain. As such the order-disorder transition temperature T{sub ODT} decreases precipitously when N{sub c} > N*{sub c}. When N{sub c} < N*{sub c}, T{sub ODT} increases weakly with N{sub c}. Experiments were conducted on cross-linked polystyrene-block-polyisoprene copolymer samples wherein the polyisoprene block was selectively cross-linked at a temperature well above the order-disorder transition temperature of the pure block copolymer. Small angle X-ray scattering (SAXS) and birefringence measurements on the cross-linked samples are consistent with the theoretical prediction. T{sub ODT} decreases rapidly when the cross-linking density exceeds the critical cross-linking density.

  10. Polybenzimidazole block copolymers for fuel cell: synthesis and studies of block length effects on nanophase separation, mechanical properties, and proton conductivity of PEM. (United States)

    Maity, Sudhangshu; Jana, Tushar


    A series of meta-polybenzimidazole-block-para-polybenzimidazole (m-PBI-b-p-PBI), segmented block copolymers of PBI, were synthesized with various structural motifs and block lengths by condensing the diamine terminated meta-PBI (m-PBI-Am) and acid terminated para-PBI (p-PBI-Ac) oligomers. NMR studies and existence of two distinct glass transition temperatures (Tg), obtained from dynamical mechanical analysis (DMA) results, unequivocally confirmed the formation of block copolymer structure through the current polymerization methodology. Appropriate and careful selection of oligomers chain length enabled us to tailor the block length of block copolymers and also to make varieties of structural motifs. Increasingly distinct Tg peaks with higher block length of segmented block structure attributed the decrease in phase mixing between the meta-PBI and para-PBI blocks, which in turn resulted into nanophase segregated domains. The proton conductivities of proton exchange membrane (PEM) developed from phosphoric acid (PA) doped block copolymer membranes were found to be increasing substantially with increasing block length of copolymers even though PA loading of these membranes did not alter appreciably with varying block length. For example when molecular weight (Mn) of blocks were increased from 1000 to 5500 then the proton conductivities at 160 °C of resulting copolymers increased from 0.05 to 0.11 S/cm. Higher block length induced nanophase separation between the blocks by creating less morphological barrier within the block which facilitated the movement of the proton in the block and hence resulting higher proton conductivity of the PEM. The structural varieties also influenced the phase separation and proton conductivity. In comparison to meta-para random copolymers reported earlier, the current meta-para segmented block copolymers were found to be more suitable for PBI-based PEM.

  11. Manipulating Interfaces through Surface Confinement of Poly(glycidyl methacrylate)-block-poly(vinyldimethylazlactone), a Dually Reactive Block Copolymer

    International Nuclear Information System (INIS)

    Lokitz, Bradley S.; Wei, Jifeng; Hinestrosa Salazar, Juan P.; Ivanov, Ilia N.; Browning, James B.; Ankner, John Francis; Kilbey, S. Michael II; Messman, Jamie M.


    The assembly of dually reactive, well-defined diblock copolymers incorporating the chemoselective/functional monomer, 4,4-dimethyl-2-vinylazlactone (VDMA) and the surface-reactive monomer glycidyl methacrylate (GMA) is examined to understand how competition between surface attachment and microphase segregation influences interfacial structure. Reaction of the PGMA block with surface hydroxyl groups not only anchors the copolymer to the surface, but limits chain mobility, creating brush-like structures comprising PVDMA blocks, which contain reactive azlactone groups. The block copolymers are spin coated at various solution concentrations and annealed at elevated temperature to optimize film deposition to achieve a molecularly uniform layer. The thickness and structure of the polymer thin films are investigated by ellipsometry, infrared spectroscopy, and neutron reflectometry. The results show that deposition of PGMA-b-PVDMA provides a useful route to control film thickness while preserving azlactone groups that can be further modified with biotin-poly(ethylene glycol)amine to generate designer surfaces. The method described herein offers guidance for creating highly functional surfaces, films, or coatings through the use of dually reactive block copolymers and postpolymerization modification.

  12. Structural Color for Additive Manufacturing: 3D-Printed Photonic Crystals from Block Copolymers. (United States)

    Boyle, Bret M; French, Tracy A; Pearson, Ryan M; McCarthy, Blaine G; Miyake, Garret M


    The incorporation of structural color into 3D printed parts is reported, presenting an alternative to the need for pigments or dyes for colored parts produced through additive manufacturing. Thermoplastic build materials composed of dendritic block copolymers were designed, synthesized, and used to additively manufacture plastic parts exhibiting structural color. The reflection properties of the photonic crystals arise from the periodic nanostructure formed through block copolymer self-assembly during polymer processing. The wavelength of reflected light could be tuned across the visible spectrum by synthetically controlling the block copolymer molecular weight and manufacture parts that reflected violet, green, or orange light with the capacity to serve as selective optical filters and light guides.

  13. Synthesis and characterization of high concentration block copolymer-mediated gold nanoparticles. (United States)

    Ray, Debes; Aswal, Vinod K; Kohlbrecher, Joachim


    The formation of high concentration gold nanoparticles at room temperature is reported in block copolymer-mediated synthesis where the nanoparticles have been synthesized from hydrogen tetrachloroaureate(III) hydrate (HAuCl(4)·3H(2)O) using block copolymer P85 (EO(26)PO(39)EO(26)) in aqueous solution. The formation of gold nanoparticles in these systems has been characterized using UV-visible spectroscopy and small-angle neutron scattering (SANS). We show that the presence of additional reductant (trisodium citrate) can enhance nanoparticle concentration by manyfold, which does not work in the absence of either of these (additional reductant and block copolymer). The stability of gold nanoparticles with increasing concentration has also been examined.

  14. Structure and Dynamics Ionic Block co-Polymer Melts: Computational Study (United States)

    Aryal, Dipak; Perahia, Dvora; Grest, Gary S.

    Tethering ionomer blocks into co-polymers enables engineering of polymeric systems designed to encompass transport while controlling structure. Here the structure and dynamics of symmetric pentablock copolymers melts are probed by fully atomistic molecular dynamics simulations. The center block consists of randomly sulfonated polystyrene with sulfonation fractions f = 0 to 0.55 tethered to a hydrogenated polyisoprene (PI), end caped with poly(t-butyl styrene). We find that melts with f = 0.15 and 0.30 consist of isolated ionic clusters whereas melts with f = 0.55 exhibit a long-range percolating ionic network. Similar to polystyrene sulfonate, a small number of ionic clusters slow the mobility of the center of mass of the co-polymer, however, formation of the ionic clusters is slower and they are often intertwined with PI segments. Surprisingly, the segmental dynamics of the other blocks are also affected. NSF DMR-1611136; NERSC; Palmetto Cluster Clemson University; Kraton Polymers US, LLC.

  15. Tuning of Block Copolymer Membrane Morphology through Water Induced Phase Inversion Technique

    KAUST Repository

    Madhavan, Poornima


    Isoporous membranes are attractive for the regulation and detection of transport at the molecular level. A well-defined asymmetric membranes from diblock copolymers with an ordered nanoporous membrane morphologies were fabricated by the combination of block copolymer self-assembly and non-solvent-induced phase separation (NIPS) technique. This is a straightforward and fast one step procedure to develop integrally anisotropic (“asymmetric”) membranes having isoporous top selective layer. Membranes prepared via this method exhibit an anisotropic cross section with a thin separation layer supported from underneath a macroporous support. These membrane poses cylindrical pore structure with ordered nanopores across the entire membrane surfaces with pore size in the range from 20 to 40 nm. Tuning the pore morphology of the block copolymer membranes before and after fabrication are of great interest. In this thesis, we first investigated the pore morphology tuning of asymmetric block copolymer membrane by complexing with small organic molecules. We found that the occurrence of hydrogen-bond formation between PS-b-P4VP block copolymer and –OH/ –COOH functionalized organic molecules significantly tunes the pore morphology of asymmetric nanoporous membranes. In addition, we studied the complexation behavior of ionic liquids with PS-b-P4VP block copolymer in solutions and investigated their effect on final membrane morphology during the non-solvent induced phase separation process. We found that non-protic ionic liquids facilitate the formation of hexagonal nanoporous block copolymer structure, while protic ionic liquids led to a lamella-structured membrane. Secondly, we demonstrated the catalytic activity of the gold nanoparticle-enhanced hollow fiber membranes by the reduction of nitrophenol. Also, we systematically investigated the pore morphology of isoporous PS-b-P4VP using 3D imaging technique. Thirdly, we developed well-distributed silver nanoparticles on the

  16. Concentration effect on tuning of block copolymer-mediated synthesis of gold nanoparticles. (United States)

    Ray, Debes; Aswal, V K; Srivastava, D


    Synthesis of gold nanoparticles has been examined using triblock copolymer Pluronic P85 (EO26PO39EO26) at different concentrations as a function of hydrogen tetrachloroaureate (III) hydrate (HAuCl4 x 3H2O) in aqueous solution. The concentration of P85 block copolymer was varied from 0.5 to 2 wt% at fixed temperature (30 degrees C) in presence of HAuCl4 x 3H2O in the range of 0.002 to 0.2 wt% for each P85 concentration. The surface plasmon resonance in the time-dependent UV-visible spectra reveals that increase in the block copolymer concentration increases the yield of the gold nanoparticles but decreases their stability. Both small-angle neutron scattering (SANS) and dynamic light scattering (DLS) show that the number density of block copolymer micelles increase almost linearly with the concentration, which is related to result in higher numbers of nucleation centers and therefore increase in the yield of gold nanoparticles. The fact that increase in the number density of nanoparticles also increases the chances of aggregation and this tends to decrease the stability at higher block copolymer concentration. Transmission electron microscopy (TEM) images confirm the larger sizes of the nanoparticles formed in these systems at higher concentrations.

  17. Pickering emulsions stabilized by biodegradable block copolymer micelles for controlled topical drug delivery. (United States)

    Laredj-Bourezg, Faiza; Bolzinger, Marie-Alexandrine; Pelletier, Jocelyne; Chevalier, Yves


    Surfactant-free biocompatible and biodegradable Pickering emulsions were investigated as vehicles for skin delivery of hydrophobic drugs. O/w emulsions of medium-chain triglyceride (MCT) oil droplets loaded with all-trans retinol as a model hydrophobic drug were stabilized by block copolymer nanoparticles: either poly(lactide)-block-poly(ethylene glycol) (PLA-b-PEG) or poly(caprolactone)-block-poly(ethylene glycol) (PCL-b-PEG). Those innovative emulsions were prepared using two different processes allowing drug loading either inside oil droplets or inside both oil droplets and non-adsorbed block copolymer nanoparticles. Skin absorption of retinol was investigated in vitro on pig skin biopsies using the Franz cell method. Supplementary experiments by confocal fluorescence microscopy allowed the visualization of skin absorption of the Nile Red dye on histological sections. Retinol and Nile Red absorption experiments showed the large accumulation of hydrophobic drugs in the stratum corneum for the Pickering emulsions compared to the surfactant-based emulsion and an oil solution. Loading drug inside both oil droplets and block copolymer nanoparticles enhanced again skin absorption of drugs, which was ascribed to the supplementary contribution of free block copolymer nanoparticles loaded with drug. Such effect allowed tuning drug delivery to skin over a wide range by means of a suitable selection of either the formulation or the drug loading process. Copyright © 2017 Elsevier B.V. All rights reserved.

  18. Fluorinated Amphiphilic Polymers and Their Blends for Fouling-Release Applications: The Benefits of a Triblock Copolymer Surface

    KAUST Repository

    Sundaram, Harihara S.


    Surface active triblock copolymers (SABC) with mixed polyethylene glycol (PEG) and two different semifluorinated alcohol side chains, one longer than the other, were blended with a soft thermoplastic elastomer (TPE), polystyrene-block-poly(ethylene-ran-butylene)-block-polystyrene (SEBS). The surface composition of these blends was probed by X-ray photoelectron spectroscopy (XPS) and near edge X-ray absorption fine structure (NEXAFS) spectroscopy. The surface reconstruction of the coatings in water was monitored qualitatively by dynamic water contact angles in air as well as air bubble contact angle measurements in water. By blending the SABC with SEBS, we minimize the amount of the SABC used while achieving a surface that is not greatly different in composition from the pure SABC. The 15 wt % blends of the SABC with long fluoroalkyl side chains showed a composition close to that of the pure SABC while the SABC with shorter perfluoroakyl side chains did not. These differences in surface composition were reflected in the fouling-release performance of the blends for the algae, Ulva and Navicula. © 2011 American Chemical Society.

  19. Collapse transitions in thermosensitive multi-block copolymers: A Monte Carlo study

    International Nuclear Information System (INIS)

    Rissanou, Anastassia N.; Tzeli, Despoina S.; Anastasiadis, Spiros H.; Bitsanis, Ioannis A.


    Monte Carlo simulations are performed on a simple cubic lattice to investigate the behavior of a single linear multiblock copolymer chain of various lengths N. The chain of type (A n B n ) m consists of alternating A and B blocks, where A are solvophilic and B are solvophobic and N = 2nm. The conformations are classified in five cases of globule formation by the solvophobic blocks of the chain. The dependence of globule characteristics on the molecular weight and on the number of blocks, which participate in their formation, is examined. The focus is on relative high molecular weight blocks (i.e., N in the range of 500–5000 units) and very differing energetic conditions for the two blocks (very good—almost athermal solvent for A and bad solvent for B). A rich phase behavior is observed as a result of the alternating architecture of the multiblock copolymer chain. We trust that thermodynamic equilibrium has been reached for chains of N up to 2000 units; however, for longer chains kinetic entrapments are observed. The comparison among equivalent globules consisting of different number of B-blocks shows that the more the solvophobic blocks constituting the globule the bigger its radius of gyration and the looser its structure. Comparisons between globules formed by the solvophobic blocks of the multiblock copolymer chain and their homopolymer analogs highlight the important role of the solvophilic A-blocks

  20. Simulation of Defect Reduction in Block Copolymer Thin Films by Solvent Annealing

    Energy Technology Data Exchange (ETDEWEB)

    Hur, Su-Mi; Khaira, Gurdaman S.; Ramírez-Hernández, Abelardo; Müller, Marcus; Nealey, Paul F.; de Pablo, Juan J.


    Solvent annealing provides an effective means to control the self-assembly of block copolymer (BCP) thin films. Multiple effects, including swelling, shrinkage, and morphological transitions, act in concert to yield ordered or disordered structures. The current understanding of these processes is limited; by relying on a theoretically informed coarse-grained model of block copolymers, a conceptual framework is presented that permits prediction and rationalization of experimentally observed behaviors. Through proper selection of several process conditions, it is shown that a narrow window of solvent pressures exists over which one can direct a BCP material to form well-ordered, defect-free structures.

  1. Synthesis by ATRP of triblock copolymers with densely grafted styrenic end blocks from a polyisobutylene macroinitiator

    DEFF Research Database (Denmark)

    Truelsen, Jens Høg; Kops, Jørgen; Pedersen, Walther Batsberg


    A macroinitiator was prepared from a triblock copolymer of polyisobutylene (PIB) with end blocks of poly(p-methylstyrene) (P(p-MeS)) by bromination to obtain initiating bromomethyl groups for atom transfer radical polymerization (ATRP). Controlled polymerization of styrene and p-acetoxystyrene yi......A macroinitiator was prepared from a triblock copolymer of polyisobutylene (PIB) with end blocks of poly(p-methylstyrene) (P(p-MeS)) by bromination to obtain initiating bromomethyl groups for atom transfer radical polymerization (ATRP). Controlled polymerization of styrene and p...

  2. Mesoscopic multiphase structures and the interfaces of block and graft copolymers in bulk

    International Nuclear Information System (INIS)

    Matsushita, Yushu


    Microphase-separated structures of copolymers with various architectures and their polymer/polymer interfaces were studied. They are SP diblock, PSP triblock, and SPP graft copolymers, where S and P denote polystyrene and poly(2-vinylpyridine), respectively. Morphological observations were carried out by means of transmission electron microscopy and small-angle X-ray scattering. Chain dimensions of component polymers were measured by small-angle neutron scattering and microphase-separated interfaces were observed by neutron reflectivity measurements using deuterium-labeled samples. It was clarified that morphological phase transitions among thermodynamically equilibrium structures for SP diblock and PSP triblock copolymers occur at almost the same compositions; however, those of SPP graft copolymers tend to occur at higher volume fraction of polystyrene, φ s , than those for block copolymers. As for alternating lamellar structures it turned out to be clear that lamellar domain spacings, D's, were scaled as the 2/3 power of the molecular weight of polymers irrespective of their architectures. S block chains of SP diblock and PSP triblock copolymers in lamellar structures were both confirmed to be deformed toward the direction perpendicular to the lamellar interfaces, but it revealed that their volumes were preserved. Further, S/P interfacial thicknesses of SP and PSP were essentially the same to each other and the values defined as the FWHM of the error functions which express the segment density distributions of the interfaces were determined to be about 4 nm. (author)

  3. Block copolymer morphologies confined by square-shaped particle: Hard and soft confinement

    International Nuclear Information System (INIS)

    Zhang Qiyi; Yang Wenyan; Hu Kaiyan


    The self-assembly of diblock copolymers confined around one square-shaped particle is studied systematically within two-dimensional self-consistent field theory (SCFT). In this model, we assume that the thin block copolymer film is confined in the vicinity of a square-shaped particle by a homopolymer melt, which is equivalent to the poor solvents. Multiple sequences of square-shaped particle-induced copolymer aggregates with different shapes and self-assembled internal morphologies are predicted as functions of the particle size, the structural portion of the copolymer, and the volume fraction of the copolymer. A rich variety of aggregates are found with complex internal self-assembled morphologies including complex structures of the vesicle, with one or several inverted micelle surrounded by the outer monolayer with the particle confined in the core. These results demonstrate that the assemblies of diblock copolymers formed around the square-shaped particle in poor solvents are of immediate interest to the assembly of copolymer and the morphology of biomembrane in the confined environment, as well as to the transitions of vesicles to micelles. (paper)

  4. Living cationic polymerization and polyhomologation: an ideal combination to synthesize functionalized polyethylene–polyisobutylene block copolymers

    KAUST Repository

    Zhang, Hefeng


    A series of hydroxyl-terminated polyisobutylene-b-polyethylene (PIB-b-PE-OH) copolymers were synthesized by combining living cationic polymerization and polyhomologation. Allyl-terminated PIBs, synthesized by living cationic polymerization, were hydroborated with BH3·THF to produce 3-arm boron-linked stars, PIB3B, which served as macroinitiators for the in situ polyhomologation of dimethylsulfoxonium methylide. The resulting 3-arm star block copolymers, (PIB-b-PE)3B, were oxidized/hydrolysed to afford PIB-b-PE-OH. Characterization of all intermediates and final products by high temperature gel permeation chromatography (HT-GPC) and proton nuclear magnetic resonance spectroscopy (1H NMR) revealed the well-defined character of the copolymers. The thermal properties of the copolymers were studied by differential scanning calorimetry (DSC).

  5. The melt rheological behavior of AB, ABA, BAB, and (AB)n block copolymers with monodisperse aramide segments

    NARCIS (Netherlands)

    Araichimani, A.; Dullaert, Konraad; Gaymans, R.J.


    The melt rheological behavior of segmented block copolymers with high melting diamide (A) hard segments (HS) and polyether (B) soft segments was studied. The block copolymers can be classified as B (monoblock), AB (diblock), ABA (triblock, diamide end segment), BAB (triblock, diamide mid-segment)

  6. Photoconductivity enhancement and charge transport properties in ruthenium-containing block copolymer/carbon nanotube hybrids. (United States)

    Lo, Kin Cheung; Hau, King In; Chan, Wai Kin


    Functional polymer/carbon nanotube (CNT) hybrid materials can serve as a good model for light harvesting systems based on CNTs. This paper presents the synthesis of block copolymer/CNT hybrids and the characterization of their photocurrent responses by both experimental and computational approaches. A series of functional diblock copolymers was synthesized by reversible addition-fragmentation chain transfer polymerizations for the dispersion and functionalization of CNTs. The block copolymers contain photosensitizing ruthenium complexes and modified pyrene-based anchoring units. The photocurrent responses of the polymer/CNT hybrids were measured by photoconductive atomic force microscopy (PCAFM), from which the experimental data were analyzed by vigorous statistical models. The difference in photocurrent response among different hybrids was correlated to the conformations of the hybrids, which were elucidated by molecular dynamics simulations, and the electronic properties of polymers. The photoresponse of the block copolymer/CNT hybrids can be enhanced by introducing an electron-accepting block between the photosensitizing block and the CNT. We have demonstrated that the application of a rigorous statistical methodology can unravel the charge transport properties of these hybrid materials and provide general guidelines for the design of molecular light harvesting systems.

