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Sample records for amphiphilic block copolymers

  1. Nanostructured Amphiphilic Star-Hyperbranched Block Copolymers for Drug Delivery.

    Science.gov (United States)

    Seleci, Muharrem; Seleci, Didem Ag; Ciftci, Mustafa; Demirkol, Dilek Odaci; Stahl, Frank; Timur, Suna; Scheper, Thomas; Yagci, Yusuf

    2015-04-21

    A robust drug delivery system based on nanosized amphiphilic star-hyperbranched block copolymer, namely, poly(methyl methacrylate-block-poly(hydroxylethyl methacrylate) (PMMA-b-PHEMA) is described. PMMA-b-PHEMA was prepared by sequential visible light induced self-condensing vinyl polymerization (SCVP) and conventional vinyl polymerization. All of the synthesis and characterization details of the conjugates are reported. To accomplish tumor cell targeting property, initially cell-targeting (arginylglycylaspactic acid; RGD) and penetrating peptides (Cys-TAT) were binding to each other via the well-known EDC/NHS chemistry. Then, the resulting peptide was further incorporated to the surface of the amphiphilic hyperbranched copolymer via a coupling reaction between the thiol (-SH) group of the peptide and the hydroxyl group of copolymer by using N-(p-maleinimidophenyl) isocyanate as a heterolinker. The drug release property and targeting effect of the anticancer drug (doxorobucin; DOX) loaded nanostructures to two different cell lines were evaluated in vitro. U87 and MCF-7 were chosen as integrin αvβ3 receptor positive and negative cells for the comparison of the targeting efficiency, respectively. The data showed that drug-loaded copolymers exhibited enhanced cell inhibition toward U87 cells in compared to MCF-7 cells because targeting increased the cytotoxicity of drug-loaded copolymers against integrin αvβ3 receptor expressing tumor cells. PMID:25816726

  2. Synthesis nad properties of amphiphilic block copolymers containing poly 5-vinyltetrazoline or methyl-4-vinylpyridinium iodide

    Czech Academy of Sciences Publication Activity Database

    Gromadzki, D.; Janata, Miroslav; Lokaj, Jan; Štěpánek, Petr

    Arcachon: European Science Foundation Collaborative Research, 2005. P2. [Self-Assembled Structures of Amphiphilic Ionic Copolymers in Solutions and Interfaces. 11.5.2005-14.5.2005, Arcachon] Institutional research plan: CEZ:AV0Z40500505 Keywords : amphiphilic block copolymers Subject RIV: CD - Macromolecular Chemistry

  3. Perfluorocyclobutyl-containing Amphiphilic Block Copolymers Synthesized by RAFT Polymerization

    Institute of Scientific and Technical Information of China (English)

    LI, Yongjun; ZHANG, Sen; FENG, Chun; ZHANG, Yaqin; LI, Qingnuan; LI, Wenxin; HUANG, Xiaoyu

    2009-01-01

    Amphiphilic block copolymers containing hydrophobic perfluorocyclobutyl-based (PFCB) polyacrylate and hydrophilic poly(ethylene glycol) (PEG) segments were prepared via reversible addition-fragmentation chain transfer (RAP-T) polymerization. The PFCB-containing acrylate monomer, p-(2-(p-tolyloxy)perfluorocyclobutoxy)phenyl acrylate, was first synthesized from commercially available compounds in good yields, and this kind of acrylate monomer can be homopolymerized by free radical polymerization or RAFT polymerization. Kinetic study showed the 2,2'-azobis(isobutyronitrile) (AIBN) initiated and cumyl dithiobenzoate (CDB) mediated RAFT polymerization was in a living fashion, as suggested by the fact that the number-average molecular weights (M_n) increased linearly with the conversions of the monomer, while the polydispersity indices kept less than 1.10. The block polymers with narrow molecular weight distributions (M_w/M_n≤1.21) were prepared through RAFT polymerization using PEG monomethyl ether capped with 4-cyanopentanoic acid dithiobenzoate end group as the macro chain transfer agent (mPEG-CTA). The length of the hydrophobic segment can be tuned by the feed ratio of the PFCB-based acrylate monomer and the extending of the polymerization time. The micellization behavior of the block copolymers in aqueous media was investigated by the fluorescence probe technique.

  4. Water Diffusion Dependence on Amphiphilic Block Design in (Amphiphilic-Hydrophobic) Diblock Copolymer Membranes.

    Science.gov (United States)

    Dorenbos, Gert

    2016-06-30

    Polyelectrolyte membranes (PEMs) are applied in polyelectrolyte fuel cells (PEFC). The proton conductive pathways within PEMs are provided by nanometer-sized water containing pores. Large-scale application of PEFC requires the production of low-cost membranes with high proton conductivity and therefore good connected pore networks. Pore network formation within four alternative model diblock (hydrophobic_amphiphilic) copolymers in the presence of water is studied by dissipative particle dynamics. Each hydrophobic block contains 50 consecutively connected hydrophobic (A) fragments, and amphiphilic blocks contain 40 hydrophobic A beads and 10 hydrophilic C beads. For one amphiphilic block the C beads are distributed uniformly along the backbone. For the other architectures C beads are located at the end of the side chains attached at regular intervals along the backbone. Water diffusion through the pores is modeled by Monte Carlo tracer diffusion through mapped morphologies. Diffusion is highest for the grafted architectures and increases with increase of length of the side chains. A consistent picture emerges in which diffusion strongly increases with the value of ⟨Nbond⟩ within the amphiphilic block, where ⟨Nbond⟩ is the average number of bonds between hydrophobic A beads and the nearest C bead. PMID:27266679

  5. Aggregation behavior of water-soluble amphiphilic block copolymers

    OpenAIRE

    Bonné, Tune Bjarke

    2007-01-01

    Polymers and block copolymers based on 2-alkyl-2-oxazoline have the advantage that their hydrophobicity can be varied by changing the length of the alkyl side chain and that fluorescence groups can be attached to the block ends. We have studied the aggregation behavior of 2-alkyl-2-oxazoline based diblock, triblock and random copolymers in aqueous solutions, using fluorescence correlation spectroscopy (FCS), where fluorescence labeled polymers were used as tracers. FCS experiments in combinat...

  6. Synthesis of Dumbbell-shaped Hyperbranched Amphiphilic Block Copolymer by Controlled Atom Transfer Radical Polymerization

    Energy Technology Data Exchange (ETDEWEB)

    Kim, In Kyoung; An, Sung Guk; Cho, Chang Gi [Center for Advanced Functional Polymers, Department of Fiber and Polymer Science, Hanyang University, Seoul (Korea); Noh, Si Tae [Department of Chemical Engineering, Hanyang University, Ansan (Korea)

    2001-04-01

    Amphiphilic block copolymers containing hydrophilic ethylene glycol core and hyperbranched polystyrene (PS) arm were synthesized by atom transfer radical polymerization using hydrophilic macroinitiator and p-chloromethyl styrene (CMS) as AB type monomer. Hydrophilic poly(ethylene glycol)(PEG) macroinitiators with difuntional groups were synthesized by reacting PEG and 2-bromopropionyl bromide. The chemical structure, molecular weight, and polydispersity index of the amphiphilic block copolymer were characterized by {sup 1}H-NMR spectroscopy and GPC analysis. The molecular weight increased as the reaction time increased. Polydispersity index of the obtained polymer was relatively narrow (below 1.39). To control chain density of the hyperbranched PS, styrene and CMS were copolymerized. It was found that amphiphilic block copolymer molecule underwent conformational change in different solvents based on the result for {sup 1}H-NMR spectroscopic analysis. 29 refs., 8 figs., 2 tabs.

  7. Synthesis and self-assembly of multiple thermoresponsive amphiphilic block copolymers

    OpenAIRE

    Weiß, Jan

    2011-01-01

    In the present thesis, the self-assembly of multi thermoresponsive block copolymers in dilute aqueous solution was investigated by a combination of turbidimetry, dynamic light scattering, TEM measurements, NMR as well as fluorescence spectroscopy. The successive conversion of such block copolymers from a hydrophilic into a hydrophobic state includes intermediate amphiphilic states with a variable hydrophilic-to-lipophilic balance. As a result, the self-organization is not following an all-or-...

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

    Directory of Open Access Journals (Sweden)

    2007-06-01

    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. AMPHIPHILIC STAR-BLOCK COPOLYMERS BY IODIDE-MEDIATED RADICAL POLYMERIZATION

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Amphiphilic star-block copolymers composed of polystyrene and poly(acrylic acid) were synthesized by iodidemediated radical polymerization. Firstly, free radical polymerization of styrene was carried out with AIBN as initiator and 1,1,1-trimethyolpropane tri(2-iodoisobutyrate) as chain transfer agent, giving iodine atom ended star-shaped polystyrene with three arm chains, R(polystyrene)3. Secondly, tert-butyl acrylate was polymerization using polystyrene obtained as macro-chain transfer agent, and star-block copolymer, R(polystyrene-b-poly(tert-butyl acrylate))3 with controlled molecular weight was obtained. Finally, amphiphilic star-block copolymer, R(polystyrene-b-poly(acrylic acid))3 was obtained by hydrolysis of R(polystyrene-b-poly(tert-butyl acrylate))3 under acidic condition.

  10. Amphiphilic block copolymers in oil-water-surfactant mixtures: efficiency boosting, structure, phase behaviour and mechanism

    Science.gov (United States)

    Gompper, G.; Richter, D.; Strey, R.

    2001-10-01

    The effect of amphiphilic block copolymers on the phase behaviour and structure of ternary microemulsions in water, oil and non-ionic surfactant mixtures is reviewed. Recent experiments have revealed that the addition of small amounts of polyethylenepropylene-polyethyleneoxide block copolymer to the ternary systems leads to a dramatic increase in the volumes of oil and water solubilized into a bicontinuous microemulsion for a given surfactant volume fraction. While phase diagrams directly show the power of the amphiphilic block copolymers as efficiency boosters, the theoretical analysis in terms of bending energy discloses the mechanism for the efficiency boosting as due to the variation of the surfactant film curvature elasticity by tethered polymers in the form of mushrooms at the interface. Neutron scattering experiments employing a high-precision two-dimensional contrast variation technique confirm this picture and demonstrate that the polymer molecules uniformly decorate the surfactant film.

  11. Non-ionic amphiphilic block copolymers by RAFT-polymerization and their self-organization

    OpenAIRE

    Garnier, Sébastien; Laschewsky, André

    2006-01-01

    Water-soluble, amphiphilic diblock copolymers were synthesized by reversible addition fragmentation chain transfer polymerization. They consist of poly(butyl acrylate) as hydrophobic block with a low glass transition temperature and three different nonionic water-soluble blocks, namely, the classical hydrophilic block poly(dimethylacrylamide), the strongly hydrophilic poly(acryloyloxyethyl methylsulfoxide), and the thermally sensitive poly(N-acryloylpyrrolidine). Aqueous micellar solutions of...

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

    International Nuclear Information System (INIS)

    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 H2O/D2O 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

  13. Bioinspired amphiphilic phosphate block copolymers as non-fluoride materials to prevent dental erosion

    OpenAIRE

    Lei, Yanda; Wang, Tongxin; Mitchell, James W; Zaidel, Lynette; Qiu, Jianhong; Kilpatrick-Liverman, LaTonya

    2014-01-01

    Inspired by the fact that certain natural proteins, e.g. casein phosphopeptide or amelogenin, are able to prevent tooth erosion (mineral loss) and to enhance tooth remineralization, a synthetic amphiphilic diblock copolymer, containing a hydrophilic methacryloyloxyethyl phosphate block (MOEP) and a hydrophobic methyl methacrylate block (MMA), was designed as a novel non-fluoride agent to prevent tooth erosion under acidic conditions. The structure of the polymer, synthesized by reversible add...

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

    International Nuclear Information System (INIS)

    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 1H nuclear magnetic resonance (1H 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 × 10−4 mg/mL and 3.9 × 10−5 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

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

    Science.gov (United States)

    Hu, Gaicen; Fan, Xiaoshan; Xu, Bingcan; Zhang, Delong; Hu, Zhiguo

    2014-10-01

    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 (1)H nuclear magnetic resonance ((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(-4)mg/mL and 3.9 × 10(-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. PMID:25175206

  16. 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: zghu@htu.cn

    2014-10-01

    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.

  17. Bioinspired amphiphilic phosphate block copolymers as non-fluoride materials to prevent dental erosion.

    Science.gov (United States)

    Lei, Yanda; Wang, Tongxin; Mitchell, James W; Zaidel, Lynette; Qiu, Jianhong; Kilpatrick-Liverman, LaTonya

    2014-01-01

    Inspired by the fact that certain natural proteins, e.g. casein phosphopeptide or amelogenin, are able to prevent tooth erosion (mineral loss) and to enhance tooth remineralization, a synthetic amphiphilic diblock copolymer, containing a hydrophilic methacryloyloxyethyl phosphate block (MOEP) and a hydrophobic methyl methacrylate block (MMA), was designed as a novel non-fluoride agent to prevent tooth erosion under acidic conditions. The structure of the polymer, synthesized by reversible addition-fragment transfer (RAFT) polymerization, was confirmed by gel permeation chromatography (GPC), Fourier transform infrared spectroscopy (FTIR), and nuclear magnetic resonance spectroscopy (NMR). While the hydrophilic PMOEP block within the amphiphilic block copolymer strongly binds to the enamel surface, the PMMA block forms a hydrophobic shell to prevent acid attack on tooth enamel, thus preventing/reducing acid erosion. The polymer treatment not only effectively decreased the mineral loss of hydroxyapatite (HAP) by 36-46% compared to the untreated control, but also protected the surface morphology of the enamel specimen following exposure to acid. Additionally, experimental results confirmed that low pH values and high polymer concentrations facilitate polymer binding. Thus, the preliminary data suggests that this new amphiphilic diblock copolymer has the potential to be used as a non-fluoride ingredient for mouth-rinse or toothpaste to prevent/reduce tooth erosion. PMID:25419457

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

    International Nuclear Information System (INIS)

    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

  19. 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

    2002-01-01

    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.)

  20. Aggregate of Amphiphilic Block Copolymer as a Pseudo-Stationary Phase in Capillary Electrophoresis

    OpenAIRE

    Nakamura, Tohru; OHKI, Akira; Mishiro, Masaki; Tsuyashima, Osamu; Maeda, Shigeru; ナカムラ, トオル; オオキ, アキラ; ミシロ, マサキ; ツヤシマ, オサム; マエダ, シゲル; 中村, 透; 大木, 章; 艶島, 修; 前田, 滋

    1999-01-01

    The use of an aggregate of amphiphilic block copolymer 1, which consists of poly[(N-acetylimino)ethylene] and poly[(N-pentanoylimino)ethylene], for a pseudo-stationary phase in capillary electrophoresis has been examined. From gel-filtration chromatography, the aggregate from 1 (1-AG) was found to incorporate phenol. When the running solution contains 1-AG and sodium dodecyl sulfate (SDS), the electrophoretic mobility becomes nearly zero. Thus, it is found that when 1-AG and SDS are added to ...

  1. 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.

    2011-01-01

    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 a

  2. Self-assembling Behavior of Amphiphilic Copolymer Containing Cross-linked Hydrophilic Block in Ethanol

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The self-assembly behavior of the amphiphilic block copolymer poly( methyl methacrylate)-block-poly( lead dimethacrylate) (PMMA-b-PLDMA) with cross-linked hydrophilic block (PLDMA) in ethanol was investigated. The results show that the size and morphology of the resulting micelle or micellar aggregates are ascribed to the content of ethanol and the nature of the solvent mixture. PbS nanoparticles were formed in the micelle by in situ reaction with H2S gas. The morphology and size of the self-assembly objects were investigated using scanning electron microscopy (SEM) and transmission electron microscopy (TEM).

  3. Analysis of the aggregation structure from amphiphilic block copolymers in solutions by small-angle x-ray scattering

    CERN Document Server

    Rong Li Xia; Wang Jun; Wei Liu He; Li Fu Mian; Li Zi Chen

    2002-01-01

    The aggregation structure of polystyrene-p vinyl benzoic amphiphilic block copolymers which were prepared in different conditions was investigated by synchrotron radiation small-angle x-ray scattering (SAXS). The micelle was self-assembled in selective solvents of the block copolymers. Authors' results demonstrate that the structure of the micelle depends on the factors, such as the composition of the copolymers, the nature of the solvent and the concentration of the solution

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

    OpenAIRE

    Fatime Eren Erol; Deniz Sinirlioglu; Sedat Cosgun; Ali Ekrem Muftuoglu

    2014-01-01

    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-M...

  5. 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)

    2013-09-26

    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.

  6. Amphiphilic Spider Silk-Like Block Copolymers with Tunable Physical Properties and Morphology for Biomedical Applications

    Science.gov (United States)

    Huang, Wenwen; Krishnaji, Sreevidhya; Kaplan, David; Cebe, Peggy

    2013-03-01

    Silk-based materials are important candidates for biomedical applications because of their excellent biocompatibility and biodegradability. To generate silk amphiphilic biopolymers with potential use in guided tissue repair and drug delivery, a novel family of spider silk-like block copolymers was synthesized by recombinant DNA technology. Block copolymer thermal properties, structural conformations, protein-water interactions, and self-assembly morphologies were studied with respect to well controlled protein amino acid sequences. A theoretical model was used to predict the heat capacity of the protein and protein-water complex. Using thermal analysis, two glass transitions were observed: Tg1 is related to conformational changes caused by bound water removal, while Tg2 (>Tg1) is the glass transition of dry protein. Real-time infrared spectroscopy and X-ray diffraction confirmed that different secondary structural changes occur during the two Tg relaxations. Using scanning electron microscopy, fibrillar networks and hollow vesicles are observed, depending on protein block copolymer sequence. This study provides a deeper understanding of the relationship between protein physical properties and amino acid sequence, with implications for design of other protein-based materials. Support was provided from the NSF CBET-0828028 and the MRI Program under DMR-0520655 for thermal analysis instrumentation.

  7. Solubility and self-assembly of amphiphilic gradient and block copolymers in supercritical CO2

    International Nuclear Information System (INIS)

    This work aims at demonstrating the interest of gradient copolymers in supercritical CO2 in comparison with block copolymers. Gradient copolymers exhibit a better solubility in supercritical CO2 than block copolymers, as attested by cloud point data. The self-assembly of gradient and block copolymers in dense CO2 has been characterized by Small-Angle Neutron Scattering (SANS); and it is shown that it is not fundamentally modified when changing from block copolymers to gradient copolymers. Therefore, gradient copolymers are advantageous thanks to their easier synthesis and their solubility at lower pressure while maintaining a good ability for self-organization in dense CO2. (authors)

  8. Preparation of amphiphilic block copolymer containing triazene moieties and fluorescence study

    Indian Academy of Sciences (India)

    Emil C Buruiana; Andreea L Chibac; Violeta Melinte; Tinca Buruiana

    2013-01-01

    The present study describes the synthesis via microwave accelerated reversible additionfragmentation chain transfer (RAFT) polymerization of an amphiphilic block copolymer poly(acrylic acid)-b-poly(dodecylacrylamide-co-1-(phenyl)-3-(2-methacryloyloxyethyl carbamoyloxyethyl)-3-methyltriazene-1) [PAA-b-(PDA-co-PUMA-T)]. The structure and the chemical composition of the block copolymer were confirmed by spectral/thermal analysis. The photoreactivity of the triazene sequences from PAA-b-(PDA-co-PUMA-T) was quantified by UV/vis irradiation in chloroform/dimethylformamide solutions and in thin film, indicating that the solvent polarity modifies with an order of magnitude the rate constant values. 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) was evidenced through fluorescence measurements using pyrene probe (10-6 M), the CMC value being of 4.64 × 10−3 g L-1 PAA--(PDA--PUMA-T) (3.27 × 10−7 M). Experiments of fluorescence quenching with various metal cations (UO$^{2+}_{2}$, Fe2+, Fe3+, Ni2+, Cu2+, Co2+, Pb2+ and Hg2+) suggested that such a block copolymer could find applications as fluorescence-based chemosensor for the detection of iron cations in homogeneous organic solutions or aqueous environments by thin films.

  9. Terminal groups control self-assembly of amphiphilic block copolymers in solution

    Science.gov (United States)

    Grzelakowski, M.; Kita-Tokarczyk, K.

    2016-03-01

    The terminal groups of amphiphilic block copolymers are shown to control macromolecular self-assembly in aqueous solutions, in the micellar/lamellar region of the phase diagram. At the same concentration and using the same self-assembly conditions, dramatic differences are observed in polymer hydration and the resulting nano-/microstructure for two series of polymers with identical block chemistry and hydrophilic-lipophilic balance (HLB). This suggests a strong contribution from end groups to the hydration as the initial step of the self-assembly process, and could be conveniently used to guide the particle morphology and size. Additionally, for polymers with those head groups which drive vesicular structures, differences in membrane organization affect their physical properties, such as permeability.The terminal groups of amphiphilic block copolymers are shown to control macromolecular self-assembly in aqueous solutions, in the micellar/lamellar region of the phase diagram. At the same concentration and using the same self-assembly conditions, dramatic differences are observed in polymer hydration and the resulting nano-/microstructure for two series of polymers with identical block chemistry and hydrophilic-lipophilic balance (HLB). This suggests a strong contribution from end groups to the hydration as the initial step of the self-assembly process, and could be conveniently used to guide the particle morphology and size. Additionally, for polymers with those head groups which drive vesicular structures, differences in membrane organization affect their physical properties, such as permeability. Electronic supplementary information (ESI) available: Fig. S1: Particle diameters for hydrated NH2-ABA-NH2 polymers with different degrees of functionalization; Fig. S2: TEM characterization of compound micelles from BA-OH polymer after extrusion; Fig. S3: Cryo-TEM and stopped flow characterization of lipid vesicles; Fig. S4 and S5: NMR spectra for ABA and BA polymers

  10. Stimuli-responsive nano-structures of amphiphilic ionic block- and gradient copolymers

    Czech Academy of Sciences Publication Activity Database

    Borisov, O.; Billon, L.; Borisova, O.; Štěpánek, Petr; Bakaeva, Zulfiya; Zhulina, E.

    Prague : Institute of Macromolecular Chemistry AS CR, 2014. s. 179. ISBN 978-80-85009-80-4. [Frontiers of Polymer Colloids: From Synthesis to Macro-Scale and Nano-Scale Applications. Prague Meeting on Macromolecules /78./. 20.07.2014-24.07.2014, Prague] Institutional support: RVO:61389013 Keywords : amphiphilic ionic copolymers * gradient copolymers Subject RIV: CD - Macromolecular Chemistry

  11. Polylactide surfaces modified by deposition of lactide-based amphiphilic block copolymers

    Czech Academy of Sciences Publication Activity Database

    Chánová, Eliška; Popelka, Štěpán; Machová, Luďka; Rypáček, František

    Prague: Czech Society for New Materials and Technologies, 2005. Poster Session II. [European Congress on Advanced Materials and Processes. 5.9.2005-8.9.2005, Prague] R&D Projects: GA AV ČR IAA4050202 Keywords : amphiphilic block copolymers * polylactide * atomic force microscopy Subject RIV: CD - Macromolecular Chemistry http://webdb.dgm.de/dgm_lit/prg/FMPro?-db=w%5fprogram&- format =prog%5fpaper%5fresults.htm&-lay=standard&TB=%3d%3d688&tgb%5fsymposium%5fund%5fnr=B14%20Engineering%20and%20Design%20of%20Biomedical%20Materials&-max=20&-skip=20&-token.0=688&-token.1=B14%20Engineering%20and%20Design%20of%20Biomedical%20Materials&-find=

  12. Highly protein-resistant coatings and suspension cell culture thereon from amphiphilic block copolymers prepared by RAFT polymerization.

    Science.gov (United States)

    Haraguchi, Kazutoshi; Kubota, Kazuomi; Takada, Tetsuo; Mahara, Saori

    2014-06-01

    Novel amphiphilic block copolymers composed of hydrophobic (poly(2-methoxyethyl acrylate): M) and hydrophilic (poly(N,N-dimethylacrylamide): D) segments were synthesized by living radical polymerization: a reversible addition-fragmentation chain-transfer polymerization. Two types of amphiphilic block copolymers, triblock (MDM) and 4-arm block ((MD)4) copolymers with specific compositions (D/M = (750-1500)/250), were prepared by a versatile one-pot synthesis. These copolymers show good adhesion to various types of substrates (e.g., polystyrene, polycarbonate, polypropylene, Ti, and glass), and the surface coating showed high protein repellency and a low contact angle for water, regardless of the substrate. The two opposing characteristics of high protein repellency and good substrate adhesion were achieved by the combined effects of the molecular architecture of the block copolymers, the high molecular weight, and the characteristics of each segment, that is, low protein adsorption capability of both segments and low glass transition temperature of the hydrophobic segment. Further, a polystyrene dish coated with the MDM block copolymer could be sterilized by γ-ray irradiation and used as a good substrate for a suspension cell culture that exhibits low cell adhesion and good cell growth. PMID:24773089

  13. Binding of amphiphilic and triphilic block copolymers to lipid model membranes: the role of perfluorinated moieties.

    Science.gov (United States)

    Schwieger, Christian; Achilles, Anja; Scholz, Sven; Rüger, Jan; Bacia, Kirsten; Saalwaechter, Kay; Kressler, Jörg; Blume, Alfred

    2014-09-01

    A novel class of symmetric amphi- and triphilic (hydrophilic, lipophilic, fluorophilic) block copolymers has been investigated with respect to their interactions with lipid membranes. The amphiphilic triblock copolymer has the structure PGMA(20)-PPO(34)-PGMA(20) (GP) and it becomes triphilic after attaching perfluoroalkyl moieties (F9) to either end which leads to F(9)-PGMA(20)-PPO(34)-PGMA(20)-F(9) (F-GP). The hydrophobic poly(propylene oxide) (PPO) block is sufficiently long to span a lipid bilayer. The poly(glycerol monomethacrylate) (PGMA) blocks have a high propensity for hydrogen bonding. The hydrophobic and lipophobic perfluoroalkyl moieties have the tendency to phase segregate in aqueous as well as in hydrocarbon environments. We performed differential scanning calorimetry (DSC) measurements on polymer bound lipid vesicles under systematic variation of the bilayer thickness, the nature of the lipid headgroup, and the polymer concentration. The vesicles were composed of phosphatidylcholines (DMPC, DPPC, DAPC, DSPC) or phosphatidylethanolamines (DMPE, DPPE, POPE). We showed that GP as well as F-GP binding have membrane stabilizing and destabilizing components. PPO and F9 blocks insert into the hydrophobic part of the membrane concomitantly with PGMA block adsorption to the lipid headgroup layer. The F9 chains act as additional membrane anchors. The insertion of the PPO blocks of both GP and F-GP could be proven by 2D-NOESY NMR spectroscopy. By fluorescence microscopy we show that F-GP binding increases the porosity of POPC giant unilamellar vesicles (GUVs), allowing the influx of water soluble dyes as well as the translocation of the complete triphilic polymer and its accumulation at the GUV surface. These results open a new route for the rational design of membrane systems with specific properties. PMID:24942348

  14. A new drug carrier: Magnetite nanoparticles coated with amphiphilic block copolymer

    Institute of Scientific and Technical Information of China (English)

    CHANG Yu; BAI YunPeng; TENG Bao; Li ZhaoLong

    2009-01-01

    This paper reports on the synthesis and characterization of 4 nm magnetite nanoparticles coated with amphiphilic block copolymers of poly(ethyl methacrylate)-b-poly(2-hydroxyethyl methacrylate) (PEMA-b-PHEMA) by surface-initiated atom transfer radical polymerization (ATRP), which can act as new po-tential carriers for hydrophobic targeted drug delivery. Vibrating sample magnetometer analysis indi-cated that the magnetite nanoparticles were superparamagnetic at room temperature. Thermogravim-etric analysis (TGA) was applied to studying the property of surface of magnetite nanoparticles, and the surface density of macromolecules was calculated. The grafting density of oleic acid, BrMPA and PEMA was 5.8, 3.9, 0.16 chain/nm2 respectively, which indicates that the initiation efficiency decreases due to the influence of large space of oleic acid molecules. In vitro progesterone and (-)-isoproterenol hy-drochloride release in phosphate buffered saline (PBS) at pH 7.0 and 37℃ was conducted in order to demonstrate the function of drug loading and release. The results showed that the amount of drug carried into the core-shell Fe3O4@PEMA-b-PHEMA depends on the length of hydrophobic segment of block copolymer. The release of progesterone (37% after 22 h in our previous work) was compared with the release of (-)-isoproterenol hydrochloride (80% after 50 min), demonstrating that the strong hy-drophobic interaction between hydrophobic segment and drug can effectively control the release of hydrophobic drugs.