  7. Two-dimensional liquid chromatography analysis of polystyrene/polybutadiene block copolymers. (United States)

    Lee, Sanghoon; Choi, Heejae; Chang, Taihyun; Staal, Bastiaan B P


    A detailed characterization of a commercial polystyrene/polybutadiene block copolymer material (StyroluxTM) was carried out using two-dimensional liquid chromatography (2D-LC). The Styrolux is prepared by statistical linking reaction of two different polystyrene-block-polybutadienyl anion precursors with a multivalent linking agent. Therefore, it is a mixture of a number of branched block copolymers different in molecular weight, composition and chain architecture. While individual LC analysis including size exclusion chromatography, interaction chromatography or liquid chromatography at critical condition is not good enough to resolve all the polymer species, 2D-LC separations coupling two chromatography methods were able to resolve all polymer species present in the sample; at least 13 block copolymer species and a homo-polystyrene blended. Four different 2D-LC analyses combining a different pair of two LC methods provide their characteristic separation results. The separation characteristics of the 2D-LC separations are compared to elucidate the elution characteristics of the block copolymer species.

  8. Rapid Ordering in "Wet Brush" Block Copolymer/Homopolymer Ternary Blends. (United States)

    Doerk, Gregory S; Yager, Kevin G


    The ubiquitous presence of thermodynamically unfavored but kinetically trapped topological defects in nanopatterns formed via self-assembly of block copolymer thin films may prevent their use for many envisioned applications. Here, we demonstrate that lamellae patterns formed by symmetric polystyrene-block-poly(methyl methacrylate) diblock copolymers self-assemble and order extremely rapidly when the diblock copolymers are blended with low molecular weight homopolymers of the constituent blocks. Being in the "wet brush" regime, the homopolymers uniformly distribute within their respective self-assembled microdomains, preventing increases in domain widths. An order-of-magnitude increase in topological grain size in blends over the neat (unblended) diblock copolymer is achieved within minutes of thermal annealing as a result of the significantly higher power law exponent for ordering kinetics in the blends. Moreover, the blends are demonstrated to be capable of rapid and robust domain alignment within micrometer-scale trenches, in contrast to the corresponding neat diblock copolymer. These results can be attributed to the lowering of energy barriers associated with domain boundaries by bringing the system closer to an order-disorder transition through low molecular weight homopolymer blending.

  9. Quantitative study of temperature-dependent order in thin films of cylindrical morphology block copolymer (United States)

    Mishra, Vindhya; Kramer, Edward


    Disordering and defect generation in block copolymer systems at high temperatures is of significance to get a better understanding of the physics governing these systems, which can also direct efforts to minimize them. We have studied the smectic-nematic-isotropic transition in confined monolayers and bilayers of cylindrical morphology poly (styrene-b-2vinyl pyridine) diblock copolymer. Previous studies of melting phenomena in block copolymer thin films have relied on quantitative AFM studies alone. We have supplemented AFM studies with grazing incidence small angle X-ray diffraction lineshape analysis to quantify the decay of translational and orientational order with increasing temperature. The results have been interpreted in the context of the Toner-Nelson theory of melting for layered systems.

  10. Self-Assembled Asymmetric Block Copolymer Membranes: Bridging the Gap from Ultra- to Nanofiltration

    KAUST Repository

    Yu, Haizhou


    The self-assembly of block copolymers is an emerging strategy to produce isoporous ultrafiltration membranes. However, thus far, it has not been possible to bridge the gap from ultra- to nanofiltration and decrease the pore size of self-assembled block copolymer membranes to below 5 nm without post-treatment. It is now reported that the self-assembly of blends of two chemically interacting copolymers can lead to highly porous membranes with pore diameters as small as 1.5 nm. The membrane containing an ultraporous, 60 nm thin separation layer can fully reject solutes with molecular weights of 600 g mol−1 in aqueous solutions with a water flux that is more than one order of magnitude higher than the permeance of commercial nanofiltration membranes. Simulations of the membrane formation process by dissipative particle dynamics (DPD) were used to explain the dramatic observed pore size reduction combined with an increase in water flux.

  11. Synthesis of tri-block copolymers through reverse atom transfer radical polymerization of methyl methacrylate using polyurethane macroiniferter

    Directory of Open Access Journals (Sweden)


    Full Text Available Reverse atom transfer radical polymerization was successfully used for the first time to synthesis tri-block copolymers. Poly (methyl methacrylate-block-polyurethane-block-poly (methyl methacrylate tri-block copolymers were synthesized using tetraphenylethane-based polyurethane as a macroiniferter, copper(II halide as a catalyst and N, N, N′, N″, N″-pentamethyldiethylenetriamine as a ligand. Controlled nature of the polymerization was confirmed by the linear increase of number average molecular weight with increasing conversion. Mole contents of poly (methyl methacrylate present in the tri-block copolymers were calculated using proton nuclear magnetic resonance spectroscopy and the results were comparable with the gel permeation chromatography results. Differential scanning calorimetric results confirmed the presence of two different types of blocks in the tri-block copolymers.

  12. Polystyrene-block-Poly(ionic liquid) Copolymers as Work Function Modifiers in Inverted Organic Photovoltaic Cells. (United States)

    Park, Jong Baek; Isik, Mehmet; Park, Hea Jung; Jung, In Hwan; Mecerreyes, David; Hwang, Do-Hoon


    Interfacial layers play a critical role in building up the Ohmic contact between electrodes and functional layers in organic photovoltaic (OPV) solar cells. These layers are based on either inorganic oxides (ZnO and TiO 2 ) or water-soluble organic polymers such as poly[(9,9-dioctyl-2,7-fluorene)-alt-(9,9-bis(3'-(N,N-dimethylamino)propyl)-2,7-fluorene)] and polyethylenimine ethoxylated (PEIE). In this work, we have developed a series of novel poly(ionic liquid) nonconjugated block copolymers for improving the performance of inverted OPV cells by using them as work function modifiers of the indium tin oxide (ITO) cathode. Four nonconjugated polyelectrolytes (n-CPEs) based on polystyrene and imidazolium poly(ionic liquid) (PSImCl) were synthesized by reversible addition-fragmentation chain transfer polymerization. The ratio of hydrophobic/hydrophilic block copolymers was varied depending on the ratio of polystyrene to the PSImCl block. The ionic density, which controls the work function of the electrode by forming an interfacial dipole between the electrode and the block copolymers, was easily tuned by simply changing the PSImCl molar ratio. The inverted OPV device with the ITO/PS 29 -b-PSImCl 60 cathode achieved the best power conversion efficiency (PCE) of 7.55% among the synthesized block copolymers, exhibiting an even higher PCE than that of the reference OPV device with PEIE (7.30%). Furthermore, the surface properties of the block copolymers films were investigated by contact angle measurements to explore the influence of the controlled hydrophobic/hydrophilic characters on the device performances.

  13. Water vapor and gas transport through a poly (butylene terephthalate) poly (ethylene oxide) block copolymer

    NARCIS (Netherlands)

    Metz, S.J.; Potreck, Jens; Mulder, M.H.V.; Wessling, Matthias


    In this paper the transport behavior of water vapor and nitrogen in a poly(butylene terephthalate) poly (ethylene oxide) block copolymer is discussed. This polymer has a high solubility for water (300 cm3 (STP)/cm3 polymer at activity 0.9). A new permeation set up has been built to determine the

  14. Segmented block copolymers based on poltbutylene terephthalate and telechelic polyesters and polyamides of dimirized fatty acids

    NARCIS (Netherlands)

    Manuel, H.J.; Manuel, H.J.; Gaymans, R.J.


    Segmented block copolymers (SBCs) based on poly(butylene terephthalate) (PBT) and telechelics based on dimerized fatty acids have been synthesized in the melt. The dimerized fatty acids were coupled with diols or diamines to synthesize polyesters and polyamides of low molar mass. With these

  15. Self-assembled block copolymer membranes: From basic research to large-scale manufacturing

    KAUST Repository

    Nunes, Suzana Pereira


    Order and porosity of block copolymer membranes have been controlled by solution thermodynamics, self-assembly, and macrophase separation. We have demonstrated how the film manufacture with long-range order can be up-scaled with the use of conventional membrane production technology.

  16. LEO resistant PI-B-PDMS block copolymer films for solar array applications

    NARCIS (Netherlands)

    Lonkhuyzen, H. van; Bongers, E.; Fischer, H.R.; Dingemans, T.J.; Semprimoschnig, C.


    Due to their low atomic oxygen erosion yields PI-b-PDMS block copolymer films have considerable potential for application onto space exposed surfaces of satellites in low earth orbit. On solar arrays these materials might be used as electrical electrical insulation film, flexprint outer layer,

  17. Gas plasma etching of PEO/PBT segmented block copolymer films

    NARCIS (Netherlands)

    Olde riekerink, M.B.; Claase, M.B.; Engbers, G.H.M.; Grijpma, Dirk W.; Feijen, Jan


    A series of poly(ethylene oxide)/poly(butylene terephthalate) (PEO/PBT) segmented block copolymer films was treated with a radio-frequency carbon dioxide (CO2) or with argon (Ar) plasma. The effects of (preferential) etching on surface structure, topography, chemistry, and wettability were studied

  18. Interfacial activity of styrene-butadiene block copolymers in low-density polyethylene/polystyrene blends

    Czech Academy of Sciences Publication Activity Database

    Fortelný, Ivan; Šlouf, Miroslav; Hlavatá, Drahomíra; Sikora, Antonín


    Roč. 13, 8-9 (2006), s. 783-799 ISSN 0927-6440 Institutional research plan: CEZ:AV0Z40500505 Keywords : compatibilization * polymer blends * block copolymers Subject RIV: CD - Macromolecular Chemistry Impact factor: 0.788, year: 2006

  19. Compartmentalization in hybrid metallacarborane nanoparticles formed by block copolymers with star-like architecture

    Czech Academy of Sciences Publication Activity Database

    Ďorďovič, V.; Uchman, M.; Zhigunov, Alexander; Nykänen, A.; Ruokolainen, J.; Matějíček, P.


    Roč. 3, č. 11 (2014), s. 1151-1155 ISSN 2161-1653 R&D Projects: GA ČR(CZ) GA14-14608S Institutional support: RVO:61389013 Keywords : nanoparticles * block copolymers * star-like architecture Subject RIV: CD - Macromolecular Chemistry Impact factor: 5.764, year: 2014

  20. Metallopolymer-Based Block Copolymers for the Preparation of Porous and Redox-Responsive Materials. (United States)

    Rüttiger, Christian; Hübner, Hanna; Schöttner, Sebastian; Winter, Tamara; Cherkashinin, Gennady; Kuttich, Björn; Stühn, Bernd; Gallei, Markus


    Metallopolymers are a unique class of functional materials because of their redox-mediated optoelectronic and catalytic switching capabilities and, as recently shown, their outstanding structure formation and separation capabilities. Within the present study, (tri)block copolymers of poly(isoprene) (PI) and poly(ferrocenylmethyl methacrylate) having different block compositions and overall molar masses up to 328 kg mol -1 are synthesized by anionic polymerization. The composition and thermal properties of the metallopolymers are investigated by state-of-the-art polymer analytical methods comprising size exclusion chromatography, 1 H NMR spectroscopy, differential scanning calorimetry, and thermogravimetric analysis. As a focus of this work, excellent microphase separation of the synthesized (tri)block copolymers is proven by transmission electron microscopy, scanning electron microcopy, energy-dispersive X-ray spectroscopy, small-angle X-ray scattering measurements showing spherical, cylindrical, and lamellae morphologies. As a highlight, the PI domains are subjected to ozonolysis for selective domain removal while maintaining the block copolymer morphology. In addition, the novel metalloblock copolymers can undergo microphase separation on cellulose-based substrates, again preserving the domain order after ozonolysis. The resulting nanoporous structures reveal an intriguing switching capability after oxidation, which is of interest for controlling the size and polarity of the nanoporous architecture.

  1. Thin block copolymer films : film formation and corrugation under the AFM tip

    NARCIS (Netherlands)

    Maas, J.H.; Cohen Stuart, M.A.; Fleer, G.J.


    The tip of an atomic force microscope was used to induce nanoscale ordering in thin films of polystyrene-poly(4-vinyl pyridine) block copolymers under low force. The AFM tip produces rims on a mesoscopic scale oriented perpendicularly to the scanning direction. A wide range of molecular weights of

  2. Phase structure of symmetric tri-block-copolymers and their blends

    Czech Academy of Sciences Publication Activity Database

    Baldrian, Josef; Steinhart, Miloš; Sikora, Antonín; Amenitsch, H.; Bernstorff, S.


    Roč. 13, č. 5 (2005), s. 35-40 ISSN 1230-3666 R&D Projects: GA ČR GA203/03/0611 Institutional research plan: CEZ:AV0Z40500505 Keywords : crystallization * block copolymers * blends Subject RIV: CD - Macromolecular Chemistry Impact factor: 0.397, year: 2005

  3. Adsorption of polyelectrolytes and charged block copolymers on oxides consequences for colloidal stability

    NARCIS (Netherlands)

    Hoogeveen, N.G.


    The aim of the study described in this thesis was to examine the adsorption properties of polyelectrolytes and charged block copolymers on oxides, and the effect of these polymers on the colloidal stability of oxidic dispersions. For this purpose the interaction of some well-characterised

  4. Self-assembly of POSS-containing block copolymers: fixing the hierarchical structure in networks

    Czech Academy of Sciences Publication Activity Database

    Matějka, Libor; Janata, Miroslav; Pleštil, Josef; Zhigunov, Alexander; Šlouf, Miroslav


    Roč. 55, č. 1 (2014), s. 126-136 ISSN 0032-3861 R&D Projects: GA ČR GAP108/12/1459 Grant - others:AV ČR(CZ) M200500903 Institutional support: RVO:61389013 Keywords : block copolymers * self-assembly * POSS Subject RIV: CD - Macromolecular Chemistry Impact factor: 3.562, year: 2014

  5. Chain elongation suppression of cyclic block copolymers in lamellar microphase-separated bulk

    NARCIS (Netherlands)

    Matsushita, Y; Iwata, H; Asari, T; Uchida, T; ten Brinke, G; Takano, A


    Chain elongation suppression of cyclic block copolymers in microphase-separated bulk was determined quantitatively. Solvent-cast and annealed films are confirmed to show alternating lamellar structure and their microdomain spacing D increases with increasing total molecular weight M according to the

  6. CO2 permeation properties of poly(ethylene oxide)-based segmented block copolymers

    NARCIS (Netherlands)

    Husken, D.; Visser, Tymen; Wessling, Matthias; Gaymans, R.J.


    This paper discusses the gas permeation properties of poly(ethylene oxide) (PEO)-based segmented block copolymers containing monodisperse amide segments. These monodisperse segments give rise to a well phase-separated morphology, comprising a continuous PEO phase with dispersed crystallised amide

  7. Tuning Ordered Pattern of Pd Species through Controlled Block Copolymer Self-Assembly

    NARCIS (Netherlands)

    De Rosa, Claudio; Auriemma, Finizia; Malafronte, Anna; Di Girolamo, Rocco; Lazzari, Massimo; Nieto-Suárez, Marina; Hermida-Merino, Daniel; Hamley, Ian William; Portale, Giuseppe


    We report a method for the preparation of ordered patterns of Pd species on a substrate based on the use of polystyrene-block-poly(ethylene oxide) copolymer (PS-b-PEO) templates and selective inclusion of palladium (Pd) species in the PEO domains. PS-b-PEO samples of different total molecular masses

  8. Asymmetric block copolymer membranes with ultrahigh porosity and hierarchical pore structure by plain solvent evaporation

    KAUST Repository

    Yu, H.


    Membranes with a hierarchical porous structure could be manufactured from a block copolymer blend by pure solvent evaporation. Uniform pores in a 30 nm thin skin layer supported by a macroporous structure were formed. This new process is attractive for membrane production because of its simplicity and the lack of liquid waste.

  9. Synthesis and properties of poly(butylene terephthalate)-b-polyisobutylene segmented block copolymers

    NARCIS (Netherlands)

    Walch, E.; Walch, E.; Gaymans, R.J.


    Segmented block copolymers of polyisobutylene (PIB) and poly(butylene terephthalate) (PBT) were made by condensation polymerization of α,θ-di-anhydride telechelic PIB, with 1,4-butanediol and dimethyl terephthalate. The inherent viscosity of the polymers was between 0.35 and 2.0 dl g−1. The

  10. Influence of chemical crosslinks on the elastic behavior of segmented block copolymers

    NARCIS (Netherlands)

    van der Schuur, J.M.; Gaymans, R.J.


    Polyether(ester–amide)s (PEEA) segmented block copolymers with di- and tri-functional poly(propylene oxide)s and amide segments were synthesized and the elastic properties studied. The difunctional polyether used had a molecular weight of 2300 g/mol end capped with 20 wt% ethylene oxide. The

  11. Nanoparticle-cell interactions: surface chemistry effects on the cellular uptake of biocompatible block copolymer assemblies

    Czech Academy of Sciences Publication Activity Database

    de Castro, C. E.; Ribeiro, C. A. S.; Alavarse, A. C.; Albuquerque, L. J. C.; da Silva, M. C. C.; Jäger, Eliezer; Surman, František; Schmidt, V.; Giacomelli, C.; Giacomelli, F. C.


    Roč. 34, č. 5 (2018), s. 2180-2188 ISSN 0743-7463 R&D Projects: GA ČR(CZ) GA17-09998S Institutional support: RVO:61389013 Keywords : biocompatibility * block copolymers * controlled drug delivery Subject RIV: CD - Macromolecular Chemistry OBOR OECD: Polymer science Impact factor: 3.833, year: 2016

  12. Synthesis of polyether-based block copolymers based on poly(propylene oxide) and terephthalates

    NARCIS (Netherlands)

    van der Schuur, J.M.; Feijen, Jan; Gaymans, R.J.


    Poly(propylene oxide) (PPO) is a low reactive telechelic polyether and the synthesis of high molecular weight poly(propylene oxide)-based block copolymers was studied. The poly(propylene oxide) used was end capped with 20 wt % ethylene oxide and had a molecular weight of 2300 g/mol (ultra-low monol

  13. Anionic polymerization and polyhomologation: An ideal combination to synthesize polyethylene-based block copolymers

    KAUST Repository

    Zhang, H.


    A novel one-pot methodology combining anionic polymerization and polyhomologation, through a "bridge" molecule (BF3OEt 2), was developed for the synthesis of polyethylene (PE)-based block copolymers. The anionically synthesized macroanion reacts with the "bridge" molecule to afford a 3-arm star (trimacromolecular borane) which serves as an initiator for the polyhomologation. 2013 The Royal Society of Chemistry.

  14. Ion Correlation Effects in Salt-Doped Block Copolymers (United States)

    Brown, Jonathan R.; Seo, Youngmi; Hall, Lisa M.


    We apply classical density functional theory to study how salt changes the microphase morphology of diblock copolymers. Polymers are freely jointed and one monomer type favorably interacts with ions, to account for the selective solvation that arises from different dielectric constants of the microphases. By including correlations from liquid state theory of an unbound reference fluid, the theory can treat chain behavior, microphase separation, ion correlations, and preferential solvation, at the same coarse-grained level. We show good agreement with molecular dynamics simulations.

  15. pH-Dependent self-assembly of polystyrene-block-poly(sulfamate-carboxylate)isoprene) copolymer in aqueous media

    Czech Academy of Sciences Publication Activity Database

    Uchman, M.; Procházka, K.; Štěpánek, M.; Mountrichas, G.; Pispas, S.; Špírková, Milena; Walther, A.


    Roč. 24, - (2008), s. 12017-12025 ISSN 0743-7463 R&D Projects: GA ČR(CZ) GA203/07/0659; GA AV ČR IAA400500505 Grant - others:GA AV ČR(CZ) IAA401110702 Institutional research plan: CEZ:AV0Z40500505 Keywords : self-assembly * amphiphilic copolymer * nanoparticles Subject RIV: CD - Macromolecular Chemistry Impact factor: 4.097, year: 2008

  16. Time-resolved GISAXS and cryo-microscopy characterization of block copolymer membrane formation

    KAUST Repository

    Marques, Debora S.


    Time-resolved grazing-incidence small-angle X-ray scattering (GISAXS) and cryo-microscopy were used for the first time to understand the pore evolution by copolymer assembly, leading to the formation of isoporous membranes with exceptional porosity and regularity. The formation of copolymer micelle strings in solution (in DMF/DOX/THF and DMF/DOX) was confirmed by cryo field emission scanning electron microscopy (cryo-FESEM) with a distance of 72 nm between centers of micelles placed in different strings. SAXS measurement of block copolymer solutions in DMF/DOX indicated hexagonal assembly with micelle-to-micelle distance of 84-87 nm for 14-20 wt% copolymer solutions. GISAXS in-plane peaks were detected, revealing order close to hexagonal. The d-spacing corresponding to the first peak in this case was 100-130 nm (lattice constant 115-150 nm) for 17 wt% copolymer solutions evaporating up to 100 s. Time-resolved cryo-FESEM showed the formation of incipient pores on the film surface after 4 s copolymer solution casting with distances between void centers of 125 nm. © 2014 Elsevier Ltd. All rights reserved.

  17. Fully Aromatic Block Copolymers for Fuel Cell Membranes with Densely Sulfonated Nanophase Domains

    DEFF Research Database (Denmark)

    Takamuku, Shogo; Jannasch, Patrick; Lund, Peter Brilner

    Two multiblock copoly(arylene ether sulfone)s with similar block lengths and ion exchange capacities (IECs) were prepared by a coupling reaction between a non-sulfonated precursor block and a highly sulfonated precursor block containing either fully disulfonated diarylsulfone or fully...... tetrasulfonated tetraaryldisulfone segments. The latter two precursor blocks were sulfonated via lithiation-sulfination reactions whereby the sulfonic acid groups were exclu- sively placed in ortho positions to the many sulfone bridges, giving these locks IECs of 4.1 and 4.6 meqg1, respectively. Copolymer...

  18. Surface Modification for Controlling the Orientation of Block Copolymers in thin film and in Cylindrical Nanopores (United States)

    Lin, Xin-Guan; Lin, Feng-Cheng; Tung, Shih-Huang


    A series of benzocyclobutene-functionalized random copolymers of styrene and 4-vinylpyridine were synthesized by nitroxide-mediated controlled radical polymerization with BPO and TEMPO. Our research was to use these random copolymers of P(S-r-BCB-r-4VP) to control the orientation of microdomains in block copolymers(BCPs) of poly(styrene-b-4-vinylpyridine)(PS-b-P4VP) thin films and in cylindrical nanopores of anodized aluminum oxide (AAO) membranes. On P(S-r-BCB-r-4VP)-modified substrate,we found that in some particular compositions of random copolymer ,the parallel orientation of the microdomains is switched to be perpendicular in PS-b-P4VP thin film. We also introduced P(S-r-BCB-r-4VP) solution into the nanopores of the AAO and nanotubes formed after solvent evaporation and pyrolysis. And then BCPs of PS-b-P4VP were drawn into the P(S-r-BCB-r-4VP)-modified nanopores in the melt via capillary action to form P(S-r-BCB-r-4VP) coated nanorods of PS-b-P4VP.Similarly,in some particular compositions of random copolymer, we observed that the interactions of the blocks with the walls are not strong or if the interactions are balanced, then the orientation of the microdomains will change from being parallel to being perpendicular to the confining walls.

  19. Synthesis of Inorganic Nanocomposites by Selective Introduction of Metal Complexes into a Self-Assembled Block Copolymer Template

    Directory of Open Access Journals (Sweden)

    Hiroaki Wakayama


    Full Text Available Inorganic nanocomposites have characteristic structures that feature expanded interfaces, quantum effects, and resistance to crack propagation. These structures are promising for the improvement of many materials including thermoelectric materials, photocatalysts, and structural materials. Precise control of the inorganic nanocomposites’ morphology, size, and chemical composition is very important for these applications. Here, we present a novel fabrication method to control the structures of inorganic nanocomposites by means of a self-assembled block copolymer template. Different metal complexes were selectively introduced into specific polymer blocks of the block copolymer, and subsequent removal of the block copolymer template by oxygen plasma treatment produced hexagonally packed porous structures. In contrast, calcination removal of the block copolymer template yielded nanocomposites consisting of metallic spheres in a matrix of a metal oxide. These results demonstrate that different nanostructures can be created by selective use of processes to remove the block copolymer templates. The simple process of first mixing block copolymers and magnetic nanomaterial precursors and then subsequently removing the block copolymer template enables structural control of magnetic nanomaterials, which will facilitate their applicability in patterned media, including next-generation perpendicular magnetic recording media.

  20. Theory for dynamical self arrest and gelation in microemulsions and the block copolymer systems

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Sangwook [Iowa State Univ., Ames, IA (United States)


    The main purpose of this work is to investigate the glassy behavior of microemulsions and block copolymers. The origin of glassy behavior in microemulsions and block copolymers is frustration due to a competition between short-range interaction and long range interaction. According to the charge frustrated Ising model, the competition between ferromagnetic interaction and antiferromagnetic interaction is the origin of frustration in microemulsions. The competition between entropic effects and stoichiometric constraints responsible for the formation of micelles in microemulsions can lead to the emergence of a self generated glassy behavior in these systems. In the block copolymer, the competition between the repulsive short range interaction between monomers in polymer chains and the long range interaction by chemical bonds can lead to the emergence of a self generated glassy behavior. The criteria for the fluctuation induced first order transition and our microemulsion and block copolymer glasses are essentially the same. Both are a consequence of the large phase space of low energy excitations (14) (62) (all states with momenta q which fulfill |q| = qm) and are of at the most a moderate supercooling of the liquid state is required. This is strongly supported by the observation in Ref. (14) that the metastable states which are first to appear at a fluctuation induced first order transition are the ones build by a superposition of large amplitude waves of wavenumber qm, but with random orientations and phases, i.e. just the ones which form the metastable states of our microemulsion and block copolymer glass. (38)

  1. Compatibilization of blends of low density polyethylene and poly(vinyl chloride) by segmented EB(SAN-block-EB)(n) block copolymers

    NARCIS (Netherlands)

    Kroeze, E; ten Brinke, G.; Hadziioannou, G

    Hydrogenated segmented poly[butadiene-block-((styrene-co-acrylonitrile)-block-butadiene)(n)] block copolymers, which were developed by use of the polymeric iniferter technique, were tested for their compatibilizing capacities for (10/90) LDPE/PVC blends. The acrylonitrile content of the SAN blocks

  2. Co-delivery of cisplatin and paclitaxel by folic acid conjugated amphiphilic PEG-PLGA copolymer nanoparticles for the treatment of non-small lung cancer. (United States)

    He, Zelai; Huang, Jingwen; Xu, Yuanyuan; Zhang, Xiangyu; Teng, Yanwei; Huang, Can; Wu, Yufeng; Zhang, Xi; Zhang, Huijun; Sun, Wenjie


    An amphiphilic copolymer, folic acid (FA) modified poly(ethylene glycol)-poly(lactic-co-glycolic acid) (FA-PEG-PLGA) was prepared and explored as a nanometer carrier for the co-delivery of cisplatin (cis-diaminodichloroplatinum, CDDP) and paclitaxel (PTX). CDDP and PTX were encapsulated inside the hydrophobic inner core and chelated to the middle shell, respectively. PEG provided the outer corona for prolonged circulation. An in vitro release profile of the CDDP + PTX-encapsulated nanoparticles revealed that the PTX chelation cross-link prevented an initial burst release of CDDP. After an incubation period of 24 hours, the CDDP+PTX-encapsulated nanoparticles exhibited a highly synergistic effect for the inhibition of A549 (FA receptor negative) and M109 (FA receptor positive) lung cancer cell line proliferation. Pharmacokinetic experiment and distribution research shows that nanoparticles have longer circulation time in the blood and can prolong the treatment times of chemotherapeutic drugs. For the in vivo treatment of A549 cells xeno-graft lung tumor, the CDDP+PTX-encapsulated nanoparticles displayed an obvious tumor inhibiting effect with an 89.96% tumor suppression rate (TSR). This TSR was significantly higher than that of free chemotherapy drug combination or nanoparticles with a single drug. For M109 cells xeno-graft tumor, the TSR was 95.03%. In vitro and in vivo experiments have all shown that the CDDP+PTX-encapsulated nanoparticles have better targeting and antitumor effects in M109 cells than CDDP+PTX-loaded PEG-PLGA nanoparticles (p nanoparticles came with reduced side-effects. No obvious body weight loss or functional changes occurred within blood components, liver, or kidneys during the treatment of A549 and M109 tumor-bearing mice with the CDDP+PTX-encapsulated nanoparticles. Thus, the FA modified amphiphilic copolymer-based combination of CDDP and PTX may provide useful guidance for effective and safe cancer chemotherapy, especially in tumors with

  3. Characterization of a Poly(styrene-block-methylacrylate-random-octadecylacrylate-block-styrene) Shape Memory ABA Triblock Copolymer (United States)

    Fei, Pengzhan; Cavicchi, Kevin


    A new ABA triblock copolymer of poly(styrene-block- methylacrylate-random-octadecylacrylate-block-styrene) (PS-b- PMA-r-PODA-b-PS) was synthesized by reversible addition fragmentation chain transfer polymerization. The triblock copolymer can generate a three-dimensional, physically crosslinked network by self-assembly, where the glassy PS domains physically crosslink the midblock chains. The side chain crystallization of the polyoctadecylacrylare (PODA) side chain generates a second reversible network enabling shape memory properties. Shape memory tests by uniaxial deformation and recovery of molded dog-bone shape samples demonstrate that shape fixities above 96% and shape recoveries above 98% were obtained for extensional strains up to 300%. An outstanding advantage of this shape memory material is that it can be very easily shaped and remolded by elevating the temperature to 140circ; C, and after remolding the initial shape memory properties are totally recovered by eliminating the defects introduced by the previous deformation cycling.

  4. Ethyl cellulose amphiphilic graft copolymers with LCST-UCST transition: Opposite self-assembly behavior, hydrophilic-hydrophobic surface and tunable crystalline morphologies. (United States)

    Yuan, Hua; Chi, Hai; Yuan, Weizhong


    Novel and well-defined graft copolymer with block copolymer side chain, ethyl cellulose-graft-(poly(ε-caprolactone)-block-poly(N,N-dimethylaminoethylmeth acrylate)) (EC-g-(PCL-b-PDMAEMA)) with a lower critical solution temperature (LCST) was successfully synthesized via the combination of ring-opening polymerization (ROP) and atom transfer radical polymerization (ATRP). EC-g-(PCL-b-PDMAEMA) copolymers with various PCL-b-PDMAEMA block lengths were obtained by adjusting the molar ratios of the N,N-dimethylaminoethyl methacrylate monomer to ε-caprolactone. The EC-g-(PCL-b-PDMAPS) with an upper critical solution temperature (UCST) was obtained via facile quaternization reaction of PDMAEMA with 1,3-propane sultone. EC-g-(PCL-b-PDMAEMA) and EC-g-(PCL-b-PDMAPS) micelle solutions showed opposite thermoresponsiviness and hydrophilic-hydrophobic surface. Moreover, the tunable crystalline morphologies could be obtained from these graft copolymers through changing the polymer structure and PDMAEMA contents. Copyright © 2016 Elsevier Ltd. All rights reserved.

  5. Merging Bottom-Up with Top-Down: Continuous Lamellar Networks and Block Copolymer Lithography (United States)

    Campbell, Ian Patrick

    Block copolymer lithography is an emerging nanopatterning technology with capabilities that may complement and eventually replace those provided by existing optical lithography techniques. This bottom-up process relies on the parallel self-assembly of macromolecules composed of covalently linked, chemically distinct blocks to generate periodic nanostructures. Among the myriad potential morphologies, lamellar structures formed by diblock copolymers with symmetric volume fractions have attracted the most interest as a patterning tool. When confined to thin films and directed to assemble with interfaces perpendicular to the substrate, two-dimensional domains are formed between the free surface and the substrate, and selective removal of a single block creates a nanostructured polymeric template. The substrate exposed between the polymeric features can subsequently be modified through standard top-down microfabrication processes to generate novel nanostructured materials. Despite tremendous progress in our understanding of block copolymer self-assembly, continuous two-dimensional materials have not yet been fabricated via this robust technique, which may enable nanostructured material combinations that cannot be fabricated through bottom-up methods. This thesis aims to study the effects of block copolymer composition and processing on the lamellar network morphology of polystyrene-block-poly(methyl methacrylate) (PS-b-PMMA) and utilize this knowledge to fabricate continuous two-dimensional materials through top-down methods. First, block copolymer composition was varied through homopolymer blending to explore the physical phenomena surrounding lamellar network continuity. After establishing a framework for tuning the continuity, the effects of various processing parameters were explored to engineer the network connectivity via defect annihilation processes. Precisely controlling the connectivity and continuity of lamellar networks through defect engineering and

  6. Differentiation of human stem cells is promoted by amphiphilic pluronic block copolymers

    Directory of Open Access Journals (Sweden)

    Doğan A


    Full Text Available Aysegül Doğan,1 Mehmet E Yalvaç,1,2 Fikrettin Şahin,1 Alexander V Kabanov,3–5 András Palotás,6 Albert A Rizvanov71Department of Genetics and BioEngineering, College of Engineering and Architecture, Yeditepe University, Istanbul, Turkey; 2Center for Gene Therapy, Nationwide Children's Hospital, Ohio State University, Columbus, OH, USA; 3Center for Drug Delivery and Nanomedicine, 4Department of Pharmaceutical Sciences, College of Pharmacy, Durham Research Center, University of Nebraska Medical Center, Omaha, NE, USA; 5Laboratory of Chemical Design of Bio-nano-materials, Department of Chemistry, Mikhail V Lomonosov Moscow State University, Moscow, Russia; 6Asklepios-Med, Szeged, Hungary; 7Institute of Fundamental Medicine and Biology, Kazan (Volga Region Federal University, Kazan, RussiaAbstract: Stem cell usage provides novel avenues of tissue regeneration and therapeutics across disciplines. Apart from ethical considerations, the selection and amplification of donor stem cells remain a challenge. Various biopolymers with a wide range of properties have been used extensively to deliver biomolecules such as drugs, growth factors and nucleic acids, as well as to provide biomimetic surface for cellular adhesion. Using human tooth germ stem cells with high proliferation and transformation capacity, we have investigated a range of biopolymers to assess their potential for tissue engineering. Tolerability, toxicity, and their ability to direct differentiation were evaluated. The majority of pluronics, consisting of both hydrophilic and hydrophobic poly(ethylene oxide chains, either exerted cytotoxicity or had no significant effect on human tooth germ stem cells; whereas F68 increased the multi-potency of stem cells, and efficiently transformed them into osteogenic, chondrogenic, and adipogenic tissues. The data suggest that differentiation and maturation of stem cells can be promoted by selecting the appropriate mechanical and chemical properties of polymers. It has been shown for the first time that F68, with its unique molecular characteristics, has a great potential to increase the differentiation of cells, which may lead to the development of new tissue engineering strategies in regenerative medicine.Keywords: biopolymer, differentiation, human tooth germ stem cell (hTGSC, mesenchymal stem cell, pluronic, toxicity

  7. Solubilization of Phenol Derivatives in Polymer Micelles Formed by Cationic Block Copolymer

    Directory of Open Access Journals (Sweden)

    Irma Fuentes


    Full Text Available The aggregation of cationic block copolymers formed by polystyrene (PS and poly(ethyl-4-vinylpyridine (PS-b-PE4VP was studied in aqueous solution. Diblock copolymers of PS and poly(4-vinylpyridine were synthesized by sequential anionic polymerization using BuLi as initiator. Subsequently, the 4-vinylpyridine units were quaternized with ethyl bromide to obtain cationic PS-b-PE4VP block copolymers with different quaternization degree. The self-aggregation of cationic block copolymers was studied by fluorescence probing, whereas the morphology and size of polymer micelles were determined by transmission electronic microscopy. Results indicate that spherical micelles with sizes lower than 100 nm were formed, whereas their micropolarity decreases with increasing quaternization degree. The partition of phenols between the micellar and aqueous phase was studied by using the pseudo-phase model, and the results show that the partition coefficients increase with increasing length of the side alkyl chain and are larger for star micelles. These results are discussed in terms of three-region model.

  8. Nano-organization of amylose-b-polystyrene block copolymer films doped with bipyridine. (United States)

    Aissou, Karim; Otsuka, Issei; Rochas, Cyrille; Fort, Sébastien; Halila, Sami; Borsali, Redouane


    This paper discusses the self-assembly of rod-coil amylose-b-polystyrene (Mal-b-PS) block copolymer thick and thin films. The nano-organization falls in an interdomain spacing d of about 10 nm, much smaller than flexible-flexible petrol block copolymer systems. Additionally, hydrogen-bonding interactions between carbohydrate rods (amylose) and 4',4-bipyridine (bipy) molecules induces phase transitions. Indeed, adding bipy in maltooctadecaose-block-polystyrene (Mal18-b-PS) copolymers results, at room temperature, in the formation of a lamellar phase having Mal18 bipy-rich nanodomains instead of hexagonal close-packed (HCP) of cylinders made of Mal18, whereas a coexistence of Mal7bipy-rich cylindrical and spherical nanodomains are formed from maltoheptaose-b-polystyrene (Mal7-b-PS) copolymers instead of a poorly organized array of Mal7-based cylinders. On heating, the Mal7bipy-b-PS system shows more rich phase behavior as compared to the Mal7-b-PS one due to weakening of hydrogen bonding with temperature. Such a system is of great interest in developing active layers in light-emitting diodes (LEDs) or in photovoltaic cells to realize devices with an optimal structure, that is, having large interface area and domain size with similar exciton diffusion length (10 nm).

  9. Reversible Micro- and Nano- Phase Programming of Anthraquinone Thermochromism Using Blended Block Copolymers. (United States)

    Zhang, Yumiao; Lovell, Jonathan F


    Here, we present an approach to generate materials with programmable thermochromic transition temperatures (TTTs), based on the reversible microcrystallization of anthraquinone dyes with the assistance of blended Pluronic block copolymers. At temperatures above block copolymer critical micellization temperature (CMT), hydrophobic anthraquinone dyes, including Sudan blue II, were dispersed in copolymer micelles, whereas at lower temperature, the dyes formed microcrystals driven by dye-dye and dye-Pluronic molecular interactions. The crystallization process altered the optical properties of the dye with bathochromatic shifts detectable by eye and the thermochromic process was fully reversible. Not only could Pluronic reversibly incorporate the anthraquinone dyes into micelles at elevated temperatures, but it also modulated the crystallization process and resulting morphology of microcrystals via tuning the molecular interactions when the temperature was lowered. Crystal melting transition points (and TTTs) were in agreement with the CMTs, demonstrating that the thermochromism was dependent on block copolymer micellization. Thermochromism could be readily programmed over a broad range of temperatures by changing the CMT by using different types and concentrations of Pluronics and combinations thereof.

  10. Synthesis of Medium-Chain-Length Polyhydroxyalkanoate Homopolymers, Random Copolymers, and Block Copolymers by an Engineered Strain of Pseudomonas entomophila. (United States)

    Wang, Ying; Chung, Ahleum; Chen, Guo-Qiang


    Medium-chain-length polyhydroxyalkanoates (mcl-PHAs), widely used in medical area, are commonly synthesized by Pseudomonas spp. This study tries to use β-oxidation pathways engineered P. entomophila to achieve single source of a series of mcl-monomers for microbial production of PHA homopolymers. The effort is proven successful for the first time to obtain a wide range of mcl-PHA homopolymers from engineered P. entomophila LAC23 grown on various fatty acids, respectively, ranging from poly(3-hydroxyheptanoate) to poly(3-hydroxytetradecanoate). Effects of a PHA monomer chain length on thermal and crystallization properties including the changes of T m , T g , and T d5% are investigated. Additionally, strain LAC23 is used to synthesize random copolymers of 3-hydroxyoctanoate (3HO) and 3-hydroxydodecanoate (3HDD) or 3-hydroxytetradecanoates, their compositions could be controlled by adjusting the ratios of two related fatty acids. Meanwhile, block copolymer P(3HO)-b-P(3HDD) is synthesized by the same strain. It is found for the first time that even- and odd number mcl-PHA homopolymers have different physical properties. When the gene of the PHA synthase in the engineered P. entomophila is replaced by phaC from Aeromonas hydrophila 4AK4, poly(3-hydroxybutyrate-co-30 mol%-3-hydroxyhexanoate) is synthesized. Therefore, P. entomophila can be used to synthesize the whole range of PHA (C7-C14) homopolymers, random- and block copolymers. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  11. Block and random copolymers bearing cholic acid and oligo(ethylene glycol) pendant groups: aggregation, thermosensitivity, and drug loading. (United States)

    Shao, Yu; Jia, Yong-Guang; Shi, Changying; Luo, Juntao; Zhu, X X


    A series of block and random copolymers consisting of oligo(ethylene glycol) and cholic acid pendant groups were synthesized via ring-opening metathesis polymerization of their norbornene derivatives. These block and random copolymers were designed to have similar molecular weights and comonomer ratios; both types of copolymers showed thermosensitivity in aqueous solutions with similar cloud points. The copolymers self-assembled into micelles in water as shown by dynamic light scattering and transmission electron microscopy. The hydrodynamic diameter of the micelles formed by the block copolymer is much larger and exhibited a broad and gradual shrinkage from 20 to 54 °C below its cloud point, while the micelles formed by the random copolymers are smaller in size but exhibited some swelling in the same temperature range. Based on in vitro drug release studies, 78% and 24% paclitaxel (PTX) were released in 24 h from micelles self-assembled by the block and random copolymers, respectively. PTX-loaded micelles formed by the block and random copolymers exhibited apparent antitumor efficacy toward the ovarian cancer cells with a particularly low half-maximal inhibitory concentration (IC50) of 27.4 and 40.2 ng/mL, respectively. Cholic acid-based micelles show promise as a versatile and potent platform for cancer chemotherapy.