  15. Chemoenzymatic Synthesis of Amphiphilic Core-Shell TMP-(PCL-b-PGMA2)3 Star-Block Copolymer.

    Science.gov (United States)

    Wang, Shuwei; Li, Yapeng; Zhang, Xiaonan; Chen, Xuesi; Wang, Jingyuan; Zhang, He-Xin; Yoon, Keun-Byoung

    2015-06-01

    A novel well-defined amphiphilic Core-Shell star-block copolymer was synthesized from trimethylolpropane, ε-caprolactone, and glycidyl methacrylate by a combination of enzymatic ring-opening polymerization and atom transfer radical polymerization. The structure and molecular weight of the macroinitiator and the star-block copolymer were confirmed by means of nuclear magnetic resonance and gel permeation chromatography. The effects of the glycidyl methacrylate sequence length on the hydrodynamic diameter and morphology of the polymer micelles were investigated by dynamic light scattering and transmission electron microscopy, respectively. PMID:26369103

  16. Theranostic Unimolecular Micelles Based on Brush-Shaped Amphiphilic Block Copolymers for Tumor-Targeted Drug Delivery and Positron Emission Tomography Imaging

    OpenAIRE

    Guo, Jintang; Hong, Hao; Chen, Guojun; Shi, Sixiang; Nayak, Tapas R.; Theuer, Charles P.; Barnhart, Todd E.; Cai, Weibo; Gong, Shaoqin

    2014-01-01

    Brush-shaped amphiphilic block copolymers were conjugated with a monoclonal antibody against CD105 (i.e., TRC105) and a macrocyclic chelator for 64Cu-labeling to generate multifunctional theranostic unimolecular micelles. The backbone of the brush-shaped amphiphilic block copolymer was poly(2-hydroxyethyl methacrylate) (PHEMA) and the side chains were poly(l-lactide)-poly(ethylene glycol) (PLLA-PEG). The doxorubicin (DOX)-loaded unimolecular micelles showed a pH-dependent drug release profile...

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

    KAUST Repository

    Wang, Shuaipeng

    2014-10-27

    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.

  18. Magnetic core–bilayer shell complex of magnetite nanoparticle stabilized with mPEG–polyester amphiphilic block copolymer

    International Nuclear Information System (INIS)

    In this article, we report the synthesis of magnetite nanoparticles (Fe3O4) coated with methoxy poly(ethylene glycol) (mPEG)–polyester amphiphilic block copolymers. The coating polymer layer contains a hydrophobic inner layer of polyester and a hydrophilic corona of mPEG. The copolymers were first prepared via a direct condensation between diacid, diol compounds and mPEG oligomer to obtain a hydrophobic polyester block and hydrophilic mPEG block and then “grafted onto” a magnetite nanoparticle surface. The copolymer composition was varied by changing the structure of the diacid, diol, and the molecular weight ( M-bar n ) of the mPEG such that particles with good dispersibility and stability in water were obtained. It was found that the copolymer prepared from 1,6-hexanediol can effectively stabilize the particles in water regardless of the types of diacid and M-bar n of mPEG used. The particle size was approximately 10 nm in diameter, and the particle dispersibility in water was quite dependent on the type and concentration of the copolymer used. Thermogravimetric analysis revealed the presence of less than 37 % Fe3O4 and about 48–53 % of the copolymer in the complexes. The percent entrapment efficiency and loading efficiency of indomethacin model drug in the copolymer-coated magnetite nanoparticles were 19 and 77 %, respectively

  19. Magnetic core–bilayer shell complex of magnetite nanoparticle stabilized with mPEG–polyester amphiphilic block copolymer

    Energy Technology Data Exchange (ETDEWEB)

    Mekkapat, Supachai; Thong-On, Bandit; Rutnakornpituk, Boonjira; Wichai, Uthai; Rutnakornpituk, Metha, E-mail: methar@nu.ac.th [Naresuan University, Department of Chemistry and Center of Excellence for Innovation in Chemistry, Faculty of Science (Thailand)

    2013-11-15

    In this article, we report the synthesis of magnetite nanoparticles (Fe{sub 3}O{sub 4}) coated with methoxy poly(ethylene glycol) (mPEG)–polyester amphiphilic block copolymers. The coating polymer layer contains a hydrophobic inner layer of polyester and a hydrophilic corona of mPEG. The copolymers were first prepared via a direct condensation between diacid, diol compounds and mPEG oligomer to obtain a hydrophobic polyester block and hydrophilic mPEG block and then “grafted onto” a magnetite nanoparticle surface. The copolymer composition was varied by changing the structure of the diacid, diol, and the molecular weight ( M-bar {sub n} ) of the mPEG such that particles with good dispersibility and stability in water were obtained. It was found that the copolymer prepared from 1,6-hexanediol can effectively stabilize the particles in water regardless of the types of diacid and M-bar {sub n} of mPEG used. The particle size was approximately 10 nm in diameter, and the particle dispersibility in water was quite dependent on the type and concentration of the copolymer used. Thermogravimetric analysis revealed the presence of less than 37 % Fe{sub 3}O{sub 4} and about 48–53 % of the copolymer in the complexes. The percent entrapment efficiency and loading efficiency of indomethacin model drug in the copolymer-coated magnetite nanoparticles were 19 and 77 %, respectively.

  20. Aggregation and self-assembly of amphiphilic block copolymers in aqueous dispersions of carbon nanotubes.

    Science.gov (United States)

    Shvartzman-Cohen, Rina; Florent, Marc; Goldfarb, Daniella; Szleifer, Igal; Yerushalmi-Rozen, Rachel

    2008-05-01

    The self-assembly (SA) of amphiphilic block copolymers (poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide)) was investigated in dispersions of single-walled and multiwalled carbon nanotubes (SWNT and MWNT, respectively) as a function of temperature. Differential scanning calorimetry (DSC) was used for characterization of the thermal behavior of the combined polymers-nanostructures system, and spin-probe electron paramagnetic resonance (EPR) was employed for probing the local dynamic and polarity of the polymer chains in the presence of nanostructures. It was found that SWNT and MWNT modify the temperature, enthalpy, and dynamic behavior of polymer SA. In particular, SWNT were found to increase the cooperativity of aggregating chains and dominate aggregate dynamics. MWNT reduced the cooperativity, while colloidal carbon black additives, studied for comparison, did not show similar effects. The experimental observations are consistent with the suggestion that dimensional matching between the characteristic radius of the solvated polymer chains and the dimensions of additives dominate polymer SA in the hybrid system. PMID:18355098

  1. Toughening of epoxies based on self-assembly of nano-sized amphiphilic block copolymer micelles

    Science.gov (United States)

    Liu, Jia

    As a part of a larger effort towards the fundamental understanding of mechanical behaviors of polymers toughened by nanoparticles, this dissertation focuses on the structure-property relationship of epoxies modified with nano-sized poly(ethylene-alt-propylene)-b-poly(ethylene oxide) (PEP-PEO) block copolymer (BCP) micelle particles. The amphiphilic BCP toughener was incorporated into a liquid epoxy resin and self-assembled into well-dispersed 15 nm spherical micelle particles. The nano-sized BCP, at 5 wt% loading, can significantly improve the fracture toughness of epoxy (ca. 180% improvement) without reducing modulus at room temperature and exhibits only a slight drop (ca. 5°C) in glass transition temperature (Tg). The toughening mechanisms were found to be BCP micelle nanoparticle cavitation, followed by matrix shear banding, which mainly accounted for the observed remarkable toughening effect. The unexpected "nano-cavitation" phenomenon cannot be predicted by existing physical models. The plausible causes for the observed nano-scale cavitation and other mechanical behaviors may include the unique structural characteristics of BCP micelles and the influence from the surrounding epoxy network, which is significantly modified by the epoxy-miscible PEO block. Other mechanisms, such as crack tip blunting, may also play a role in the toughening. Structure-property relationships of this nano-domain modified polymer are discussed. In addition, other important factors, such as strain rate dependence and matrix crosslink density effect on toughening, have been investigated. This BCP toughening approach and conventional rubber toughening techniques are compared. Insights on the decoupling of modulus, toughness, and Tg for designing high performance thermosetting materials with desirable physical and mechanical properties are discussed.

  2. Amphiphilic block copolymers as flexible membrane materials generating structural and functional mimics of green bacterial antenna complexes.

    Science.gov (United States)

    Collins, A M; Timlin, J A; Anthony, S M; Montaño, G A

    2016-08-11

    We describe the ability of a short-chain amphiphilic block copolymer to self-assemble to form an artificial supramolecular light-harvesting system. Specifically, we demonstrate that the 2.5 kDa, poly(ethylene oxide)-block-poly(butadiene) (PEO-b-PBD), exhibits sufficient morphological flexibility as a membrane material and enables generation of mimics of three-dimensional chlorosomes as well as supported membrane bilayers containing energy acceptors. This overall architecture replicates green bacterial light-harvesting function whereby these assemblies exhibit long-range order and three-dimensional morphology similar to native chlorosomes and are capable of energy transfer internally and to external acceptors, located in a supporting biomimetic polymer membrane. Unlike native green bacterial systems that use multiple lipids as a matrix to generate the appropriate environment for chlorosome assembly and function, the described system matrix is comprised entirely of a single polymer amphiphile. This work demonstrates the potential of short-chain amphiphilic block copolymers in generating self-assembled, bio-mimetic membrane architectures, and in doing so, generates scalable, spatial-energetic landscapes for photonic applications. Finally, the results presented provide evidence of minimal requirements to induce chlorosome-like organization and function. PMID:27481550

  3. Self-assembly of novel amphiphilic block-gradient copolymers of styrene and acrylic acid

    Czech Academy of Sciences Publication Activity Database

    Štěpánek, Petr; Černochová, Zulfiya; Borisova, O.; Billon, L.; Borisov, O.

    Český Krumlov, 2015. s. 34. [Discussion workshop on ( bio )Macromolecular Ionic Systems. 10.05.2015-14.05.2015, Český Krumlov] R&D Projects: GA MŠk(CZ) LH14079 Institutional support: RVO:61389013 Keywords : block copolymers * gradient copolymers * light scattering Subject RIV: CD - Macromolecular Chemistry

  4. Synthesis and Characterization of Biodegradable Amphiphilic Star and Y-Shaped Block Copolymers as Potential Carriers for Vinorelbine

    Directory of Open Access Journals (Sweden)

    Fatemeh Bahadori

    2014-01-01

    Full Text Available Two amphiphilic block copolymers using hydrophobic poly(ε-caprolactone (PCL and hydrophilic poly(ethylene glycol (PEG were successfully synthesized. One of them is an (A-b-B4 type star polymer [(PCL-b-PEG4] and the other one is a Y-shaped PEG–(PCL2. A star-shaped polymer (PCL-b-PEG4 was prepared by ring-opening polymerization (ROP of ε-caprolactone continued by click reaction of (PCL-azide4 and PEG-alkyne. The synthesis of Y-shaped PEG–(PCL2 block copolymer was carried out via Diels-Alder click reaction of a furan protected maleimide end-functionalized PEG (PEG-MI with an anthracene end-functionalized PCL following the ROP of ε-caprolactone. The characterization of micelles is carried out using both materials in aqueous media as drug delivery vehicles, which showed satisfying results and enhanced the cytotoxic effect of the anti-cancer drug vinorelbine (VLB. However, micelles consisted of Y-shaped unimers were found to be more convenient for delivery of hydrophobic drugs such as VLB because they formed in lower concentration, carrying a higher amount of drugs and owing a monomodal distribution. We concluded that the free tails of hydrophobic chains in Y-shaped block copolymer facilitate the assembly of amphiphilic material in water to form micelles.

  5. Stable, polymer-directed and SPION-nucleated magnetic amphiphilic block copolymer nanoprecipitates with readily reversible assembly in magnetic fields

    Science.gov (United States)

    Giardiello, Marco; Hatton, Fiona L.; Slater, Rebecca A.; Chambon, Pierre; North, Jocelyn; Peacock, Anita K.; He, Tao; McDonald, Tom O.; Owen, Andrew; Rannard, Steve P.

    2016-03-01

    The formation of inorganic-organic magnetic nanocomposites using reactive chemistry often leads to a loss of super-paramagnetisim when conducted in the presence of iron oxide nanoparticles. We present here a low energy and chemically-mild process of co-nanoprecipitation using SPIONs and homopolymers or amphiphilic block copolymers, of varying architecture and hydrophilic/hydrophobic balance, which efficiently generates near monodisperse SPION-containing polymer nanoparticles with complete retention of magnetism, and highly reversible aggregation and redispersion behaviour. When linear and branched block copolymers with inherent water-solubility are used, a SPION-directed nanoprecipitation mechanism appears to dominate the nanoparticle formation presenting new opportunities for tailoring and scaling highly functional systems for a range of applications.The formation of inorganic-organic magnetic nanocomposites using reactive chemistry often leads to a loss of super-paramagnetisim when conducted in the presence of iron oxide nanoparticles. We present here a low energy and chemically-mild process of co-nanoprecipitation using SPIONs and homopolymers or amphiphilic block copolymers, of varying architecture and hydrophilic/hydrophobic balance, which efficiently generates near monodisperse SPION-containing polymer nanoparticles with complete retention of magnetism, and highly reversible aggregation and redispersion behaviour. When linear and branched block copolymers with inherent water-solubility are used, a SPION-directed nanoprecipitation mechanism appears to dominate the nanoparticle formation presenting new opportunities for tailoring and scaling highly functional systems for a range of applications. Electronic supplementary information (ESI) available: Additional experimental details, NMR spectra, GPC chromatograms, kinetics experiments, graphs of nanopreciptate aggregation and cycling studies and SPION characterisation. See DOI: 10.1039/c6nr00788k

  6. Amphiphilic Fluorinated Block Copolymer Synthesized by RAFT Polymerization for Graphene Dispersions

    Directory of Open Access Journals (Sweden)

    Hyang Moo Lee

    2016-03-01

    Full Text Available Despite the superior properties of graphene, the strong π–π interactions among pristine graphenes yielding massive aggregation impede industrial applications. For non-covalent functionalization of highly-ordered pyrolytic graphite (HOPG, poly(2,2,2-trifluoroethyl methacrylate-block-poly(4-vinyl pyridine (PTFEMA-b-PVP block copolymers were prepared by reversible addition-fragmentation chain transfer (RAFT polymerization and used as polymeric dispersants in liquid phase exfoliation assisted by ultrasonication. The HOPG graphene concentrations were found to be 0.260–0.385 mg/mL in methanolic graphene dispersions stabilized with 10 wt % (relative to HOPG PTFEMA-b-PVP block copolymers after one week. Raman and atomic force microscopy (AFM analyses revealed that HOPG could not be completely exfoliated during the sonication. However, on-line turbidity results confirmed that the dispersion stability of HOPG in the presence of the block copolymer lasted for one week and that longer PTFEMA and PVP blocks led to better graphene dispersibility. Force–distance (F–d analyses of AFM showed that PVP block is a good graphene-philic block while PTFEMA is methanol-philic.

  7. How the chemical structure influence the dynamics of association of amphiphilic block copolymers

    Czech Academy of Sciences Publication Activity Database

    Deniau-Lejeune, E.; Charbonneau, C.; Borisova, O.; Chassenieux, C.; Colombani, O.; Štěpánek, Petr; Borisov, O.

    Saint-Petersburg: Institute of Macromolecular Compounds RAS, 2014. s. 46. ISBN 978-5-98340-329-1. [International Symposium "Molecular Order and Mobility in Polymer Systems" /8./. 02.06.2014-06.06.2014, St. Petersburg] Institutional support: RVO:61389013 Keywords : block copolymer * nanoparticles Subject RIV: CD - Macromolecular Chemistry

  8. Amphiphilic Fluorinated Block Copolymer Synthesized by RAFT Polymerization for Graphene Dispersions

    OpenAIRE

    Hyang Moo Lee; Suguna Perumal; In Woo Cheong

    2016-01-01

    Despite the superior properties of graphene, the strong π–π interactions among pristine graphenes yielding massive aggregation impede industrial applications. For non-covalent functionalization of highly-ordered pyrolytic graphite (HOPG), poly(2,2,2-trifluoroethyl methacrylate)-block-poly(4-vinyl pyridine) (PTFEMA-b-PVP) block copolymers were prepared by reversible addition-fragmentation chain transfer (RAFT) polymerization and used as polymeric dispersants in liquid phase exfoliation assiste...

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

    Science.gov (United States)

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

    2015-09-16

    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. PMID:26323031

  10. NMR study of thermoresponsive micelles of amphiphilic block copolymers in aqueous solution

    Czech Academy of Sciences Publication Activity Database

    Spěváček, Jiří; Konefal, Rafal; Čadová, Eva

    Zurich: Swiss Federal Institute of Technology, 2014. s. 387. ISBN 978-3-906031-54-5. [Euromar 2014. Magnetic Resonance Conference. 29.06.2014-03.07.2014, Zürich] R&D Projects: GA ČR(CZ) GA13-23392S Institutional support: RVO:61389013 Keywords : thermoresponsive block copolymer * poly(N-isopropylacrylamide) * poly(ethylene glycol) Subject RIV: CD - Macromolecular Chemistry

  11. Amphiphilic block copolymer-stabilized PtRu nanoparticles highly dispersed on multi-walled carbon nanotube for methanol oxidation.

    Science.gov (United States)

    Guo, Dao-Jun; Cai, Peng; You, Jin-Mao

    2012-02-15

    We report a one-pot synthesis of amphiphilic block copolymer-stabilized PtRu nanoparticle modified multi-walled carbon nanotubes (MWCNTs) using RuCl(3)·xH(2)O and H(2)PtCl(6)·6H(2)O as ruthenium and platinum sources, and block copolymer poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) as stabilizer agent. PtRu alloyed nanoparticles with an average diameter of 4.6nm are well decorated homogeneously on the exterior surfaces of the MWCNTs. The electrochemical catalytic activity for methanol oxidation of PtRu/MWCNTs and commercial PtRu/C (E-TEK) is comparatively investigated using cyclic voltammetry and chronoamperometry. It is revealed that the PtRu nanoparticle modified MWCNT samples display an enhanced electrochemical catalytic activity than commercial PtRu/C electrode. These results show that PtRu nanoparticles may find applications to fuel cells. PMID:22104276

  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)

    2008-03-01

    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. Small-angle neutron scattering study on amphiphilic block copolymer in aqueous solutions

    International Nuclear Information System (INIS)

    The small angle neutron scattering has been employed to investigate the structural transition of thermosensitive block copolymer consisting of poly(2-ethoxyethyl vinyl ether-b-2-hydroxyethyl vinyl ether) (EOVE-HOVE) in aqueous solutions. The EOVE-HOVE undergoes micellization with EOVE core of ca. 20 nm in radius and HOVE corona around 17-21degC, depending on the polymer concentration. At higher temperatures, a second transition takes place from micelle to macro-lattice structures with body-centered cubic (bcc) symmetry. The radii of the spheres were quantitatively analyzed by curve fitting with a theoretical scattering function in which the various types of smearing effects, such as polydispersity of spheres, incident beam smearing, and a smearing due to a finite wavelength distribution of the incident neutron beam. (author)

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

    Directory of Open Access Journals (Sweden)

    Alok Chaurasia

    2015-01-01

    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. Phase behavior and rheological analysis of reverse liquid crystals and W/I2, W/H2 gel emulsions using an amphiphilic block copolymer.

    OpenAIRE

    May Masnou, Anna; Aramaki, Kenji; Gutiérrez González, José María, 1953-

    2011-01-01

    This article reports the phase behavior determi- nation of a system forming reverse liquid crystals and the formation of novel disperse systems in the two-phase region. The studied system is formed by water, cyclohexane, and Pluronic L-121, an amphiphilic block copolymer considered of special interest due to its aggregation and structural proper- ties. This system forms reverse cubic (I2) and reverse hexagonal (H2) phases at high polymer concentrations. These reverse phases are of particular ...

  16. 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: yguan@ecust.edu.cn [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)

    2013-01-01

    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.

  17. Unimolecular micelles of amphiphilic cyclodextrin-core star-like block copolymers for anticancer drug delivery.

    Science.gov (United States)

    Xu, Zhigang; Liu, Shiying; Liu, Hui; Yang, Cangjie; Kang, Yuejun; Wang, Mingfeng

    2015-11-11

    Well-defined star-like amphiphilic polymers composed of a β-cyclodextrin core, from which 21 hydrophobic poly(lactic acid) arms and hydrophilic poly(ethylene glycol) arms are grafted sequentially, form robust and uniform unimolecular micelles that are biocompatible and efficient in the delivery of anticancer drugs. PMID:26121632

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

    DEFF Research Database (Denmark)

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

    2015-01-01

    lamellae-forming L-b-AC ionic supramolecules made up of the same parent diblock copolymer, a body of experimental data showing small variations in the repeat distance of the LAM micro-segregated structure (dLAM) could be obtained by making appropriate combinations of X, lsc and m. For such lamellae...

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

    Science.gov (United States)

    Zhao, Yamei; Tian, Wei; Yang, Guang; Fan, Xiaodong

    2014-01-01

    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. PMID:25550733

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

    Directory of Open Access Journals (Sweden)

    Yamei Zhao

    2014-11-01

    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.

  1. Synthesis, micellar properties and application of amphiphilic linear block copolymers with different microstructure but same molecular weight

    OpenAIRE

    Schmitz, Christof Jan Wilhelm

    2009-01-01

    This dissertation is concerned with the synthesis and micellisation behaviour of linear block copolymers based on methacrylates by means of the modern controlled radical polymerisation technique, namely the atom transfer radical polymerisation (ATRP). The objective was the synthesis of linear block copolymers with different microstructure but same molecular weight. The chosen synthesis strategy should be applicable for various monomer pairs with different polarities and should include the use...

  2. 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)

    2010-10-01

    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.

  3. Amphiphilic block-graft copolymer templates for organized mesoporous TiO2 films in dye-sensitized solar cells

    Science.gov (United States)

    Lim, Jung Yup; Lee, Chang Soo; Lee, Jung Min; Ahn, Joonmo; Cho, Hyung Hee; Kim, Jong Hak

    2016-01-01

    Amphiphilic block-graft copolymers composed of poly(styrene-b-butadiene-b-styrene) (SBS) backbone and poly(oxyethylene methacrylate) (POEM) side chains are synthesized and combined with hydrophilically preformed TiO2 (Pre-TiO2), which works as a structural binder as well as titania source. This results in the formation of crack free, 6-μm-thick, organized mesoporous TiO2 (OM-TiO2) films via one-step doctor-blading based on self-assembly of SBS-g-POEM as well as preferential interaction of POEM chains with Pre-TiO2. SBS-g-POEM with different numbers of ethylene oxide repeating units, SBS-g-POEM(500) and SBS-g-POEM(950), are used to form OM-TiO2(500) and OM-TiO2(950), respectively. The efficiencies of dye-sensitized solar cells (DSSCs) with a quasi-solid-state polymer electrolyte reach 5.7% and 5.8% at 100 mW/cm2 for OM-TiO2(500) and OM-TiO2(950), respectively. The surface area of OM-TiO2(950) was greater than that of OM-TiO2(500) but the light reflectance was lower in the former, which is responsible for similar efficiency. Both DSSCs exhibit much higher efficiency than one (4.8%) with randomly-organized particulate TiO2 (Ran-TiO2), which is attributed to the higher dye loading, reduced charge recombination and improved pore infiltration of OM-TiO2. When utilizing poly((1-(4-ethenylphenyl)methyl)-3-butyl-imidazolium iodide) (PEBII) and mesoporous TiO2 spheres as the solid electrolyte and the scattering layer, the efficiency increases up to 7.5%, one of the highest values for N719-based solid-state DSSCs.

  4. Novel 4-Arm Poly(Ethylene Glycol)-Block-Poly(Anhydride-Esters) Amphiphilic Copolymer Micelles Loading Curcumin: Preparation, Characterization, and In Vitro Evaluation

    OpenAIRE

    Li Lv; Yuanyuan Shen; Min Li; Xiaofen Xu; Mingna Li; Shengrong Guo; Shengtang Huang

    2013-01-01

    A novel 4-arm poly(ethylene glycol)-block-poly(anhydride-esters) amphiphilic copolymer (4-arm PEG-b-PAE) was synthesized by esterization of 4-arm poly(ethylene glycol) and poly(anhydride-esters) which was obtained by melt polycondensation of α -, ω -acetic anhydride terminated poly(L-lactic acid). The obtained 4-arm PEG-b-PAE was characterized by 1H-NMR and gel permeation chromatography. The critical micelle concentration of 4-arm PEG-b-PAE was 2.38  μ g/mL. The curcumin-loaded 4-arm PEG-b-PA...

  5. Theranostic unimolecular micelles based on brush-shaped amphiphilic block copolymers for tumor-targeted drug delivery and positron emission tomography imaging.

    Science.gov (United States)

    Guo, Jintang; Hong, Hao; Chen, Guojun; Shi, Sixiang; Nayak, Tapas R; Theuer, Charles P; Barnhart, Todd E; Cai, Weibo; Gong, Shaoqin

    2014-12-24

    Brush-shaped amphiphilic block copolymers were conjugated with a monoclonal antibody against CD105 (i.e., TRC105) and a macrocyclic chelator for (64)Cu-labeling to generate multifunctional theranostic unimolecular micelles. The backbone of the brush-shaped amphiphilic block copolymer was poly(2-hydroxyethyl methacrylate) (PHEMA) and the side chains were poly(L-lactide)-poly(ethylene glycol) (PLLA-PEG). The doxorubicin (DOX)-loaded unimolecular micelles showed a pH-dependent drug release profile and a uniform size distribution. A significantly higher cellular uptake of TRC105-conjugated micelles was observed in CD105-positive human umbilical vein endothelial cells (HUVEC) than nontargeted micelles due to CD105-mediated endocytosis. In contrast, similar and extremely low cellular uptake of both targeted and nontargeted micelles was observed in MCF-7 human breast cancer cells (CD105-negative). The difference between the in vivo tumor accumulation of (64)Cu-labeled TRC105-conjugated micelles and that of nontargeted micelles was studied in 4T1 murine breast tumor-bearing mice, by serial positron emission tomography (PET) imaging and validated by biodistribution studies. These multifunctional unimolecular micelles offer pH-responsive drug release, noninvasive PET imaging capability, together with both passive and active tumor-targeting abilities, thus making them a desirable nanoplatform for cancer theranostics. PMID:24628452

  6. 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;

    2013-01-01

    the samples. The morphology of the microphase separated state was mapped out on 'master' microdomain morphology diagrams as a function of the volume fraction of the AmphComb blocks (Φ AmphComb) and the compositional window of each microdomain morphology was determined. It was observed that, (i) within...... 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...

  7. Self-assembly of block copolymers

    Directory of Open Access Journals (Sweden)

    Hidenori Otsuka

    2001-05-01

    Full Text Available Block copolymers in a selective solvent have a tendency to self-assemble at surfaces and into micelles1–4. At an aqueous interface, the amphiphilic property of block copolymers composed of hydrophilic and hydrophobic segments can cause the distal end of the hydrophilic chain to extend into the bulk aqueous solution, anchoring the hydrophilic block to the substrate surface through hydrophobic segments1, 2. In an aqueous solution, micelles with core-shell structure are formed by the segregation of insoluble blocks into the core, which is surrounded by a hydrophilic shell composed of hydrophilic blocks3, 4. This interfacial activity of amphiphilic block copolymers provides their utility in the biomedical field as colloidal dispersants, surface modifiers and drug carriers, prompting many studies of block copolymer adsorption on solid surfaces5, 6, 7, 8, force measurements between tethered layers9, 10, 11 and the characterization of micelle properties12, 13, 14.

  8. Role of Amphiphilic Block Copolymer Composition on Pore Characteristics of Micelle-Templated Mesoporous Cobalt Oxide Films.