  12. Responsive Hydrogels from Associative Block Copolymers: Physical Gelling through Polyion Complexation

    Directory of Open Access Journals (Sweden)

    Christine M. Papadakis


    Full Text Available The present review article highlights a specific class of responsive polymer-based hydrogels which are formed through association of oppositely charged polyion segments. The underpinning temporary three-dimensional network is constituted of hydrophilic chains (either ionic or neutral physically crosslinked by ion pair formation arising from intermolecular polyionic complexation of oppositely charged repeating units (polyacid/polybase ionic interactions. Two types of hydrogels are presented: (i hydrogels formed by triblock copolymers bearing oppositely charged blocks (block copolyampholytes, forming self-assembled networks; and (ii hydrogels formed by co-assembly of oppositely charged polyelectrolyte segments belonging to different macromolecules (either block copolymers or homopolyelectrolytes. Due to the weak nature of the involved polyions, these hydrogels respond to pH and are sensitive to the presence of salts. Discussing and evaluating their solution, rheological and structural properties in dependence on pH and ionic strength, it comes out that the hydrogel properties are tunable towards potential applications.

  13. Solution Construction of Multigeometry Nanoparticles and Multicompartment Superstructures from Block Copolymer Mixtures (United States)

    Zhu, Jiahua; Zhang, Shiyi; Wooley, Karen; Pochan, Darrin


    Novel soft objects with both compositional and geometric complexity at nanoscale have been constructed through solution supramolecular assembly from block copolymer mixtures due to their non-ergodic character. The mixture is composed of two block copolymers with distinctive hydrophobic blocks but the same poly(acrylic acid) hydrophilic block. First, multigeometry nanoparticles, due to segregation of unlike block copolymer molecules into multiple subdomains trapped within the same micelle-like structures, have been assembled in tetrahydrofuran/water solution. Through carefully designed molecular architecture, mixing ratio and pathway kinetics, both size and shape of subdomains can be controlled to produce a novel class of multigeometry nanoparticles, including sphere-sphere, sphere-cylinder, cylinder-cylinder, cylinder-disk, and sphere-disk hybrid nanoparticles. Second, hierarchical multicompartment superstructures including particle chains, rings and other nano to micro cluster formations, have been built up from pre-formed multigeometry nanoparticles by taking advantage of their surface anisotropy and the controlled particle-particle association. The interparticle association can be achieved via either covalent or non-covalent bindings due to different post-polymerization chemical modifications with hydroxyethyl acrylate or crown ether functionalities, respectively.

  14. Inducing β Phase Crystallinity in Block Copolymers of Vinylidene Fluoride with Methyl Methacrylate or Styrene

    Directory of Open Access Journals (Sweden)

    Nahal Golzari


    Full Text Available Block copolymers of poly(vinylidene fluoride (PVDF with either styrene or methyl methacrylate (MMA were synthesized and analyzed with respect to the type of the crystalline phase occurring. PVDF with iodine end groups (PVDF-I was prepared by iodine transfer polymerization either in solution with supercritical CO2 or in emulsion. To activate all iodine end groups Mn2(CO10 is employed. Upon UV irradiation Mn(CO5 radicals are obtained, which abstract iodine from PVDF-I generating PVDF radicals. Subsequent polymerization with styrene or methyl methacrylate (MMA yields block copolymers. Size exclusion chromatography and NMR results prove that the entire PVDF-I is converted. XRD, FT-IR, and differential scanning calorimetry (DSC analyses allow for the identification of crystal phase transformation. It is clearly shown that the original α crystalline phase of PVDF-I is changed to the β crystalline phase in case of the block copolymers. For ratios of the VDF block length to the MMA block length ranging from 1.4 to 5 only β phase material was detected.

  15. Nanostructure of self-assembled rod-coil block copolymer films for photovoltaic applications

    International Nuclear Information System (INIS)

    Heiser, T.; Adamopoulos, G.; Brinkmann, M.; Giovanella, U.; Ould-Saad, S.; Brochon, C.; Wetering, K. van de; Hadziioannou, G.


    The nanostructures of a series of rod-coil block copolymers, designed for photovoltaic applications, are studied by atomic force microscopy and transmission electron microscopy. The copolymers are composed of a semiconducting poly-p-phenylenevinylene rod with (2'-ethyl)-hexyloxy side chains and a functionalized coil block of various length and flexibility. Both, as deposited and annealed block copolymer films were investigated. The results show that highly ordered structures are only obtained if the coil block is characterized by a glass transition temperature which is significantly lower than the melting temperature of the alkyl side chains. For this material a high molecular mobility and strong driving force for crystallization of the rigid block can be achieved simultaneously. For the smallest coil to rod length ratio, we found a lamellar morphology with perpendicularly oriented lamellae with respect to the substrate. Electron diffraction data show the presence of a periodical molecular arrangement with a characteristic distance of 0.94 nm that is attributed to the distance between conjugated chains separated by the layers of alkyl sidechains

  16. Sans Studies Insight Into Improving of Yield of Block Copolymer-Stabilized Gold Nanoparticles (United States)

    Ray, Debes; Aswal, V. K.


    Triblock copolymer poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) (PEO-PPO-PEO) are well known as dispersion stabilizers. It has also been recently found that they can act as reducing agents along with stabilizers and these two properties of block copolymers together have provided a single-step synthesis and stabilization of gold nanoparticles at ambient temperature. We have studied the synthesis of stable gold nanoparticle solutions using block copolymer P85. Gold nanoparticles are prepared from 1 wt% aqueous solution of P85 mixed with varying concentration of HAuCl4.3H2O salt in the range 0.001 to 0.1 wt%. Surface plasmon resonance (SPR) band in UV-visible absorption spectra confirm the formation of the gold nanoparticles and the maximum yield of the nanoparticles is found to be quite low at 0.005 wt% of the salt solution. Small-angle neutron scattering (SANS) measurements in these systems suggest that a very small fraction of the block copolymers (nanoparticles and remaining form their own micelles, which probably results in the low yield. This can be explained as on an average a high block copolymer-to-gold ion ratio r0 (22) is required for 1 wt% P85 in the reduction reaction to produce gold nanoparticles. Based on this understanding, a step-addition method is used to enhance the yield of gold nanoparticles by manifold where the gold salt is added in small steps to maintain higher value of r(>r0) and therefore continuous formation of nanoparticles.

  17. Effects of copolymer composition on the formation of ionic species, hydrogen evolution, and free-radical reaction in γ-irradiated styrene-butadiene random and block copolymers

    International Nuclear Information System (INIS)

    Basheer, R.; Dole, M.


    Block and random copolymers of butadiene and styrene as well as polybutadiene and polystyrene homopolymers have been investigated with respect to formation of trapped electrons, contribution of ionic species to crosslinking, and hydrogen gas evolution due to γ radiation. The decay kinetics of the disubstituted benzyl radical has also been studied. The yields of electron trapping G(e - ) are measured. The G(e - ) increase linearly with increased polystyrene content in block polymers, while in random copolymer a deviation from a linear relation is observed. The contribution of ionic reactions to crosslinking is about 25-35% of the total crosslinking yield. Hydrogen production in block copolymers is approximately a linear function of the weight-fraction additivity of the yield of hydrogen formation in polystrene and polybutadiene homopolymers. Energy transfer from butadiene units to styrene units in random copolymers resulted in a deviation from such an additivity relation. The decay of the disubstituted benzyl free radical in block copolymers is a second-order reaction. In random copolymer, the decay is best interpreted in terms of equation based on a second-order decay mechanism of a fraction of the free radicals decaying in the presence of other nondecaying free radicals. 24 references, 11 figures, 3 tables

  18. The effect of film thickness and molecular structure on order and disorder in thin films of compositionally asymmetric block copolymers (United States)

    Mishra, Vindhya

    Directed self-assembly of thin film block copolymers offer a high throughput-low cost route to produce next generation lithographic devices, if one can bring the defect densities in the self assembled patterns below tolerance limits. However, the ability to control the nanoscale structure or morphology in thin film block copolymers presents challenges due to confinement effects on equilibrium behavior. Using structure characterization techniques such as grazing incidence small angle X-ray scattering (GISAXS), transmission electron and atomic force microscopy as well as self-consistent field theory, we have investigated how film thickness, annealing temperature and block copolymer structure affects the equilibrium behavior of asymmetric block copolymer films. Our studies have revealed the complicated dependence of order-disorder transitions, order-order transitions and symmetry transitions on film thickness. We found that the thickness dependent transition in the packing symmetry of spherical morphology diblock copolymers can be suppressed by blending with a small amount of majority block homopolymer, which allowed us to resolve the driving force behind this transition. Defect densities in, and the order-disorder transition temperature of, thin films of graphoepitaxially aligned diblock copolymer cylinders showed surprising sensitivity to the microdomain spacing. Methods to mitigate defect formation in thin films have been identified. The challenge of quantification of structural order in these systems was overcome using GISAXS, which allowed us to study the phenomena of disordering in two and three dimensions. Through studies on block copolymers which exhibit an order-order transition in bulk, we found that that subtle differences in the packing frustration of the spherical and cylindrical phases as well as the higher configurational entropy of free chain ends at the surface can drive the equilibrium configuration in thin films away from the stable bulk structure

  19. Block copolymer self-assembly fundamentals and applications in formulation of nano-structured fluids (United States)

    Sarkar, Biswajit

    Dispersions of nanoparticles in polymer matrices form hybrid materials that can exhibit superior structural and functional properties and find applications in e.g. thermo-plastics, electronics, polymer electrolytes, catalysis, paint formulations, and drug delivery. Control over the particle location and orientation in the polymeric matrices are essential in order to realize the enhanced mechanical, electrical, and optical properties of the nanohybrids. Block copolymers, composed of two or more different monomers, are promising for controlling particle location and orientation because of their ability to organize into ordered nanostructures. Fundamental questions pertaining to nanoparticle-polymer interfacial interactions remain open and formulate the objectives of our investigation. Particle-polymer enthalpic and entropic interactions control the nanoparticle dispersion in polymer matrices. Synthetic chemical methods for modifying the particle surface in order to control polymer-particle interactions are involved and large scale production is not possible. In the current approach, a physical method is employed to control polymer-particle interactions. The use of commercially available solvents is found to be effective in modifying particle-polymer interfacial interactions. The approach is applicable to a wide range of particle-polymer systems and can thereby enable large scale processing of polymer nanohybrids. The systems of silica nanoparticles dispersed in long-range or short-range self-assembled structures of aqueous poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) (PEO-PPO-PEO) block copolymers (Pluronics) is considered here. The effect of various parameters such as the presence of organic solvents, pH, and particle size on the block copolymer organization and the ensuing particle-polymer interactions are investigated. Favorable surface interactions between the deprotonated silica nanoparticle and PEO-rich domain facilitate particle

  20. Approaching a flat boundary with a block copolymer coated emulsion drop: late stage drainage dynamics (United States)

    Rozairo, Damith; Croll, Andrew

    Understanding the dynamics of the formation and drainage of the thin fluid film that becomes trapped by a deformable droplet as it approaches another object is crucial to the advancement of many industrial and biomedical applications. Adding amphiphilic diblock copolymers, which are becoming more commonly used in drug delivery and oil recovery, only add to the complexity. Despite their increased use, little is known about how long polymer chains fill an emulsion drop's interface or how the molecules influence hydrodynamic processes. We study the drainage dynamics of a thin water film trapped between mica and a diblock copolymer saturated oil droplet. Specifically, we examine several different polystyrene-b-poly(ethylene oxide) (PS-PEO) molecules self-assembled at a toluene-water interface using laser scanning confocal microscopy. Our experiments reveal that the molecular details of the polymer chains deeply influence the drainage times, indicating that they are not acting as a 'simple' surfactant. The presence of the chains creates a much slower dynamic as fluid is forced to drain through an effective polymer brush, the brush itself determined by chain packing at the interface. We present a simple model which accounts for the basic physics of the interface.

  1. Highly Efficient One-Pot Synthesis of COS-Based Block Copolymers by Using Organic Lewis Pairs. (United States)

    Yang, Jia-Liang; Cao, Xiao-Han; Zhang, Cheng-Jian; Wu, Hai-Lin; Zhang, Xing-Hong


    A one-pot synthesis of block copolymer with regioregular poly(monothiocarbonate) block is described via metal-free catalysis. Lewis bases such as guanidine, quaternary onium salts, and Lewis acid triethyl borane (TEB) were equivalently combined and used as the catalysts. By using polyethylene glycol (PEG) as the macromolecular chain transfer agent (CTA), narrow polydispersity block copolymers were obtained from the copolymerization of carbonyl sulfide (COS) and propylene oxide (PO). The block copolymers had a poly(monothiocarbonate) block with perfect alternating degree and regioregularity. Unexpectedly, the addition of CTA to COS/PO copolymerization system could dramatically improve the turnover frequency (TOF) of PO (up to 240 h -1 ), higher than that of the copolymerization without CTA. In addition, the conversion of CTA could be up to 100% in most cases, as revealed by ¹H NMR spectra. Of consequence, the number-average molecular weights ( M n s) of the resultant block copolymers could be regulated by varying the feed ratio of CTA to PO. Oxygen-sulfur exchange reaction (O/S ER), which can generate randomly distributed thiocarbonate and carbonate units, was effectively suppressed in all of the cases in the presence of CTA, even at 80 °C. This work presents a versatile method for synthesizing sulfur-containing block copolymers through a metal-free route, providing an array of new block copolymers.

  2. Preparation of gold microparticles using halide ions in bulk block copolymer phases via photoreduction

    International Nuclear Information System (INIS)

    Cha, Sang-Ho; Kim, Ki-Hyun; Lee, Won-Ki; Lee, Jong-Chan


    Gold microparticles were prepared from the gold salt in the solid bulk phase of a poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) block copolymer via a photoreduction process in the presence of halide ions. The shapes and sizes of the gold microparticles were found to be dependent on the types and amount of halide ions as well as the types of cations used due to the combined effects of the adsorption power and oxidative dissolution ability of the additives on gold surfaces. Gold nanorods were obtained when poly(ethylene oxide) was used instead of the block copolymer. This suggests that the poly(propylene oxide) (PPO) parts in the block copolymer are essential for the formation of gold microparticles, even though the degree of the direct interaction between the PPO blocks and gold salt is not significant. - Graphical abstract: Gold microparticles were successfully prepared using halide ions as additives in the polymeric bulk phase via photoreduction with the glow lamp irradiation.

  3. Block copolymer-templated chemistry on Si, Ge, InP, and GaAs surfaces. (United States)

    Aizawa, Masato; Buriak, Jillian M


    Patterning of semiconductor surfaces is an area of intense interest, not only for technological applications, such as molecular electronics, sensing, cellular recognition, and others, but also for fundamental understanding of surface reactivity, general control over surface properties, and development of new surface reactivity. In this communication, we describe the use of self-assembling block copolymers to direct semiconductor surface chemistry in a spatially defined manner, on the nanoscale. The proof-of-principle class of reactions evaluated here is galvanic displacement, in which a metal ion, M+, is reduced to M0 by the semiconductor, including Si, Ge, InP, and GaAs. The block copolymer chosen has a polypyridine block which binds to the metal ions and brings them into close proximity with the surface, at which point they undergo reaction; the pattern of resulting surface chemistry, therefore, mirrors the nanoscale structure of the parent block copolymer. This chemistry has the added advantage of forming metal nanostructures that result in an alloy or intermetallic at the interface, leading to strongly bound metal nanoparticles that may have interesting electronic properties. This approach has been shown to be very general, functioning on a variety of semiconductor substrates for both silver and gold deposition, and is being extended to organic and inorganic reactions on a variety of conducting, semiconducting, and insulating substrates.

  4. Block copolymer systems: from single chain to self-assembled nanostructures. (United States)

    Giacomelli, Cristiano; Schmidt, Vanessa; Aissou, Karim; Borsali, Redouane


    Recent advances in the field of macromolecular engineering applied to the fabrication of nanostructured materials using block copolymer chains as elementary building blocks are described in this feature article. By highlighting some of our work in the area and accounting for the contribution of other groups, we discuss the relationship between the physical-chemical properties of copolymer chains and the characteristics of nano-objects originating from their self-assembly in solution and in bulk, with emphasis on convenient strategies that allow for the control of composition, functionality, and topology at different levels of sophistication. In the case of micellar nanoparticles in solution, in particular, we present approaches leading to morphology selection via macromolecular architectural design, the functionalization of external solvent-philic shells with biomolecules (polysaccharides and proteins), and the maximization of micelle loading capacity by the suitable choice of solvent-phobic polymer segments. The fabrication of nanomaterials mediated by thin block copolymer films is also discussed. In this case, we emphasize the development of novel polymer chain manipulation strategies that ultimately allow for the preparation of precisely positioned nanodomains with a reduced number of defects via block-selective chemical reactivity. The challenges facing the soft matter community, the urgent demand to convert huge public and private investments into consumer products, and future possible directions in the field are also considered herein.

  5. Enhancing relative permittivity by incorporating PDMS-PEG multi block copolymers in binary polymer blends

    DEFF Research Database (Denmark)

    A Razak, Aliff Hisyam; Szabo, Peter; Skov, Anne Ladegaard

    Polydimethylsiloxanes (PDMS) are well-known to actuate with relatively large strains due to low modulus, but they possess lowpermittivity. Contrary, polyethyleneglycols (PEG) are not stretchable but possess high permittivity. Combination of the two polymers in a block copolymer depicts a possibil......Polydimethylsiloxanes (PDMS) are well-known to actuate with relatively large strains due to low modulus, but they possess lowpermittivity. Contrary, polyethyleneglycols (PEG) are not stretchable but possess high permittivity. Combination of the two polymers in a block copolymer depicts...... a possibility for substantial improvement of properties such as high permittivity, stretchability and non-conductivity – if carefully designed. The objective is to synthesize PDMS-PEG multiblock copolymer assembling into discontinuous morphologies in PEG based on variation of volume fractions of PDMS....... The utilized synthesis of PDMS-PEG multiblock copolymer is based on hydrosilylation reaction, which is amended from Klasner et al.1 and Jukarainen etal.2 Variation in the ratio between the two constituents introduces distinctive properties in terms of dielectric permittivity and rheological behaviour. PDMS...

  6. Water vapor and gas transport through PEO PBT block copolymers

    NARCIS (Netherlands)

    Metz, S.J.; Potreck, Jens; Mulder, M.H.V.; Wessling, Matthias


    Introduction At the bore well natural gas is saturated with water. Downstream the presence of water may cause: formation of methane hydrates (blocking eventually the pipeline), condensation of water in the pipeline and corrosion effects. A process used for the dehydration of natural gas is glycol

  7. Nonaqueous Dispersion Formed by an Emulsion Solvent Evaporation Method Using Block-Random Copolymer Surfactant Synthesized by RAFT Polymerization. (United States)

    Ezaki, Naofumi; Watanabe, Yoshifumi; Mori, Hideharu


    As surfactants for preparation of nonaqueous microcapsule dispersions by the emulsion solvent evaporation method, three copolymers composed of stearyl methacrylate (SMA) and glycidyl methacrylate (GMA) with different monomer sequences (i.e., random, block, and block-random) were synthesized by reversible addition-fragmentation chain transfer (RAFT) polymerization. Despite having the same comonomer composition, the copolymers exhibited different functionality as surfactants for creating emulsions with respective dispersed and continuous phases consisting of methanol and isoparaffin solvent. The optimal monomer sequence for the surfactant was determined based on the droplet sizes and the stabilities of the emulsions created using these copolymers. The block-random copolymer led to an emulsion with better stability than obtained using the random copolymer and a smaller droplet size than achieved with the block copolymer. Modification of the epoxy group of the GMA unit by diethanolamine (DEA) further decreased the droplet size, leading to higher stability of the emulsion. The DEA-modified block-random copolymer gave rise to nonaqueous microcapsule dispersions after evaporation of methanol from the emulsions containing colored dyes in their dispersed phases. These dispersions exhibited high stability, and the particle sizes were small enough for application to the inkjet printing process.

  8. Micellar Self-Assembly of Block Copolymers for Fabrication of Nanostructured Membranes

    KAUST Repository

    Marques, Debora S.


    This research work examines the process of block copolymer membrane fabrication by self-assembly combined by non-solvent induced phase separation. Self-assembly takes place from the preparation of the primordial solution until the moment of immersion in a non-solvent bath. These mechanisms are driven thermodynamically but are limited by kinetic factors. It is shown in this work how the ordering of the assembly of micelles is improved by the solution parameters such as solvent quality and concentration of block copolymer. Order transitions are detected, yielding changes in the morphology. The evaporation of the solvents after casting is demonstrated to be essential to reach optimum membrane structure. The non-solvent bath stops the phase separation at an optimum evaporation time.

  9. Iron Oxide Arrays Prepared from Ferrocene- and Silsesquioxane-Containing Block Copolymers

    Directory of Open Access Journals (Sweden)

    Raita Goseki


    Full Text Available Arrays of iron oxides as precursors of iron clusters were prepared by oxygen plasma treatment of block copolymer microphase-separated nanostructures in thin films. Block copolymers composed of ferrocene-containing and silsesquioxane-containing polymethacrylate (PMAPOSS-b-PMAHFC were successfully prepared, with different molecular weights and compositions and narrow molecular weight distributions, by living anionic polymerization. The formed microphase-separated nanostructures in the bulk were characterized by wide- and small-angle X-ray scattering (WAXS and SAXS, scanning electron microscopy (SEM, and transmission electron microscopy (TEM. Thin films were prepared from a solution of PMAPOSS-b-PMAHFC in tetrahydrofuran by spin coating onto silicon wafers. Fingerprint-type line nanostructures were formed in the PMAPOSS-b-PMAHFCs thin films after solvent annealing with carbon disulfide. Oxygen plasma treatment provided the final line arrays of iron oxides based on the formed nanostructural patterns.

  10. Structural and Mechanical Hysteresis at the Order-Order Transition of Block Copolymer Micellar Crystals

    Directory of Open Access Journals (Sweden)

    Theresa A. LaFollette


    Full Text Available Concentrated solutions of a water-soluble block copolymer (PEO20-(PPO70-(PEO20 show a thermoreversible transition from a liquid to a gel. Over a range of concentration there also exists an order-order transition (OOT between cubically-packed spherical micelles and hexagonally-packed cylindrical micelles. This OOT displays a hysteresis between the heating and cooling transitions that is observed at both the macroscale through rheology and nanoscale through small angle neutron scattering (SANS. The hysteresis is caused by the persistence of the cubically-packed spherical micelle phase into the hexagonally-packed cylindrical micelle phase likely due to the hindered realignment of the spherical micelles into cylindrical micelles and then packing of the cylindrical micelles into a hexagonally-packed cylindrical micelle phase. This type of hysteresis must be fully characterized, and possibly avoided, for these block copolymer systems to be used as templates in nanocomposites.

  11. Thermally induced structural evolution and performance of mesoporous block copolymer-directed alumina perovskite solar cells.

    KAUST Repository

    Tan, Kwan Wee


    Structure control in solution-processed hybrid perovskites is crucial to design and fabricate highly efficient solar cells. Here, we utilize in situ grazing incidence wide-angle X-ray scattering and scanning electron microscopy to investigate the structural evolution and film morphologies of methylammonium lead tri-iodide/chloride (CH3NH3PbI(3-x)Cl(x)) in mesoporous block copolymer derived alumina superstructures during thermal annealing. We show the CH3NH3PbI(3-x)Cl(x) material evolution to be characterized by three distinct structures: a crystalline precursor structure not described previously, a 3D perovskite structure, and a mixture of compounds resulting from degradation. Finally, we demonstrate how understanding the processing parameters provides the foundation needed for optimal perovskite film morphology and coverage, leading to enhanced block copolymer-directed perovskite solar cell performance.

  12. Thermally Induced Structural Evolution and Performance of Mesoporous Block Copolymer-Directed Alumina Perovskite Solar Cells (United States)


    Structure control in solution-processed hybrid perovskites is crucial to design and fabricate highly efficient solar cells. Here, we utilize in situ grazing incidence wide-angle X-ray scattering and scanning electron microscopy to investigate the structural evolution and film morphologies of methylammonium lead tri-iodide/chloride (CH3NH3PbI3–xClx) in mesoporous block copolymer derived alumina superstructures during thermal annealing. We show the CH3NH3PbI3–xClx material evolution to be characterized by three distinct structures: a crystalline precursor structure not described previously, a 3D perovskite structure, and a mixture of compounds resulting from degradation. Finally, we demonstrate how understanding the processing parameters provides the foundation needed for optimal perovskite film morphology and coverage, leading to enhanced block copolymer-directed perovskite solar cell performance. PMID:24684494

  13. Room Temperature, High-yield Synthesis of Block Copolymer-mediated Gold Nanoparticles (United States)

    Ray, Debes; Aswal, V. K.; Kohlbrecher, J.


    We report the high-yield synthesis of gold nanoparticles in block copolymer-mediated synthesis where the nanoparticles have been synthesized from hydrogen tetrachloroaureate (III) hydrate (HAuCl4ṡ3H2O) using P85 (EO26PO39EO26) block copolymers in aqueous solution at room temperature. The formation of gold nanoparticles in these systems has been confirmed by UV-visible spectroscopy. The yield of nanoparticles simply does not increase with the increase in the gold salt concentration, which is limited by the gold ions reduction. Therefore, we have used the presence of additional reductant (tri-sodium citrate) to enhance the yield by manifold. The size distribution of the nanoparticles has been obtained by small-angle neutron scattering (SANS) and the average size is found to increase with the yield.

  14. Wafer-Scale Nanopillars Derived from Block Copolymer Lithography for Surface-Enhanced Raman Spectroscopy

    DEFF Research Database (Denmark)

    Li, Tao; Wu, Kaiyu; Rindzevicius, Tomas


    We report a novel nanofabrication process via block copolymer lithography using solvent vapor annealing. The nanolithography process is facile and scalable, enabling fabrication of highly ordered periodic patterns over entire wafers as substrates for surface-enhanced Raman spectroscopy (SERS......). Direct silicon etching with high aspect ratio templated by the block copolymer mask is realized without any intermediate layer or external precursors. Uniquely, an atomic layer deposition (ALD)-assisted method is introduced to allow reversing of the morphology relative to the initial pattern. As a result......, highly ordered silicon nanopillar arrays are fabricated with controlled aspect ratios. After metallization, the resulting nanopillar arrays are suitable for SERS applications. These structures readily exhibit an average SERS enhancement factor of above 108, SERS uniformities of 8.5% relative standard...

  15. Block Copolymers for Alkaline Fuel Cell Membrane Materials (United States)


    nitrate . The NaNO3 solution was titrated to determine the amount of free bromide ions with 0.0992 M AgNO3 solution by using K2CrO4 as color...produced through either reacting butadiene or 4-methylstyrene as the first block. However, the chain transfer to toluene in butyllithium initiated anionic...including THF, toluene , chloroform, tetrachloroethane, and xylenes. The polymer was soluble enough in chloroform at low concentration to perform 1H NMR

  16. Shear devices for in situ structural studies of block copolymer melts and solutions

    DEFF Research Database (Denmark)

    Mortensen, K.; Almdal, K.; Bates, F.S.


    Structural studies of soft material while exposed in situ to stretch or shear provide a new experimental technique which gives important insight into polymer dynamics. Such devices can be used for making single-domain block-copolymer and colloidal mesophases, and to study various growth mechanism....... In addition, combined structure and shear instruments can give detailed insight into the influence of fluctuations. Two types of shear device, the Couette cell and a parallel plate device, are presented, and some applications are shown....

  17. CdS-containing nano-assemblies of double hydrophilic block copolymers in water

    Czech Academy of Sciences Publication Activity Database

    Uchman, M.; Procházka, K.; Gatsouli, K.; Pispas, S.; Špírková, Milena


    Roč. 289, č. 9 (2011), s. 1045-1053 ISSN 0303-402X R&D Projects: GA ČR GCP205/11/J043; GA ČR GAP208/10/0353 Institutional research plan: CEZ:AV0Z40500505 Keywords : double hydrophilic block copolymers * polymer self-assembly * light scattering Subject RIV: CD - Macromolecular Chemistry Impact factor: 2.331, year: 2011

  18. Temperature-induced phase transition in aqueous solutions of poly(N-isopropylacrylamide)-based block copolymer

    Czech Academy of Sciences Publication Activity Database

    Spěváček, Jiří; Konefal, Rafal; Dybal, Jiří


    Roč. 369, č. 1 (2016), s. 92-96 ISSN 1022-1360. [International IUPAC Conference on Polymer-Solvent Complexes and Intercalates /11./ - POLYSOLVAT-11. Kolkata, 27.01.2016-30.01.2016] R&D Projects: GA ČR(CZ) GA15-13853S Institutional support: RVO:61389013 Keywords : aqueous solutions * block copolymers * micelles Subject RIV: CD - Macromolecular Chemistry

  19. Water Transport in Bicontinuous, Phase-Separated Membranes Made from Reactive Block Copolymers (United States)


    Membranes Made from Reactive Block Copolymers 5a. CONTRACT NUMBER ORISE 1120-1120-99 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR(S...semipermeable membrane that allows sweat to escape a chemical protection garment , while rejecting chemical agents, would provide a potential solution... garment in chemical agent protection. 15. SUBJECT TERMS ionomer, membrane, water vapor, cocontinuous, bicontinuous 16. SECURITY CLASSIFICATION OF

  20. Contribution of orientational effects into radiation-chemical properties of segregated block copolymers

    International Nuclear Information System (INIS)

    Bol'bit, N.M.; Korneev, Yu.N.


    Model of radiolysis of microphase-separated block copolymers of PS with PB is proposed. According this scheme the radiation-chemical yields of paramagnetic centres and crosslinks in PB domains differ from those for the PB homopolymer by the value proportional to the fraction of ordered chain segments. This orientational small-scale order arises as a result of the deformation of chains in a domain in the direction perpendicular to the interphase

  1. Micellization of a novel type of hydrophilic/hydrophobic block copolymers

    Czech Academy of Sciences Publication Activity Database

    Tuzar, Zdeněk; Lochmann, Lubomír; Janata, Miroslav; Munk, P.


    Roč. 6, č. 5 (2001), s. 437-444 ISSN 1023-666X R&D Projects: GA ČR GA203/95/1240; GA ČR GA203/96/1381; GA AV ČR KSK2050602 Institutional research plan: CEZ:AV0Z4050913 Keywords : hydrophilic/hydrophobic block copolymers * polymeric micelles * static and dynamic light scattering Subject RIV: CD - Macromolecular Chemistry Impact factor: 0.490, year: 2001

  2. Applying of spectroscopy 1HNMR in analysis of block copolymers of propylene oxide and ethylene oxide

    International Nuclear Information System (INIS)

    Janik, R.; Plucinski, J.


    It was examined the precision and conformity of results of determination of ethylene oxide content in block copolymers of propylene oxide and ethylene oxide (nonionic surface active agents of Pluronic type) by means of spectroscopy 1 HNMR. It was found a full suitability of this method for preparations containing ca. 6/80% by weight of ethylene oxide in molecule, what corresponds to the range appearing in the commercial products. (author)

  3. Efficient Switching of RAFT to Hydroxyl Capped Polymers as a Versatile Scaffold for Block Copolymer Synthesis


    Schmid, Christina Maria


    The RAFT polymerization is a versatile technique to synthesize polymers with narrow dispersity and high chain-end functionality. To enable a switch from RAFT to other polymerization protocols, the RAFT polymers were transformed via a novel end-group conversion into OH functional polymers. The procedure was employed to synthesize a variety of sulfur-free (multi-) block (star) copolymers. The complex polymers were analyzed via LCCC-SEC, SEC/ESI-MS, and SEC/FT-IR.

  4. Association and Structure of Thermo Sensitive Comblike Block Copolymers in Aqueous Solutions

    International Nuclear Information System (INIS)

    Cheng, Gang


    The structures and association properties of thermo sensitive poly(methoxyoligo(ethylene glycol) norbornenyl esters) block copolymers in D2O were investigated by Small Angle Neutron Scattering (SANS). Each block is a comb-like polymer with a polynorbornene (PNB) backbone and oligo ethylene glycol (OEG) side chains (one side chain per NB monomer). The chemical formula of the block copolymer is (OEG3NB)79-(OEG6.6NB)67, where subscripts represent the degree of polymerization (DP) of OEG and NB in each block The polymer concentration was fixed at 2.0 wt % and the structural changes were investigated over a temperature range between 25 C and 68 C. It was found that at room temperature polymers associate to form micelles with a spherical core formed by the block (OEG3NB)79 and corona formed by the block (OEG6.6NB)67 and that the shape of the polymer in the corona could be described by the form factor of rigid cylinders. At elevated temperatures, the aggregation number increases and the micelles become more compact. At temperatures round the cloud point temperature (CPT) T = 60 C a correlation peak started to appear and became pronounced at 68 C due to the formation of a partially ordered structure with a correlation length ∼ 349

  5. High-Pressure Micellar Solutions of Symmetric and Asymmetric Styrene?Diene Diblocks in Compressible Near Critical Solvents: Micellization Pressures and Cloud Pressures Respond but Micellar Cloud Pressures Insensitive to Copolymer Molecular Weight, Concentration, and Block Ratio Changes

    Energy Technology Data Exchange (ETDEWEB)

    Winoto, Winoto [University of Wyoming, Laramie; Tan, Sugata [University of Wyoming, Laramie; Shen, Youqin [University of Wyoming, Laramie; Radosz, Maciej [University of Wyoming, Laramie; Hong, Kunlun [ORNL; Mays, Jimmy [ORNL


    Micellar solutions of polystyrene-block-polybutadiene and polystyrene-block-polyisoprene in propane are found to exhibit significantly lower cloud pressures than the corresponding hypothetical nonmicellar solutions. Such a cloud-pressure reduction indicates the extent to which micelle formation enhances the apparent diblock solubility in near-critical and hence compressible propane. Concentration-dependent pressure-temperature points beyond which no micelles can be formed, referred to as the micellization end points, are found to depend on the block type, size, and ratio. The cloud-pressure reduction and the micellization end point measured for styrene-diene diblocks in propane should be characteristic of all amphiphilic diblock copolymer solutions that form micelles in compressible solvents.

  6. Photoresponsive Azopolyester–PMMA Block Copolymers Obtained by Combination of ATRP, Polycondensation, and “Click” Chemistry

    DEFF Research Database (Denmark)

    Berges, Cristina; Javakhishvili, Irakli; Hvilsted, Søren


    Novel azobenzene‐containing block copolymers (BCs) with a polyester block bearing azobenzene moieties in the side chain and a poly (methyl methacrylate) (PMMA) block have been synthesized by the combination of atom transfer radical polymerization (ATRP), polycondensation, and “click” chemistry. Two...

  7. Electrostatic self-assembly in polyelectrolyte-neutral block copolymers and oppositely charged surfactant solutions

    International Nuclear Information System (INIS)

    Berret, J.-F.Jean-Francois; Oberdisse, Julian


    We report on small-angle neutron scattering (SANS) of colloidal complexes resulting from the electrostatic self-assembly of polyelectrolyte-neutral copolymers and oppositely charged surfactants. The polymers are double hydrophilic block copolymers of low molecular weight (between 5000 and 50 000 g/mol). One block is a polyelectrolyte chain, which can be either positively or negatively charged, whereas the second block is neutral and in good solvent conditions. In aqueous solutions, surfactants with an opposite charge to that of the polyelectrolyte interact strongly with these copolymers. The two species associate into stable 100 nm-colloidal complexes which exhibit a core-shell microstructure. For different polymer/surfactant couples, we have shown that the core is constituted from densely packed surfactant micelles connected by the polyelectrolyte chains. The outer part of the complex is a corona formed by the neutral soluble chains. Using a model of aggregation based on a Monte-Carlo algorithm, we have simulated the internal structure of the aggregates. The model assumes spherical cages containing one to several hundreds of micelles in a closely packed state. The agreement between the model and the data is remarkable

  8. Electrically and chemically tunable soft-solid block copolymer structural color (Conference Presentation) (United States)

    Park, Cheolmin


    1D photonic crystals based on the periodic stacking of two different dielectric layers have been widely studied due to their potential use in low-power reflective mode displays, e-books and sensors, but the fabrication of mechanically flexible polymer structural color (SC) films, with electro-active color switching, remains challenging. Here, we demonstrate free-standing electric field tunable ionic liquid swollen block copolymer films. Placement of a polymer/ionic liquid (IL) film-reservoir adjacent to a self-assembled poly(styrene-block-quaternized 2vinyl pyridine) (PS-b-QP2VP) copolymer SC film allowed the development of R, G and B full-color SC block copolymer films by swelling of the QP2VP domains by the ionic liquid associated with water molecules. The IL-polymer/BCP SC film is mechanically flexible with excellent color stability over several days at ambient conditions. The selective swelling of the QP2VP domains could be controlled by both the ratio of the IL to a polymer in the gel-like IL reservoir layer and by an applied voltage in the range of -3V to +6V using a metal/IL reservoir/SC film/IL reservoir/metal capacitor type device.

  9. Simulation study of the effect of differences in block energy and density on the self-assembly of block copolymers (United States)

    Lawson, Richard A.; Peters, Andrew J.; Nation, Benjamin; Ludovice, Peter J.; Henderson, Clifford L.


    Implementation of directed self-assembly (DSA) of block copolymers (BCPs) introduces a series of engineering challenges that have not been completely addressed in previous block copolymer and lithography studies. One of the required innovations for further DSA development and implementation is the accurate simulation of specific block copolymer chemistries and their interactions with interfaces. Many of the BCP simulation tools developed so far have limitations or difficulty in terms of matching many of the common issues found in experimental BCP systems such as polydispersity and different statistical segment lengths. One of the potentially most important issues is the fact that real BCPs often have block energy and/or density asymmetry, meaning that each block has a different homopolymer density and/or cohesive energy density (CED). A simulation of BCP behavior and DSA processes based on molecular dynamics (MD) of coarse-grained polymer chains has been developed that can independently parameterize and control the density and CED of each block to more accurately match the asymmetry found in experimental BCPs. This model was used to study the effect of block asymmetry on the order-disorder transition (ODT), domain scaling, and self-assembly of thin films of BCPs. BCPs whose blocks each have a different density show deviations from the mean-field ODT coexistence curve, exhibiting an order-disorder transition or co-existence curve that is asymmetric with shifts and tilts in the direction of majority highest density block. This impact of density and cohesive energy differences diblock copolymers on their phase behavior can explain some of the unexpected shapes found experimentally in BCP ODT curves. Asymmetry in the BCP block energy or density does not appear to have a significant effect on domain scaling behavior compared to the mean-field estimates. Self-assembly of thin films of BCPs with mismatches in CED shows significant deviations in the expected morphologies

  10. Role of textile substrate hydrophobicity on the adsorption of hydrosoluble nonionic block copolymers. (United States)

    Song, Junlong; Salas, Carlos; Rojas, Orlando J


    The adsorption of polyalkylene glycols and co-polymers of ethylene oxide and propylene oxide on substrates relevant to textiles with varying surface energies (cellulose, polypropylene, nylon and polyester) was studied by using quartz crystal microgravimetry. Langmuirian-type isotherms were observed for the adsorption profiles of nonionic block polymers of different architectures. The affinity with the surfaces is discussed based on experimental observations, which highlights the role of hydrophobic effects. For a given type of block polymer, micellar and monomeric adsorption is governed by the balance of polymer structure (mainly, chain length of hydrophobic segments) and substrate's surface energy. Copyright © 2015 Elsevier Inc. All rights reserved.

  11. Block Copolymer-Based Supramolecular Elastomers with High Extensibility and Large Stress Generation Capability (United States)

    Noro, Atsushi; Hayashi, Mikihiro

    We prepared block copolymer-based supramolecular elastomers with high extensibility and large stress generation capability. Reversible addition fragmentation chain transfer polymerizations were conducted under normal pressure and high pressure to synthesize several large molecular weight polystyrene-b-[poly(butyl acrylate)-co-polyacrylamide]-b-polystyrene (S-Ba-S) block copolymers. Tensile tests revealed that the largest S-Ba-S with middle block molecular weight of 3140k achieved a breaking elongation of over 2000% with a maximum tensile stress of 3.6 MPa and a toughness of 28 MJ/m3 while the reference sample without any middle block hydrogen bonds, polystyrene-b-poly(butyl acrylate)-b-polystyrene with almost the same molecular weight, was merely viscous and not self-standing. Hence, incorporation of hydrogen bonds into a long soft middle block was found to be beneficial to attain high extensibility and large stress generation capability probably due to concerted combination of entropic changes and internal potential energy changes originaing from the dissociation of multiple hydrogen bonds by elongation. This work was supported by JSPS KAKENHI Grant Numbers 13J02357, 24685035, 15K13785, and 23655213 for M.H. and A.N. A.N. also expresses his gratitude for Tanaka Rubber Science & Technology Award by Enokagaku-Shinko Foundation, Japan.