    Science.gov (United States)

    Wang, Siyang; Tangvijitsakul, Pattarasai; Qiang, Zhe; Bhaway, Sarang M; Lin, Kehua; Cavicchi, Kevin A; Soucek, Mark D; Vogt, Bryan D

    2016-04-26

    Block copolymer templating is a versatile approach for the generation of well-defined porosity in a wide variety of framework chemistries. Here, we systematically investigate how the composition of a poly(methoxy poly[ethylene glycol] methacrylate)-block-poly(butyl acrylate) (PMPEG-PBA) template impacts the pore characteristics of mesoporous cobalt oxide films. Three templates with a constant PMPEG segment length and different hydrophilic block volume fractions of 17%, 51%, and 68% for the PMPEG-PBA are cooperatively assembled with cobalt nitrate hexahydrate and citric acid. Irrespective of template composition, a spherical nanostructure is templated and elliptical mesostructures are obtained on calcination due to uniaxial contraction of the film. The average pore size increases from 11.4 ± 2.8 to 48.5 ± 4.3 nm as the length of the PBA segment increases as determined from AFM. For all three templates examined, a maximum in porosity (∼35% in all cases) and surface area is obtained when the precursor solids contain 35-45 wt % PMPEG-PBA. This invariance suggests that the total polymer content drives the structure through interfacial assembly. The composition for maximizing porosity and surface area with the micelle-templating approach results from a general decrease in porosity with increasing cobalt nitrate hexahydrate content and the increasing mechanical integrity of the framework to resist collapse during template removal/crystallization as the cobalt nitrate hexahydrate content increases. Unlike typical evaporation induced self-assembly with sol-gel chemistry, the hydrophilic/hydrophobic composition of the block copolymer template is not a critical component to the mesostructure developed with micelle-templating using metal nitrate-citric acid as the precursor. PMID:27040316

  9. Thermo-Responsive Polyurethane Hydrogels Based on Poly(ε-caprolactone Diol and Amphiphilic Polylactide-Poly(Ethylene Glycol Block Copolymers

    Directory of Open Access Journals (Sweden)

    Shan-hui Hsu

    2016-07-01

    Full Text Available Waterborne polyurethane (PU based on poly(ε-caprolactone (PCL diol and an amphiphilic polylactide-poly(ethylene glycol (PLA-PEG diblock copolymer was synthesized. The molar ratio of PCL/PLA-PEG was 9:1 with different PLA chain lengths. The PU nanoparticles were characterized by dynamic light scattering (DLS, small angle X-ray scattering (SAXS and rheological analysis. The water contact angle measurement, infrared spectroscopy, wide angle X-ray scattering (WAXS, thermal and mechanical analyses were conducted on PU films. Significant changes in physio-chemical properties were observed for PUs containing 10 mol % of amphiphilic blocks. The water contact angle was reduced to 12°–13°, and the degree of crystallinity was 5%–10%. The PU dispersions underwent sol-gel transition upon the temperature rise to 37 °C. The gelation time increased as the PLA chain length increased. In addition, the fractal dimension of each gel was close to that of a percolation cluster. Moreover, PU4 with a solid content of 26% could support the proliferation of human mesenchymal stem cells (hMSCs. Therefore, thermo-responsive hydrogels with tunable properties are promising injectable materials for cell or drug delivery.

  10. Sequence-specific nucleic acid mobility using a reversible block copolymer gel matrix and DNA amphiphiles (lipid-DNA) in capillary and microfluidic electrophoretic separations.

    Science.gov (United States)

    Wagler, Patrick; Minero, Gabriel Antonio S; Tangen, Uwe; de Vries, Jan Willem; Prusty, Deepak; Kwak, Minseok; Herrmann, Andreas; McCaskill, John S

    2015-10-01

    Reversible noncovalent but sequence-dependent attachment of DNA to gels is shown to allow programmable mobility processing of DNA populations. The covalent attachment of DNA oligomers to polyacrylamide gels using acrydite-modified oligonucleotides has enabled sequence-specific mobility assays for DNA in gel electrophoresis: sequences binding to the immobilized DNA are delayed in their migration. Such a system has been used for example to construct complex DNA filters facilitating DNA computations. However, these gels are formed irreversibly and the choice of immobilized sequences is made once off during fabrication. In this work, we demonstrate the reversible self-assembly of gels combined with amphiphilic DNA molecules, which exhibit hydrophobic hydrocarbon chains attached to the nucleobase. This amphiphilic DNA, which we term lipid-DNA, is synthesized in advance and is blended into a block copolymer gel to induce sequence-dependent DNA retention during electrophoresis. Furthermore, we demonstrate and characterize the programmable mobility shift of matching DNA in such reversible gels both in thin films and microchannels using microelectrode arrays. Such sequence selective separation may be employed to select nucleic acid sequences of similar length from a mixture via local electronics, a basic functionality that can be employed in novel electronic chemical cell designs and other DNA information-processing systems. PMID:26095642

  11. Metallo-supramolecular block copolymers : from synthesis to smart nanomaterials

    OpenAIRE

    Guillet, Pierre

    2008-01-01

    Supramolecular copolymers have become of increasing interest in recent years for the search of new materials with tunable properties. In particular, metallo-supramolecular block copolymers have seen important progresses since the last five years. In this thesis, a library of metallo-supramolecular amphiphilic block copolymers containing a hydrophilic block, linked to a hydrophobic block, through a metal-ligand complex has been investigated. The micelles formed in water from these copolymers...

  12. Modulating the self-assembly of amphiphilic X-shaped block copolymers with cyclodextrins: structure and mechanisms.

    Science.gov (United States)

    González-Gaitano, Gustavo; Müller, Céline; Radulescu, Aurel; Dreiss, Cécile A

    2015-04-14

    Inclusion complexes between cyclodextrins and polymers-so-called pseudopolyrotaxanes (PPR)-are at the origin of fascinating supramolecular structures, which are finding increasing uses in biomedical and technological fields. Here we explore the impact of both native and a range of modified cyclodextrins (CD) on the self-assembly of X-shaped poly(ethylene oxide)-poly(propylene oxide) block copolymers, so-called Tetronics or poloxamines, by focusing on Tetronic 904 (T904, Mw 6700). The effects are markedly dependent on the type and arrangement of the substituents on the macrocycle. While native CDs drive the formation of a solid PPR, most substituted CDs induce micellar breakup, with dimethylated β-CD (DIMEB) having the strongest impact and randomly substituted CDs a much weaker disruptive effect. Using native α-CD as a "molecular trap", we perform competitive binding experiments-where two types of CDs thread together onto the polymer chains-to establish that DIMEB indeed has the highest propensity to form an inclusion complex with the polymer, while hydroxypropylated CDs do not thread. 1D (1)H NMR and ROESY experiments confirm the formation of a soluble PPR with DIMEB in which the CD binds preferentially to the PO units, thus providing the drive for the observed demicellization. A combination of dynamic light scattering (DLS) and small-angle neutron scattering (SANS) is used to extract detailed structural parameters on the micelles. A binding model is proposed, which exploits the chemical shifts of selected protons from the CD in conjunction with the Hill equation, to prove that the formation of the PPR is a negatively cooperative process, in which threaded DIMEBs hamper the entrance of subsequent macrocycles. PMID:25785814

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

    DEFF Research Database (Denmark)

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

    2014-01-01

    The aim of this work is to produce polymer modifiers in order to develop hydrophilic polymeric surfaces for use in microfluidics. The use of hydrophilic polymers in microfluidics will have many advantages e.g. preventing protein absorbance. Here we present an amphiphilic diblock copolymer...... 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......-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...

  14. Effect of temperature on self-assembly of amphiphilic block-gradient copolymers of styrene and acrylic acid

    Czech Academy of Sciences Publication Activity Database

    Borisova, O. V.; Billon, L.; Černochová, Zulfiya; Lapp, A.; Štěpánek, Petr; Borisov, O. V.

    Vol. 348 (1). Weinheim: WILEY-VCH Verlag GmbH, 2015, s. 25-32. ISSN 1022-1360. [International Symposium "Molecular Order and Mobility in Polymer Systems" /8./. St. Petersburg (RU), 02.06.2014-06.06.2014] R&D Projects: GA MŠk(CZ) LH14292 Institutional support: RVO:61389013 Keywords : gradient copolymer s * self-assembly * small angle neutron scattering Subject RIV: CC - Organic Chemistry

  15. Synthesis of antibacterial amphiphilic elastomer based on polystyrene-block-polyisoprene-block-polystyrene via thiol-ene addition

    International Nuclear Information System (INIS)

    A new type of amphiphilic antibacterial elastomer has been described. Thermoplastic elastomer, polystyrene–block-polyisoprene–block-polystyrene (PS–b-PI–b-PS) triblock copolymer was functionalized in toluene solution by free radical mercaptan addition in order to obtain an amphiphilic antibacterial elastomer. Thiol terminated PEG was grafted through the double bonds of PS–b-PI–b-PS via free radical thiol-ene coupling reaction. The antibacterial properties of the amphiphilic graft copolymers were observed. The original and the modified polymers were used to create microfibers in an electro-spinning process. Topology of the electrospun micro/nanofibers were studied by using scanning electron microscopy (SEM). The chemical structures of the amphiphilic comb type graft copolymers were elucidated by the combination of elemental analysis, 1H NMR, 13C NMR, GPC and FTIR. - Graphical abstract: Double bonds of polyisoprene units in polystyrene–block-polyisoprene–block-polystyrene triblock copolymer were partially capped with PEG containing mercapto end group via thiol-ene addition in order to obtain antibacterial amphiphilic elastomer. Nano fibers from amphiphilic graft polymers solution were produced by electrospinning. The PEG grafted copolymer inhibits very effectively bacterial growth. Highlights: ► A commercial synthetic elastomer was grafted with PEG to obtain amphiphilic elastomer. ► Amphiphilic elastomer shows antibacterial properties. ► Electrospun micro fibers of the amphiphilic elastomer tend to globular formation

  16. Novel 4-Arm Poly(Ethylene Glycol-Block-Poly(Anhydride-Esters Amphiphilic Copolymer Micelles Loading Curcumin: Preparation, Characterization, and In Vitro Evaluation

    Directory of Open Access Journals (Sweden)

    Li Lv

    2013-01-01

    Full Text Available A novel 4-arm poly(ethylene glycol-block-poly(anhydride-esters amphiphilic copolymer (4-arm PEG-b-PAE was synthesized by esterization of 4-arm poly(ethylene glycol and poly(anhydride-esters which was obtained by melt polycondensation of α-, ω-acetic anhydride terminated poly(L-lactic acid. The obtained 4-arm PEG-b-PAE was characterized by 1H-NMR and gel permeation chromatography. The critical micelle concentration of 4-arm PEG-b-PAE was 2.38 μg/mL. The curcumin-loaded 4-arm PEG-b-PAE micelles were prepared by a solid dispersion method and the drug loading content and encapsulation efficiency of the micelles were 7.0% and 85.2%, respectively. The curcumin-loaded micelles were spherical with a hydrodynamic diameter of 151.9 nm. Curcumin was encapsulated within 4-arm PEG-b-PAE micelles amorphously and released from the micelles, faster in pH 5.0 than pH 7.4, presenting one biphasic drug release pattern with rapid release at the initial stage and slow release later. The hemolysis rate of the curcumin-loaded 4-arm PEG-b-PAE micelles was 3.18%, which was below 5%. The IC50 value of the curcumin-loaded micelles against Hela cells was 10.21 μg/mL, lower than the one of free curcumin (25.90 μg/mL. The cellular uptake of the curcumin-loaded micelles in Hela cell increased in a time-dependent manner. The curcumin-loaded micelles could induce G2/M phase cell cycle arrest and apoptosis of Hela cells.

  17. Structure of adsorption layers of amphiphilic copolymers on inorganic or organic particle surfaces

    OpenAIRE

    Bulychev, Nikolay; Dervaux, Bart; Dimberger, Klaus; Zubov, Vitali; Du Prez, Filip; Eisenbach, Claus D

    2010-01-01

    The structure of adsorption layers of amphiphilic block and block-like copolymers of poly(isobornyl acrylate) and poly(acrylic acid) on the surface of hydrophilic titanium dioxide and hydrophobic copper phthalocyanine (CuPc) pigments in an aqueous studied by the electrokinetic sonic amplitude (ESA) method. The electroacoustic behaviour of the polyelectrolyte block copolymer-coated particles could be described in the context of the polymer gel layer theory. The polymer layer around the particl...

  18. Bactericidal block copolymer micelles.

    Science.gov (United States)

    Vyhnalkova, Renata; Eisenberg, Adi; van de Ven, Theo

    2011-05-12

    Block copolymer micelles with bactericidal properties were designed to deactivate pathogens such as E. coli bacteria. The micelles of PS-b-PAA and PS-b-P4VP block copolymers were loaded with biocides TCMTB or TCN up to 20 or 30 wt.-%, depending on the type of antibacterial agent. Bacteria were exposed to loaded micelles and bacterial deactivation was evaluated. The micelles loaded with TCN are bactericidal; bacteria are killed in less than two minutes of exposure. The most likely interpretation of the data is that the biocide is transferred to the bacteria by repeated micelle/bacteria contacts, and not via the solution. PMID:21275041

  19. Functionalization of Block Copolymer Vesicle Surfaces

    Directory of Open Access Journals (Sweden)

    Wolfgang Meier

    2011-01-01

    Full Text Available In dilute aqueous solutions certain amphiphilic block copolymers self-assemble into vesicles that enclose a small pool of water with a membrane. Such polymersomes have promising applications ranging from targeted drug-delivery devices, to biosensors, and nanoreactors. Interactions between block copolymer membranes and their surroundings are important factors that determine their potential biomedical applications. Such interactions are influenced predominantly by the membrane surface. We review methods to functionalize block copolymer vesicle surfaces by chemical means with ligands such as antibodies, adhesion moieties, enzymes, carbohydrates and fluorophores. Furthermore, surface-functionalization can be achieved by self-assembly of polymers that carry ligands at their chain ends or in their hydrophilic blocks. While this review focuses on the strategies to functionalize vesicle surfaces, the applications realized by, and envisioned for, such functional polymersomes are also highlighted.

  20. Block copolymer battery separator

    Energy Technology Data Exchange (ETDEWEB)

    Wong, David; Balsara, Nitash Pervez

    2016-04-26

    The invention herein described is the use of a block copolymer/homopolymer blend for creating nanoporous materials for transport applications. Specifically, this is demonstrated by using the block copolymer poly(styrene-block-ethylene-block-styrene) (SES) and blending it with homopolymer polystyrene (PS). After blending the polymers, a film is cast, and the film is submerged in tetrahydrofuran, which removes the PS. This creates a nanoporous polymer film, whereby the holes are lined with PS. Control of morphology of the system is achieved by manipulating the amount of PS added and the relative size of the PS added. The porous nature of these films was demonstrated by measuring the ionic conductivity in a traditional battery electrolyte, 1M LiPF.sub.6 in EC/DEC (1:1 v/v) using AC impedance spectroscopy and comparing these results to commercially available battery separators.

  1. Phase behavior and rheological analysis of reverse liquid crystals and W/I2 and W/H2 gel emulsions using an amphiphilic block copolymer.

    Science.gov (United States)

    May, Anna; Aramaki, Kenji; Gutiérrez, José María

    2011-03-15

    This article reports the phase behavior determi-nation of a system forming reverse liquid crystals and the formation of novel disperse systems in the two-phase region. The studied system is formed by water, cyclohexane, and Pluronic L-121, an amphiphilic block copolymer considered of special interest due to its aggregation and structural properties. This system forms reverse cubic (I2) and reverse hexagonal (H2) phases at high polymer concentrations. These reverse phases are of particular interest since in the two-phase region, stable high internal phase reverse emulsions can be formed. The characterization of the I2 and H2 phases and of the derived gel emulsions was performed with small-angle X-ray scattering (SAXS) and rheometry, and the influence of temperature and water content was studied. The H2 phase experimented a thermal transition to an I2 phase when temperature was increased, which presented an Fd3m structure. All samples showed a strong shear thinning behavior from low shear rates. The elastic modulus (G') in the I2 phase was around 1 order of magnitude higher than in the H2 phase. G' was predominantly higher than the viscous modulus (G''). In the gel emulsions, G' was nearly frequency-independent, indicating their gel type nature. Contrarily to water-in-oil (W/O) normal emulsions, in W/I2 and W/H2 gel emulsions, G', the complex viscosity (|η*|), and the yield stress (τ0) decreased with increasing water content, since the highly viscous microstructure of the continuous phase was responsible for the high viscosity and elastic behavior of the emulsions, instead of the volume fraction of dispersed phase and droplet size. A rheological analysis, in which the cooperative flow theory, the soft glass rheology model, and the slip plane model were analyzed and compared, was performed to obtain one single model that could describe the non-Maxwellian behavior of both reverse phases and highly concentrated emulsions and to characterize their microstructure with

  2. Non-Surface Activity of Cationic Amphiphilic Diblock Copolymers

    International Nuclear Information System (INIS)

    Cationic amphiphilic diblock copolymers containing quaternized poly (2-vinylpyridine) chain as a hydrophilic segment (PIp-b-PNMe2VP) were synthesized by living anionic polymerization. By IR measurement, we confirmed the quaternization of the polymer (PIp-b-PNMe2VP), and determined the degree of quaternization by conductometric titration. The surface tension experiment showed that the polymers are non-surface active in nature. The foam formation of the polymer solutions was also investigated with or without added salt. Almost no foam formation behavior was observed without added salt, while a little foam was observed in the presence of 1M NaCl. The critical micelle concentration (cmc) of the diblock copolymers with 3 different chain lengths was measured by the static light scattering method. The cmc values obtained in this study were much lower than the values obtained for anionic non-surface active diblock polymers studied previously. The hydrodynamic radii of the polymer micelle increased slightly in the presence of 1 M NaCl. The transmission electron microscopic images revealed spherical micelles in pure water. In the presence of salt, the cmc values increased as was the case for anionic polymers, which is unlike conventional surfactant systems but consistent with non-surface active anionic block copolymers. The microviscosity of the micelle core was evaluated using Coumarin-153 as a fluorescent anisotropy probe using steady-sate fluorescence depolarization. Non-surface activity has been proved to be universal for ionic amphiphilic block copolymers both for anionic and cationic. Hence, the origin of non-surface activity is not the charged state of water surface itself, but should be an image charge repulsion at the air/water interface.

  3. 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.

    2012-01-01

    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

  4. 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.

    2014-01-01

    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

  5. Hydrophobically modified amphiphilic block copolymer micelles in non-aqueous polar solvents. Fluorometric, light scattering and computer-based Monte Carlo study

    Czech Academy of Sciences Publication Activity Database

    Matějíček, P.; Uhlík, F.; Limpouchová, Z.; Procházka, K.; Tuzar, Zdeněk; Webber, S. E.

    2002-01-01

    Roč. 67, č. 5 (2002), s. 531-556. ISSN 0010-0765 R&D Projects: GA ČR GA203/01/0536 Grant ostatní: GA UK(XC) 215/00 Institutional research plan: CEZ:AV0Z4050913 Keywords : micelles * block copolymers * micellization Subject RIV: CD - Macromolecular Chemistry Impact factor: 0.848, year: 2002

  6. Microphase separation of diblock copolymers with amphiphilic segment

    NARCIS (Netherlands)

    Kriksin, Yury A.; Khalatur, Pavel G.; Erukhimovich, Igor Ya.; ten Brinke, Gerrit; Khokhlov, Alexei R.

    2009-01-01

    We present a statistical mechanical approach for predicting the self-assembled morphologies of amphiphilic diblock copolymers in the melt. We introduce two conformationally asymmetric linear copolymer models with a local structural asymmetry, one of a "comb-tail'' type and another that we call "cont

  7. Protein-Resistant Biodegradable Amphiphilic Graft Copolymer Vesicles as Protein Carriers.

    Science.gov (United States)

    Wang, Yupeng; Yan, Lesan; Li, Bin; Qi, Yanxin; Xie, Zhigang; Jing, Xiabin; Chen, Xuesi; Huang, Yubin

    2015-09-01

    The protein adsorption and self-assembly behavior of biocompatible graft copolymer, poly(lactide-co-diazidomethyl trimethylene carbonate)-g-poly(ethylene glycol) [P(LA-co-DAC)-g-PEG], were systematically studied. The graft copolymers showed enhanced resistance to non-specific protein adsorption compared with their block copolymer counterparts, indicative of the increased effect of PEG density beyond PEG length. Diverse nanostructures including vesicles can be assembled from the amphiphilic graft copolymers with well-defined nano-sizes. Hemoglobin (Hb), as a model protein, can be entrapped in the formed vesicles and keep the gas-binding capacity. The reduced release rate of Hb from graft copolymer vesicles indicated the relatively stable membrane packing compared with block copolymer counterpart. PMID:26036907

  8. Novel amphiphilic diblock copolymers by RAFT-polymerization, their self-organization and surfactant properties

    OpenAIRE

    Garnier, Sébastien

    2006-01-01

    The Reversible Addition Fragmentation Chain Transfer (RAFT) process using the new RAFT agent benzyldithiophenyl acetate is shown to be a powerful polymerization tool to synthesize novel well-defined amphiphilic diblock copolymers composed of the constant hydrophobic block poly(butyl acrylate) and of 6 different hydrophilic blocks with various polarities, namely a series of non-ionic, non-ionic comb-like, anionic and cationic hydrophilic blocks. The controlled character of the polymerizations ...

  9. 两亲性苯乙烯嵌段共聚物的合成及结构表征%Synthesis and Characterization of Styrene Amphiphilic Block Copolymer

    Institute of Scientific and Technical Information of China (English)

    游倩倩; 张二琴; 张予东; 庄玉伟; 张普玉

    2012-01-01

    The block copolymer of polystyrene-b-poly [ oligo ( ethylene oxide ) monomethyl ethermethacrylale]-b-polystyrene(PSt-b-POEOMA-b-PSt) with the end of-COOH functional group has been synthesized by reversible addition fragmentation chain-transfer(RAFT) using S,S'-his(a,a'-dimethyl-α-acetic acid)-trithiocarbonate( BDATC) as the chain transfer agent. Such block copolymer containing hydrophilic end groups can be self-assembled into the core-shell nanoparticles for drug-loaded polymer template. The architecture of the copolymer was confirmed by FTIR,'HNMR spectra and GPC. Furthermore, through thermogravimetric( TG) analysis and differential scanning calorimetry (DSC) ,the thermal properties of the three block copolymers of different proportions were studied. The results show that RAFT polymerization was a successful method for the synthesis of the designed block copolymer: the molecular weight distribution of the controlled block copolymer was about 1. 35. And the block copolymers had good thermal stability: the compatibility of the two components could be speculated by the change of the glass transition temperature( T8).%以α,α’-二甲基-α-乙酸-三硫代碳酸酯(BDATC)为链转移剂,采用可逆-加成-断裂链转移(RAFT)自南基聚合方法合成了末端带有—COOH官能团的两亲性嵌段共聚物聚苯乙烯-b-聚甲基丙烯酸聚乙二醇单甲醚-b-聚苯乙烯(PSt-b-POEOMA-b-PSt),这种含有亲水性端基的嵌段共聚物可以自组装成核-壳结构的纳米微粒,用于载药高分子的模板研究.利用FTIR、1HNMR、GPC对产物结构进行表征,用热失重(TG)和差示扫描量热(DSC)的方法研究了3种不同比例的嵌段共聚物的热性能.实验结果表明,通过RAFT聚合方法得到了所设计的嵌段共聚物,相对分子质量(简称分子量,下同)分布1.35左右;嵌段共聚物的热稳定性较好,通过玻璃化转变温度(Tg)的变化推测出嵌段共聚物中两种嵌段比例对两嵌段相容性的影响.

  10. The Synthesis, Self-Assembly and Self-Organisation of Polysilane Block Copolymers

    OpenAIRE

    Holder, Simon J.; Jones, Richard G.

    2008-01-01

    Block copolymers containing polysilane blocks are unique in that the polysilane components possess electro-active properties and are readily photodegradable. This review will discuss and assess the two major approaches to the synthesis of polysilane block copolymers via pre-formed polymer chain coupling and living polymerisation techniques. The self-organisation of polysilane block copolymers and the morphologies adopted in thin films are reviewed. Amphiphilic polysilane-containing block copo...

  11. Hybrid, Nanoscale Phospholipid/Block Copolymer Vesicles

    Directory of Open Access Journals (Sweden)

    Bo Liedberg

    2013-09-01

    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.

  12. New amphiphilic diblock copolymers: surfactant properties and solubilization in their micelles.

    Science.gov (United States)

    Garnier, Sébastien; Laschewsky, André

    2006-04-25

    Several series of amphiphilic diblock copolymers are investigated as macrosurfactants in comparison to reference low-molar-mass and polymeric surfactants. The various copolymers share poly(butyl acrylate) as a common hydrophobic block but are distinguished by six different hydrophilic blocks (one anionic, one cationic, and four nonionic hydrophilic blocks) with various compositions. Dynamic light scattering experiments indicate the presence of micelles over the whole concentration range from 10(-4) to 10 g x L(-1). Accordingly, the critical micellization concentrations are very low. Still, the surface tension of aqueous solutions of block copolymers decreases slowly but continuously with increasing concentration, without exhibiting a plateau. The longer the hydrophobic block, the shorter the hydrophilic block, and the less hydrophilic the monomer of the hydrophilic block is, the lower the surface tension is. However, the effects are small, and the copolymers reduce the surface tension much less than standard low-molar-mass surfactants. Also, the copolymers foam much less and even act as anti-foaming agents in classical foaming systems composed of standard surfactants. The copolymers stabilize O/W emulsions made of methyl palmitate as equally well as standard surfactants but are less efficient for O/W emulsions made of tributyrine. However, the copolymer micelles exhibit a high solubilization power for hydrophobic dyes, probably at their core-corona interface, in dependence on the initial geometry of the micelles and the composition of the block copolymers. Whereas micelles of copolymers with strongly hydrophilic blocks are stable upon solubilization, solubilization-induced micellar growth is observed for copolymers with moderately hydrophilic blocks. PMID:16618143

  13. Globules of annealed amphiphilic copolymers: Surface structure and interactions

    Science.gov (United States)

    Jarkova, E.; Johner, A.; Maresov, E. A.; Semenov, A. N.

    2006-12-01

    A mean-field theory of globules of random amphiphilic copolymers in selective solvents is developed for the case of an annealed copolymer sequence: each unit can be in one of two states, H (insoluble) or P (soluble or less insoluble). The study is focussed on the regime when H and P units tend to form long blocks, and when P units dominate in the dilute phase, but are rare in the globule core. A first-order coil-to-globule transition is predicted at some T = Tcg. The globule core density at the transition point increases as the affinity of P units to the solvent, tildeɛ, is increased. Two collapse transitions, coil → “loose” globule and “loose” globule → “dense” globule, are predicted if tildeɛ is high enough and P units are marginally soluble or weakly insoluble. H and P concentration profiles near the globule surface are obtained and analyzed in detail. It is shown that the surface excess of P units rises as tildeɛ is increased. The surface tension decreases in parallel. Considering the interaction between close enough surfaces of two globules, we show that they always attract each other at a complete equilibrium. It is pointed out, however, that such equilibrium may be difficult to reach, so that partially equilibrium structures (defined by the condition that a chain forming one globule does not penetrate into the core of the other globule) are relevant. It is shown that at such partial equilibrium the interaction is repulsive, so the globules may be stabilized from aggregation. The strongest repulsion is predicted at the coil-to-globule transition point Tcg: the repulsion force decreases with the distance between the surfaces according to a power law. In the general case (apart from Tcg) the force vs. distance decay becomes exponential; the decay length ξ diverges as T → Tcg. The developed theory explains certain anomalous properties observed for globules of amphiphilic homopolymers.