  12. Fluctuations, conformational asymmetry and block copolymer phase behaviour

    DEFF Research Database (Denmark)

    Bates, F.S.; Schulz, M.F.; Khandpur, A.K.


    ) and a bicontinuous cubic morphology with Ia ($) over bar 3d space group symmetry. Two non-classical parameters, epsilon and ($) over bar N, control the occurrence and distribution of these phases, in addition to the classical variables f and N-chi, where f, chi and N are the composition, segment-segment interaction...... parameter and degree of polymerization, respectively. epsilon accounts for differences in the conformational and volume-filling characteristics of each block. Conformational asymmetry, epsilon not equal 1, produces an asymmetric phase diagram around f = 1/2. The importance of fluctuation effects...... are inversely related to the magnitude of ($) over bar N, a type of Ginzburg parameter that is proportional to N. As ($) over bar N decreases, the bicontinuous Ia ($) over bar 3d phase appears adjacent to the ODT. Development of this cubic phase can be rationalized based on chain-packing frustration near...

  13. Silver based SERS substrates fabricated from block copolymer thin film (United States)

    Zhang, Xin; Lee, Wonjoo; Lee, Seung Yong; Gao, Zhenghan; Rabin, Oded; Briber, R. M.


    Poly (styrene-block-4-vinyl pyridine) (PS-b-P4VP, Mw = 47-b-10 kDa, PDI =1.10) thin films were used to form large-scale long range ordered self-assembled hexagonal patterns of vertically P4VP oriented cylinders in a PS matrix on Si substrates. The P4VP cylindrical domains were crosslinked and quaternized using 1,4-dibromobutane. Negatively charged 15nm gold nanoparticles were attached to the quaternized P4VP domains through Coulombic interactions. Silver was then grown on the gold seeds to create nanometer scale gaps between the nanoparticles. The gap between the nanoparticles was fine tuned by controlling the silver growth time. The substrates showed large enhancement factors in the Raman scattering signal for a broad range of incident wavelengths. Present address: LG Chem Ltd, Information Technology & Electronic Materials R&D, Yuseong-gu Daejeon, South Korea

  14. Rationally designed dual functional block copolymers for bottlebrush-like coatings: In vitro and in vivo antimicrobial, antibiofilm, and antifouling properties. (United States)

    Gao, Qiang; Yu, Meng; Su, Yajuan; Xie, Meihua; Zhao, Xin; Li, Peng; Ma, Peter X


    , poor blood compatibility and cytotoxicity, etc. To overcome these drawbacks, a robust PEGylated cationic amphiphilic peptides-based bottlebrush-like surface coating is demonstrated here, which fulfil the requirements of antimicrobial and antifouling as well as biocompatibility in the meantime. Briefly, the rational designed g-PEG n -b-AMP block copolymers (n=10/45/90) were synthesized and grafted on silicone surface. This bottlebrush-like coating efficiently kill the contacted bacteria and prevent the biofilm formation, greatly reduced protein and platelet adhesion. It also exhibits excellent blood compatibility and low cytotoxicity in vitro. In particular, g-PEG 45 -b-AMP coating exhibits significant anti-infection effect in vivo. This coating offering an effective strategy for combating biomedical devices-associated infections. Copyright © 2017 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

  15. Meso-scale Modeling of Block Copolymers Self-Assembly in Casting Solutions for Membrane Manufacture

    KAUST Repository

    Moreno Chaparro, Nicolas


    Isoporous membranes manufactured from diblock copolymer are successfully produced at laboratory scale under controlled conditions. Because of the complex phenomena involved, membrane preparation requires trial and error methodologies to find the optimal conditions, leading to a considerable demand of resources. Experimental insights demonstrate that the self-assembly of the block copolymers in solution has an effect on the final membrane structure. Nevertheless, the complete understanding of these multi-scale phenomena is elusive. Herein we use the coarse-grained method Dissipative Particle Dynamics to study the self-assembly of block copolymers that are used for the preparation of the membranes. To simulate representative time and length scales, we introduce a framework for model reduction of polymer chain representations for dissipative particle dynamics, which preserves the properties governing the phase equilibria. We reduce the number of degrees of freedom by accounting for the correlation between beads in fine-grained models via power laws and the consistent scaling of the simulation parameters. The coarse-graining models are consistent with the experimental evidence, showing a morphological transition of the aggregates as the polymer concentration and solvent affinity change. We show that hexagonal packing of the micelles can occur in solution within different windows of polymer concentration depending on the solvent affinity. However, the shape and size dispersion of the micelles determine the characteristic arrangement. We describe the order of crew-cut micelles using a rigid-sphere approximation and propose different phase parameters that characterize the emergence of monodisperse-spherical micelles in solution. Additionally, we investigate the effect of blending asymmetric diblock copolymers (AB/AC) over the properties of the membranes. We observe that the co-assembly mechanism localizes the AC molecules at the interface of A and B domains, and induces

  16. The Self-Assembly of Copolymers with One Hydrophobic and One Polyelectrolyte Block in Aqueous Media: A Dissipative Particle Dynamics Study.

    Czech Academy of Sciences Publication Activity Database

    Lísal, Martin; Limpouchová, Z.; Procházka, K.


    Roč. 18, č. 24 (2016), s. 16127-16136 ISSN 1463-9076 R&D Projects: GA ČR(CZ) GA13-02938S Institutional support: RVO:67985858 Keywords : amphiphilic diblock copolymers * hybrid olymeric micelles * simulations Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 4.123, year: 2016

  17. Crosslinkable surfactants based on linoleic acid-functionalized block copolymers of ethylene oxide and e-caprolactone for the preparation of stable PMMA latices

    NARCIS (Netherlands)

    Tan, B.H.; Grijpma, Dirk W.; Nabuurs, Tijs; Feijen, Jan


    Amphiphilic diblock and triblock copolymers consisting of poly(ethylene oxide) (PEO) as (central) hydrophilic segment and poly(ε-caprolactone) (PCL) as hydrophobic segment(s) were prepared by ring opening polymerization. The length of the PEO segment was kept constant View the MathML source, whereas

  18. Mesoporous Silica Formation by Block Copolymers and Cetyltrimethylammonium Bromide as Structure Control Agent

    Directory of Open Access Journals (Sweden)

    Mohamad Ali Semsarzadeh


    Full Text Available Block copolymers and cetyltrimethylammonium bromide were used as templates in nano silica structure formation like MCM-41Mobil Composition of Matter, SBA16 Santa Barbara Amorphous and a new compound namely SPB  silicone mesoporous particles, prepared by sol-gel method using PPG-PEG-PPG block copolymer to compare the porosity and regularity of the products together. In this work tetraethylorthosilicate  TEOS, as silica source and alcohol as surface modifying agent were used because of having the main advantage, compared to an ionic template such as etyltrimethylammonium bromide, in producing larger pores  and thicker walls for holding larger catalytic molecules in their pores or increasing  their resistance towards fragmentation. In order to study the copolymer as a template,  SPB structure was prepared and compared with SBA16 which was found to have  broader  pore-size  distribution  and  smaller  specifc  surface  area.  Using  alcohol  in particle production resulted in higher formation rate of micelles with improved  morphology. Nitrogen adsorption-desorption, X-ray diffraction and electron scanning  microscopy confrmed the mesoporous structure and regularity of these synthesized  materials. Finally a mechanism is proposed for the formation of these structures.

  19. Nanostructured Double Hydrophobic Poly(Styrene-b-Methyl Methacrylate) Block Copolymer Membrane Manufactured Via Phase Inversion Technique

    KAUST Repository

    Karunakaran, Madhavan


    In this paper, we demonstrate the formation of nanostructured double hydrophobic poly(styrene-b-methyl methacrylate) (PS-b-PMMA) block copolymer membranes via state-of-the-art phase inversion technique. The nanostructured membrane morphologies are tuned by different solvent and block copolymer compositions. The membrane morphology has been investigated using FESEM, AFM and TEM. Morphological investigation shows the formation of both cylindrical and lamellar structures on the top surface of the block copolymer membranes. The PS-b-PMMA having an equal block length (PS160K-b-PMMA160K) exhibits both cylindrical and lamellar structures on the top layer of the asymmetric membrane. All membranes fabricated from PS160K-b-PMMA160K shows an incomplete pore formation in both cylindrical and lamellar morphologies during the phase inversion process. However, PS-b-PMMA (PS135K-b-PMMA19.5K) block copolymer having a short PMMA block allowed us to produce open pore structures with ordered hexagonal cylindrical pores during the phase inversion process. The resulting PS-b-PMMA nanostructured block copolymer membranes have pure water flux from 105-820 l/ and 95% retention of PEG50K

  20. Influence of the ratio of amphiphilic copolymers used as emulsifiers on the microstructure, physical stability and rheology of α-pinene emulsions stabilized with gellan gum. (United States)

    García, Maria Carmen; Alfaro, Maria Carmen; Muñoz, José


    α-Pinene is a terpenic solvent whose use in the formulation of emulsions entails a double benefit from the environmental point of view since it is a green solvent, easily biodegradable, which also has certain antimicrobial properties. In this work a combination of Atlas™ G-5000 and Atlox™ 4913 amphiphilic copolymers was used to obtain O/W emulsions formulated with α-pinene and gellan gum. These emulsions may find applications related to the design of complex biotechnological systems with different uses. In order to investigate the microstructure and the physical stability of these emulsions, a combination of different techniques such as rheology, microscopy, laser diffraction and multiple light scattering turn out to be a useful methodology. The results demonstrated the need to include a minimum amount of Atlas™ G-5000 copolymer in the formulation of these emulsions to improve their stability. These results were supported by the information revealed by optical micrographs, according to which Atlas™ G-5000 is directed to the continuous medium to structure water (this surfactant is particularly effective at forming hydrogen bonds with water). On the other hand Atlox™ 4913 is preferentially adsorbed at the α-pinene-water interface, such that a high Atlox™ 4913/Atlas™ G-5000 mass ratio slows down the kinetics of coalescence as shown by multiple light scattering. However, a very low relative concentration of Atlas™ G-5000 causes creaming to become the dominant destabilization mechanism. Increasing the Atlas™ G-5000/Atlox™ 4913 mass ratio yields emulsions with enhanced viscosity and viscoelasticity. Copyright © 2015 Elsevier B.V. All rights reserved.

  1. Blending of styrene-block-butadiene-block-styrene copolymer with sulfonated vinyl aromatic polymers


    Ruggeri, Giacomo; Passaglia, Elisa; Giorgi, Ivan; Picchioni, Francesco; Aglietto, Mauro


    Different polymers containing sulfonic groups attached to the phenyl rings were prepared by sulfonation of polystyrene (PS) and styrene-block-(ethylene-co-1-butene)-block-styrene (SEBS). The sulfonation degree (SD) was varied between 1 and 20 mol% of the styrene units. Polyphase materials containing sulfonated units were prepared by blending styrene-block-butadiene-block-styrene (SBS), with both sulfonated PS and sulfonated SEBS in a Brabender mixer. Such a procedure was performed as an alter...

  2. Control of Protein Affinity of Bioactive Nanocellulose and Passivation Using Engineered Block and Random Copolymers. (United States)

    Vuoriluoto, Maija; Orelma, Hannes; Zhu, Baolei; Johansson, Leena-Sisko; Rojas, Orlando J


    We passivated TEMPO-oxidized cellulose nanofibrils (TOCNF) toward human immunoglobulin G (hIgG) by modification with block and random copolymers of poly(2-(dimethylamino)ethyl methacrylate) (PDMAEMA) and poly(oligo(ethylene glycol) methyl ether methacrylate) (POEGMA). The block copolymers reversibly adsorbed on TOCNF and were highly effective in preventing nonspecific interactions with hIgG, especially if short PDMAEMA blocks were used. In such cases, total protein rejection was achieved. This is in contrast to typical blocking agents, which performed poorly. When an anti-human IgG biointerface was installed onto the passivated TOCNF, remarkably high affinity antibody-antigen interactions were observed (0.90 ± 0.09 mg/m(2)). This is in contrast to the nonpassivated biointerface, which resulted in a significant false response. In addition, regeneration of the biointerface was possible by low pH aqueous wash. Protein A from Staphylococcus aureus was also utilized to successfully increase the sensitivity for human IgG recognition (1.28 ± 0.11 mg/m(2)). Overall, the developed system based on TOCNF modified with multifunctional polymers can be easily deployed as bioactive material with minimum fouling and excellent selectivity.

  3. Quasi-Block Copolymers Based on a General Polymeric Chain Stopper. (United States)

    Sanguramath, Rajashekharayya A; Nealey, Paul F; Shenhar, Roy


    Quasi-block copolymers (q-BCPs) are block copolymers consisting of conventional and supramolecular blocks, in which the conventional block is end-terminated by a functionality that interacts with the supramolecular monomer (a "chain stopper" functionality). A new design of q-BCPs based on a general polymeric chain stopper, which consists of polystyrene end-terminated with a sulfonate group (PS-SO3 Li), is described. Through viscosity measurements and a detailed diffusion-ordered NMR spectroscopy study, it is shown that PS-SO3 Li can effectively cap two types of model supramolecular monomers to form q-BCPs in solution. Furthermore, differential scanning calorimetry data and structural characterization of thin films by scanning force microscopy suggests the existence of the q-BCP architecture in the melt. The new design considerably simplifies the synthesis of polymeric chain stoppers; thus promoting the utilization of q-BCPs as smart, nanostructured materials. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  4. Exploiting Molecular Weight Distribution Shape to Tune Domain Spacing in Block Copolymer Thin Films. (United States)

    Gentekos, Dillon T; Jia, Junteng; Tirado, Erika S; Barteau, Katherine P; Smilgies, Detlef-M; DiStasio, Robert A; Fors, Brett P


    We report a method for tuning the domain spacing ( D sp ) of self-assembled block copolymer thin films of poly(styrene- block-methyl methacrylate) (PS- b-PMMA) over a large range of lamellar periods. By modifying the molecular weight distribution (MWD) shape (including both the breadth and skew) of the PS block via temporal control of polymer chain initiation in anionic polymerization, we observe increases of up to 41% in D sp for polymers with the same overall molecular weight ( M n ≈ 125 kg mol -1 ) without significantly changing the overall morphology or chemical composition of the final material. In conjunction with our experimental efforts, we have utilized concepts from population statistics and least-squares analysis to develop a model for predicting D sp based on the first three moments of the MWDs. This statistical model reproduces experimental D sp values with high fidelity (with mean absolute errors of 1.2 nm or 1.8%) and provides novel physical insight into the individual and collective roles played by the MWD moments in determining this property of interest. This work demonstrates that both MWD breadth and skew have a profound influence over D sp , thereby providing an experimental and conceptual platform for exploiting MWD shape as a simple and modular handle for fine-tuning D sp in block copolymer thin films.

  5. Orienting Block Copolymer Thin Films via Entropy and Surface Plasma Treatment (United States)

    Ho, Rong-Ming; Lu, Kai-Yuan; Lo, Ting-Ya; Dehghan, Ashkan; Shi, An-Chang; Prokopios, Georgopanos; Avgeropoulos, Apostolos

    Controlling the orientation of nanostructured thin films of block copolymers (BCPs) is essential for next generation lithography. In the thin-film state, how to achieve the perpendicular orientation of the nanostructured microdomains remains challenging due to the interfacial effects from the air and also the substrate, especially for the blocks with silicon containing segments which usually have different surface energies, favoring parallel microdomain orientation. Here, we show that entropic effect can be used to control the orientation of BCP thin films. Specifically, we used the architecture of star-block copolymers consisting of polystyrene (PS) and poly(dimethylsiloxane) (PDMS) blocks to regulate the entropic contribution to the self-assembled nanostructures. Moreover, we aim to achieve the formation of perpendicular orientation from the air surface via surface plasma treatment to neutralize the interfacial energy difference. By combining the architecture effect (entropy effect) on BCP self-assembly and the surface plasma treatment (enthalpy effect), well-defined perpendicular PDMS microdomains in the PS-b-PDMS thin film can be formed from the bottom of non-neutral substrate and the top of the thin film surface, giving great potential for lithographic applications.

  6. Improving dielectric permittivity by incorporating PDMS-PEG block copolymer into PDMS network

    DEFF Research Database (Denmark)

    A Razak, Aliff Hisyam; Szabo, Peter; Skov, Anne Ladegaard

    Polydimethylsiloxane (PDMS) based elastomers are well-known to actuate with large strain mainly due to their low modulus and their non-conducting nature. On the other hand, polyethyleneglycols(PEG) are not stretchable but they have high permittivity and are conductive. Combination of the two...... polymers as a block copolymer depicts a possibility for substantial improvement of properties such as high permittivity and non-conductivity – if carefully designed. The objective is to synthesize PDMS-PEG multiblock copolymer assembling into different morphologies1 such as lamellar,cylinder, gyroid...... and spheres based on variation of volume fractions of PDMS and PEG. The synthesisis amended from Klasner et al.2 and Jukarainen et al.3 Variation in the ratio between the two constituents introduces distinctive properties in terms of dielectric permittivity and rheological behaviour. PDMS-PEG multiblock...

  7. Fabrication of poly (butadiene-block-ethylene oxide) based amphiphilic polymersomes: An approach for improved oral pharmacokinetics of Sorafenib. (United States)

    Khan, Muhammad Adeeb; Ali, Shaukat; Venkatraman, Subbu S; Sohail, Muhammad Farhan; Ovais, Muhammad; Raza, Abida


    Sorafenib (SFN), a hydrophobic anticancer drug, has several limitations predominantly poor aqueous solubility and hepatic first-pass effect, limiting its oral delivery that results into several other complications. Present study aims to develop Sorafenib loaded polymersomes using poly butadiene block poly ethylene oxide (PB-b-PEO), an amphiphilic co-block polymer. Prior to drug loading, critical aggregate concentration (CAC) of polymer was calculated for stable formulation synthesis. The developed SFN loaded PB-b-PEO polymersomes (SFN-PB-b-PEO, test formulation) characterized by DLS and cryo-TEM showed particle size 282 nm, polydispersity (PDI) of less than 0.29 and membrane thickness of about 20 nm. SFN-PB-b-PEO polymersomes demonstrated encapsulation efficiency of 71% and showed sustained drug release up to 144 h. Formulation remained stable for 3 months in suspension form. In vitro cytotoxicity against HepG2 cells showed 1.7 folds improved toxicity compared to SFN suspension. In addition, oral administration of SFN-PB-b-PEO polymersomes in BALB/c mice showed increased C max and AUC 0-96 by 1.7 and 2.77-fold respectively (p < 0.05) compared to those of SFN suspension (reference formulation). Findings suggest that the SFN-PB-b-PEO polymersomes can be a potential candidate for oral delivery of SFN. Copyright © 2018 Elsevier B.V. All rights reserved.

  8. Ion transport mechanisms in lamellar phases of salt-doped PS–PEO block copolymer electrolytes

    KAUST Repository

    Sethuraman, Vaidyanathan


    We use a multiscale simulation strategy to elucidate, at an atomistic level, the mechanisms underlying ion transport in the lamellar phase of polystyrene–polyethylene oxide (PS–PEO) block copolymer (BCP) electrolytes doped with LiPF6 salts. Explicitly, we compare the results obtained for ion transport in the microphase separated block copolymer melts to those for salt-doped PEO homopolymer melts. In addition, we also present results for dynamics of the ions individually in the PEO and PS domains of the BCP melt, and locally as a function of the distance from the lamellar interfaces. When compared to the PEO homopolymer melt, ions were found to exhibit slower dynamics in both the block copolymer (overall) and in the PEO phase of the BCP melt. Such results are shown to arise from the effects of slower polymer segmental dynamics in the BCP melt and the coordination characteristics of the ions. Polymer backbone-ion residence times analyzed as a function of distance from the interface indicate that ions have a larger residence time near the interface compared to that near the bulk of lamella, and demonstrates the influence of the glassy PS blocks and microphase segregation on the ion transport properties. Ion transport mechanisms in BCP melts reveal that there exist five distinct mechanisms for ion transport along the backbone of the chain and exhibit qualitative differences from the behavior in homopolymer melts. We also present results as a function of salt concentration which show that the mean-squared displacements of the ions decrease with increasing salt concentration, and that the ion residence times near the polymer backbone increase with increasing salt concentration.

  9. Synthesis of β-cyclodextrin-Based Star Block Copolymers with Thermo-Responsive Behavior

    Directory of Open Access Journals (Sweden)

    Agnes Wycisk


    Full Text Available Star polymers are one example of three-dimensional macromolecules containing several arms with similar molecular weight connected to a central core. Due to their compact structure and their enhanced segment density in comparison to linear polymers of the same molecular weight, they have attracted significant attention during recent years. The preparation of block-arm star copolymers with a permanently hydrophilic block and an “environmentally” sensitive block, which can change its nature from hydrophilic to hydrophobic, leads to nanometer-sized responsive materials with unique properties. These polymers are able to undergo a conformational change or phase transition as a reply to an external stimulus resulting in the formation of core–shell nanoparticles, which further tend to aggregate. Star-shaped copolymers with different cores were synthesized via atom transfer radical polymerization (ATRP. The core-first method chosen as synthetic strategy allows good control over the polymer architecture. First of all the multifunctional initiators were prepared by esterification reaction of the hydroxyl groups with 2-chloropropionyl chloride. Using β-cyclodextrin as core molecules, which possess a well-defined number of functional groups up to 21, allows defining the number of arms per star polymer. In order to prepare stimuli-responsive multi-arm copolymers, containing a stimuli-responsive (poly(N-isopropylacrylamide (PNIPAAm and a non-responsive block (poly(N,N-dimethylacrylamide (PDMAAm, consecutive ATRP was carried out. The polymers were characterized intensively using NMR spectroscopy and size exclusion chromatography (SEC, whereas the temperature-depending aggregation behavior in aqueous solution was determined via turbidimetry and differential scanning calorimetry (DSC.

  10. Hierarchical Nanostructures Self-Assembled from a Mixture System Containing Rod-Coil Block Copolymers and Rigid Homopolymers (United States)

    Li, Yongliang; Jiang, Tao; Lin, Shaoliang; Lin, Jiaping; Cai, Chunhua; Zhu, Xingyu


    Self-assembly behavior of a mixture system containing rod-coil block copolymers and rigid homopolymers was investigated by using Brownian dynamics simulations. The morphologies of formed hierarchical self-assemblies were found to be dependent on the Lennard-Jones (LJ) interaction ɛRR between rod blocks, lengths of rod and coil blocks in copolymer, and mixture ratio of block copolymers to homopolymers. As the ɛRR value decreases, the self-assembled structures of mixtures are transformed from an abacus-like structure to a helical structure, to a plain fiber, and finally are broken into unimers. The order parameter of rod blocks was calculated to confirm the structure transition. Through varying the length of rod and coil blocks, the regions of thermodynamic stability of abacus, helix, plain fiber, and unimers were mapped. Moreover, it was discovered that two levels of rod block ordering exist in the helices. The block copolymers are helically wrapped on the homopolymer bundles to form helical string, while the rod blocks are twistingly packed inside the string. In addition, the simulation results are in good agreement with experimental observations. The present work reveals the mechanism behind the formation of helical (experimentally super-helical) structures and may provide useful information for design and preparation of the complex structures.

  11. Amphiphilic poly{[α-maleic anhydride-ω-methoxypoly(ethylene glycol]-co-(ethyl cyanoacrylate} graft copolymer nanoparticles as carriers for transdermal drug delivery

    Directory of Open Access Journals (Sweden)

    Jinfeng Xing


    Full Text Available Jinfeng Xing, Liandong Deng, Jun Li, Anjie DongDepartment of Polymer Science and Engineering, School of Chemical Engineering and Technology, Tianjin University, Tianjin, People’s Republic of ChinaAbstract: In this study, the transdermal drug delivery properties of D,L-tetrahydropalmatine (THP-loaded amphiphilic poly{[α-maleic anhydride-ω-methoxy-poly(ethylene glycol]-co-(ethyl cyanoacrylate} (PEGECA graft copolymer nanoparticles (PEGECAT NPs were evaluated by skin penetration experiments in vitro. The transdermal permeation experiments in vitro were carried out in Franz diffusion cells using THP-loaded PEGECAT NPs as the donor system. Transmission electron microscopy and Fourier transform infrared spectroscopy were used to characterize the receptor fluid. The results indicate that the THP-loaded PEGECAT NPs are able to penetrate the rat skin. Fluorescent microscopy measurements demonstrate that THP-loaded PEGECAT NPs can penetrate the skin not only via appendage routes but also via epidermal routes. This nanotechnology has potential application in transdermal drug delivery. Keywords: poly{[α-maleic anhydride-ω-methoxy-poly(ethylene glycol]-co-(ethyl cyanoacrylate}, nanoparticles, transdermal drug delivery, D,L-tetrahydropalmatine

  12. Synthesis of PMMA-b-PU-b-PMMA tri-block copolymers through ARGET ATRP in the presence of air

    Directory of Open Access Journals (Sweden)

    P. Krol


    Full Text Available ARGET (activators regenerated by electron transfer ATRP (atom transfer radical polymerization has been successfully performed (in flasks fitted with rubber septa without the need for use of Schlenk line in the presence of limited amount of air and with a very small (370 ppm amount of copper catalyst together with an appropriate reducing agent Cu(0. Novelty of this work is that the poly(methyl methacrylate-block-polyurethane-block-poly(methyl methacrylate triblock copolymers were synthesized for the first time through ARGET ATRP, by using tertiary bromine-terminated polyurethane as a macroinitiator (MBP-PU-MBP, CuBr2 or CuCl2 as a catalyst and N,N,N',N",N"-pentamethyldiethylenetriamine (PMDETA or 2,2'-bipyridine (Bpy as a complexing agent. As the polymerization time increases, both the monomer conversion and ln([M]0/[M] increased and the molecular weight of copolymer increases linearly with increasing conversion. Theoretical number-average molecular weight (Mn, th of the tri-block copolymers was found to be comparable with number-average molecular weight determined by GPC analyses (Mn, GPC. These results indicate that the formation of the tri-block copolymers was through atom transfer radical polymerization mechanism. 1H and 13C NMR spectral methods were employed to confirm chemical structures of synthesized macroinitiator and tri-block copolymers. Mole percentage of PMMA in the tri-block copolymers was calculated using 1H NMR spectroscopy and was found to be comparable with the GPC results. Additionally, the studies of surface properties (confocal microscopy and SFE of tri-block copolymer coatings confirmed the presence of MMA segments.

  13. Novel Amphiphilic, Biodegradable, Biocompatible, Thermo-Responsive ABA Triblock Copolymers Based on PCL and PEG Analogues via a Combination of ROP and RAFT: Synthesis, Characterization, and Sustained Drug Release from Self-Assembled Micelles

    Directory of Open Access Journals (Sweden)

    Wenyan Ning


    Full Text Available Well-defined novel, linear, biodegradable, amphiphilic thermo-responsive ABA-type triblock copolymers, poly[2-(2-methoxyethoxy ethyl methacrylate-co-oligo(ethylene glycol methacrylate]-b-poly(ε-caprolactone-b-poly[2-(2-methoxyethoxy ethyl methacrylate-co-oligo(ethylene glycol methacrylate] [P(MEO2MA-co-OEGMA-b-PCL-b-P(MEO2MA-co-OEGMA] (tBPs, were synthesized via a combination of ring-opening polymerization (ROP of ε-caprolactone (εCL and reversible addition-fragmentation chain transfer polymerization (RAFT of MEO2MA and OEGMA comonomers. The chemical structures and compositions of these copolymers were characterized using Fourier transform infrared spectroscopy (FT-IR and proton nuclear magnetic resonance (1H NMR. The molecular weights of the copolymers were obtained using gel permeation chromatography (GPC measurements. Thermo-responsive micelles were obtained by self-assembly of copolymers in aqueous medium. The temperature sensitivity and micelllization behavior of amphiphilic triblock copolymers solutions were studied by transmittance, fluorescence probe, surface tension, dynamic light scattering (DLS and transmission electron microscopy (TEM. A hydrophobic drug, anethole, was encapsulated in micelles by using the dialysis method. The average particle sizes of drug-loaded micelles were determined by dynamic light scattering measurement. In vitro, the sustained release of the anethole was performed in pH 7.4 phosphate-buffered saline (PBS at different temperatures. Results showed that the triblock copolymer’s micelles were quite effective in the encapsulation and controlled release of anethole. The vial inversion test demonstrated that the triblock copolymers could trigger the sol-gel transition which also depended on the temperature, and its sol-gel transition temperature gradually decreased with increasing concentration. The hydrogel system could also be used as a carrier of hydrophobic drugs in medicine.

  14. Directed Self-assembly of Block Copolymer with Sub-15 nm Domain Spacing Using Nanoimprinted Photoresist Templates (United States)

    Sun, Zhiwei; Chen, Zhenbin; Zhang, Wenxu; Coughlin, E. Bryan; Xiao, Shuaigang; Russell, Thomas

    There has been increasing interest in preparing block copolymer thin films with ultra-small domain spacings for use as etching masks for ultra-high resolution nanolithography. One method to prepare block copolymer materials with small feature sizes is salt doping, increasing the Flory-Huggins interaction and allowing microphase separation to be maintained at lower molecular weights. Lamellae-forming P2VP- b-PS- b-P2VP block copolymer with various molecular weight was synthesized using RAFT polymerization with a dual functional chain transfer agent. Copper (II) Chloride or Gold (III) chloride was found to be selectively associated with P2VP block and increase the unfavorable interactions between PS and P2VP blocks, driving the disordered block copolymer into the ordered state. A 14 nm lamellar spacing of P2VP- b-PS- b-P2VP thin film was prepared using copper (II) Chloride doping after acetone vapor annealing on neutral brushes. Metallic nano-wire arrays were prepared after selective infiltration of platinum salt into the P2VP domain and oxygen plasma treatment. The directed self-assembly of salt doped P2VP- b-PS- b-P2VP triblock copolymer having long-rang lateral order on nanoimprinted photoresist templates with shallow trenches was also studied.

  15. Self-aggregated nanoparticles based on amphiphilic poly(lactic acid-grafted-chitosan copolymer for ocular delivery of amphotericin B

    Directory of Open Access Journals (Sweden)

    Zhou WJ


    Full Text Available Wenjun Zhou,1 Yuanyuan Wang,2 Jiuying Jian,2 Shengfang Song1 1Department of Ophthalmology, Yongchuan Hospital, Chongqing Medical University, Chongqing, People’s Republic of China; 2College of Life Science, Chongqing Medical University, Chongqing, People’s Republic of China Background: The purpose of this study was to develop a self-aggregated nanoparticulate vehicle using an amphiphilic poly(lactic acid-grafted-chitosan (PLA-g-CS copolymer and to evaluate its potential for ocular delivery of amphotericin B. Methods: A PLA-g-CS copolymer was synthesized via a “protection-graft-deprotection” procedure and its structure was confirmed by Fourier transform infrared spectroscopy, 1H nuclear magnetic resonance, and X-ray diffraction spectra. Amphotericin B-loaded nanoparticles based on PLA-g-CS (AmB/PLA-g-CS were prepared by the dialysis method and characterized for particle size, zeta potential, and encapsulation efficiency. Studies of these AmB/PLA-g-CS nanoparticles, including their mucoadhesive strength, drug release properties, antifungal activity, ocular irritation, ocular pharmacokinetics, and corneal penetration were performed in vitro and in vivo. Results: Fourier transform infrared spectroscopy, 1H nuclear magnetic resonance, and X-ray diffraction spectra showed that the PLA chains were successfully grafted onto chitosan molecules and that crystallization of chitosan was suppressed. The self-aggregated PLA-g-CS nanoparticles had a core-shell structure with an average particle size of approximately 200 nm and zeta potentials higher than 30 mV. Amphotericin B was incorporated into the hydrophobic core of the nanoparticles with high encapsulation efficiency. Sustained drug release from the nanoparticles was observed in vitro. The ocular irritation study showed no sign of irritation after instillation of the PLA-g-CS nanoparticles into rabbit eyes. The minimal inhibitory concentration of the AmB/PLA-g-CS nanoparticles showed antifungal

  16. Effect of block composition on thermal properties and melt viscosity of poly[2-(dimethylaminoethyl methacrylate], poly(ethylene oxide and poly(propylene oxide block co-polymers

    Directory of Open Access Journals (Sweden)


    Full Text Available To modify the rheological properties of certain commercial polymers, a set of block copolymers were synthesized through oxyanionic polymerization of 2-(dimethylaminoethyl methacrylate to the chain ends of commercial prepolymers, namely poly(ethylene oxide (PEO, poly(ethylene oxide-block-poly(propylene oxide-block-poly(ethylene oxide (PEO-PPO-PEO, and poly(propylene oxide (PPO. The formed block copolymers were analysed with size exclusion chromatography and nuclear magnetic resonance spectroscopy in order to confirm block formation. Thermal characterization of the resulting polymers was done with differential scanning calorimetry. Thermal transition points were also confirmed with rotational rheometry, which was primarily used to measure melt strength properties of the resulting block co-polymers. It was observed that the synthesised poly[2-(dimethylaminoethyl methacrylate]-block (PDM affected slightly the thermal transition points of crystalline PEO-block but the influence was stronger on amorphous PPO-blocks. Frequency sweeps measured above the melting temperatures for the materials confirmed that the pre-polymers (PEO and PEO-PPO-PEO behave as Newtonian fluids whereas polymers with a PDM block structure exhibit clear shear thinning behaviour. In addition, the PDM block increased the melt viscosity when compared with that one of the pre-polymer. As a final result, it became obvious that pre-polymers modified with PDM were in entangled form, in the melted state as well in the solidified form.

  17. Synthesis and Self-Assembly of Block Copolymers Containing Temperature Sensitive and Degradable Chain Segments. (United States)

    Gong, Hong-Liang; Lei, Lei; Shi, Shu-Xian; Xia, Yu-Zheng; Chen, Xiao-Nong


    In this work, polylactide-b-poly(N-isopropylacrylamide) were synthesized by the combination of controlled ring-opening polymerization and reversible addition fragmentation chain transfer polymerization. These block copolymers with molecular weight range from 7,900 to 12,000 g/mol and narrow polydispersity (≤1.19) can self-assemble into micelles (polylactide core, poly(N-isopropylacrylamide) shell) in water at certain temperature range, which have been evidenced by laser particle size analyzer proton nuclear magnetic resonance and transmission electron microscopy. Such micelles exhibit obvious thermo-responsive properties: (1) Poly(N-isopropylacrylamide) blocks collapse on the polylactide core as system temperature increase, leading to reduce of micelle size. (2) Micelles with short poly(N-isopropylacrylamide) blocks tend to aggregate together when temperature increased, which is resulted from the reduction of the system hydrophilicity and the decreased repulsive force between micelles.

  18. Influence of topographically patterned angled guidelines on directed self-assembly of block copolymers (United States)

    Rebello, Nathan; Sethuraman, Vaidyanathan; Blachut, Gregory; Ellison, Christopher J.; Willson, C. Grant; Ganesan, Venkat


    Single chain in mean-field Monte Carlo simulations were employed to study the self-assembly of block copolymers (BCP) in thin films that use trapezoidal guidelines to direct the orientation and alignment of lamellar patterns. The present study explored the influence of sidewall interactions and geometry of the trapezoidal guidelines on the self-assembly of perpendicularly oriented lamellar morphologies. When both the sidewall and the top surface exhibit preferential interactions to the same block of the BCP, trapezoidal guidelines with intermediate taper angles were found to result in less defective perpendicularly orientated morphologies. Similarly, when the sidewall and top surface are preferential to distinct blocks of the BCP, intermediate tapering angles were found to be optimal in promoting defect free structures. Such results are rationalized based on the energetics arising in the formation of perpendicularly oriented lamella on patterned substrates.

  19. Preparation of ordered silver angular nanoparticles array in block copolymer film for surface-enhanced Raman spectroscopy

    International Nuclear Information System (INIS)

    Svanda, J.; Gromov, M. V.; Kalachyova, Y.; Postnikov, P. S.; Svorcik, V.; Lyutakov, O.


    We report a single-step method of preparation of ordered silver nanoparticles array through template-assisted nanoparticles synthesis in the semidried block copolymer film. Ordered nanoparticles were prepared on different substrates by the proper choice of solvents combination and preparation procedure. In particular, block copolymer and silver nitrate were dissolved in the mix of tetrahydrofuran, toluene, and n-methylpyrolidone. During short spin-coating procedure ordering of block copolymer, evaporation of toluene and preferential silver redistribution into poly(4-vinylpyridine) block occurred. Rapid heating of semidry film initiated silver reduction, removing of residual solvent and creation of ordered silver array. After polymer removing silver nanoparticles array was tested as a suitable candidate for subdiffraction plasmonic application–surface-enhanced Raman scattering. Enhancement factor was calculated and compared with the literature data.

  20. Preparation of ordered silver angular nanoparticles array in block copolymer film for surface-enhanced Raman spectroscopy (United States)

    Svanda, J.; Gromov, M. V.; Kalachyova, Y.; Postnikov, P. S.; Svorcik, V.; Lyutakov, O.


    We report a single-step method of preparation of ordered silver nanoparticles array through template-assisted nanoparticles synthesis in the semidried block copolymer film. Ordered nanoparticles were prepared on different substrates by the proper choice of solvents combination and preparation procedure. In particular, block copolymer and silver nitrate were dissolved in the mix of tetrahydrofuran, toluene, and n-methylpyrolidone. During short spin-coating procedure ordering of block copolymer, evaporation of toluene and preferential silver redistribution into poly(4-vinylpyridine) block occurred. Rapid heating of semidry film initiated silver reduction, removing of residual solvent and creation of ordered silver array. After polymer removing silver nanoparticles array was tested as a suitable candidate for subdiffraction plasmonic application-surface-enhanced Raman scattering. Enhancement factor was calculated and compared with the literature data.

  1. Polystyrene Chain Growth from Di-End-Functional Polyolefins for Polystyrene-Polyolefin-Polystyrene Block Copolymers

    Directory of Open Access Journals (Sweden)

    Chung Sol Kim


    Full Text Available Triblock copolymers of polystyrene (PS and a polyolefin (PO, e.g., PS-block-poly(ethylene-co-1-butene-block-PS (SEBS, are attractive materials for use as thermoplastic elastomers and are produced commercially by a two-step process that involves the costly hydrogenation of PS-block-polybutadiene-block-PS. We herein report a one-pot strategy for attaching PS chains to both ends of PO chains to construct PS-block-PO-block-PS directly from olefin and styrene monomers. Dialkylzinc compound containing styrene moieties ((CH2=CHC6H4CH2CH22Zn was prepared, from which poly(ethylene-co-propylene chains were grown via “coordinative chain transfer polymerization” using the pyridylaminohafnium catalyst to afford di-end functional PO chains functionalized with styrene and Zn moieties. Subsequently, PS chains were attached at both ends of the PO chains by introduction of styrene monomers in addition to the anionic initiator Me3SiCH2Li·(pmdeta (pmdeta = pentamethyldiethylenetriamine. We found that the fraction of the extracted PS homopolymer was low (~20% and that molecular weights were evidently increased after the styrene polymerization (ΔMn = 27–54 kDa. Transmission electron microscopy showed spherical and wormlike PS domains measuring several tens of nm segregated within the PO matrix. Optimal tensile properties were observed for the sample containing a propylene mole fraction of 0.25 and a styrene content of 33%. Finally, in the cyclic tensile test, the prepared copolymers exhibited thermoplastic elastomeric properties with no breakage up over 10 cycles, which is comparable to the behavior of commercial-grade SEBS.

  2. Periodic organic-organometallic microdomain structures in poly(styrene-block-ferrocenyldimethylsilane) copolymers and blends with corresponding homopolymers

    NARCIS (Netherlands)

    Lammertink, Rob G.H.; Hempenius, Mark A.; Thomas, Edwin L.; Vancso, Gyula J.


    A series of poly(styrene-block-ferrocenyldimethylsilane) copolymers (SF) with different relative molar masses of the blocks were prepared by sequential anionic polymerization. The bulk morphology of these polymers, studied by TEM and SAXS, showed well-ordered lamellar and cylindrical domains as well

  3. Biosynthesis and characterization of diblock copolymer of p(3-hydroxypropionate)-block-p(4-hydroxybutyrate) from recombinant Escherichia coli

    DEFF Research Database (Denmark)

    Tripathi, Lakshmi; Wu, Linping; Meng, Dechuan


    Poly(4-hydroxybutyrate) (P4HB) is a highly elastic polymer, whereas poly(3-hydroxypropionate) (P3HP) is a polymer with enormous tensile strength. This study aimed to biosynthesize a block copolymer consisting of soft P4HB block with a strong P3HP block to gain unique and excellent material...... properties. A recombinant Escherichia coli strain that produces homopolymers of P3HP and P4HB was employed for the block copolymer synthesis. When the strain was grown in the presence of 1,4-butanediol (BDO) as a 4HB precursor, P4HB block was formed. Sequential supplementation of 1,3-propanediol (PDO) as a 3......HP precursor allowed the strain to produce P3HP block. Thermal, NMR, fractionation, and mechanical characterizations confirmed the resulting polymer as a block copolymer of P3HP-b-P4HB. Two block copolymers were formed from this study, including the P3HP-b-29% P4HB and P3HP-b-37% P4HB, they showed...