  14. Amphiphilic Block Copolymer-Toughened Epoxy Resins%两亲性嵌段共聚物增韧环氧树脂

    Institute of Scientific and Technical Information of China (English)

    李宏静; 刘伟区; 魏振杰

    2011-01-01

    Dimethyl siloxane and polyether amine(D-230) of block copolymers were synthesized.Modification on bisphenol A epoxy resin(E-51) was conducted by epoxy-terminated silicone and block copolymer separately.The results show that,using the epoxy-terminated silicone and D-230 of the block copolymer modified epoxy resin(EP) is better than epoxy-terminated silicone of the way epoxy modified.After pre-reaction on EP by epoxy-terminated silicone,the systems containing m(EP)∶m(epoxy-terminated silicone)=100∶4 is found that its Tg reaches 164.81 ℃,which is higher than that of unmodified EP with 1.58 ℃.In addition to improved thermal resistance,the tensile strength almost remains unchanged and elongation rate decreases 38.62% to 30.53%.The impact strength increases from 20.23 kJ/m2 to 32.51 kJ/m2.%合成了端环氧基硅油与聚醚胺(D-230)的嵌段共聚物。采用端环氧基硅油和嵌段共聚物对双酚A型环氧树脂(E-51)进行改性。结果表明,采用端环氧基硅油和D-230的嵌段共聚物改性环氧树脂(EP),效果优于端环氧基硅油改性的方式。采用4份端环氧基硅油预反应改性EP后,Tg由未改性的163.23℃提高到164.81℃。除耐热性有所提高外,其拉伸强度也几乎能保持不变,断裂伸长率由38.62%降低到30.53%,冲击强度由20.23 kJ/m2提高到32.51 kJ/m2。

  15. Multidimensional hierarchical self-assembly of amphiphilic cylindrical block comicelles

    Science.gov (United States)

    Qiu, Huibin; Hudson, Zachary M.; Winnik, Mitchell A.; Manners, Ian

    2015-03-01

    Self-assembly of molecular and block copolymer amphiphiles represents a well-established route to micelles with a wide variety of shapes and gel-like phases. We demonstrate an analogous process, but on a longer length scale, in which amphiphilic P-H-P and H-P-H cylindrical triblock comicelles with hydrophobic (H) or polar (P) segments that are monodisperse in length are able to self-assemble side by side or end to end in nonsolvents for the central or terminal segments, respectively. This allows the formation of cylindrical supermicelles and one-dimensional (1D) or 3D superstructures that persist in both solution and the solid state. These assemblies possess multiple levels of structural hierarchy in combination with existence on a multimicrometer-length scale, features that are generally only found in natural materials.

  16. Interface-enforced complexation between copolymer blocks.

    Science.gov (United States)

    Steinschulte, Alexander A; Xu, Weinan; Draber, Fabian; Hebbeker, Pascal; Jung, Andre; Bogdanovski, Dimitri; Schneider, Stefanie; Tsukruk, Vladimir V; Plamper, Felix A

    2015-05-14

    Binary diblock copolymers and corresponding ternary miktoarm stars are studied at oil-water interfaces. All polymers contain oil-soluble poly(propylene oxide) PPO, water-soluble poly(dimethylaminoethyl methacrylate) PDMAEMA and/or poly(ethylene oxide) PEO. The features of their Langmuir compression isotherms are well related to the ones of the corresponding homopolymers. Within the Langmuir-trough, PEO-b-PPO acts as the most effective amphiphile compared to the other PPO-containing copolymers. In contrast, the compression isotherms show a complexation of PPO and PDMAEMA for PPO-b-PDMAEMA and the star, reducing their overall amphiphilicity. Such complex formation between the blocks of PPO-b-PDMAEMA is prevented in bulk water but facilitated at the interface. The weakly-interacting blocks of PPO-b-PDMAEMA form a complex due to their enhanced proximity in such confined environments. Scanning force microscopy and Monte Carlo simulations with varying confinement support our results, which are regarded as compliant with the mathematical random walk theorem by Pólya. Finally, the results are expected to be of relevance for e.g. emulsion formulation and macromolecular engineering. PMID:25807174

  17. 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

    2013-01-07

    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

  18. Drug-polymer interactions at water-crystal interfaces and implications for crystallization inhibition: molecular dynamics simulations of amphiphilic block copolymer interactions with tolazamide crystals.

    Science.gov (United States)

    Gao, Yi; Olsen, Kenneth W

    2015-07-01

    A diblock copolymer, poly(ethylene glycol)-block-poly(lactic acid) (PEG-b-PLA), modulates the crystal growth of tolazamide (TLZ), resulting in a crystal morphology change from needles to plates in aqueous media. To understand this crystal surface drug-polymer interaction, we conducted molecular dynamics simulations on crystal surfaces of TLZ in water containing PEG-b-PLA. A 130-ns simulation of the polymer in a large water box was run before initiating 50 ns simulations with each of the crystal surfaces. The simulations demonstrated differentiated drug-polymer interactions that are consistent with experimental studies. Interaction of PEG-b-PLA with the (001) face occurred more rapidly (≤10 ns) and strongly (total interaction energy of -121.1 kJ/mol/monomer) than that with the (010) face (∼35 ns, -85.4 kJ/mol/monomer). There was little interaction with the (100) face. Hydrophobic and van der Waals (VDW) interactions were the dominant forces, accounting for more than 90% of total interaction energies. It suggests that polymers capable of forming strong hydrophobic and VDW interactions might be more effective in inhibiting crystallization of poorly water-soluble and hydrophobic drugs in aqueous media (such as gastrointestinal fluid) than those with hydrogen-bonding capacities. Such in-depth analysis and understanding facilitate the rational selection of polymers in designing supersaturation-based enabling formulations. PMID:26045147

  19. Novel Amphiphilic copolymers and design of smart nanoparticule for triggered drug delivery systems

    OpenAIRE

    Cajot, Sébastien; Jérôme, Christine

    2009-01-01

    Over the last decade, polymer micelles attracted an increasing interest in drug pharmaceutical research because they could be used as efficient drug delivery systems. Micelles of amphiphilic block copolymers are supramolecular core-shell type assemblies of tens of nanometers in diameter. In principle, the micelles core is usually constructed with biodegradable hydrophobic polymers such as aliphatic polyesters, e.g. poly(epsilon-caprolactone) (PCL), which serves as a reservoir for the inc...

  20. 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 of...... PP (by its 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....

  1. Chain length dependence of non-surface activity and micellization behavior of cationic amphiphilic diblock copolymers.

    Science.gov (United States)

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

    2014-04-01

    The cationic and anionic amphiphilic diblock copolymers with a critical chain length and block ratio do not adsorb at the air/water interface but form micelles in solution, which is a phenomenon called "non-surface activity". This is primarily due to the high charge density of the block copolymer, which creates a strong image charge effect at the air/water interface preventing adsorption. Very stable micelle formation in bulk solution could also play an important role in the non-surface activity. To further confirm these unique properties, we studied the adsorption and micellization behavior of cationic amphiphilic diblock copolymers of poly(n-butyl acrylate)-b-poly(3-(methacryloyloxy)ethyl)trimethylammonium chloride) (PBA-b-PDMC) with different molecular weights of hydrophobic blocks but with the same ionic block length. These block copolymers were successfully prepared via consecutive reversible addition-fragmentation chain transfer (RAFT) polymerization. The block copolymer with the shortest hydrophobic block length was surface-active; the solution showed surface tension reduction and foam formation. However, above the critical block ratio, the surface tension of the solution did not decrease with increasing polymer concentration, and there was no foam formation, indicating lack of surface activity. After addition of 0.1 M NaCl, stable foam formation and slight reduction of surface tension were observed, which is reminiscent of the electrostatic nature of the non-surface activity. Fluorescence and dynamic and static light scattering measurements showed that the copolymer with the shortest hydrophobic block did not form micelles, while the block copolymers formed spherical micelles having radii of 25-30 nm. These observations indicate that micelle formation is also important for non-surface activity. Upon addition of NaCl, cmc did not decrease but rather increased as observed for non-surface-active block copolymers previously studied. The micelles formed were

  2. Rheological and Mechanical behaviour of Block copolymers, Multigraft copolymers and Block copolymer Nanocomposites

    OpenAIRE

    Thunga, Mahendra

    2009-01-01

    Block copolymers are commercially significant and fundamentally interesting class of polymeric materials. The ability to undergo interfacial thermodynamics-controlled microphase separation from a completely disordered state in the melt to a specifically defined ordered structure through self-organization makes the block copolymers based materials unique. Block copolymer are strongly replacing many of the commercially available polymers due to their unique microstructure and properties. The mo...

  3. Comparing Fluid and Elastic Block Copolymer Shells

    Science.gov (United States)

    Rozairo, Damith; Croll, Andrew B.

    2014-03-01

    Emulsions can be stabilized with the addition of an amphiphilic diblock copolymer, resulting in droplets surrounded and protected by a polymer monolayer. Such droplets show considerable promise as advanced cargo carriers in pharmaceuticals or cosmetics due to their strength and responsiveness. Diblock copolymer interfaces remain mostly fluid and may not be able to attain the mechanical performance desired by industry. To strengthen block copolymer emulsion droplets we have developed a novel method for creating thin elastic shells using polystyrene-b-poly(acrylic acid)-b-polystyrene (PS-PAA-PS). Characterization of the fluid filled elastic shells is difficult with traditional means which lead us to develop a new and general method of mechanical measurement. Specifically, we use laser scanning confocal microscopy to achieve a high resolution measure of the deformation of soft spheres under the influence of gravity. To prove the resilience of the technique we examine both a polystyrene-b-poly(ethylene oxide) (PS-PEO) stabilized emulsion and the PS-PAA-PS emulsion. The mechanical measurement allows the physics of the polymer at the interface to be examined, which will ultimately lead to the rational development of these technologies.

  4. Curvature-coupled hydration of Semicrystalline Polymer Amphiphiles yields flexible Worm Micelles but favors rigid Vesicles: polycaprolactone-based block copolymers

    OpenAIRE

    Rajagopal, Karthikan; Mahmud, Abdullah; Christian, David A.; Pajerowski, J. David; Brown, Andre E. X.; Sharon M Loverde; Discher, Dennis E.

    2010-01-01

    Crystallization processes are in general sensitive to detailed conditions, but our present understanding of underlying mechanisms is insufficient. A crystallizable chain within a diblock copolymer assembly is expected to couple curvature to crystallization and thereby impact rigidity as well as preferred morphology, but the effects on dispersed phases have remained unclear. The hydrophobic polymer polycaprolactone (PCL) is semi-crystalline in bulk (Tm = 60°C) and is shown here to generate fle...

  5. Synthesis of amphiphilic block copolymer via graft polymerization of DAAM and SA%双丙酮丙烯酰胺与海藻酸钠接枝聚合制备双亲性药物载体

    Institute of Scientific and Technical Information of China (English)

    徐亚雷; 倪才华

    2012-01-01

    Amphiphilic DAAM-SA block copolymer was synthesized via graft polymerization of DAAM and SA with potassium persulfate as initiator, the grafting rate can reach 43 % . Through self-assembly in water phase,the product can be formed a micelle with diameter of 300 ~500 nm. The products were characterized by FTIR, TGA, FS, EA, SEM and Zeta potential analysis. The results showed that the negatively charged micelles can be well dispersed and stabilized in water. Then the products cross-linked with calcium ions to form gelatin, which can control the loading and release behavior of model drug ibuprofen, the drug-loading rates was up to 12% .%双丙酮丙烯酰胺(DAAM)与海藻酸钠(SA)进行接枝聚合反应,过硫酸钾作为引发剂,制备了海藻酸钠-双丙酮丙烯酰胺两亲性共聚物,接枝率可以达到43%,该产物在水相中发生自聚集,形成直径300~500 nm的胶束.用红外光谱(FTIR)、热重分析(TGA)、荧光光谱(FS)、元素分析(EA)、扫描电镜(SEM)和Zeta电位对产物进行了表征.结果表明,胶体粒子表面带负电荷,在水中分散,结构稳定.将其用钙离子交联后形成凝胶,对于模型药物布洛芬(ibuprofen)有较好的负载率和缓释行为,载药率可以达到12%.

  6. NANOSTRUCTURES OF FUNCTIONAL BLOCK COPOLYMERS

    Institute of Scientific and Technical Information of China (English)

    Guojun Liu

    2000-01-01

    Nanostructure fabrication from block copolymers in my group normally involves polymer design, synthesis, selfassembly, selective domain crosslinking, and sometimes selective domain removal. Preparation of thin films with nanochannels was used to illustrate the strategy we took. In this particular case, a linear triblock copolymer polyisopreneblock-poly(2-cinnamoylethyl methacrylate)-block-poly(t-butyl acrylate), PI-b-PCEMA-b-PtBA, was used. Films, 25 to50μm thick, were prepared from casting on glass slides a toluene solution of PI-b-PCEMA-b-PtBA and PtBA homopolymer,hPtBA, where hPtBA is shorter than the PtBA block. At the hPtBA mass fraction of 20% relative to the triblock or the total PtBA (hPtBA and PtBA block) volume fraction of 0.44, hPtBA and PtBA formed a seemingly continuous phase in the matrix of PCEMA and PI. Such a block segregation pattern was locked in by photocrosslinking the PCEMA domain. Nanochannels were formed by extracting out hPtBA with solvent. Alternatively, larger channels were obtained from extracting out hPtBA and hydrolyzing the t-butyl groups of the PtBA block. Such membranes were not liquid permeable but had gas permeability constants ~6 orders of magnitude higher than that of low-density polyethylene films.

  7. Interfaces between Block Copolymer Domains

    Science.gov (United States)

    Kim, Jaeup; Jeong, Seong-Jun; Kim, Sang Ouk

    2011-03-01

    Block copolymers naturally form nanometer scale structures which repeat their geometry on a larger scale. Such a small scale periodic pattern can be used for various applications such as storage media, nano-circuits and optical filters. However, perfect alignment of block copolymer domains in the macroscopic scale is still a distant dream. The nanostructure formation usually occurs with spontaneously broken symmetry; hence it is easily infected by topological defects which sneak in due to entropic fluctuation and incomplete annealing. Careful annealing can gradually reduce the number of defects, but once kinetically trapped, it is extremely difficult to remove all the defects. One of the main reasons is that the defect finds a locally metastable morphology whose potential depth is large enough to prohibit further morphology evolution. In this work, the domain boundaries between differently oriented lamellar structures in thin film are studied. For the first time, it became possible to quantitatively study the block copolymer morphology in the transitional region, and it was shown that the twisted grain boundary is energetically favorable compared to the T-junction grain boundary. [Nano Letters, 9, 2300 (2010)]. This theoretical method successfully explained the experimental results.

  8. Anomalous Micellization of Pluronic Block Copolymers

    Science.gov (United States)

    Leonardi, Amanda; Ryu, Chang Y.

    2014-03-01

    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.

  9. Micellization and Dynamics of a Block Copolymer

    DEFF Research Database (Denmark)

    Hvidt, Søren

    2006-01-01

    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 length...... copolymer mixtures, and evidence in favor of a multi-equilibria unimer-micelle model will be presented. Results obtained by liquid chromatographic methods will be shown and it will be demonstrated that commercial EPE copolymers are inhomogeneous at several levels and many of their unusual properties reflect...

  10. Nanostructured Polysulfone-Based Block Copolymer Membranes

    KAUST Repository

    Xie, Yihui

    2016-05-01

    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

  11. PEO-related block copolymer surfactants

    DEFF Research Database (Denmark)

    Mortensen, K.

    2001-01-01

    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 ...

  12. STUDY ON POLYSULFONE-POLYESTER BLOCK COPOLYMERS

    Institute of Scientific and Technical Information of China (English)

    DING Youjun; QI Daquan

    1988-01-01

    Synthesis and characterization of a series of Polysulfone (PSF)-Polyester (PEs) block copolymers were studied.The degree of randomness (B) of these block copolymers was calculated from the intensities of their proton signals in 1H NMR spectra and lies in the region of 0 < B < 1. It was shown that the degree of randomness (B) and the average sequence length (L) in block copolymers were relatively dependent on the reaction conditions, various feed ratios and structure of diols.The phenomenon was observed, when the PSF-PEs block copolymers dissolved in different solvents they had different viscosities and molecular conformations.The PSF-PEs block copolymers had better solvent resistance than homo-polysulfone.

  13. Resilient self-assembling hydrogels from block copolypeptide amphiphiles

    Science.gov (United States)

    Nowak, Andrew Paul

    The ability to produce well defined synthetic polypeptides has been greatly improved by the discovery of transition metal species that mediate the controlled polymerization of N-carboxyanhydrides (NCAs). These metal species create a living polymerization system by producing control over chain length, low polydispersities, and the ability to form complex block architectures. We have applied this system to the synthesis of block copolypeptide amphiphiles. Initial block copolymers synthesized were composed of hydrophilic, cationic poly(L-Lysine) combined with hydrophobic, alpha-helical poly(L-Leucine). These Lysine- block-Leucine copolypeptides were found to form stiff, clear hydrogels at low concentration (˜1 wt%) in low ionic strength water. Based on this unexpected result we used the flexibility of our transition metal polymerization chemistry to better understand the nature and mechanisms of gel formation in these materials. Systematic changes to the original Lysine-block-Leucine copolypeptides were made by altering overall chain size, relative block length, polyelectrolyte charge, and hydrophobic secondary structure. Rheological characterization revealed that the strength of these hydrogels was primarily dependent on degree of polymerization, relative block length, and a well ordered secondary structure in the hydrophobic segment. The Lysine-block-Leucine hydrogels were formed by direct addition of water to dry polypeptide material which swelled to homogeneously fill the entire volume of liquid with no special processing. CryoTEM showed a percolating cellular network at ˜100nm that appears to be comprised of both membranes and fibers. Larger length scales studied with Laser Scanning Confocal Microscopy revealed a spontaneously formed microporous network with large (˜10mum) water rich voids. These hydrogels also displayed interesting mechanical properties including rapid recovery of solid like behavior after being sheared to a liquid and mechanical stability

  14. Adsorption and aqueous lubricating properties of charged and neutral amphiphilic diblock copolymers at a compliant, hydrophobic interface.

    Science.gov (United States)

    Røn, Troels; Javakhishvili, Irakli; Jankova, Katja; Hvilsted, Søren; Lee, Seunghwan

    2013-06-25

    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 and charged PAA buoyant blocks with all other conditions identical, the former showed superior adsorption onto nonpolar, hydrophobic PDMS surfaces from a neutral aqueous solution. PEG-based copolymers showed substantial adsorption for both PS and PMEA as the anchoring block, whereas PAA-based copolymers showed 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-PDMS sliding contact was well correlated with the poor adsorption properties. PAA-b-PMEA copolymers, despite their sizable amount of adsorbed mass, showed insignificant lubricating effects. When the charges of the PAA-b-PMEA diblock copolymers were screened by either adding NaCl to the aqueous solution or by lowering the pH, both the adsorption and lubricity improved. We ascribe the poor adsorption and inferior aqueous lubricating properties of the PAA-based diblock copolymers compared to their PEG-based counterparts mainly to the electrostatic repulsion between charged PAA blocks, hindering the facile formation of the lubricating layer under cyclic tribological stress at the sliding PDMS-PDMS interface. PMID:23725290

  15. Controlling morphology and dynamics of nano-scale assemblies of amphiphilic copolymers in aqueous environment

    Czech Academy of Sciences Publication Activity Database

    Borisova, O. V.; Billon, L.; Grassl, B.; Štěpánek, Petr; Bakaeva, Zulfiya; Zaremski, M.; Zhulina, E. B.; Borisov, O. V.

    Pisa : European Polymer Federation, 2013. O3-7. [European Polymer Congress - EPF 2013. 16.06.2013-21.06.2013, Pisa] Institutional support: RVO:61389013 Keywords : nanoparticles * amphiphilic copolymers Subject RIV: CD - Macromolecular Chemistry

  16. Diblock copolymers comprising poly(2-vinylpyridine-co-acrylonitrile) and polystyrene blocks by nitroxide-mediated radical polymerization

    Czech Academy of Sciences Publication Activity Database

    Lokaj, Jan; Poláková, Lenka; Holler, Petr; Starovoytova, Larisa; Štěpánek, Petr; Diat, O.

    Prague : Institute of Macromolecular Chemistry AS CR, 2006. s. 41. [SONS Networking Activity Workshop: Structure and properties of self-organized amphiphilic copolymers. 04.10.2006-07.10.2006, Prague] R&D Projects: GA ČR GESON/03/E001 Keywords : block copolymers * nitroxide-mediated radical polymerization * 2-vinylpyridine Subject RIV: CD - Macromolecular Chemistry

  17. Acid-Labile Amphiphilic PEO-b-PPO-b-PEO Copolymers: Degradable Poloxamer Analogs.

    Science.gov (United States)

    Worm, Matthias; Kang, Biao; Dingels, Carsten; Wurm, Frederik R; Frey, Holger

    2016-05-01

    Poly ((ethylene oxide)-b-(propylene oxide)-b-(ethylene oxide)) triblock copolymers commonly known as poloxamers or Pluronics constitute an important class of nonionic, biocompatible surfactants. Here, a method is reported to incorporate two acid-labile acetal moieties in the backbone of poloxamers to generate acid-cleavable nonionic surfactants. Poly(propylene oxide) is functionalized by means of an acetate-protected vinyl ether to introduce acetal units. Three cleavable PEO-PPO-PEO triblock copolymers (Mn,total = 6600, 8000, 9150 g·mol(-1) ; Mn,PEO = 2200, 3600, 4750 g·mol(-1) ) have been synthesized using anionic ring-opening polymerization. The amphiphilic copolymers exhibit narrow molecular weight distributions (Ð = 1.06-1.08). Surface tension measurements reveal surface-active behavior in aqueous solution comparable to established noncleavable poloxamers. Complete hydrolysis of the labile junctions after acidic treatment is verified by size exclusion chromatography. The block copolymers have been employed as surfactants in a miniemulsion polymerization to generate polystyrene (PS) nanoparticles with mean diameters of ≈200 nm and narrow size distribution, as determined by dynamic light scattering and scanning electron microscopy. Acid-triggered precipitation facilitates removal of surfactant fragments from the nanoparticles, which simplifies purification and enables nanoparticle precipitation "on demand." PMID:27000789

  18. Functional Nanoporous Polymers from Block Copolymer Precursors

    OpenAIRE

    Guo, Fengxiao

    2010-01-01

    Abstract Self-assembly of block copolymers provides well-defined morphologies with characteristic length scales in the nanometer range. Nanoporous polymers prepared by selective removal of one block from self-assembled block copolymers offer great technological promise due to their many potential applications as, e.g., membranes for separation and purification, templates for nanostructured materials, sensors, substrates for catalysis, low dielectric constant materials, photonic materials, and...

  19. Syntheses of amphiphilic biodegradable copolymers of poly(ethyl ethylene phosphate) and poly(3-hydroxybutyrate) for drug delivery

    Institute of Scientific and Technical Information of China (English)

    CHENG Jing; WANG Jun

    2009-01-01

    Biodegradable and amphiphilic triblock copolymers poly(ethyl ethylene phosphate)-poly(3-hydroxybutyrate)-poly(ethyl ethylene phosphate) (PEEP-b-PHB-b-PEEP) have been successfully synthesized through ring-opening polymerization.The structures are confirmed by gel permeation chromatography and NMR analyses.Crystallization investigated by X-ray diffraction reveals that the block copolymer with higher content of poly(ethyl ethylene phosphate) (PEEP) is more amorphous,showing decreased crystallizability.The obtained copolymers self-assemble into biodegradable nanoparticles with a coreshell micellar structure in aqueous solution,verified by the probe-based fluorescence measurements and transmission electronic microscopy (TEM) observation.The hydrophobic poly(3-hydroxybutyrate) (PHB) block serves as the core of the micelles and the micelles are stabilized by the hydrophilic PEEP block.The size and size distribution are related to the compositions of the copolymers.Paclitaxel (PTX) has been encapsulated into the micelles as a model drug and a sustained drug release from the micelles is observed.MTT assay also demonstrates that the block copolymers are biocompatible,rendering these copolymers attractive for drug delivery.

  20. Syntheses of amphiphilic biodegradable copolymers of poly(ethyl ethylene phosphate) and poly(3-hydroxybutyrate) for drug delivery

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    Biodegradable and amphiphilic triblock copolymers poly(ethyl ethylene phosphate)-poly(3-hydroxybutyrate)-poly(ethyl ethylene phosphate) (PEEP-b-PHB-b-PEEP) have been successfully synthesized through ring-opening polymerization. The structures are confirmed by gel permeation chromatography and NMR analyses. Crystallization investigated by X-ray diffraction reveals that the block copolymer with higher content of poly(ethyl ethylene phosphate) (PEEP) is more amorphous, showing decreased crystallizability. The obtained copolymers self-assemble into biodegradable nanoparticles with a coreshell micellar structure in aqueous solution, verified by the probe-based fluorescence measurements and transmission electronic microscopy (TEM) observation. The hydrophobic poly(3-hydroxybutyrate) (PHB) block serves as the core of the micelles and the micelles are stabilized by the hydrophilic PEEP block. The size and size distribution are related to the compositions of the copolymers. Paclitaxel (PTX) has been encapsulated into the micelles as a model drug and a sustained drug release from the micelles is observed. MTT assay also demonstrates that the block copolymers are biocompatible, rendering these copolymers attractive for drug delivery.

  1. Biodegradable block-copolymer micelles:Synthesis, characterization and radiolabelling for biodistribution studies

    Czech Academy of Sciences Publication Activity Database

    Machová, Luďka; Malinova, V.; Nováková, K.; Lázníček, M.; Koňák, Čestmír; Rypáček, František

    Antalya : Ankara University, Tissue Engineering and Biomaterials Laboratory, 2002. s. P-36. [International Symposium on Biomedical Science and Technology BIOMED /9./. 19.09.2002-22.09.2002, Antalya ] R&D Projects: GA AV ČR IAA4050202 Keywords : amphiphilic block copolymers * micelle * PLA-PEO Subject RIV: CD - Macromolecular Chemistry

  2. Poly(dimethylsiloxane)-poly(ethyleneoxide)-heparin block copolymers. I. Synthesis and characterization

    NARCIS (Netherlands)

    Grainger, D.W.; Kim, S.W.; Feijen, J.

    1988-01-01

    Amphiphilic block copolymers containing poly(dimethylsiloxane), poly(ethylene oxide), and heparin (PDMS-PEO-Hep) have been prepared via a series of coupling reactions using functionalized prepolymers, diisocyanates, and derivatized heparins. All intermediate steps of the synthesis yield quantifiable

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

    DEFF Research Database (Denmark)

    Jankova Atanasova, Katja

    networks and demonstrate good Li+ complexation and conductivity. These make the materials a potential for solid electrolyte applications in Li+ ion batteries (4, 6). iii. Amphiphilic water soluble star block copolymers with a polyacrylic acid core form hydrogels at room temperature above concentration 22g...

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

    NARCIS (Netherlands)

    Li, F.

    2009-01-01

    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

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

    KAUST Repository

    Mugemana, Clement

    2014-01-01

    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.

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

    DEFF Research Database (Denmark)

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

    2014-01-01

    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...

  7. Modification of polylactide surfaces with PLA-b-PEO block copolymers deposited from selective solvents

    Czech Academy of Sciences Publication Activity Database

    Chánová, Eliška; Popelka, Štěpán; Machová, Luďka; Rypáček, František

    New Rochelle: Mary Ann Liebert, Inc, 2008. s. 881 R&D Projects: GA MŠk 1M0538; GA AV ČR(CZ) 1QS500110564 EU Projects: European Commission(XE) 500283 - EXPERTISSUES Institutional research pla n: CEZ:AV0Z40500505 Keywords : amphiphilic block copolymers * polylactide * drug delivery systems Subject RIV: CD - Macromolecular Chemistry

  8. Photo-Induced Micellization of Block Copolymers

    OpenAIRE

    Satoshi Kuwayama; Eri Yoshida

    2010-01-01

    We found novel photo-induced micellizations through photolysis, photoelectron transfer, and photo-Claisen rearrangement. The photolysis-induced micellization was attained using poly(4-tert-butoxystyrene)-block-polystyrene diblock copolymer (PBSt-b-PSt). BSt-b-PSt showed no self-assembly in dichloromethane and existed as isolated copolymers. Dynamic light scattering demonstrated that the copolymer produced spherical micelles in this solvent due to irradiation with a high-pressure mercury lamp ...

  9. Block Copolymer Membranes for Biofuel Purification

    Science.gov (United States)

    Evren Ozcam, Ali; Balsara, Nitash

    2012-02-01

    Purification of biofuels such as ethanol is a matter of considerable concern as they are produced in complex multicomponent fermentation broths. Our objective is to design pervaporation membranes for concentrating ethanol from dilute aqueous mixtures. Polystyrene-b-polydimethylsiloxane-b-polystyrene block copolymers were synthesized by anionic polymerization. The polydimethylsiloxane domains provide ethanol-transporting pathways, while the polystyrene domains provide structural integrity for the membrane. The morphology of the membranes is governed by the composition of the block copolymer while the size of the domains is governed by the molecular weight of the block copolymer. Pervaporation data as a function of these two parameters will be presented.

  10. 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 of...... such PEG-based block copolymers in aqueous suspensions are reviewed. Based on scattering experiments using either X-ray or neutrons, the phase behavior is characterized, showing that the thermo-reversible gelation is a result of micellar ordering into mesoscopic crystalline phases of cubic, hexagonal...

  11. Functional Nanoporous Polymers from Block Copolymer Precursors

    DEFF Research Database (Denmark)

    Guo, Fengxiao

    functionalities remains a great challenge due to the limitation of available polymer synthesis and the nanoscale confinement of the porous cavities. The main topic of this thesis is to develop methods for fabrication of functional nanoporous polymers from block copolymer precursors. A method has been developed......Abstract Self-assembly of block copolymers provides well-defined morphologies with characteristic length scales in the nanometer range. Nanoporous polymers prepared by selective removal of one block from self-assembled block copolymers offer great technological promise due to their many potential......, where living anionic polymerization and atom transfer radical polymerization (ATRP) are combined to synthesize a polydimethylsiloxane-b-poly(tert-butyl acrylate)-b-polystyrene (PDMS-b-PtBA-b-PS) triblock copolymer precursor. By using either anhydrous hydrogen fluoride or trifluoroacetic acid, PtBA block...

  12. Self-Assembly of Novel Amphiphilic 21-Arm, Star-Like Coil-Rod Diblock Copolymers at Interfaces

    Science.gov (United States)

    Lin, Zhiqun; Zhao, Lei; Pang, Xinchang; Feng, Chaowei

    2012-02-01

    A series of novel amphiphilic 21-arm, star-like diblock copolymers, poly(acrylic acid)-b-poly(3-hexylthiophene) (PAA-b-P3HT) based on β-cyclodextrin (β-CD) with well defined molecular architectures and ratio of two chemically distinct blocks were prepared, for the first time, via a combination of quasi-living Grignard metathesis method (GRIM), click reaction, and atom transfer radical polymerization (ATRP). The star-like PAA-b-P3HT diblock copolymers consist of hydrophilic coil-like PAA cores and hydrophobic rod-like P3HT shells with narrow molecular weight distribution and controllable molecular weight of each block. Owing to the compact structure, the amphiphilic star-like PAA-b-P3HT formed a unimolecular micelle. Vesicles based on these novel amphiphilic star-like, coil-rod diblock copolymers were readily produced at the oil/water interface by crosslinking hydrophilic coil-like PAA cores with a bifunctional crosslinker, ethylenediamine. They also self-assembled into a nanotubular structure at the air/water interface.

  13. Block copolymer membranes for aqueous solution applications

    KAUST Repository

    Nunes, Suzana Pereira

    2016-03-22

    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.

  14. Preparation and evaluation of a linoleic-acid-modified amphiphilic polypeptide copolymer as a carrier for controlled drug release

    International Nuclear Information System (INIS)

    In the present study, we describe the synthesis, characterization and self-assembly of a novel amphiphilic linoleic acid (LA)-modified polypeptide copolymer and its drug release behavior in vitro as well. Initially, an amphiphilic ABA triblock copolymer comprising polytetrahydrofuran (PTHF) as a central hydrophobic block and poly(L-lysine)s as outer hydrophilic blocks was prepared via the ring-opening polymerization of ε-benzyloxycarbonyl-L-lysine N-carboxyanhydride with a distal amine-terminated PTHF as a macroinitiator, followed by the removal of the protecting group. The resulting triblock copolymer was then reacted with linoleic acid in the presence of N-ethyl-N'-(3-dimethylaminopropyl)carbodiimide hydrochloride (EDC.HCl)/N-hydroxysuccinimide (HOSu) to give rise to a target LA-modified polypeptide copolymer. It was found to self-assemble into nanoparticles in water. Its critical aggregation concentration was assessed by fluorescence measurement with N-phenyl-1-naphthylamine employed as a molecular probe. The particle sizes of the aggregates were determined by dynamic light scattering, and the aggregate morphologies were evidenced by transmission electron microscopy measurements. Finally, the drug-loading capacity and release behavior in vitro were investigated by using doxorubicin as a model drug.

  15. Rapid self-assembly of block copolymers to photonic crystals

    Energy Technology Data Exchange (ETDEWEB)

    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.

    2016-07-05

    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.

  16. Controlled hydrophobic functionalization of natural fibers through self-assembly of amphiphilic diblock copolymer micelles.

    Science.gov (United States)

    Aarne, Niko; Laine, Janne; Hänninen, Tuomas; Rantanen, Ville; Seitsonen, Jani; Ruokolainen, Janne; Kontturi, Eero

    2013-07-01

    The functionalization of natural fibers is an important task that has recently received considerable attention. We investigated the formation of a hydrophobic layer from amphiphilic diblock copolymer micelles [polystyrene-block-poly(N-methyl-4-vinyl pyridinium iodide)] on natural fibers and on a model surface (mica). A series of micelles were prepared. The micelles were characterized by using cryoscopic TEM and light scattering, and their hydrophobization capability was studied through contact angle measurements, water adsorption, and Raman imaging. Mild heat treatment (130 °C) was used to increase the hydrophobization capability of the micelles. The results showed that the micelles could not hydrophobize a model surface, but could render the natural fibers water repellent both with and without heat treatment. This effect was systematically studied by varying the composition of the constituent blocks. The results showed that the micelle size (and the molecular weight of the constituent diblock copolymers) was the most important parameter, whereas the cationic (hydrophilic) part played only a minor role. We hypothesized that the hydrophobization effect could be attributed to a combination of the micelle size and the shrinkage of the natural fibers upon drying. The shrinking caused the roughness to increase on the fiber surface, which resulted in a rearrangement of the self- assembled layer in the wet state. Consequently, the fibers became hydrophobic through the roughness effects at multiple length scales. Mild heat treatment melted the micelle core and decreased the minimum size necessary for hydrophobization. PMID:23687082

  17. Micelle assembly. Multidimensional hierarchical self-assembly of amphiphilic cylindrical block comicelles.

    Science.gov (United States)

    Qiu, Huibin; Hudson, Zachary M; Winnik, Mitchell A; Manners, Ian

    2015-03-20

    Self-assembly of molecular and block copolymer amphiphiles represents a well-established route to micelles with a wide variety of shapes and gel-like phases. We demonstrate an analogous process, but on a longer length scale, in which amphiphilic P-H-P and H-P-H cylindrical triblock comicelles with hydrophobic (H) or polar (P) segments that are monodisperse in length are able to self-assemble side by side or end to end in nonsolvents for the central or terminal segments, respectively. This allows the formation of cylindrical supermicelles and one-dimensional (1D) or 3D superstructures that persist in both solution and the solid state. These assemblies possess multiple levels of structural hierarchy in combination with existence on a multimicrometer-length scale, features that are generally only found in natural materials. PMID:25792323

  18. Asymmetrical Self-assembly From Fluorinated and Sulfonated Block Copolymers in Aqueous Media

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Xiaojun [ORNL; Hong, Kunlun [ORNL; Baskaran, Durairaj [University of Tennessee, Knoxville (UTK); Goswami, Monojoy [ORNL; Sumpter, Bobby G [ORNL; Mays, Jimmy [ORNL

    2011-01-01

    Block copolymers of fluorinated isoprene and partially sulfonated styrene form novel tapered rods and ribbon-like micelles in aqueous media due to a distribution of sulfonation sites and a large Flory-Huggins interaction parameter. A combination of microscopy, light scattering, and simulation demonstrates the presence of these unique nanostructures. This study sheds light on the micellization behavior of amphiphilic block polymers by revealing a new mechanism of self-assembly.

  19. Thermally sensitive block copolymer hydrogels in bulk and with decreased dimensions

    OpenAIRE

    Nykänen, Antti

    2013-01-01

    The research on stimuli-responsive polymers has increased rapidly during the last two decades. Poly(N-isopropylacrylamide) (PNIPAM) is one of the most studied thermally responsive polymer because its lower critical solution temperature (LCST) 32 ℃ is close to the ambient conditions. Below 32 ℃, PNIPAM is water soluble, but at temperatures above 32 ℃ the polymer phase separates from water. In this thesis, amphiphilic triblock copolymer polystyrene-block-poly(N-isopropylacrylamide)-block-polys...

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

    International Nuclear Information System (INIS)

    Graphical abstract: TEM image of Pt nanoparticles produced by reducing by NaBH4 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

  1. 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: nhoda@akdeniz.edu.tr [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)

    2013-09-01

    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.

  2. 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.;

    1997-01-01

    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...... 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...

  3. An amphiphilic graft copolymer-based nanoparticle platform for reduction-responsive anticancer and antimalarial drug delivery

    Science.gov (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

    2016-08-01

    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

  4. 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...... depending on block length ratios and temperature. The micellization process with increasing temperature or concentration has been followed by a number of techniques including differential scanning calorimetry and surface tension measurements. The detailed micellar mechanism is not well understood and...... different models have been proposed. Results obtained by a range of liquid chromatographic methods will be shown and it will be demonstrated that commercial EPE copolymers are inhomogeneous at several levels and many of their unusual properties reflect the presence of impurities....

  5. ADVANCES IN MICROEMULSION PHASE ON SELF-ASSEMBLY AND MICELLE EXTRACTION WITH BLOCK COPOLYMERS

    Institute of Scientific and Technical Information of China (English)

    Chen Guo; Hao Wen; Huizhou Liu

    2005-01-01

    In this paper we review our work on self-assembly of the system, poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) (PEO-PPO-PEO) block copolymers, which is a kind of macromolecular complex fluids. The control of self-assembly could be obtained by adding inorganic salts or aliphatic alcohols. By self-assembly of amphiphilic block copolymers, a microemulsion phase is formed, which could be applied in micelle extraction, such as hollow-fiber membrane micelle extraction, magnetic micelle extraction and immobilized micelle extraction.

  6. Flow-directed block copolymer micelle morphologies via microfluidic self-assembly.

    Science.gov (United States)

    Wang, Chih-Wei; Sinton, David; Moffitt, Matthew G

    2011-11-23

    The self-assembly of amphiphilic block copolymers in a gas-liquid microfluidic reactor produces variable, flow-directed micellar morphologies entirely different from off-chip equilibrium structures. A polystyrene-block-poly(acrylic acid) copolymer, which forms exclusively spheres off-chip, generates kinetic cylinders, Y-junctions, bilayers, and networks by a mechanism of collision-coalescence enabled by strong and localized on-chip shear fields. Variation in the size and relative amount of flow-directed nanostructures is achieved by changing the water content and flow rate. These results demonstrate on-chip processing routes to specific functional colloidal nanostructures. PMID:21992654

  7. Substrate tolerant direct block copolymer nanolithography

    DEFF Research Database (Denmark)

    Li, Tao; Wang, Zhongli; Schulte, Lars;

    2016-01-01

    simplifies the main stream BC lithography process, showing a broad substrate tolerance and allowing for efficient pattern transfer over wafer scale. PDMS-rich poly(styrene-b-dimethylsiloxane) (PS-b-PDMS) copolymers are directly applied on substrates including polymers, silicon and graphene. A single oxygen......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....

  8. Amphiphilic Surface Active Triblock Copolymers with Mixed Hydrophobic and Hydrophilic Side Chains for Tuned Marine Fouling-Release Properties

    Energy Technology Data Exchange (ETDEWEB)

    Park, D.; Weinman, C; Finlay, J; Fletcher, B; Paik, M; Sundaram, H; Dimitriou, M; Sohn, K; Callow, M; et al.

    2010-01-01

    Two series of amphiphilic triblock surface active block copolymers (SABCs) were prepared through chemical modification of two polystyrene-block-poly(ethylene-ran-butylene)-block-polyisoprene ABC triblock copolymer precursors. The methyl ether of poly(ethylene glycol) [M{sub n} {approx} 550 g/mol (PEG550)] and a semifluorinated alcohol (CF{sub 3}(CF{sub 2}){sub 9}(CH{sub 2}){sub 10}OH) [F10H10] were attached at different molar ratios to impart both hydrophobic and hydrophilic groups to the isoprene segment. Coatings on glass slides consisting of a thin layer of the amphiphilic SABC deposited on a thicker layer of an ABA polystyrene-block-poly(ethylene-ran-butylene)-block-polystyrene thermoplastic elastomer were prepared for biofouling assays with algae. Dynamic water contact angle analysis, X-ray photoelectron spectroscopy (XPS) and near-edge X-ray absorption fine structure (NEXAFS) measurements were utilized to characterize the surfaces. Clear differences in surface structure were realized as the composition of attached side chains was varied. In biofouling assays, the settlement (attachment) of zoospores of the green alga Ulva was higher for surfaces incorporating a large proportion of the hydrophobic F10H10 side chains, while surfaces with a large proportion of the PEG550 side chains inhibited settlement. The trend in attachment strength of sporelings (young plants) of Ulva did not show such an obvious pattern. However, amphiphilic SABCs incorporating a mixture of PEG550 and F10H10 side chains performed the best. The number of cells of the diatom Navicula attached after exposure to flow decreased as the content of PEG550 to F10H10 side chains increased.

  9. Thermodynamic Interactions in Organometallic Block Copolymers

    International Nuclear Information System (INIS)

    The thermodynamic interactions in anionically synthesized poly(styrene-block-ferrocenyldimethylsilane) (SF) copolymers were examined using birefringence, small angle X-ray and neutron scattering (SAXS and SANS). We show that birefringence detection of the order-disorder transition is possible in colored samples provided the wavelength of the incident beam is in the tail of the absorption spectrum. The location of the order-disorder transition was confirmed by SAXS. The temperature-dependence of the Flory-Huggins parameter, χ, of SF copolymers, determined by SAXS, is similar in magnitude to that between polystyrene and polyisoprene chains. We find that χ is independent of block copolymer composition (within experimental error). We also demonstrate that the neutron scattering length densities of styrene and ferrocenyldimethylsilane moieties are identical due to a surprising cancellation of factors related to density and atomic composition

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

    DEFF Research Database (Denmark)

    Ek, Pramod Kumar

    This thesis investigated the role of amphiphilic triblock copolymer micelle nanomaterials in nanosensors, with emphasis on the synthesis of micelle particle sensors. The thesis is focused on the role of synthetic and dimensional synthetic organic chemistry in amphiphilic triblock core...... micelles. Shell cross-linking on PEG-b-PAEMA-b-PS micelles was performed by amidation reactions between the amino groups of PAEMA blocks using a di-carboxylic acid cross-linker. Also a dendritic cross-linker based click chemistry was used to stabilize the PEG-b-PAEMA-b-PES micelle having click readied PES...

  11. Block and Graft Copolymers of Polyhydroxyalkanoates

    Science.gov (United States)

    Marchessault, Robert H.; Ravenelle, François; Kawada, Jumpei

    2004-03-01

    Polyhydroxyalkanoates (PHAs) were modified for diblock copolymer and graft polymer by catalyzed transesterification in the melt and by chemical synthesis to extend the side chains of the PHAs, and the polymers were studied by transmission electron microscopy (TEM) X-ray diffraction, thermal analysis and nuclear magnetic resonance (NMR). Catalyzed transesterification in the melt is used to produce diblock copolymers of poly[3-hydroxybutyrate] (PHB) and monomethoxy poly[ethylene glycol] (mPEG) in a one-step process. The resulting diblock copolymers are amphiphilic and self-assemble into sterically stabilized colloidal suspensions of PHB crystalline lamellae. Graft polymer was synthesized in a two-step chemical synthesis from biosynthesized poly[3-hydroxyoctanoate-co-3-hydroxyundecenoate] (PHOU) containing ca. 25 mol chains. 11-mercaptoundecanoic acid reacts with the side chain alkenes of PHOU by the radical addition creating thioether linkage with terminal carboxyl functionalities. The latter groups were subsequently transformed into the amide or ester linkage by tridecylamine or octadecanol, respectively, producing new graft polymers. The polymers have different physical properties than poly[3-hydroxyoctanoate] (PHO) which is the main component of the PHOU, such as non-stickiness and higher thermal stability. The combination of biosynthesis and chemical synthesis produces a hybrid thermoplastic elastomer with partial biodegradability.

  12. 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; Hvilsted, Søren; Lee, Seunghwan

    2014-01-01

    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...

  13. Transport of Water in Semicrystalline Block Copolymer Membranes

    Science.gov (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.

  14. Novel pH or thermosensitive block copolymers for triggered drug-delivery systems

    OpenAIRE

    Jérôme, Christine

    2007-01-01

    Over the last decade, polymer micelles and nanoparticles have attracted an increasing interest as efficient drug delivery systems. Polymer micelles from amphiphilic block copolymers are supramolecular core-shell type assemblies of some tens of nanometers in diameter. They are highly stable in aqueous solution because of their low intrinsic critical micelle concentration, which prevents their dissociation upon dilution in the blood stream after intravenous injection. The combination of poly(e...

  15. Poly(dimethylsiloxane)-poly(ethyleneoxide)-heparin block copolymers. I. Synthesis and characterization

    OpenAIRE

    D.W. Grainger; S. W. Kim; Feijen, J.

    1988-01-01

    Amphiphilic block copolymers containing poly(dimethylsiloxane), poly(ethylene oxide), and heparin (PDMS-PEO-Hep) have been prepared via a series of coupling reactions using functionalized prepolymers, diisocyanates, and derivatized heparins. All intermediate steps of the synthesis yield quantifiable products with reactive end-groups, while the final products demonstrate bioactive, covalently bound heparin moieties. Due to the solvent systems required, commercial sodium heparin was converted t...

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

    OpenAIRE

    Li, F

    2009-01-01

    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 can serve as containers or templates for different nanotechnological applications. Polymer vesicles, for example, can encapsulate both hydrophobic and hydrophilic molecules, and are therefore cons...

  17. Regulating block copolymer phases via selective homopolymers

    International Nuclear Information System (INIS)

    The phase behavior of strongly segregated AB diblock copolymer and selective C homopolymer blends is examined theoretically using a combination of strong stretching theory (SST) and self-consistent field theory (SCFT). The C-homopolymer is immiscible with the B-blocks but strongly attractive with the A-blocks. The effect of homopolymer content on the order-order phase transitions is analyzed. It is observed that, for AB diblock copolymers with majority A-blocks, the addition of the C-homopolymers results in lamellar to cylindrical to spherical phase transitions because of the A/C complexation. For diblock copolymers with minor A-blocks, adding C-homopolymers leads to transitions from spherical or cylindrical morphology with A-rich core to lamellae to inverted cylindrical and spherical morphologies with B-rich core. The results from analytical SST and numerical SCFT are in good agreement within most regions of the phase diagram. But the deviation becomes more obvious when the composition of A-blocks is too small and the content of added C-homopolymers is large enough, where the SCFT predicts a narrow co-existence region between different ordered phases. Furthermore, it is found that the phase behavior of the system is insensitive to the molecular weight of C-homopolymer

  18. pH and ionic strength responsive polyelectrolyte block copolymer micelles prepared by ring opening metathesis polymerization

    NARCIS (Netherlands)

    Stubenrauch, K.; Voets, I.K.; Popovski, G.F.; Trimmel, G.

    2009-01-01

    Well-defined amphiphilic block copolymers were prepared by ring opening metathesis polymerization and their stimuli responsive behavior of formed micelles in aqueous solution was investigated. The hydrophobic core of the micelles consists of either a poly[5,6-bis(ethoxymethyl)bicyclo[2.2.1]hept-2-en

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

    Energy Technology Data Exchange (ETDEWEB)

    Michael Duane Determan

    2005-12-17

    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

  20. Synthesis of carboxylic block copolymers via reversible addition fragmentation transfer polymerization for tooth erosion prevention.

    Science.gov (United States)

    Lei, Y; Wang, T; Mitchell, J W; Qiu, J; Kilpatrick-Liverman, L

    2014-12-01

    Dental professionals are seeing a growing population of patients with visible signs of dental erosion. The approach currently being used to address the problem typically leverages the enamel protection benefits of fluoride. In this report, an alternative new block copolymer with a hydrophilic polyacrylic acid (PAA) block and a hydrophobic poly(methyl methacrylate) (PMMA) block was developed to similarly reduce the mineral loss from enamel under acidic conditions. This series of PMMA-b-PAA block copolymers was synthesized by reversible addition fragmentation transfer (RAFT) polymerization. Their structures were characterized by gel permeation chromatography (GPC) and (1)H nuclear magnetic resonance (NMR) spectra. The molar fractions of acrylic acid (AA) in the final block copolymer were finely controlled from 0.25 to 0.94, and the molecular weight (Mn) of PMMA-b-PAA was controlled from 10 kDa to 90 kDa. The binding capability of the block copolymer with hydroxyapatite (HAP) was investigated by ultraviolet-visible spectroscopy (UV-Vis) and Fourier transform infrared (FTIR) spectroscopy. FTIR spectra confirmed that the PMMA-b-PAA block copolymer could bind to HAP via bridging bidentate bonds. Both UV-Vis and FTIR spectra additionally indicated that a high polymer concentration and low solution pH favored the polymer binding to HAP. The erosion-preventing efficacy of the PMMA-b-PAA block copolymer in inhibiting HAP mineral loss was quantitatively evaluated by atomic absorption spectroscopy (AAS). Based on the results, polymer treatment reduced the amount of calcium released by 27% to 30% in comparison with the unprotected samples. Scanning electron microscope (SEM) observations indicated that PMMA-b-PAA polymer treatment protected enamel from acid erosion. This new amphiphilic block copolymer has significant potential to be integrated into dentifrices or mouthrinses as an alternative non-fluoride ingredient to reduce tooth erosion. PMID:25248611

  1. Dynamics of Block Copolymer Nanocomposites

    Energy Technology Data Exchange (ETDEWEB)

    Mochrie, Simon G. J.

    2014-09-09

    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.

  2. NOVEL AMPHIPHILIC FLUORESCENT GRAFT COPOLYMER: SYNTHESIS,CHARACTERIZATION AND ENCAPSULATION OF A HYDROPHOBIC AGENT

    Institute of Scientific and Technical Information of China (English)

    Zhao-qiang Wu; Shu Yang; Wen-yan Liao; Ling-zhi Meng

    2006-01-01

    Novel amphiphilic fluorescent graft copolymer (PVP-PyAHy) was successfully synthesized by the free radical copolymerization of hydrophobic monomer N-(1-pyrenebutyryl)-N'-acryloyl hydrazide (PyAHy) with hydrophilic precursor polymers of vinyl-functionalized poly(N-vinylpyrrolidone) (PVP) in DMF. The copolymer is amphiphilic and has intrinsic fluorescence. FT-IR, 1H-NMR, TEM, gel permeation chromatography-multi-angle laser light scattering, UV-Vis spectroscopy and fluorescence spectroscopy were used to characterize this copolymer. The TEM observation shows that the copolymer PVP-PyAHy forms micelles in aqueous solution. Results of fluorometric measurements illustrate that the critical micelle concentration (CMC) value of PVP-PyAHy in aqueous solution is about 0.90 mg/mL. To examine the encapsulation ability of the copolymer in aqueous media, methyl yellow was employed as a model hydrophobic agent. The loading level of the polymer to methyl yellow is 8.8 mg/g. The cytotoxicity assays for Madin Darby Canine Kidney (MDCK) cells shows good biocompatibility of PVP-PyAHy in vitro. These results suggest the potential of this copolymer PVP-PyAHy as drugs delivery carrier and fluorescent tracer.

  3. Materials Design for Block Copolymer Lithography

    Science.gov (United States)

    Sweat, Daniel Patrick

    Block copolymers (BCPs) have attracted a great deal of scientific and technological interest due to their ability to spontaneously self-assemble into dense periodic nanostructures with a typical length scale of 5 to 50 nm. The use of self-assembled BCP thin-films as templates to form nanopatterns over large-area is referred to as BCP lithography. Directed self-assembly of BCPs is now viewed as a viable candidate for sub-20 nm lithography by the semiconductor industry. However, there are multiple aspects of assembly and materials design that need to be addressed in order for BCP lithography to be successful. These include substrate modification with polymer brushes or mats, tailoring of the block copolymer chemistry, understanding thin-film assembly and developing epitaxial like methods to control long range alignment. The rational design, synthesis and self-assembly of block copolymers with large interaction parameters (chi) is described in the first part of this dissertation. Two main blocks were chosen for introducing polarity into the BCP system, namely poly(4-hydroxystyrene) and poly(2-vinylpyridine). Each of these blocks are capable of ligating Lewis acids which can increase the etch contrast between the blocks allowing for facile pattern transfer to the underlying substrate. These BCPs were synthesized by living anionic polymerization and showed excellent control over molecular weight and dispersity, providing access to sub 5-nm domain sizes. Polymer brushes consist of a polymer chain with one end tethered to the surface and have wide applicability in tuning surface energy, forming responsive surfaces and increasing biocompatibility. In the second part of the dissertation, we present a universal method to grow dense polymer brushes on a wide range of substrates and combine this chemistry with BCP assembly to fabricate nanopatterned polymer brushes. This is the first demonstration of introducing additional functionality into a BCP directing layer and opens up

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

    International Nuclear Information System (INIS)

    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 (Dh) 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 C19 to 19.2 nm for C57). Furthermore, increasing the polyoxazoline (i.e., hydrophilic block) length leads to a moderate linear increase of the Dh-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 copolymers based on

  5. 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: Christophe.Travelet@cermav.cnrs.fr [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

    2013-06-15

    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

  6. Single-chain crosslinked star polymers via intramolecular crosslinking of self-folding amphiphilic copolymers in water

    OpenAIRE

    Terashima, Takaya; Sugita, Takanori; Sawamoto, Mitsuo

    2015-01-01

    Single-chain crosslinked star polymers with multiple hydrophilic short arms and a hydrophobic core were created as novel microgel star polymers of single polymer chains. The synthetic process involves the intramolecular crosslinking of self-folding amphiphilic random copolymers in water. For this process, amphiphilic random copolymers bearing hydrophilic poly(ethylene glycol) (PEG) and hydrophobic olefin pendants were synthesized by ruthenium-catalyzed living radical copolymerization of PEG m...

  7. 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

    2014-06-01

    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.

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

    KAUST Repository

    Tong, Jing

    2010-08-02

    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.

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

    KAUST Repository

    Fetsch, Corinna

    2014-12-22

    © 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.

  10. Ultrasound responsive block copolymer micelle of poly(ethylene glycol)-poly(propylene glycol) obtained through click reaction.

    Science.gov (United States)

    Li, Fayong; Xie, Chuan; Cheng, Zhengang; Xia, Hesheng

    2016-05-01

    The well-defined amphiphilic poly(ethylene glycol)-block-poly(propylene glycol) copolymer containing 1, 2, 3-triazole moiety and multiple ester bonds (PEG-click-PPG) was prepared by click reaction strategy. The PEG-click-PPG copolymer can self-assemble into spherical micelles in aqueous solution. It is found that high intensity focused ultrasound (HIFU) can open the copolymer PEG-click-PPG micelles and trigger the release of the payload in the micelle. The multiple ester bonds introduced in the junction point of the copolymer chain through click reactions were cleaved under HIFU, and leads to the disruption of the copolymer micelle and fast release of loaded cargo. The click reaction provides a convenient way to construct ultrasound responsive copolymer micelles with weak bonds. PMID:26703197

  11. From Block Copolymers to Nano-porous Materials

    DEFF Research Database (Denmark)

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

    2003-01-01

    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...

  12. Ion Transport in Nanostructured Block Copolymer/Ionic Liquid Membranes

    OpenAIRE

    Hoarfrost, Megan Lane

    2012-01-01

    Incorporating an ionic liquid into one block copolymer microphase provides a platform for combining the outstanding electrochemical properties of ionic liquids with a number of favorable attributes provided by block copolymers. In particular, block copolymers thermodynamically self-assemble into well-ordered nanostructures, which can be engineered to provide a durable mechanical scaffold and template the ionic liquid into continuous ion-conducting nanochannels. Understanding how the additio...

  13. Synthesis, Micellization and Characterization of Novel Amphiphilic β-Cyclodextrin/Poly(L-aspartate) Copolymer

    Institute of Scientific and Technical Information of China (English)

    GUO Yan-ling; CUI Zhao-shan; HAN Min

    2013-01-01

    A novel amphiphilic β-cyclodextrin/poly(L-aspartate)(β-CD-PASP) copolymer was prepared by ringopening polymerization of polysuccinimide(PSI).This copolymer bears β-CD units along the macromolecular chain and the structure was characterized by infrared(IR) and proton nuclear magnetic resonance(1H NMR).The molecular weight of the copolymer was determined by gel permeation chromatography(GPC).The copolymer micelle were prepared by direct dissolution method.The critical micelle concentration(CMC) of the copolymer micelle was measured by flourescence technique with pyrene as probe.The size distribution of micelle was characterized on a dynamic laser light scattering particle size analyzer and its shape was observed by transmission electron microscopy(TEM).The results show that the copolymer could self-assemble into micelle with a low CMC,and the effective diameter of the micelle was 116.3 nm.The methotrexate(MTX)-loaded micelle were prepared and the drug loading content(DLC) was 22.86%.The MTX-loaded copolymer exhibited a better water-solubility than the free drug.