  4. Incipient microphase separation in short chain perfluoropolyether-block-poly(ethylene oxide) copolymers. (United States)

    Chintapalli, Mahati; Timachova, Ksenia; Olson, Kevin R; Banaszak, Michał; Thelen, Jacob L; Mecham, Sue J; DeSimone, Joseph M; Balsara, Nitash P


    Incipient microphase separation is observed by wide angle X-ray scattering (WAXS) in short chain multiblock copolymers consisting of perfluoropolyether (PFPE) and poly(ethylene oxide) (PEO) segments. Two PFPE-PEO block copolymers were studied; one with dihydroxyl end groups and one with dimethyl carbonate end groups. Despite having a low degree of polymerization (N ∼ 10), these materials exhibited significant scattering intensity, due to disordered concentration fluctuations between their PFPE-rich and PEO-rich domains. The disordered scattering intensity was fit to a model based on a multicomponent random phase approximation to determine the value of the interaction parameter, χ, and the radius of gyration, R g . Over the temperature range 30-90 °C, the values of χ were determined to be very large (∼2-2.5), indicating a high degree of immiscibility between the PFPE and PEO blocks. In PFPE-PEO, due to the large electron density contrast between the fluorinated and non-fluorinated block and the high value of χ, disordered scattering was detected at intermediate scattering angles, (q ∼ 2 nm -1 ) for relatively small polymer chains. Our ability to detect concentration fluctuations was enabled by both a relatively large value of χ and significant scattering contrast.

  5. Blending of styrene-block-butadiene-block-styrene copolymer with sulfonated vinyl aromatic polymers

    NARCIS (Netherlands)

    Ruggeri, Giacomo; Passaglia, Elisa; Giorgi, Ivan; Picchioni, Francesco; Aglietto, Mauro


    Different polymers containing sulfonic groups attached to the phenyl rings were prepared by sulfonation of polystyrene (PS) and styrene-block-(ethylene-co-1-butene)-block-styrene (SEBS). The sulfonation degree (SD) was varied between 1 and 20 mol% of the styrene units. Polyphase materials containing

  6. Tunable Mesoporous Bragg Reflectors Based on Block-Copolymer Self-Assembly

    KAUST Repository

    Guldin, Stefan


    Mesoporous Bragg reflectors are a promising materials platform for photovoltaics, light emission, and sensing. A fast and versatile fabrication route that relies on the self-assembly of the block copolymer poly(isoprene-b-ethylene oxide) in combination with simple sol-gel chemistry is reported. The method allows extended control over porosity and pore size in the resulting inorganic material and results in high-quality optical elements. © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  7. Self-assembled isoporous block copolymer membranes with tuned pore sizes

    KAUST Repository

    Yu, Haizhou


    The combination of nonsolvent-induced phase separation and the self-assembly of block copolymers can lead to asymmetric membranes with a thin highly ordered isoporous skin layer. The effective pore size of such membranes is usually larger than 15 nm. We reduced the pore size of these membranes by electroless gold deposition. We demonstrate that the pore sizes can be controlled precisely between 3 and 20 nm leading to a tunable sharp size discrimination in filtration processes. Besides fractionation of nanoparticles and biomaterials, controlled drug delivery is an attractive potential application. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  8. Optimizing the network topology of block copolymer liquid crystal elastomers for enhanced extensibility and toughness (United States)

    Nowak, Christian; Escobedo, Fernando A.


    Molecular simulations are used to study the effect of synthesis conditions on the tensile response of liquid-crystalline elastomers formed by block copolymer chains. Remarkably, it is found that despite the significant presence of trapped entanglements, these networks can exhibit the sawtooth tensile response previously predicted for ideal unentangled networks. It is also found that the monomer concentration during crosslinking can be tuned to limit the extent of entanglements and inhomogeneities while also maximizing network extensibility. It is predicted that networks synthesized at a "critical" concentration will have the greatest toughness.

  9. Self-assembled isoporous block copolymer membranes with tuned pore sizes. (United States)

    Yu, Haizhou; Qiu, Xiaoyan; Nunes, Suzana P; Peinemann, Klaus-Viktor


    The combination of nonsolvent-induced phase separation and the self-assembly of block copolymers can lead to asymmetric membranes with a thin highly ordered isoporous skin layer. The effective pore size of such membranes is usually larger than 15 nm. We reduced the pore size of these membranes by electroless gold deposition. We demonstrate that the pore sizes can be controlled precisely between 3 and 20 nm leading to a tunable sharp size discrimination in filtration processes. Besides fractionation of nanoparticles and biomaterials, controlled drug delivery is an attractive potential application. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  10. Poly(L-lysine)-based star-block copolymers as pH-responsive nanocarriers for anionic drugs. (United States)

    Yan, Yunsong; Li, Jiayan; Zheng, Jinhong; Pan, Ying; Wang, Jinzhi; He, Xiaoying; Zhang, Lumian; Liu, Daojun


    Star-block copolymers PEI-g-(PLL-b-PEG) with a branched polyethylenimine (PEI) core, a poly(l-lysine) (PLL) inner shell, and a poly(ethylene glycol) (PEG) outer shell have been synthesised and evaluated as potential nanocarriers for anionic drugs. The star-block copolymers were synthesised by a ring-opening polymerisation of ɛ-benzyloxycarbonyl-L-lysine N-carboxyanhydride initiated by the peripheral primary amino groups of PEI, surface modification with activated PEG 4-nitrophenyl carbonate, and subsequent deprotection of benzyl groups on the side chains of the PLL inner shell. The synthesised star-block copolymers were characterised by (1)H NMR, gel permeation chromatography (GPC), and dynamic light scattering (DLS). The encapsulation properties of these star-block copolymers were characterised by spectrophotometric titration and dialysis. These techniques demonstrated that anionic model dyes, such as methyl orange and rose Bengal, and the model drug diclofenac sodium can be encapsulated efficiently by PEI-g-(PLL-b-PEG) at physiological pH. The entrapped model compounds demonstrated sustained release at physiological pH and accelerated release when the pH was either increased to 10.0-11.0 or decreased to 2.0-3.0. The efficient encapsulation as well as the pH-responsive releasing properties of these star-block copolymers could be potentially used in the controlled release of anionic drugs. Copyright © 2012 Elsevier B.V. All rights reserved.

  11. Block-copolymer-induced long-range depletion interaction and clustering of silica nanoparticles in aqueous solution (United States)

    Kumar, Sugam; Lee, M.-J.; Aswal, V. K.; Choi, S.-M.


    Small-angle neutron scattering (SANS) has been carried out to examine the block-copolymer-induced depletion interaction of charged silica nanoparticles in aqueous solution. The measurements have been performed on fixed concentrations (1 and 10 wt. %) of anionic Ludox silica nanoparticles having sizes of 8 and 16 nm in the presence of 0.1M NaCl and varying concentration of polyethylene oxide-polypropylene oxide-polyethylene oxide P85 [(EO)26(PO)39(EO)26] block copolymer. The presence of the block copolymer induces an attractive depletion interaction between charge-stabilized nanoparticles. The effective interaction of silica nanoparticles is modeled by a combination of two Yukawa potentials accounting for attractive depletion and repulsive electrostatic forces. The depletion interaction is found to be a long-range attraction whose magnitude and range increase with block-copolymer concentration. The depletion interaction is further enhanced by tuning the self-assembly of the block copolymer through the variation of temperature. The increase of the depletion interaction ultimately leads to clustering of nanoparticles and is confirmed by the presence of a Bragg peak in the SANS data. The positioning of the Bragg peak suggests simple-cubic-type packing of particles within the clusters. The scattering from the clusters in the low-Q region is governed by the Porod scattering, indicating that clusters are quite large (order of microns). The depletion interaction is also found to be strongly dependent on the size of the nanoparticles.

  12. Morphology, directed self-assembly and pattern transfer from a high molecular weight polystyrene-block-poly(dimethylsiloxane) block copolymer film (United States)

    Cheng, Li-Chen; Bai, Wubin; Fernandez Martin, Eduardo; Tu, Kun-Hua; Ntetsikas, Konstantinos; Liontos, George; Avgeropoulos, Apostolos; Ross, C. A.


    The self-assembly of block copolymers with large feature sizes is inherently challenging as the large kinetic barrier arising from chain entanglement of high molecular weight (MW) polymers limits the extent over which long-range ordered microdomains can be achieved. Here, we illustrate the evolution of thin film morphology from a diblock copolymer of polystyrene-block-poly(dimethylsiloxane) exhibiting total number average MW of 123 kg mol-1, and demonstrate the formation of layers of well-ordered cylindrical microdomains under appropriate conditions of binary solvent mix ratio, commensurate film thickness, and solvent vapor annealing time. Directed self-assembly of the block copolymer within lithographically patterned trenches occurs with alignment of cylinders parallel to the sidewalls. Fabrication of ordered cobalt nanowire arrays by pattern transfer was also implemented, and their magnetic properties and domain wall behavior were characterized.

  13. The effect of amphiphilic polymers with a continuous amphiphilicity profile on the membrane properties in a bicontinuous microemulsions studied by neutron scattering (United States)

    Klemmer, Helge F. M.; Frielinghaus, Henrich; Allgaier, Jürgen; Ohl, Michael; Holderer, Olaf


    Microemulsion systems consisting of oil, water and surfactant have been studied with neutron scattering techniques. The amount of surfactant needed to form a microemulsion can be dramatically reduced by the addition of small amounts of amphiphilic block copolymers (boosting effect). Here, we studied the influence of block copolymers with gradually changing amphiphilicity from hydrophilic to hydrophobic. Small angle neutron scattering (SANS), neutron spin echo spectroscopy (NSE) and phase diagram measurements in combination give access to the elastic properties of the membrane. The underlying NSE experiments for this interpretation rely on smallest changes of the relaxation curves (of ca. 1% steps) for still small changes of the bending rigidity (of ca. 10% steps). This high reliability of the experiments conducted at the SNS-NSE displays the accuracy of the instrument itself and the latest developments of the evaluation software, which were necessary to interpret such tiny changes of the bending rigidity reliably.

  14. Reversible pH Stimulus-Response Material Based on Amphiphilic Block Polymer Self-Assembly and Its Electrochemical Application

    Directory of Open Access Journals (Sweden)

    Tianyi Wang


    Full Text Available Stimulus-responsive microporous solid thin films were successfully fabricated by simple molecular self-assembly via an amphiphilic block polymer, polystryene–b–polyacrylic acid (PS–b–PAA. The solid thin films exhibit different surface morphologies in response to external stimuli, such as environments with different pH values in aqueous solutions. The experiments have successfully applied atomic force microscope (AFM technology to observe in-situ surface morphological changes. There is a reversible evolution of the microstructures in buffer solutions over a pH range of 2.4–9.2. These observations have been explained by positing that there is no conventional PAA swelling but that the PAA chains in the micropores stretch and contract with changes in the pH of the solution environment. The hydrophobicity of the solid thin film surface was transformed into super-hydrophilicity, as captured by optical contact angle measurements. The stimulus-responsive dynamics of pore sizes was described by a two-stage mechanism. A promising electrochemical application of this film is suggested via combination with an electrochemical impedance technique. This study is aimed at strategies for the functionalization of stimulus-responsive microporous solid thin films with reversible tunable surface morphologies, and exploring new smart materials with switch-on/switch-off behavior.

  15. Phase Structure and Properties of a Biodegradable Block Copolymer Coalesced from It's Crystalline Inclusion Compound Formed with alpha-Cyclodextrin (United States)

    Shuai, Xintao; Wei, Min; Probeni, Francis; Bullions, Todd A.; Shin, I. Daniel; Tonelli, Alan E.


    A well-defined biodegradable block copolymer of poly(epsilon caprolactone) (PCL) and poly(L-lactic acid) (PLLA) was synthesized and characterized and then included as a guest in an inclusion compound (IC) formed with the host alpha-cyclodextrin (CD). The PCL-b-PLLA block copolymer was subsequently coalesced from it's CD-IC crystals by either treatment with hot water (50 C) or an aqueous amylase solution at 25 C. The coalesced PCL-b-PLLA was examined by FTIR, DSC, TGA, and WAXD and was found to be much more homogeneosly organized, with much less segregation and crystallinity of the PCL and PLLA microphases. The morpholgy, crystallization kinetics, thermal behavior, and biodegradability of the coalesced PCL-b-PLLA block copolymer was studied by comparison to similar observations made on as-synthesized PCL-b-PLLA, PCL and PLLA homopolymers, and their solution-cast blend. The PCL and PLLA blocks are found to be more intimately mixed, with less phase segregation, in the coalesced diblock copolymer, and this leads to homogeneous bulk crystallization, which is not observed for the as-synthesized diblock copolymer. The coalesced PCL-b-PLLA was also found to be more quickly biodegraded (lipase from Rhizopus arrhizus)than the as-synthesized PCL-b-PLLA or the physical blend of PCL and PLLA homopolymers. Overall, the coalescence of the inherently phase segregated diblock copolymer PCL-b-PLLA results in a small amount of compact, chain-extended PCL and PLLA crystals embedded in an amorphous phase, largely consisting of well-mixed PCL and PLLA blocks. Thus, we have demonstrated that it is possible to control the morpholgy of a biodegradable diblock copolymer, thereby significantly modifying it's properties, by coalescence from it's CD-IC crystals.

  16. Controlled release of cortisone drugs from block copolymers synthetized by ATRP

    Energy Technology Data Exchange (ETDEWEB)

    Valenti, G.; La Carta, S.; Rapisarda, M.; Carbone, D.; Recca, G.; Rizzarelli, P., E-mail: [Istituto per i Polimeri, Compositi e Biomateriali, Consiglio Nazionale delle Ricerche Via P. Gaifami 18, 95129 Catania (Italy); Mazzotti, G.; Giorgini, L. [Dipartimento di Chimica Industriale «Toso Montanari», Università di Bologna Via Risorgimento 4, 40136 Bologna (Italy); Perna, S. [ST Microelectronics Srl, Stradale Primosole, 50–95121 Catania (Italy); Di Gesù, R. [Merck Serono S.p.A., Via L. Einaudi, 11–00012 Guidonia Montecelio, Rome (Italy)


    Diseases affecting posterior eye segment, like macular edema, infection and neovascularization, may cause visual impairment. Traditional treatments, such as steroidal-drugs intravitreal injections, involve chronic course of therapy usually over a period of years. Moreover, they can require frequent administrations of drug in order to have an adequately disease control. This dramatically reduce patient’s compliance. Efforts have been made to develop implantable devices that offer an alternative therapeutic approach to bypass many challenges of conventional type of therapy. Implantable drug delivery systems (DDS) have been developed to optimize therapeutic properties of drugs and ensure their slow release in the specific site. Polymeric materials can play an essential role in modulating drug delivery and their use in such field has become indispensable. During last decades, acrylic polymers have obtained growing interest. Biocompatibility and chemical properties make them extremely versatile, allowing their use in many field such as biomedical. In particular, block methacrylate copolymer with a balance of hydrophilic and hydrophobic properties can be suitable for prolonged DDS in biomedical devices. In this work, we focused on the realization of a system for controlled and long term release of betamethasone 17,21-dipropionate (BDP), a cortisone drug, from methacrylic block copolymers, to be tested in the treatment of the posterior eye’s diseases. Different series of methyl methacrylate/hydroxyethyl methacrylate (MMA/HEMA) block and random copolymers, with different monomer compositions (10–60% HEMA), were synthetized by Atom Transfer Radical Polymerization (ATRP) to find the best hydrophilic/hydrophobic ratio, able to ensure optimal kinetic release. Copolymer samples were characterized by NMR spectroscopy ({sup 1}H-NMR, {sup 13}C-NMR, CosY), SEC, TGA and DSC. Monitoring of drug release from films loaded with BDP was carried out by HPLC analysis. Evaluation of

  17. Thermally sensitive block copolymer particles prepared via aerosol flow reactor method: Morphological characterization and behavior in water


    Nykänen, Antti; Rahikkala, Antti; Hirvonen, Sami-Pekka; Aseyev, Vladimir; Tenhu, Heikki; Mezzenga, Raffaele; Raula, Janne; Kauppinen, Esko; Ruokolainen, Janne


    This work describes properties of thermo-sensitive submicron sized particles having the same chemical composition but different morphologies. These particles have been prepared with an aerosol technique using dimethylformamide solutions of linear polystyrene-block-poly(N-isopropylacrylamide-block-polystyrene, PS-b-PNIPAM-b-PS. The particles were characterized by cryo-electron microscopy, microcalorimetry, and light scattering. Block-copolymers self-assembled within the particles forming onion...

  18. Fabrication of Hyperbranched Block-Statistical Copolymer-Based Prodrug with Dual Sensitivities for Controlled Release. (United States)

    Zheng, Luping; Wang, Yunfei; Zhang, Xianshuo; Ma, Liwei; Wang, Baoyan; Ji, Xiangling; Wei, Hua


    Dendrimer with hyperbranched structure and multivalent surface is regarded as one of the most promising candidates close to the ideal drug delivery systems, but the clinical translation and scale-up production of dendrimer has been hampered significantly by the synthetic difficulties. Therefore, there is considerable scope for the development of novel hyperbranched polymer that can not only address the drawbacks of dendrimer but maintain its advantages. The reversible addition-fragmentation chain transfer self-condensing vinyl polymerization (RAFT-SCVP) technique has enabled facile preparation of segmented hyperbranched polymer (SHP) by using chain transfer monomer (CTM)-based double-head agent during the past decade. Meanwhile, the design and development of block-statistical copolymers has been proven in our recent studies to be a simple yet effective way to address the extracellular stability vs intracellular high delivery efficacy dilemma. To integrate the advantages of both hyperbranched and block-statistical structures, we herein reported the fabrication of hyperbranched block-statistical copolymer-based prodrug with pH and reduction dual sensitivities using RAFT-SCVP and post-polymerization click coupling. The external homo oligo(ethylene glycol methyl ether methacrylate) (OEGMA) block provides sufficient extracellularly colloidal stability for the nanocarriers by steric hindrance, and the interior OEGMA units incorporated by the statistical copolymerization promote intracellular drug release by facilitating the permeation of GSH and H + for the cleavage of the reduction-responsive disulfide bond and pH-liable carbonate link as well as weakening the hydrophobic encapsulation of drug molecules. The delivery efficacy of the target hyperbranched block-statistical copolymer-based prodrug was evaluated in terms of in vitro drug release and cytotoxicity studies, which confirms both acidic pH and reduction-triggered drug release for inhibiting proliferation of He

  19. From blood dialysis to desalination: A one-size fits all block copolymer based membrane system (United States)

    Sanna Kotrappanavar, Nataraj; Zavala-Rivera, Paul; Chonnon, Kevin; Almuhtaseb, Shaheen S. A.; Sivaniah, Easan; University of Cambridge Team; Qatar University Collaboration


    Asymmetric membrane with ultrahigh selective self-assembled nanoporous block copolymer layer were developed successfully on polyimide (PI) support, which demonstrated excellent thermal, chemical and mechanical stability. Membranes with specific nano- structural architectures and optimized cascades of block assemblies on the top selective skin have been used largely for separation of colour from aqueous streams, wastewater treatment, desalination, blood filtration and gas separation with dense layer transformation. A consistent and reliable method of membrane preparation and measuring separation performance has been adopted. A homologous series of ethylene oxide oligomers covering a large range was used to characterise MWCO of Membrane and were able to provide many points to give a comprehensive description of the membrane performance in the nanofiltration range.

  20. Data on macrophage mediated muscle transfection upon delivery of naked plasmid DNA with block copolymers

    Directory of Open Access Journals (Sweden)

    Vivek Mahajan


    Full Text Available The data contains 14 figures supporting the research article “Horizontal gene transfer from macrophages to ischemic muscles upon delivery of naked DNA with Pluronic block copolymers” [1]. The data explains the surgical procedure and histological characterization of Murine Hind Limb Ischemia. The data also shows the kinetics of luciferase gene expression, spread of GFP expression through muscle and the colocalization of GFP with cellular markers in ischemic muscles injected with pDNA alone or pDNA/Pluronic. Finally the data shows the effect of Pluronic Block Copolymer to enhance total gene expression (cmv-promoter driven luciferase gene in coculture of DNA transfected MØs with muscle cells.