  14. Surface tension of micellar block copolymer films

    International Nuclear Information System (INIS)

    Surface tensions of micellar block copolymers of poly(styrene-b-dimethylsiloxane) (PS-b-PDMS) films are obtained by X-ray diffuse scattering. PS-b-PDMS films on Si substrates with the thicknesses from 36 to 588 nm were investigated at temperatures of 30 - 215 .deg. C. The surface tension reflects the concentration of PDMS micelles which are preferably located at the surface. The molar fraction of PDMS micelles near the surface is estimated by using angle-resolved X-ray photoelectron spectroscopy.

  15. Oriented Protein Nanoarrays on Block Copolymer Template.

    Science.gov (United States)

    Shen, Lei; Zhu, Jintao

    2016-03-01

    Here, a simple yet robust method is developed to fabricate oriented protein nanoarrays by employing a block copolymer (BCP) template, which presents nano-scaled spot areas at high-density arrays. Unlike the conventional BCP nanolithography, the BCP platform described here resists nonspecific protein adsorption and prevents the denaturation of immobilized proteins in aqueous solution. The orderly arranged array areas are functionalized by linking chemistry which allows for the precise control of protein orientation. This approach allows us to generate potentially oriented protein nanoarrays at high-density array spots, which is useful for miniaturized nanoarrays within high-throughput proteomic applications. PMID:26785818

  16. Synthesis and Morphological Characterization of Block Copolymers for Improved Biomaterials

    OpenAIRE

    Schricker, Scott; Palacio, Manuel; Thirumamagal, B.T.S.; Bhushan, Bharat

    2010-01-01

    Biocompatible polymers are known to act as scaffolds for the regeneration and growth of bone. Block copolymers are of interest as scaffold materials because a number of the blocks are biocompatible, and their nanostructure is easily tunable with synthetic techniques. In this paper, we report the synthesis of a novel class of biomaterials from block copolymers containing a hydrophobic block of methyl methacrylate and a hydrophilic block of either acrylic acid, dimethyl acrylamide, or 2-hydroxy...

  17. Versatile antifouling polyethersulfone filtration membranes modified via surface grafting of zwitterionic polymers from a reactive amphiphilic copolymer additive.

    Science.gov (United States)

    Zhao, Yi-Fan; Zhang, Pei-Bin; Sun, Jian; Liu, Cui-Jing; Yi, Zhuan; Zhu, Li-Ping; Xu, You-Yi

    2015-06-15

    Here we describe the development of versatile antifouling polyethersulfone (PES) filtration membranes modified via surface grafting of zwitterionic polymers from a reactive amphiphilic copolymer additive. Amphiphilic polyethersulfone-block-poly(2-hydroxyethyl methacrylate) (PES-b-PHEMA) was beforehand designed and used as the blending additive of PES membranes prepared by phase inversion technique. The surface enriched PHEMA blocks on membrane surface acted as an anchor to immobilize the initiating site. Poly(sulfobetaine methacrylate) (PSBMA) were subsequently grafted onto the PES blend membranes by surface-initiated atom transfer radical polymerization (SI-ATRP). The analysis of surface chemistry confirmed the successful grafting of zwitterionic PSBMA brushes on PES membrane surface. The resulted PES-g-PSBMA membranes were capable of separating proteins from protein solution and oil from oil/water emulsion efficiently. Furthermore, the modified membranes showed high hydrophilicity and strongly antifouling properties due to the incorporation of well-defined PSBMA layer. In addition, the PES-g-PSBMA membranes exhibited excellent blood compatibility and durability during the washing process. The developed antifouling PES membranes are versatile and can find their applications in protein filtration, blood purification and oil/water separation, etc. PMID:25752579

  18. Controlling Structure in Sulfonated Block Copolymer Membranes

    Science.gov (United States)

    Truong, Phuc; Stein, Gila; Strzalka, Joe

    2015-03-01

    In many ionic block copolymer systems, the strong incompatibility between ionic and non-ionic segments will trap non-equilibrium structures in the film, making it difficult to engineer the optimal domain sizes and transport pathways. The goal of this work is to establish a framework for controlling the solid-state structure of sulfonated pentablock copolymer membranes. They have ABCBA block sequence, where A is poly(t-butyl styrene), B is poly(hydrogenated isoprene), and C is poly(styrene sulfonate). To process into films, the polymer is dissolved in toluene/n-propanol solvent mixtures, where the solvent proportions and the polymer loading were both varied. Solution-state structure was measured with small angle X-ray scattering (SAXS). We detected micelles with radii that depend on the solvent composition and polymer loading. Film structure was measured with grazing-incidence SAXS, which shows (i) domain periodicity is constant throughout film thickness; (ii) domain periodicity depends on solvent composition and polymer loading, and approximately matches the micelle radii in solutions. The solid-state packing is consistent with a hard sphere structure factor. Results suggest that solid-state structure can be tuned by manipulating the solution-state self-assembly.

  19. Pattern formation and phase behavior in PS-B-Si containing block copolymer thin film

    Science.gov (United States)

    Hsieh, I.-Fan

    (PGMEA) solvent. Unlike other block copolymer thin film systems, this solvent induced spherical structure possesses very high meta-stability and can be stabilized during thermal annealing up to 200 °C. This unusual high meta-stability can be attributed to the large chi value between PS and PDMS blocks thus result in a high energy barrier for morphology transition. In the contrast, a unique structure evolution route was observed during solvent treatments. Another approach to address the issues is utilizing the self-assembly of a class of shape amphiphiles. Shape amphiphiles refer to a class of asymmetric nano-entities molecules possessing amphiphilic features based on differences in the shape of the molecular segments. Shape amphiphiles are capable of self-assembling into hierarchical structures that can cover the feature sizes of sub-10 nm, which is relatively hard to achieve by traditional coil-coil block copolymer system. A series of PS-tethered hydrophilic POSS thin films with different PS molecular weight were studied here and an interesting result was found in PS-POSS thin film system with cylindrical phase. GISAXS experiments proved that a special metastable phase with compressed packed symmetry was found in PS-POSS thin film system with parallel cylinder morphology after solvent annealing process, and this metastable phase was found in both PS-APOSS and PS-DPOSS thin film system regardless of the film thickness and solvent properties used during annealing. The phase behavior of coil-coil block-copolymers is thermodynamically controlled by the conformational entropies of two blocks and the interfacial energy. On the contrary, giant shape amphiphiles are consisted of particles and polymer chains. There is no conformational entropy for particles, and the interfacial energy is different from the block-copolymer cases. The polymer chains in giant shape amphiphiles also show more stretched near interface compared to block-copolymers. These unique properties make giant

  20. Micelles, Lamellaes and Connected Bilayer Membranes in Block Copolymer Melts, Blends and Solutions

    Science.gov (United States)

    Mortensen, Kell

    1997-03-01

    Block copolymers of poly(ethylene oxide), PEO, and poly(propylene oxide), PPO, provide a unique model system for studies of aqueous systems of amphilic macromolecules, as the amphiphilic character can be changed continuously by changing temperature(K Mortensen, W Brown, B. Nordén , Phys. Rev. Letters 13 2340 (1992)) or pressure(K Mortensen, D Schwahn S Janssen Phys. Rev. Letters 71 1728 (1993)). The structural characteristics of aqueous solutions of the PEO-PPO-PEO copolymers and their self-associated assemblies are reviewed(K Mortensen, J. Phys. Cond. Matter 8 A103 (1996)). It is shown by small-angle neutron scattering that at low temperatures and/or concentration the individual copolymers exist in solution as individual unimers. Depending on molecular design, i.e. size of the individual blocks, various aggregates are formed, including spherical, worm-like and disc-shaped micelles. The spherical micelles provide the basis for liquid-crystalline mesophases of cubic structure. The crystallization can be understood as a simple hard-sphere condensation. Worm- or rod-like micelles may form nematic or hexagonally ordered structures, whereas the discs may condense into lamellar phases. While bi-continuous microemulsions frequently appear in ternary phase diagrams of oil, water and low-molecular surfactants, there has only recently been observations of such phases in binary systems of block copolymers and solvent. The first observation was made in an aqueous solution of a low PEO-content PEO-PPO-PEO triblock copolymer(E Hecht, K Mortensen, H Hoffmann, Macromolecules 28 5465, 1995). More recently, the microemulsion sponge phase has been observed in a system of tri-block copolymers dissolved in homopolymers( JH Laurer, JC Fung, JW Sedat, DA Agard, SD Schmit, J Samseth, K Mortensen, RJ Spontak, Langmuir, submitted) and in a ternary systems of diblock copolymer and homopolymers(FS Bates, WW Maurer, PM Lipic MA Hillmyer, KA Almdal, K Mortensen, TP Lodge Science, submitted).

  1. Self-assembled materials from thermosensitive and biohybrid block copolymers

    NARCIS (Netherlands)

    de Graaf, A.J.

    2012-01-01

    In this research, several block copolymers were synthesized and characterized with regard to possible pharmaceutical applications. All block copolymers were thermosensitive and self-assembled at 37 °C into structures like micelles and hydrogels, which can be used for innovative drug delivery purpose

  2. Modification of nanofibrillated cellulose using amphiphilic block-structured galactoglucomannans.

    Science.gov (United States)

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

    2014-09-22

    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. PMID:24906743

  3. Synthesis and Characterization of Novel Magnetite Nanoparticle Block Copolymer Complexes

    OpenAIRE

    Zhang, Qian

    2007-01-01

    Superparamagnetic Magnetite (Fe3O4) nanoparticles were synthesized and complexed with carboxylate-functionalized block copolymers, and aqueous dispersions of the complexes were investigated as functions of their chemical and morphological structures. The block copolymer dispersants possessed either poly(ethylene oxide), poly(ethylene oxide-co-propylene oxide), or poly(ethylene oxide-b-propylene oxide) outer blocks, and all contained a polyurethane center block with pendant carboxylate functi...

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

    International Nuclear Information System (INIS)

    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-Fe2O3 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

  5. Block copolymer ion gels for gas separation

    Science.gov (United States)

    Gu, Yuanyan; Lodge, Timothy

    2012-02-01

    Carbon dioxide removal from light gases (eg. N2, CH4, and H2) is a very important technology for industrial applications such as natural gas sweetening, CO2 capture from coal-fire power plant exhausts and hydrogen production. Current CO2 separation method uses amine-absorption, which is energy-intensive and requires frequent maintenance. Membrane separation is a cost-effective solution to this problem, especially in small-scale applications. Ionic liquids have recently received increasing interest in this area because of their selective solubility for CO2 and non-volatility. However, ionic liquid itself lacks the persistent structure and mechanical integrity to withstand the high pressure for gas separation. Here, we report the development and gas separation performances of physically crosslinked ion gels based on self-assembly of ABA-triblock copolymers in ionic liquids. Three different types of polymers was used to achieve gelation in ionic liquids. Specifically, a triblock copolymer ion gel with a polymerized ionic liquid mid-block shows performances higher than the upper bound of well-known ``Robeson Plot'' for CO2/N2.

  6. Synthesis and morphological characterization of block copolymers for improved biomaterials

    International Nuclear Information System (INIS)

    Biocompatible polymers are known to act as scaffolds for the regeneration and growth of bone. Block copolymers are of interest as scaffold materials because a number of the blocks are biocompatible, and their nanostructure is easily tunable with synthetic techniques. In this paper, we report the synthesis of a novel class of biomaterials from block copolymers containing a hydrophobic block of methyl methacrylate and a hydrophilic block of either acrylic acid, dimethyl acrylamide, or 2-hydroxyethyl methacrylate. The block copolymers were synthesized using a combination of reversible addition-fragmentation chain transfer (RAFT) polymerization and click chemistry. Since the surface morphology is critical for successful cell growth, atomic force microscopy (AFM) studies were conducted for selected block copolymers. The topography, phase angle and friction maps were obtained in dry and physiological buffer environments to study the morphology. Results of AFM imaging identified the presence of polymer domains corresponding to the copolymer components. The distribution of nanoscale features in these block copolymers is comparable to those found on other surfaces that exhibit favorable cell adhesion and growth. In physiological buffer medium, the hydrophilic component of the block copolymer (acrylic acid or hydroxyethyl methacrylate) appears to be present in greater amounts on the surface as a consequence of water absorption and swelling.

  7. Synthesis and morphological characterization of block copolymers for improved biomaterials

    Energy Technology Data Exchange (ETDEWEB)

    Schricker, Scott, E-mail: Schricker.1@osu.edu [Restorative and Prosthetic Dentistry Section, College of Dentistry, The Ohio State University, Columbus, OH 43210 (United States); Palacio, Manuel [Nanoprobe Laboratory for Bio- and Nanotechnology and Biomimetics, The Ohio State University, Columbus, OH 43210 (United States); Thirumamagal, B.T.S. [Restorative and Prosthetic Dentistry Section, College of Dentistry, The Ohio State University, Columbus, OH 43210 (United States); Bhushan, Bharat [Nanoprobe Laboratory for Bio- and Nanotechnology and Biomimetics, The Ohio State University, Columbus, OH 43210 (United States)

    2010-05-15

    Biocompatible polymers are known to act as scaffolds for the regeneration and growth of bone. Block copolymers are of interest as scaffold materials because a number of the blocks are biocompatible, and their nanostructure is easily tunable with synthetic techniques. In this paper, we report the synthesis of a novel class of biomaterials from block copolymers containing a hydrophobic block of methyl methacrylate and a hydrophilic block of either acrylic acid, dimethyl acrylamide, or 2-hydroxyethyl methacrylate. The block copolymers were synthesized using a combination of reversible addition-fragmentation chain transfer (RAFT) polymerization and click chemistry. Since the surface morphology is critical for successful cell growth, atomic force microscopy (AFM) studies were conducted for selected block copolymers. The topography, phase angle and friction maps were obtained in dry and physiological buffer environments to study the morphology. Results of AFM imaging identified the presence of polymer domains corresponding to the copolymer components. The distribution of nanoscale features in these block copolymers is comparable to those found on other surfaces that exhibit favorable cell adhesion and growth. In physiological buffer medium, the hydrophilic component of the block copolymer (acrylic acid or hydroxyethyl methacrylate) appears to be present in greater amounts on the surface as a consequence of water absorption and swelling.

  8. Synthesis and applications of polystyrene-block-poly(N-vinyl-2-pyrrolidone copolymers

    Directory of Open Access Journals (Sweden)

    Marcelo Alexandre de Farias

    2016-02-01

    Full Text Available Abstract This work describes the synthesis and applications of amphiphilic polystyrene-block-poly(N-vinyl-2-pyrrolidone (PS-b-PVP copolymers as a silver and silica nanoparticle surface modification agent. The synthesis of PS-b-PVP was carried out using controlled/living radical polymerization techniques. The synthesis of the block copolymers was confirmed by gel permeation chromatography and hydrogen nuclear magnetic resonance, presenting a polydispersity index of around 1.4 and number average molecular weight ranging between 10,000-14,000 g mol-1. The PS-b-PVP copolymers were applied as a silver nanoparticle (AgNP stabilizing agent. These nanoparticles were produced by a single step and presented an 11 ± 1 nm diameter. Furthermore, the PS-b-PVP copolymers were also applied as a silica nanoparticle (SiO2NP surface modification agent. The SiO2NP were synthesized by the Stöber method presenting a 72 ± 9 nm diameter. The SiO2NP surface modification by adsorption of PS-b-PVP caused the formation of a 5 ± 1 nm thick polymeric layer, providing the SiO2NP with a hydrophobic surface character. The structural and chemical characteristics shown by PS-b-PVP copolymers highlights their versatility for several applications, such as: water-in-oil emulsifier, stabilizing or coupling agents between inorganic particles and polymeric matrices.

  9. 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.; Mouritsen, Ole G.

    1997-01-01

    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......A comparative study is conducted on the influence of two types of polymeric compounds on the phase behavior of 1,2-dihexadecanoyl-s,n-glycero-3-phosphotidylcholine (DC16PC) lipid bilayers. The first polymeric compound is a lipopolymer, mer, with two different lengths of a hydrophilic polyethylene...... 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...

  10. Block Copolymer Metastability: Scientific Nightmare or Engineering Dream?

    Science.gov (United States)

    Bates, Frank S.

    1997-03-01

    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.

  11. Multicompartment Micelles From π-Shaped ABC Block Copolymers

    Institute of Scientific and Technical Information of China (English)

    XIA Jun; ZHONG Chong-Li

    2007-01-01

    Dissipative particle dynamics simulations were performed on the morphology and structure of multicompartment micelles formed from n-shaped ABC block copolymers in water. The influences of chain architectures were studied in a systematic way, and a rich variety of morphologies were observed, such as spherical, wormlike,X-shaped, Y-shaped, ribbon-like, layered rod-like, layered disk-like, as well as network morphologies. The simulations show that the distance between the two grafts plays an important role in control of the morphology. Since π-shaped ABC block copolymers can be reduced to linear ABC and star ABC block copolymers, they are good model copolymers for studying the self-assembly of complex block copolymers into micelles. The knowledge obtained in this work as well as the new morphologies identified provide useful information for future rational design and synthesis of novel multicompartment micelles.

  12. Poly(trimethylene carbonate)/Poly(malic acid) Amphiphilic Diblock Copolymers as Biocompatible Nanoparticles.

    Science.gov (United States)

    Barouti, Ghislaine; Khalil, Ali; Orione, Clement; Jarnouen, Kathleen; Cammas-Marion, Sandrine; Loyer, Pascal; Guillaume, Sophie M

    2016-02-01

    Amphiphilic polycarbonate-poly(hydroxyalkanoate) diblock copolymers, namely, poly(trimethylene carbonate) (PTMC)-b-poly(β-malic acid) (PMLA), are reported for the first time. The synthetic strategy relies on commercially available catalysts and initiator. The controlled ring-opening polymerization (ROP) of trimethylene carbonate (TMC) catalyzed by the organic guanidine base 1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD), associated with iPrOH as an initiator, provided iPrO-PTMC-OH, which served as a macroinitiator in the controlled ROP of benzyl β-malolactonate (MLABe) catalyzed by the neodymium triflate salt (Nd(OTf)3 ). The resulting hydrophobic iPrO-PTMC-b-PMLABe-OH copolymers were then hydrogenolyzed into the parent iPrO-PTMC-b-PMLA-OH copolymers. A range of well-defined copolymers, featuring different sizes of segments (Mn,NMR up to 9300 g mol(-1) ; ÐM =1.28-1.40), were thus isolated in gram quantities, as evidenced by NMR spectroscopy, size exclusion chromatography, thermogravimetric analysis, differential scanning calorimetry, and contact angle analyses. Subsequently, PTMC-b-PMLA copolymers with different hydrophilic weight fractions (11-75 %) self-assembled in phosphate-buffered saline upon nanoprecipitation into well-defined nano-objects with Dh =61-176 nm, a polydispersity index <0.25, and a negative surface charge, as characterized by dynamic light scattering and zeta-potential analyses. In addition, these nanoparticles demonstrated no significant effect on cell viability at low concentrations, and a very low cytotoxicity at high concentrations only for PTMC-b-PMLA copolymers exhibiting hydrophilic fractions over 47 %, thus illustrating the potential of these copolymers as promising nanoparticles. PMID:26791328

  13. Amphiphilic copolymer coated upconversion nanoparticles for near-infrared light-triggered dual anticancer treatment

    Science.gov (United States)

    Yang, Shun; Li, Najun; Liu, Zhuang; Sha, Wenwei; Chen, Dongyun; Xu, Qingfeng; Lu, Jianmei

    2014-11-01

    The light-triggered controlled release of anticancer drugs accompanied with NIR-responsive photodynamic therapy was prepared via a self-assembly process. Firstly, Mn2+-doped upconversion nanoparticles (UCNPs) were coated with a mesoporous silica shell and modified with photosensitizer (Chlorin e6) and long alkyl chains. And then the NIR light-responsive amphiphilic copolymer containing 9,10-dialkoxyanthracene groups was synthesized and then coated as the outermost layer. Upon irradiation with a 980 nm laser, the CCUCNPs@PM would absorb and then convert the NIR light to higher-energy visible red light (660 nm) via the UCNPs-based core, which could excite Chlorin e6 (Ce-6) to produce singlet oxygen (1O2). Then the 1O2-sensitive dialkoxyanthracene group in the amphiphilic copolymer would be degraded and detach from the surface of the CCUCNPs@PM, followed by the controlled release of the pre-loaded drugs and the photodynamic therapy for cancer cells caused by the excess 1O2. In vitro and in vivo experiments also demonstrated that the drug-loaded CCUCNPs@PM possessed better therapeutic efficacy compared with vacant ones. Therefore, the NIR light-controlled chemotherapy and photodynamic therapy could be realized simultaneously by CCUCNPs@PM.The light-triggered controlled release of anticancer drugs accompanied with NIR-responsive photodynamic therapy was prepared via a self-assembly process. Firstly, Mn2+-doped upconversion nanoparticles (UCNPs) were coated with a mesoporous silica shell and modified with photosensitizer (Chlorin e6) and long alkyl chains. And then the NIR light-responsive amphiphilic copolymer containing 9,10-dialkoxyanthracene groups was synthesized and then coated as the outermost layer. Upon irradiation with a 980 nm laser, the CCUCNPs@PM would absorb and then convert the NIR light to higher-energy visible red light (660 nm) via the UCNPs-based core, which could excite Chlorin e6 (Ce-6) to produce singlet oxygen (1O2). Then the 1O2-sensitive

  14. PVP-b-PEO block copolymers for stable aqueous and ethanolic graphene dispersions.

    Science.gov (United States)

    Perumal, Suguna; Park, Kyung Tae; Lee, Hyang Moo; Cheong, In Woo

    2016-02-15

    The ability to disperse pristine (unfunctionalized) graphene is important for various applications, coating, nanocomposites, and energy related systems. Herein we report that amphiphilic copolymers of poly(4-vinyl pyridine)-block-poly(ethylene oxide) (PVP-b-PEO) are able to disperse graphene with high concentrations about 2.6mg/mL via sonication and centrifugation. Ethanolic and aqueous highly-ordered pyrolytic graphite (HOPG) dispersions with block copolymers were prepared and they were compared with the dispersions stabilized by P-123 Pluronic® (P123) and poly(styrene)-block-poly(ethylene oxide) (PS-b-PEO) synthesized. Transmission electron microscopy, scanning electron microscopy, atomic force microscopy, X-ray diffraction, Raman and UV-visible spectroscopic studies confirmed that PVP-b-PEO block copolymers are better stabilizers for HOPG graphene than P123 and PS-b-PEO. X-ray photoelectron spectroscopy and force-distance (F-d) curve analyses revealed that the nitrogen of vinyl pyridine plays a vital role in better attractive interaction with surface of graphene sheet. Thermogravimetric analysis showed that larger amount of PVP-b-PEO was adsorbed onto graphene with longer poly(4-vinyl pyridine) (PVP) block length and in aqueous medium, respectively, and which was consistent with electrical conductivity decreases. This study presents the dispersion efficiency of graphene using PVP-b-PEO varies substantially depending on the lengths of their hydrophobic (PVP) domains. PMID:26606378

  15. Morphological studies on block copolymer modified PA 6 blends

    Energy Technology Data Exchange (ETDEWEB)

    Poindl, M., E-mail: marcus.poindl@ikt.uni-stuttgart.de, E-mail: christian.bonten@ikt.uni-stuttgart.de; Bonten, C., E-mail: marcus.poindl@ikt.uni-stuttgart.de, E-mail: christian.bonten@ikt.uni-stuttgart.de [Institut für Kunststofftechnik, University of Stuttgart (Germany)

    2014-05-15

    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.

  16. Molecular Transfer Printing Using Block Copolymers

    Science.gov (United States)

    Ji, Shengxiang; Liu, Chi-Chun; Liu, Guoliang; Nealey, Paul

    2009-03-01

    We report a new parallel patterning technique, molecular transfer printing (MTP), for replicating geometrically complex patterns over macroscopic areas with sub-15 nm feature dimensions, and the ability to replicate the same pattern multiple times. In MTP, inks are mixed with block copolymers (BCPs) and deposited as films on a substrate. The inks are compatible with only one block of the BCP, and sequestered into domains of nanometer scale dimensions after microphase separation. A second substrate is then placed in contact with the surface of the film. By designing the inks to react, adsorb, or otherwise interact with the second substrate, inks are transferred to the second substrate in the exact pattern of domains present at the surface of the ``master'' BCP film. Here we demonstrate high degrees of perfection on both line and dot patterns. We also show that 1) the master template can be regenerated, 2) the resultant replica can be used to direct the assembly of BCPs and as a daughter master for MTP, and 3) the master and daughter templates can be reused tens of times.

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

    KAUST Repository

    Pati, Debasis

    2015-12-21

    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.

  18. Synthesis of amphiphilic triblock copolymers as multidentate ligands for biocompatible coating of quantum dots

    OpenAIRE

    Wang, Tongxin; Sridhar, Rajagopalan; Korotcov, Alexandru; Ting, Andy Hai; Francis, Kyethann; Mitchell, James; Wang, Paul C.

    2011-01-01

    One barrier to apply current tri-octylphosphine oxide (TOPO) based quantum dots (QDs) to biomedical imaging is that the TOPO on TOPO-QDs can be replaced by the proteins in living system, which may cause the degradation of QDs and/or deactivation of protein. In order to develop biocompatible optical imaging agents, a novel triblock copolymer, designed as a multidentate ligand, was synthesized to coat quantum dot nanocrystals (QDs). The copolymer consists of a polycarboxylic acid block at one e...

  19. Functional Block Copolymers via Anionic Polymerization for Electroactive Membranes

    OpenAIRE

    Schultz, Alison

    2013-01-01

           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...

  20. Radiation crosslinked block copolymer blends with improved impact resistance

    International Nuclear Information System (INIS)

    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

  1. Stereo block copolymers of L- and D-lactides

    NARCIS (Netherlands)

    Yui, Nobuhiko; Dijkstra, Pieter J.; Feijen, Jan

    1990-01-01

    Sequential diblock copolymers composed of L- and D-lactic acid residues were synthesized through a living ring-opening polymerization of L- and D-lactide initiated by aluminium tris(2-propanolate). The composition of the block copolymers was varied by changing the reaction conditions and monomer ove

  2. Thin Isoporous Block Copolymer Membranes: It Is All about the Process.

    Science.gov (United States)

    Hahn, Janina; Clodt, Juliana I; Abetz, Clarissa; Filiz, Volkan; Abetz, Volker

    2015-09-30

    The combination of the self-assembly of amphiphilic block copolymers and the nonsolvent induced phase inversion process offers an efficient way to isoporous integral-asymmetric membranes. In this context we report fast, easily upscalable and material reducing ways to thin self-assembled membranes. Therefore, we succeeded to implement a spray or dip coating step into the membrane formation process of different diblock copolymers like polystyrene-block-poly(4-vinylpyridine), poly(α-methylstyrene)-bock-poly(4-vinylpyridine), and polystyrene-block-poly(iso-propylglycidyl methacrylate). The formation of hexagonal pore structures was possible using a highly diluted one solvent system allowing the reduction of diblock copolymer consumption and therefore the production costs are minimized compared to conventional blade casting approaches. The broad applicability of the process was proven by using different flat and hollow fiber support materials. Furthermore, the membranes made by this new method showed a more than 6-fold increase in water flux compared to conventional polystyrene-block-poly(4-vinylpyridine) membranes with similar pore sizes prepared by blade casting. The membranes could be proven to be stable at transmembrane pressures of 2 bar and showed a pH responsive flux behavior over several cycles. PMID:26349610

  3. Colloidal ionic assembly between anionic native cellulose nanofibrils and cationic block copolymer micelles into biomimetic nanocomposites.

    Science.gov (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

    2011-06-13

    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. PMID:21517114

  4. THE AMPHIPHILIC MULTIARM COPOLYMERS BASED ON HYPERBRANCHED POLYESTER AND LYSINE: SYNTHESIS AND SELF-ASSEMBLY

    Institute of Scientific and Technical Information of China (English)

    Jing Wang; Yuan Yao; Bing Ji; Wei Huang; Yong-feng Zhou; De-yue Yan

    2011-01-01

    The amphiphilic multiarm copolymers were synthesized through the modification of commercially available hyperbranched polyesters (Boltom H40) with N-ε-carbobenzoxy-L-Lysine N-carboxyanhydride (ZLys-NCA). After being condensed with N-Boc-phenylalanine (Boc-NPhe) and deprotected the Boc-groups in trifluoroacetic acid (TFA), the original terminal hydroxyl groups were transformed into the amino groups and then initiated the ring-opening polymerization of ZLys-NCA. The hydrophilic poly(L-lysine) was grafted to the surface of Boltorn H40 successfully after the protecting benzyl groups were removed by the HBr solution in glacial acetic acid (33 wt%). The resulting multiarm copolymers were characterized by the 1H-NMR, GPC and FTIR. The arm length calculated by NMR and GPC analysis was about 3 and 13 lysine-units for H40-Phe-PLysl and H40-Phe-PLys2 respectively. Due to the amphiphilic molecular structure, they displayed ability to self-assemble into spherical micelles in aqueous solution with the average diameter in the range from 70 nm to 250 nm. The CMC of H40-Phe-PLysl and H40-Phe-PLys2 was 0.013 mg/mL and 0.028 mg/mL, respectively,indicating that H40-Phe-PLysl with shorter arm length is easier to self-assemble than H40-Phe-PLys2 with longer arm length.

  5. Comparison of facially amphiphilic versus segregated monomers in the design of antibacterial copolymers.

    Science.gov (United States)

    Gabriel, Gregory J; Maegerlein, Janet A; Nelson, Christopher F; Dabkowski, Jeffrey M; Eren, Tarik; Nüsslein, Klaus; Tew, Gregory N

    2009-01-01

    A direct comparison of two strategies for designing antimicrobial polymers is presented. Previously, we published several reports on the use of facially amphiphilic (FA) monomers which led to polynorbornenes with excellent antimicrobial activities and selectivities. Our polymers obtained by copolymerization of structurally similar segregated monomers, in which cationic and non-polar moieties reside on separate repeat units, led to polymers with less pronounced activities. A wide range of polymer amphiphilicities was surveyed by pairing a cationic oxanorbornene with eleven different non-polar monomers and varying the comonomer feed ratios. Their properties were tested using antimicrobial assays and copolymers possessing intermediate hydrophobicities were the most active. Polymer-induced leakage of dye-filled liposomes and microscopy of polymer-treated bacteria support a membrane-based mode of action. From these results there appears to be profound differences in how a polymer made from FA monomers interacts with the phospholipid bilayer compared with copolymers from segregated monomers. We conclude that a well-defined spatial relationship of the whole polymer is crucial to obtain synthetic mimics of antimicrobial peptides (SMAMPs): charged and non-polar moieties need to be balanced locally, for example, at the monomer level, and not just globally. We advocate the use of FA monomers for better control of biological properties. It is expected that this principle will be usefully applied to other backbones such as the polyacrylates, polystyrenes, and non-natural polyamides. PMID:19021176

  6. Preparation of pH-responsive membranes with amphiphilic copolymers by surface segregation method☆

    Institute of Scientific and Technical Information of China (English)

    Yanlei Su; Yuan Liu; Xueting Zhao; Yafei Li; Zhongyi Jiang

    2015-01-01

    Novel pH-responsive membranes were prepared by blending pH-responsive amphiphilic copolymers with pol-yethersulfone (PES) via a nonsolvent-induced phase separation (NIPS) technique. The amphiphilic copolymers bearing Pluronic F127 and poly(methacrylic acid) (PMAA) segments, abbreviated as PMAAn–F127–PMAAn, were synthesized by free radical polymerization. The physical and chemical properties of the blend membranes were evaluated by scanning electron microscopy (SEM), Fourier transform infrared (FTIR) spectrum, water con-tact angle, Zeta potential and X-ray photoelectron spectroscopy (XPS). The enrichment of hydrophilic PMAA seg-ments on the membrane surfaces was attributed to surface segregation during the membrane preparation process. The blend membranes had significant pH-responsive properties due to the conformational changes of surface-segregated PMAA segments under different pH values of feed solutions. Fluxes of the blend membranes were larger at low pH values of feed solutions than that at high pH values. The pH-responsive ability of the mem-branes was enhanced with the increase of the degree of PMAA near-surface coverage.

  7. Nanostructure protein repellant amphiphilic copolymer coatings with optimized surface energy by Inductively Excited Low Pressure Plasma.

    Science.gov (United States)

    Bhatt, Sudhir; Pulpytel, Jérome; Ceccone, Giacomo; Lisboa, Patricia; Rossi, François; Kumar, Virendra; Arefi-Khonsari, Farzaneh

    2011-12-01

    Statistically designed amphiphilic copolymer coatings were deposited onto Thermanox, Si wafer, and quartz crystal microbalance (QCM) substrates via Plasma Enhanced Chemical Vapor Deposition of 1H,1H,2H,2H-perfluorodecyl acrylate and diethylene glycol vinyl ether in an Inductively Excited Low Pressure Plasma reactor. Plasma deposited amphiphilic coatings were characterized by Field Emission Scanning Electron Microscopy, X-ray Photoelectron Spectroscopy, Atomic Force Microscopy, and Water Contact Angle techniques. The surface energy of the coatings can be adjusted between 12 and 70 mJ/m(2). The roughness of the coatings can be tailored depending on the plasma mode used. A very smooth coating was deposited with a CW (continuous wave) power, whereas a rougher surface with R(a) in the range of 2 to 12 nm was deposited with the PW (pulsed wave) mode. The nanometer scale roughness of amphiphilic PFDA-co-DEGVE coatings was found to be in the range of the size of the two proteins namely BSA and lysozyme used to examine for the antifouling properties of the surfaces. The results show that the statistically designed surfaces, presenting a surface energy around 25 mJ/m(2), present no adhesion with respect to both proteins measured by QCM. PMID:22029599

  8. 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)

    2008-01-01

    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

  9. Synthesis of Amylose-b-P2 VP Block Copolymers.

    Science.gov (United States)

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

    2015-12-01

    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. PMID:26437256

  10. Nanopatterned articles produced using surface-reconstructed block copolymer films

    Energy Technology Data Exchange (ETDEWEB)

    Russell, Thomas P.; Park, Soojin; Wang, Jia-Yu; Kim, Bokyung

    2016-06-07

    Nanopatterned surfaces are prepared by a method that includes forming a block copolymer film on a substrate, annealing and surface reconstructing the block copolymer film to create an array of cylindrical voids, depositing a metal on the surface-reconstructed block copolymer film, and heating the metal-coated block copolymer film to redistribute at least some of the metal into the cylindrical voids. When very thin metal layers and low heating temperatures are used, metal nanodots can be formed. When thicker metal layers and higher heating temperatures are used, the resulting metal structure includes nanoring-shaped voids. The nanopatterned surfaces can be transferred to the underlying substrates via etching, or used to prepare nanodot- or nanoring-decorated substrate surfaces.

  11. Ionic Block Copolymers for Anion Exchange Membranes

    Science.gov (United States)

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

    2013-03-01

    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)

  12. Adsorption of semiflexible block copolymers on homogeneous surfaces

    OpenAIRE

    Cerdà, Joan J.; Sintes, Tomàs; Sumithra, K.

    2005-01-01

    We present the results of extensive numerical off-lattice Monte Carlo simulations of semiflexible block-copolymer chains adsorbed onto flat homogeneous surfaces. We have compared the behavior of several chain structures, such as homopolymers, diblocks, (AαBα) block copolymers, and random heteropolymers. In all the cases studied, we have found the adsorption process to be favored with an increase of the chain rigidity. Particularly, the adsorption of diblock structures becomes a two-step proce...

  13. Self-assembled materials from thermosensitive and biohybrid block copolymers

    OpenAIRE

    De Graaf, A.J.

    2012-01-01

    In this research, several block copolymers were synthesized and characterized with regard to possible pharmaceutical applications. All block copolymers were thermosensitive and self-assembled at 37 °C into structures like micelles and hydrogels, which can be used for innovative drug delivery purposes. Some of the synthesized polymers were biohybrid, in the sense that they contained peptide segments which enabled their cleavage by enzymes that are upregulated in diseased tissues. First, method...

  14. New adhesive systems based on functionalized block copolymers

    Energy Technology Data Exchange (ETDEWEB)

    Kent, M.; Saunders, R.; Hurst, M.; Small, J.; Emerson, J.; Zamora, D.

    1997-05-01

    The goal of this work was to evaluate chemically-functionalized block copolymers as adhesion promoters for metal/thermoset resin interfaces. Novel block copolymers were synthesized which contain pendant functional groups reactive toward copper and epoxy resins. In particular, imidazole and triazole functionalities that chelate with copper were incorporated onto one block, while secondary amines were incorporated onto the second block. These copolymers were found to self-assemble from solution onto copper surfaces to form monolayers. The structure of the adsorbed monolayers were studied in detail by neutron reflection and time-of-flight secondary ion mass spectrometry. The monolayer structure was found to vary markedly with the solution conditions and adsorption protocol. Appropriate conditions were found for which the two blocks form separate layers on the surface with the amine functionalized block exposed at the air surface. Adhesion testing of block copolymer-coated copper with epoxy resins was performed in both lap shear and peel modes. Modest enhancements in bond strengths were observed with the block copolymer applied to the native oxide. However, it was discovered that the native oxide is the weak link, and that by simply removing the native oxide, and then applying an epoxy resin before the native oxide can reform, excellent bond strength in the as-prepared state as well as excellent retention of bond strength after exposure to solder in ambient conditions are obtained. It is recommended that long term aging studies be performed with and without the block copolymer. In addition, the functionalized block copolymer method should be evaluated for another system that has inherently poor bonding, such as the nickel/silicone interface, and for systems involving metals and alloys which form oxides very rapidly, such as aluminum and stainless steel, where bonding strategies involve stabilizing the native oxide.

  15. Spontaneous condensation in DNA-polystyrene- b-poly(l-lysine) polyelectrolyte block copolymer mixtures

    Science.gov (United States)

    Castelletto, V.; Hamley, I. W.; Kerstens, S. L. H.; Deacon, S.; Thomas, C. D.; Lübbert, A.; Klok, H.-A.

    2006-05-01

    We investigated the condensation of calf thymus DNA by amphiphilic polystyrenem-b-poly(l-lysine)n block copolymers ( PSm-b- PLysn, m, n = degree of polymerization), using small-angle X-ray scattering, polarized optical microscopy and laser scanning confocal microscopy. Microscopy studies showed that the DNA condenses in the form of fibrillar precipitates, with an irregular structure, due to electrostatic interactions between PLys and DNA. This is not modified by the presence of hydrophobic PS block. Scattering experiments show that the structure of the polyplexes corresponds to a local order of DNA rods which becomes more compact upon increasing n. It can be concluded that for DNA/ PSm-b- PLysn polyplexes, the balance between the PLys block length and the excess charge in the system plays an essential role in the formation of a liquid crystalline phase.

  16. New routes to the synthesis of amylose-block-polystyrene rod-coil block copolymers

    NARCIS (Netherlands)

    Loos, Katja; Müller, Axel H.E.

    2002-01-01

    Hybrid block copolymers amylose-block-polystyrene were synthesized by covalent attachment of maltoheptaose derivatives to end-functionalized polystyrene and subsequent enzymatic grafting from polymerization. The maltoheptaose derivatives were attached by reductive amination or hydrosilation to amino

  17. Perpendicularly Aligned, Anion Conducting Nanochannels in Block Copolymer Electrolyte Films

    Energy Technology Data Exchange (ETDEWEB)

    Arges, Christopher G.; Kambe, Yu; Suh, Hyo Seon; Ocola, Leonidas E.; Nealey, Paul F.

    2016-03-08

    Connecting structure and morphology to bulk transport properties, such as ionic conductivity, in nanostructured polymer electrolyte materials is a difficult proposition because of the challenge to precisely and accurately control order and the orientation of the ionic domains in such polymeric films. In this work, poly(styrene-block-2-vinylpyridine) (PSbP2VP) block copolymers were assembled perpendicularly to a substrate surface over large areas through chemical surface modification at the substrate and utilizing a versatile solvent vapor annealing (SVA) technique. After block copolymer assembly, a novel chemical vapor infiltration reaction (CVIR) technique selectively converted the 2-vinylpyridine block to 2-vinyl n-methylpyridinium (NMP+ X-) groups, which are anion charge carriers. The prepared block copolymer electrolytes maintained their orientation and ordered nanostructure upon the selective introduction of ion moieties into the P2VP block and post ion-exchange to other counterion forms (X- = chloride, hydroxide, etc.). The prepared block copolymer electrolyte films demonstrated high chloride ion conductivities, 45 mS cm(-1) at 20 degrees C in deionized water, the highest chloride ion conductivity for anion conducting polymer electrolyte films. Additionally, straight-line lamellae of block copolymer electrolytes were realized using chemoepitaxy and density multiplication. The devised scheme allowed for precise and accurate control of orientation of ionic domains in nanostructured polymer electrolyte films and enables a platform for future studies that examines the relationship between polymer electrolyte structure and ion transport.

  18. Synthesis of Electroneutralized Amphiphilic Copolymers with Peptide Dendrons for Intramuscular Gene Delivery.

    Science.gov (United States)

    Pu, Linyu; Wang, Jiali; Li, Na; Chai, Qiuxia; Irache, Juan M; Wang, Gang; Tang, James Zhenggui; Gu, Zhongwei

    2016-06-01

    Intramuscular gene delivery materials are of great importance in plasmid-based gene therapy system, but there is limited information so far on how to design and synthesize them. A previous study showed that the peptide dendron-based triblock copolymer with its components arranged in a reversed biomembrane architecture could significantly increase intramuscular gene delivery and expression. Herein, we wonder whether copolymers with biomembrane-mimicking arrangement may have similar function on intramuscular gene delivery. Meanwhile, it is of great significance to uncover the influence of electric charge and molecular structure on the function of the copolymers. To address the issues, amphiphilic triblock copolymers arranged in hydrophilic-hydrophobic-hydrophilic structure were constructed despite the paradoxical characteristics and difficulties in synthesizing such hydrophilic but electroneutral molecules. The as-prepared two copolymers, dendronG2(l-lysine-OH)-poly propylene glycol2k(PPG2k)-dendronG2(l-lysine-OH) (rL2PL2) and dendronG3(l-lysine-OH)-PPG2k-dendronG3(l-lysine-OH) (rL3PL3), were in similar structure but had different hydrophilic components and surface charges, thus leading to different capabilities in gene delivery and expression in skeletal muscle. rL2PL2 was more efficient than Pluronic L64 and rL3PL3 when mediating luciferase, β-galactosidase, and fluorescent protein expressions. Furthermore, rL2PL2-mediated growth-hormone-releasing hormone expression could significantly induce mouse body weight increase in the first 21 days after injection. In addition, both rL2PL2 and rL3PL3 showed good in vivo biosafety in local and systemic administration. Altogether, rL2PL2-mediated gene expression in skeletal muscle exhibited applicable potential for gene therapy. The study revealed that the molecular structure and electric charge were critical factors governing the function of the copolymers for intramuscular gene delivery. It can be concluded that, combined

  19. Manipulating the morphologies of poly(vinyl alcohol) block copolymer surfactants

    Science.gov (United States)

    Repollet-Pedrosa, Milton H.

    Amphiphilic block copolymers (ABCs) are macromolecules containing well-defined hydrophilic and hydrophobic segments that self-assemble into nanoscale aggregates such as spherical and cylindrical micelles and vesicles, when dispersed in block-selective solvents. ABCs possess a miniscule critical micelle concentration, which results in kinetically trapped and persistent assemblies in solution with slow chain exchange between aggregates. This makes them useful as rheological modifiers for personal care products, enhanced oil recovery, and drug delivery formulations. Their utility in many of these applications is crucially dependent on the ability to control the micellar morphologies that they adopt in selective solvents. Triggering ABC micellar morphological transformations, i.e. from spherical to cylindrical micelles, is important for generating "on-demand" stimuli-responsive morphologies that control the aggregate morphology and the bulk solution properties in any given application. In this thesis, we develop the straightforward synthesis of biodegradable and biocompatible ABCs comprised of poly(vinyl acetate) (PVAc) and poly(vinyl alcohol) (PVA), with narrow molecular distributions and variable yet well-defined compositions. These block copolymer amphiphiles readily form spherical micelles in aqueous dispersions. We demonstrate that the addition of a water-soluble poly(ethylene oxide) (PEO) homopolymer to these dispersions results in a rapid transformation of these spherical micelles into cylindrical micelles. Dilution of these cylindrical micelles with water induces their reversion to spherical micelles. Our results indicate that the reversible morphology change depends sensitively on the PEO homopolymer concentration and molecular weight, as well as the length of the PVA corona block of the micelles. Through a series of quantitative 1H NMR studies, we found that the preferential partitioning of PEO homopolymer into the PVAc micellar core drives this morphological

  20. Mechano-responsive hydrogels crosslinked by reactive block copolymer micelles

    Science.gov (United States)

    Xiao, Longxi

    Hydrogels are crosslinked polymeric networks that can swell in water without dissolution. Owing to their structural similarity to the native extracelluar matrices, hydrogels have been widely used in biomedical applications. Synthetic hydrogels have been designed to respond to various stimuli, but mechanical signals have not incorporated into hydrogel matrices. Because most tissues in the body are subjected to various types of mechanical forces, and cells within these tissues have sophisticated mechano-transduction machinery, this thesis is focused on developing hydrogel materials with built-in mechano-sensing mechanisms for use as tissue engineering scaffolds or drug release devices. Self-assembled block copolymer micelles (BCMs) with reactive handles were employed as the nanoscopic crosslinkers for the construction of covalently crosslinked networks. BCMs were assembled from amphiphilic diblock copolymers of poly(n-butyl acrylate) and poly(acrylic acid) partially modified with acrylate. Radical polymerization of acrylamide in the presence of micellar crosslinkers gave rise to elastomeric hydrogels whose mechanical properties can be tuned by varying the BCM composition and concentration. TEM imaging revealed that the covalently integrated BCMs underwent strain-dependent reversible deformation. A model hydrophobic drug, pyrene, loaded into the core of BCMs prior to the hydrogel formation, was dynamically released in response to externally applied mechanical forces, through force-induced reversible micelle deformation and the penetration of water molecules into the micelle core. The mechano-responsive hydrogel has been studied for tissue repair and regeneration purposes. Glycidyl methacrylate (GMA)-modified hyaluronic acid (HA) was photochemically crosslinked in the presence of dexamethasone (DEX)-loaded crosslinkable BCMs. The resultant HA gels (HAxBCM) contain covalently integrated micellar compartments with DEX being sequestered in the hydrophobic core. Compared

  1. Block Copolymers of Ethylene Oxide and Styrene Oxide.New Copolymer Surfactants(Ⅱ)

    Institute of Scientific and Technical Information of China (English)

    Zhuo Yang; David Attwood; Colin Booth

    2003-01-01

    @@ 3.2. Association Number Figure 5 shows the dependence of the weight-average association number (Nw,measured by static light scattering, solution temperature 30 °C) on hydrophobe block length for ES and ESEblock copolymers.

  2. Graphene oxide-enhanced sol-gel transition sensitivity and drug release performance of an amphiphilic copolymer-based nanocomposite

    Science.gov (United States)

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

    2016-01-01

    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

  3. Passive targeting of thermosensitive diblock copolymer micelles to the lungs: synthesis and characterization of poly(N-isopropylacrylamide)-block-poly(ε-caprolactone)

    OpenAIRE

    Lee, Ren-Shen; Lin, Chih-Hung; Aljuffali, Ibrahim A.; Hu, Kai-Yin; Fang, Jia-You

    2015-01-01

    Background Amphiphilic poly(N-isopropylacrylamide)-block-poly(ε-caprolactone) (PNiPAAm-b-PCL) copolymers were synthesized by ring-opening polymerization to form thermosensitive micelles as nanocarriers for bioimaging and carboplatin delivery. Results The critical micelle concentration increased from 1.8 to 3.5 mg/l following the decrease of the PNiPAAm chain length. The copolymers revealed a lower critical solution temperature (LCST) between 33 and 40°C. The copolymers self-assembled to form ...

  4. Ion Transport in Nanostructured Block Copolymer/Ionic Liquid Membranes

    Science.gov (United States)

    Hoarfrost, Megan Lane

    Incorporating an ionic liquid into one block copolymer microphase provides a platform for combining the outstanding electrochemical properties of ionic liquids with a number of favorable attributes provided by block copolymers. In particular, block copolymers thermodynamically self-assemble into well-ordered nanostructures, which can be engineered to provide a durable mechanical scaffold and template the ionic liquid into continuous ion-conducting nanochannels. Understanding how the addition of an ionic liquid affects the thermodynamic self-assembly of block copolymers, and how the confinement of ionic liquids to block copolymer nanodomains affects their ion-conducting properties is essential for predictable structure-property control. The lyotropic phase behavior of block copolymer/ionic liquid mixtures is shown to be reminiscent of mixtures of block copolymers with selective molecular solvents. A variety of ordered microstructures corresponding to lamellae, hexagonally close-packed cylinders, body-centered cubic, and face-centered cubic oriented micelles are observed in a model system composed of mixtures of imidazolium bis(trifluoromethylsulfonyl)imide ([Im][TFSI]) and poly(styrene- b-2-vinyl pyridine) (PS-b-P2VP). In contrast to block copolymer/molecular solvent mixtures, the interfacial area occupied by each PS-b-P2VP chain decreases upon the addition of [Im][TFSI], indicating a considerable increase in the effective segregation strength of the PS-b-P2VP copolymer with ionic liquid addition. The relationship between membrane structure and ionic conductivity is illuminated through the development of scaling relationships that describe the ionic conductivity of block copolymer/ionic liquid mixtures as a function of membrane composition and temperature. It is shown that the dominant variable influencing conductivity is the overall volume fraction of ionic liquid in the mixture, which means there is incredible freedom in designing the block copolymer architecture

  5. Aqueous Self-Assembly of Non-Ionic Bottlebrush Block Copolymer Surfactants with Tunable Molecular Shapes

    Science.gov (United States)

    Rzayev, Javid

    2015-03-01

    Polymer amphiphiles provide a robust and versatile platform for the fabrication of nanostructured soft matter. In this research, we explore a new class of polymer surfactants based on comb-like bottlebrush architecture as highly tunable molecular building blocks for aqueous self-assembly. Excluded volume interactions between densely grafted polymer side chains in the bottlebrush architecture are alleviated by backbone stretching, which leads to the formation of shape-persistent cylindrical macromolecules whose molecular dimensions can be precisely tailored during chemical synthesis. Amphiphilic bottlebrush block copolymers containing hydrophobic polylactide (PLA) and hydrophilic poly(oligoethylene oxide methacrylate) (PEO) side chains of various lengths were synthesized by a combination of controlled radical and ring-opening polymerizations. In dilute aqueous solutions, bottlebrush surfactants rapidly assembled into spherical, cylindrical and bilayer aggregates, as visualized by cryogenic transmission electron microscopy (cryo-TEM). Depending on the compositional side chain asymmetry, the formation of spherical micelles with different sizes and dispersities was observed. The molecular shape-dependent assembly was analyzed with help of a packing parameter (p) computed from the molecular composition data akin to small molecule surfactants, with most uniform spherical aggregates observed for bottlebrush amphiphiles with p close to 0.3. The formation of highly uniform micelles and the presence of a rich morphological diagram with relatively narrow compositional windows were attributed to the lack of conformational freedom in bottlebrush surfactants. Similarly, the unusual formation of cylindrical micelles with long aspect ratios for such high molecular weight amphiphiles was attributed to their inability to stabilize morphological defects, such as Y-junctions, with large deviations from mean curvature. Financial support for this work was provided by the National

  6. Hierarchical multiscale hyperporous block copolymer membranes via tunable dual-phase separation.

    Science.gov (United States)

    Yoo, Seungmin; Kim, Jung-Hwan; Shin, Myoungsoo; Park, Hyungmin; Kim, Jeong-Hoon; Lee, Sang-Young; Park, Soojin

    2015-07-01

    The rational design and realization of revolutionary porous structures have been long-standing challenges in membrane science. We demonstrate a new class of amphiphilic polystyrene-block-poly(4-vinylpyridine) block copolymer (BCP)-based porous membranes featuring hierarchical multiscale hyperporous structures. The introduction of surface energy-modifying agents and the control of major phase separation parameters (such as nonsolvent polarity and solvent drying time) enable tunable dual-phase separation of BCPs, eventually leading to macro/nanoscale porous structures and chemical functionalities far beyond those accessible with conventional approaches. Application of this BCP membrane to a lithium-ion battery separator affords exceptional improvement in electrochemical performance. The dual-phase separation-driven macro/nanopore construction strategy, owing to its simplicity and tunability, is expected to be readily applicable to a rich variety of membrane fields including molecular separation, water purification, and energy-related devices. PMID:26601212

  7. Ion and temperature sensitive polypeptide block copolymer.

    Science.gov (United States)

    Joo, Jae Hee; Ko, Du Young; Moon, Hyo Jung; Shinde, Usha Pramod; Park, Min Hee; Jeong, Byeongmoon

    2014-10-13

    A poly(ethylene glycol)/poly(L-alanine) multiblock copolymer incorporating ethylene diamine tetraacetic acid ([PA-PEG-PA-EDTA(m)) was synthesized as an ion/temperature dual stimuli-sensitive polymer, where the effect of different metal ions (Cu(2+), Zn(2+), and Ca(2+)) on the thermogelation of the polymer aqueous solution was investigated. The dissociation constants between the metal ions and the multiblock copolymer were calculated to be 1.2 × 10(-7), 6.6 × 10(-6), and 1.2 × 10(-4) M for Cu(2+), Zn(2+), and Ca(2+), respectively, implying that the binding affinity of the multiblock copolymer for Cu(2+) is much greater than that for Zn(2+) or Ca(2+). Atomic force microscopy and dynamic light scattering of the multiblock copolymer containing metal ions suggested micelle formation at low temperature, which aggregated as the temperature increased. Circular dichroism spectra suggested that changes in the α-helical secondary structure of the multiblock copolymer were more pronounced by adding Cu(2+) than other metal ions. The thermogelation of the multiblock copolymer aqueous solution containing Cu(2+) was observed at a lower temperature, and the modulus of the gel was significantly higher than that of the system containing Ca(2+) or Zn(2+), in spite of the same concentration of the metal ions and their same ionic valence of +2. The above results suggested that strong ionic complexes between Cu(2+) and the multiblock copolymer not only affected the secondary structure of the polymer but also facilitated the thermogelation of the polymer aqueous solution through effective salt-bridge formation even in a millimolar range of the metal ion concentration. Therefore, binding affinity of metal ions for polymers should be considered first in designing an effective ion/temperature dual stimuli-sensitive polymer. PMID:25178662

  8. Influencing the structure of block copolymer micelles with small molecule additives

    Science.gov (United States)

    Robertson, Megan; Singh, Avantika; Cooksey, Tyler; Kidd, Bryce; Piemonte, Rachele; Wang, Shu; Mai Le, Kim; Madsen, Louis

    Amphiphilic block copolymer micelles in water are under broad exploration for drug delivery applications due to their high loading capacity and targeted drug delivery. We aim to understand the kinetic and thermodynamic processes that underlie the self-assembly of diblock copolymer micelle systems. The present work focuses on diblock copolymers containing poly(ethylene oxide) (a hydrophilic polymer) and polycaprolactone (a hydrophobic polymer), which spontaneously self-assemble into spherical micelles in water. Addition of a common good solvent (a co-solvent) for both of the constituting blocks, such as tetrahydrofuran (THF), reduces the interfacial tension at the core-corona interface. We are currently investigating the effect of this phenomenon on the micelle structural properties, using small-angle scattering and nuclear magnetic resonance. We have characterized the hydrodynamic radius, core radius, corona thickness, aggregation number, degree of swelling of the micelle core with the co-solvent, and unimer (free chain) concentration, as a function of the co-solvent concentration. Fundamental knowledge from these studies will inform design of drug delivery systems by allowing us to tailor micelle properties for optimal cargo loading.

  9. Highly conductive side chain block copolymer anion exchange membranes.

    Science.gov (United States)

    Wang, Lizhu; Hickner, Michael A

    2016-06-28

    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. PMID:27216558

  10. 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, Doug Hyun; Park, Soojin; Xu, Ting

    2015-10-13

    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.

  11. Self-assembly of inorganic nanoparticle vesicles and tubules driven by tethered linear block copolymers.

    Science.gov (United States)

    He, Jie; Liu, Yijing; Babu, Taarika; Wei, Zengjiang; Nie, Zhihong

    2012-07-18

    Controllable self-assembly of nanoscale building blocks into larger specific structures provides an effective route for the fabrication of new materials with unique optical, electronic, and magnetic properties. The ability of nanoparticles (NPs) to self-assemble like molecules is opening new research frontiers in nanoscience and nanotechnology. We present a new class of amphiphilic "colloidal molecules" (ACMs) composed of inorganic NPs tethered with amphiphilic linear block copolymers (BCPs). Driven by the conformational changes of tethered BCP chains, such ACMs can self-assemble into well-defined vesicular and tubular nanostructures comprising a monolayer shell of hexagonally packed NPs in selective solvents. The morphologies and geometries of these assemblies can be controlled by the size of NPs and molecular weight of BCPs. Our approach also allows us to control the interparticle distance, thus fine-tuning the plasmonic properties of the assemblies of metal NPs. This strategy provides a general means to design new building blocks for assembling novel functional materials and devices. PMID:22746265

  12. Observed frustration in confined block copolymers

    International Nuclear Information System (INIS)

    Symmetric diblock copolymers confined between two solid surfaces were studied by neutron reflectivity. A multilayered morphology with an integral number of layers oriented parallel to the solid interfaces was found in all cases. The period of the confined multilayers deviated from the bulk period in a cyclic manner as a function of the confined film thickness. A first-order transition occurred between the expanded and contracted states of the copolymer chains. The data suggest that the deviation of the period from the bulk value decreases with increasing separation distance

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

    Directory of Open Access Journals (Sweden)

    J. Puiggali

    2013-01-01

    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.

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

    KAUST Repository

    Hilke, Roland

    2014-12-01

    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.

  15. Characterization of Lithium Polysulfide Salts in Homopolymers and Block Copolymers

    Science.gov (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.

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

    International Nuclear Information System (INIS)

    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.)

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

    KAUST Repository

    Sutisna, Burhannudin

    2016-05-18

    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.

  18. Controlling block copolymer phase behavior using ionic surfactant

    Science.gov (United States)

    Ray, D.; Aswal, V. K.

    2016-05-01

    The phase behavior of poly(ethylene oxide)-poly(propylene oxide-poly(ethylene oxide) PEO-PPO-PEO triblock copolymer [P85 (EO26PO39EO26)] 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.

  19. Interfacial Phenomena of Solvent-diluted Block Copolymers

    OpenAIRE

    Cohen, Shai; Andelman, David

    2013-01-01

    A phenomenological mean-field theory is used to investigate the properties of solvent-diluted di-block copolymers (BCP), in which the two BCP components (A and B) form a variety of phases that are diluted by a solvent (S). Using this approach, we model mixtures of di-block copolymers and a solvent and obtained the corresponding critical behavior. In the low solvent limit, we find how the critical point depends on the solvent density. Due to the non-linear nature of the coupling between the A/...

  20. Structure-directing star-shaped block copolymers: supramolecular vesicles for the delivery of anticancer drugs.

    Science.gov (United States)

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

    2015-06-28

    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

  1. Dynamics of amphiphilic diblock copolymers at the air-water interface

    OpenAIRE

    STOCCO, Antonio; Tauer, Klaus; Pispas, Stergios; Sigel, Reinhard

    2011-01-01

    Two polyisoprene-polyethyleneoxide diblock copolymers with different block length ratios adsorbed to the water surface were investigated by multiple angle of incidence ellipsometry, evanescent wave light scattering, and surface tension experiments. In a semidilute interfacial regime, the transition from a two-dimensional to a "mushroom" regime, in which polymer chains form loops and tails in the subphase, was discussed. A diffusion mechanism parallel to the interface was probed by evanescent ...

  2. Synthesis and characterization of biodegradable poly(ethylene glycol)-block-poly(5-benzyloxy-trimethylene carbonate) copolymers for drug delivery.

    Science.gov (United States)

    Zeng, Faquan; Liu, Jubo; Allen, Christine

    2004-01-01

    Amphiphilic diblock copolymers with various block compositions were synthesized with monomethoxy-terminated poly(ethylene glycol) (MePEG) as the hydrophilic block and poly(5-benzyloxy-trimethylene carbonate) (PBTMC) as the hydrophobic block. When the copolymerization was conducted using MePEG as a macroinitiator and stannous 2-ethylhexanoate (Sn(Oct)2) as a catalyst, the molecular weight of the second block was uncontrollable, and the method only afforded a mixture of homopolymer and copolymer with a broad molecular weight distribution. By contrast, the use of the triethylaluminum-MePEG initiator yielded block copolymers with controllable molecular weight and a more narrow molecular weight distribution than the copolymers obtained using Sn(Oct)2. GPC and 1H NMR studies confirmed that the macroinitiator was consumed and the copolymer composition was as predicted. Two of the newly synthesized MePEG-b-PBTMC copolymers were evaluated in terms of properties primarily relating to their use in micellar drug delivery. MePEG-b-PBTMC micelles with a narrow monomodal size distribution were prepared using a high-pressure extrusion technique. The MePEG-b-PBTMC copolymers were also confirmed to be biodegradable and noncytotoxic. PMID:15360292

  3. Amphiphilic graft copolymer based on poly(styrene-co-maleic anhydride) with low molecular weight polyethylenimine for efficient gene delivery

    OpenAIRE

    Duan XP; Xiao JS; Yin Q; Zhang ZW; Mao SR; Li YP

    2012-01-01

    Xiaopin Duan,1,2 Jisheng Xiao,2 Qi Yin,2 Zhiwen Zhang,2 Shirui Mao,1 Yaping Li21School of Pharmacy, Shenyang Pharmaceutical University, Shenyang, 2Center of Pharmaceutics, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, ChinaBackground and methods: A new amphiphilic comb-shaped copolymer (SP) was synthesized by conjugating poly(styrene-co-maleic anhydride) with low molecular weight polyethyleneimine for gene delivery. Fourier transform infrared spectrum, 1H nuclea...

  4. Chain exchange kinetics of block copolymer micelles in ionic liquids

    Science.gov (United States)

    Ma, Yuanchi; Lodge, Timothy

    The chain exchange kinetics of block copolymer micelles has been studied using time-resolved small-angle neutron scattering (TR-SANS), a key tool in determining the average micelle composition in contrast-matched solvents. In this work, PMMA-block-PnBMA was selected as the model block copolymer, which has a LCST behavior in the common ionic liquids, [EMIM][TFSI] and [BMIM][TFSI]. We examined the chain exchange kinetics of three PMMA-block-PnBMA copolymers, with identical PMMA block length (MPMMA = 25000) and different PnBMA block lengths (MPnBMA = 24000, 35000 and 53000); the Flory-Huggins interaction parameter (χ) between the core (PnBMA) and the solvent were varied by mixing [EMIM][TFSI] and [BMIM][TFSI] in different ratios. We found that the relaxation of the initial segregation of h- and d- micelles followed the same form with the time as previously developed by our group. Assuming that single chain expulsion is the rate limiting step, the thermal barrier was found to depend linearly on the core block length (Ncore) . Furthermore, the effect of χ on the chain exchange kinetics will also be discussed.

  5. 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

    Science.gov (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

  6. Segmented block copolymers with polyesteramide blocks of uniform length: synthesis

    NARCIS (Netherlands)

    Gaymans, R.J.; Haan, de J.L.

    1993-01-01

    Segmented copolymers were synthesized from poly(tetramethylene oxide) with hydroxy end-groups or aliphatic diols and a short-chain diester diamide with a uniform length. The diester diamide (N,N'-bis(p-carbomethoxybenzoyl)butanediamine) (Tm = 257°C) used is made from butanediamine and an excess of d

  7. Stability of ordered phases in block copolymer melts and solutions

    Indian Academy of Sciences (India)

    Kell Mortensen

    2008-11-01

    Block copolymer melts and solutions assemble into nanosized objects that order into a variety of phases, depending on molecular parameters and mutual interactions. Beyond the classical phases of lamella ordered sheets, hexagonally ordered cylinders and cubic ordered spheres, the complex bicontinuous gyroid phase and the modulated lamellar phase are observed near the phase boundaries. The stability of these phases has been discussed on the basis of theoretical calculations. Here, we will discuss new experimental results showing that the given ordered phase depends critically on both molecular purity and mechanical treatment of the sample. While a variety of block copolymer micellar systems have been shown to undergo the liquid-to-bcc-to-fcc phase sequence upon varying micellar parameters (or temperature), we find for a purified system a different sequence, namely liquid-to-fcc-to-bcc [1]. The latter sequence is by the way the one predicted for pure block copolymer melts. External fields like shear or stress may also affect the ordered phase. Applying well-controlled large-amplitude oscillatory shear can be used to effectively control the texture of soft materials in the ordered states. As an example, we present results on a body-centred-cubic phase of a block copolymer system, showing how a given texture can be controlled with the application of specific shear rate and shear amplitude [2,3]. Shear may however also affect the thermodynamic ground state, causing shear-induced ordering and disordering (melting), and shear-induced order–order transitions. We will present data showing that the gyroid state of diblock copolymer melts is unstable when exposed to large amplitude/frequency shear, transforming into the hexagonal cylinder phase [4]. The transformation is completely reversible. With the rather slow kinetics in the transformation of copolymer systems, it is possible in detail to follow the complex transformation process, where we find transient ordered

  8. Low molecular weight block copolymers as plasticizers for polystyrene

    DEFF Research Database (Denmark)

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

    2005-01-01

    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...... of approximately 1 kg/mol and an alkyl block with a molecular weight of approximately of 0.3 kg/mol. The efficiency of the block copolymers as plasticizers increases with decreasing molecular weight and polystyrene content. In addition, polystyrene-b-alkyl is found to be an efficient plasticizer also...

  9. Equilibrium exchange kinetics in PEP-PEO block copolymer micelles. A time resolved SANS study

    International Nuclear Information System (INIS)

    The chain exchange kinetics in polymeric micelles has been studied by a novel time resolved small angle neutron scattering (TR-SANS) technique. The system investigated was the amphiphilic block copolymer poly(ethylene-alt-propylene)-poly(ethylene oxide) (PEP-PEO) in water/N,N-dimethylformamide (DMF) mixtures as selective solvent for PEO. The TR-SANS technique exploits the large difference in scattering length density of deuterated and protonated species allowing for a detailed study of chain exchange kinetics with virtually no perturbation from equilibrium. The measured relaxation curves show a fast initial decay which gradually slows down at longer times. This extremely broad and heterogeneous decay drastically deviates from single exponential predicted by the scaling theory of Halperin and Alexander. Instead, the data appear to follow a logarithmic time dependence. This behavior most likely stems from a heterogeneous release of core chains caused by strong topological correlations inside the small micellar cores

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

    KAUST Repository

    Peinemann, Klaus-Viktor

    2013-06-01

    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.

  11. Complexes of block copolymers in solution: tree approximation

    NARCIS (Netherlands)

    Geurts, Bernard J.; Damme, van Ruud

    1989-01-01

    We determine the statistical properties of block copolymer complexes in solution. These complexes are assumed to have the topological structure of (i) a tree or of (ii) a line-dressed tree. In case the structure is that of a tree, the system is shown to undergo a gelation transition at sufficiently

  12. Asymmetric block copolymers confined in a thin film

    NARCIS (Netherlands)

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

    2000-01-01

    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.

  13. Fast assembly of ordered block copolymer nanostructures through microwave annealing.

    Science.gov (United States)

    Zhang, Xiaojiang; Harris, Kenneth D; Wu, Nathanael L Y; Murphy, Jeffrey N; Buriak, Jillian M

    2010-11-23

    Block copolymer self-assembly is an innovative technology capable of patterning technologically relevant substrates with nanoscale precision for a range of applications from integrated circuit fabrication to tissue interfacing, for example. In this article, we demonstrate a microwave-based method of rapidly inducing order in block copolymer structures. The technique involves the usage of a commercial microwave reactor to anneal block copolymer films in the presence of appropriate solvents, and we explore the effect of various parameters over the polymer assembly speed and defect density. The approach is applied to the commonly used poly(styrene)-b-poly(methyl methacrylate) (PS-b-PMMA) and poly(styrene)-b-poly(2-vinylpyridine) (PS-b-P2VP) families of block copolymers, and it is found that the substrate resistivity, solvent environment, and anneal temperature all critically influence the self-assembly process. For selected systems, highly ordered patterns were achieved in less than 3 min. In addition, we establish the compatibility of the technique with directed assembly by graphoepitaxy. PMID:20964379

  14. SANS study of nanoparticles based on block copolymer micelles

    Czech Academy of Sciences Publication Activity Database

    Pleštil, Josef; Pospíšil, Herman; Kuklin, A. I.

    Dubna: Joint Institute for Nuclear Research, Lomonosov Moscow State University, 2005. s. 22. ISBN 5-9530-0086-3. [Workshop on Investigations at the IBR-2 Pulsed Reactor /4./. 15.6.2005-18.6.2005, Dubna] R&D Projects: GA ČR GA203/03/0600 Keywords : SANS * block copolymer micelles * nanoparticles Subject RIV: CD - Macromolecular Chemistry

  15. Spectroscopic study of thermoresponsive block copolymers in aqueous solution

    Czech Academy of Sciences Publication Activity Database

    Spěváček, Jiří; Konefal, Rafal; Dybal, Jiří; Čadová, Eva

    Amsterdam: Elsevier, 2015. P116. [International Colloids Conference /5./. 21.06.2015-24.06.2015, Amsterdam] R&D Projects: GA ČR(CZ) GA15-13853S Institutional support: RVO:61389013 Keywords : thermoresponsive polymer * block copolymer * poly(N-isopropylacrylamide) Subject RIV: CD - Macromolecular Chemistry

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

    OpenAIRE

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

    2014-01-01

    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...

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

    KAUST Repository

    Peinemann, Klaus-Viktor

    2015-04-16

    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.

  18. In vitro controlled release of clove essential oil in self-assembly of amphiphilic polyethylene glycol-block-polycaprolactone.

    Science.gov (United States)

    Thonggoom, O; Punrattanasin, N; Srisawang, N; Promawan, N; Thonggoom, R

    2016-05-01

    In this study, a micellar delivery system with an amphiphilic diblock copolymer of poly (ethylene glycol) and poly (ɛ-caprolactone) was synthesised and used to incorporate hydrophobic clove essential oil (CEO). To determine an optimal delivery system, the effects of the copolymer's hydrophobic block length and the CEO-loading content on the encapsulation of CEO were investigated. Percentages of entrapment efficiency (%EE), CEO loading (%CEO), and in vitro release profiles were determined. The size, size distribution, zeta potential, and morphology of the obtained micelles were determined by DLS, FE-SEM, and TEM. The %EE, %CEO, and in vitro release profiles of CEO incorporated in micelles were analysed by HPLC. The study revealed a sustained release profile of CEO from CEO-loaded micelles. The results indicate the successful formulation of CEO-loaded PEG-b-PCL micelle nanoparticles. It is suggested that this micelle system has considerably potential applications in the sustained release of CEO in intravascular drug delivery. PMID:26988617

  19. Stereo block copolymers of L- and D-lactides

    OpenAIRE

    Yui, Nobuhiko; Pieter J. Dijkstra; Feijen, Jan

    1990-01-01

    Sequential diblock copolymers composed of L- and D-lactic acid residues were synthesized through a living ring-opening polymerization of L- and D-lactide initiated by aluminium tris(2-propanolate). The composition of the block copolymers was varied by changing the reaction conditions and monomer over initiator ratio and confirmed by 1H NMR analysis, molecular weight determination and optical rotation measurements. Molecular weights ranged from 1,3 to 2,0 · 104 with 1,2 < Mw/Mn < 1,4. Stereoco...

  20. Polymers and block copolymers of fluorostyrenes by ATRP

    DEFF Research Database (Denmark)

    Hvilsted, Søren; Borkar, Sachin; Abildgaard, Lillian; Georgieva, V.; Siesler, H.W.; Jankova, Katja Atanassova

    2002-01-01

    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....

  1. Ion complex membranes of acrylonitrile copolymers having methacrylic acid and amphiphilic quaternized ammonium groups for uracil molecular imprinting

    International Nuclear Information System (INIS)

    Copolymers having methacrylic acid and amphiphilic quaternized ammonium groups were used for preparation of molecular imprinting membrane of uracil (URA) template. The imprinted polymeric membranes were prepared by phase inversion molecular imprinting by using poly(acrylonitrile-co-methylacrylic acid) [P(AN-co-MAA)] and poly(acrylonitrile-co-vinylbenzyl-stearyldimethylamine chloride) [P(AN-co-SMA)]. Evidence confirmed that both copolymers were mixed to form ion complex by electrostatic interaction between the methacrylic acid and the quaternized ammonium groups. The electrostatic networks of the resultant membranes made the membrane dense and useful for molecule recognition of the template. The imprinted membranes made of different mole ratio of their copolymer segments were examined in binding of URA and other analog molecules

  2. Block copolymer-nanoparticle hybrid self-assembly

    KAUST Repository

    Hoheisel, Tobias N.

    2015-01-01

    © 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.

  3. Design and Application of Nanoscale Actuators Using Block-Copolymers

    Directory of Open Access Journals (Sweden)

    Paul D. Topham

    2010-10-01

    Full Text Available Block copolymers are versatile designer macromolecules where a “bottom-up” approach can be used to create tailored materials with unique properties. These simple building blocks allow us to create actuators that convert energy from a variety of sources (such as chemical, electrical and heat into mechanical energy. In this review we will discuss the advantages and potential pitfalls of using block copolymers to create actuators, putting emphasis on the ways in which these materials can be synthesised and processed. Particular attention will be given to the theoretical background of microphase separation and how the phase diagram can be used during the design process of actuators. Different types of actuation will be discussed throughout.

  4. Formation and Characterization of Anisotropic Block Copolymer Gels

    Science.gov (United States)

    Liaw, Chya Yan; Joester, Derk; Burghardt, Wesley; Shull, Kenneth

    2012-02-01

    Cylindrical micelles formed from block copolymer solutions closely mimic biological fibers that are presumed to guide mineral formation during biosynthesis of hard tissues like bone. The goal of our work is to use acrylic block copolymers as oriented templates for studying mineral formation reactions in model systems where the structure of the underlying template is well characterized and reproducible. Self-consistent mean field theory is first applied to investigate the thermodynamically stable micellar morphologies as a function of temperature and block copolymer composition. Small-angle x-ray scattering, optical birefringence and shear rheometry are used to study the morphology development during thermal processing. Initial experiments are based on a thermally-reversible alcohol-soluble system that can be converted to an aqueous gel by hydrolysis of a poly(t-butyl methacrylate) block to a poly(methacrylic acid) block. Aligned cylindrical domains are formed in the alcohol-based system when shear is applied in an appropriate temperature regime, which is below the critical micelle temperature but above the temperature at which the relaxation time of the gels becomes too large. Processing strategies for producing the desired cylindrical morphologies are being developed that account for both thermodynamic and kinetic effects.

  5. Gas Permeation through Polystyrene-Poly(ethylene oxide) Block Copolymers

    Science.gov (United States)

    Hallinan, Daniel, Jr.; Minelli, Matteo; Giacinti-Baschetti, Marco; Balsara, Nitash

    2013-03-01

    Lithium air batteries are a potential technology for affordable energy storage. They consist of a lithium metal anode and a porous air cathode separated by a solid polymer electrolyte membrane, such as PEO/LiTFSI (PEO = poly(ethylene oxide), LiTFSI = lithium bis-trifluoromethane sulfonimide). For extended operation of such a battery, the polymer electrolyte must conduct lithium ions while blocking electrons and gases present in air. In order to maintain a pressure difference the membrane must be mechanically robust, which can be achieved by incorporating the PEO into a block copolymer with a glassy block such as PS (PS = polystyrene). To protect the lithium electrode, the membrane must have low permeability to gases in air such as CO2, N2, and O2. We have therefore studied the permeation of pure gases through a PS-PEO block copolymer. A high molecular weight, symmetric block copolymer with a lamellar morphology was used to cast free-standing membranes. Gas permeability was measured through these membranes with a standard, pressure-based technique. A model was developed to account for transport through the polymer membrane consisting of semi-crystalline PEO lamellae and amorphous PS lamellae. PEO crystallinity was extracted from the permeation model and compares well with values from differential scanning calorimetry measurements.

  6. Synthesis and interactions with blood of polyetherurethaneurea/polypeptide block copolymers.

    Science.gov (United States)

    Ito, Y; Miyashita, K; Kashiwagi, T; Imanishi, Y

    1993-01-01

    Polyurethane/polypeptide block copolymers were synthesized. Infrared spectroscopy and differential scanning calorimetry revealed that in the block copolymers both segments undergo phase-mixing, while in polyurethane/polypeptide blend both components undergo phase-separation. Contact angle measurement showed that in the block copolymers polyurethane segments tended to appear on the membrane surface, whereas in polyurethane/polypeptide blend polypeptide components appeared on the membrane surface. In vitro nonthrombogenicity of the block copolymers was similar to that of homopolymers or polymer blends, though adhesion and deformation of platelets were suppressed on the block copolymer membranes. PMID:8260582

  7. Heat Capacity of Spider Silk-like Block Copolymers

    OpenAIRE

    Huang, Wenwen; Krishnaji, Sreevidhya; Hu, Xiao; Kaplan, David; Cebe, Peggy

    2011-01-01

    We synthesized and characterized a new family of di-block copolymers based on the amino acid sequences of Nephila clavipes major ampulate dragline spider silk, having the form HABn and HBAn (n=1–3), comprising an alanine-rich hydrophobic block, A, a glycine-rich hydrophilic block, B, and a histidine tag, H. The reversing heat capacities, Cp(T), for temperatures below and above the glass transition, Tg, were measured by temperature modulated differential scanning calorimetry. For the solid sta...

  8. Self-assembly of Block and Graft Copolymers in Aerosol Nanoparticles

    OpenAIRE

    Rahikkala, Antti

    2015-01-01

    This study examined how to control the self-assembly of block and graft copolymers during the aerosol process, which produces nanoparticles with phase-separated inner structure and phase dimensions ranging from 3 nm to 30 nm. The nanoparticles were also studied for the possibility of their use as a drug carriers. Block copolymers consist of two or more chemically different polymer blocks covalently bound together. In graft copolymers molecules are bound as side-chains to the copolymer backbon...

  9. Adsorption of polyelectrolytes and charged block copolymers on oxides. Consequences for colloidal stability.

    OpenAIRE

    Hoogeveen, N.G.

    1996-01-01

    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 polyelectrolytes and block copolymers with oxidic substrates has been systematically studied. A set of block copolymers with one charged block and one neutral water-soluble block had to be synthesised becaus...

  10. Construction and characterization of hybrid nanoparticles via block copolymer blends and kinetic control of solution assembly

    Science.gov (United States)

    Chen, Yingchao

    Amphiphilic block copolymers are able to self-assemble into well-defined nanostructures in aqueous solutions or aqueous/miscible organic solutions. These structures include traditional spheres, cylinders and vesicles, which mimic nanostructures formed by small molecule analogs like lipids and surfactants. The large molecular weight and complex macromolecular architectures provide several advantages over small molecule amphiphiles, including the large chemical versatility, control over the size and shape of the solution assemblies, unique slow chain exchange and exceptional increased versatility in possible nanostructures. These advantages have motivated the noteworthy study of constructing well-defined, controlled and, especially, multicompartment and multigeometry polymeric nanoobjects for potential multiple nanotechnology applications. To reach complexity and well-controlled nanostructures, the facile utility and fundamental understanding of the parameters that influence the effective construction of solution assemblies needs to be continued. Given these motivations, this dissertation demonstrated the design of block copolymers, manipulation of kinetic control parameters of solution assembly, and characterization of hybrid nanostructures with the aim of creating new, well-defined nanostructures. The first objective of this dissertation was to explore the effects of solvent processing rates in influencing multicompartment and multigeometry nanoparticle construction, structure evolution over long-time aging and nanoparticle formation mechanisms. The noticeable effects of water addition rates on the formation of various nanostructures were studied by cryogenic transmission electron microscopy, selective staining and small angle scattering. It was revealed that the water addition rate have significant influence over the final assemblies in block copolymer blends. New shapes of multicompartment and multigeometry nanoparticles have been constructed including hybrid

  11. Ultralow Oil-Fouling Heterogeneous Poly(ether sulfone) Ultrafiltration Membrane via Blending with Novel Amphiphilic Fluorinated Gradient Copolymers.

    Science.gov (United States)

    Zhang, Guangfa; Jiang, Jingxian; Zhang, Qinghua; Gao, Fan; Zhan, Xiaoli; Chen, Fengqiu

    2016-02-01

    A novel amphiphilic fluorinated gradient copolymer was prepared by semibatch reversible addition-fragmentation chain transfer (RAFT) method using poly(ethylene glycol) methyl ether methacrylate (PEGMA) and 3,3,4,4,5,5,6,6,7,7,8,8,8-tridecafluorooctyl acrylate (TFOA) as monomers. The resultant amphiphilic copolymers were then incorporated into the poly(ether sulfone) (PES) to fabricate PES blend membranes via the non-solvent-induced phase separation method (NIPS). During the phase inversion process, both hydrophilic (PEGMA) and low surface energy (TFOA) segments significantly enriched on the membrane surface by surface segregation to form an amphiphilic surface, which was demonstrated by surface wetting properties and X-ray photoelectron spectroscopy (XPS) measurements. According to the filtration experiments of oil-in-water emulsion, the heterogeneous membranes exhibited superior oil-fouling resistant properties, that is, low flux decay (as low as 15.4%) and high flux recovery (almost 100%), compared to the pure PES membrane. The synergistic effect of fouling-resistant and fouling-release mechanisms was found to be responsible for the excellent antifouling capacities. The findings of this study offer a facile and robust strategy for fabricating ultralow oil-fouling membranes that might be used for effective oil/water separation. PMID:26780307

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

    OpenAIRE

    Ek, Pramod Kumar; Andresen, Thomas Lars; Almdal, Kristoffer

    2012-01-01

    This thesis investigated the role of amphiphilic triblock copolymer micelle nanomaterials in nanosensors, with emphasis on the synthesis of micelle particle sensors. The thesis is focused on the role of synthetic and dimensional synthetic organic chemistry in amphiphilic triblock core-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 nanosenso...

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

    Directory of Open Access Journals (Sweden)

    Timothy J. Deming

    2013-01-01

    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.

  14. Biocompatibility of epoxidized styrene-butadiene-styrene block copolymer membrane

    International Nuclear Information System (INIS)

    Styrene-butadiene-styrene block copolymer (SBS) membrane was prepared by solution casting method and then was epoxidized with peroxyformic acid generated in situ to yield the epoxidized styrene-butadiene-styrene block copolymer membrane (ESBS). The structure and properties of ESBS were characterized with infrared spectroscopy, Universal Testing Machine, differential scanning calorimetry (DSC), and thermogravimetry analysis (TGA). The performances of contact angle, water content, protein adsorption, and water vapor transmission rate on ESBS membrane were determined. After epoxidation, the hydrophilicity of the membrane increased. The water vapor transmission rate of ESBS membrane is similar to human skin. The biocompatibility of ESBS membrane was evaluated with the cell culture of fibroblasts on the membrane. It revealed that the cells not only remained viable but also proliferated on the surface of the various ESBS membranes and the population doubling time for fibroblast culture decreased.

  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. Preparation of Pickering Double Emulsions Using Block Copolymer Worms

    OpenAIRE

    Thompson, Kate L.; Mable, Charlotte J.; Lane, Jacob A.; Derry, Mathew J.; Fielding, Lee A.; Armes, Steven P.

    2015-01-01

    The rational formulation of Pickering double emulsions is described using a judicious combination of hydrophilic and hydrophobic block copolymer worms as highly anisotropic emulsifiers. More specifically, RAFT dispersion polymerization was utilized to prepare poly(lauryl methacrylate)–poly(benzyl methacrylate) worms at 20% w/w solids in n-dodecane and poly(glycerol monomethacrylate)–poly(2-hydroxypropyl methacrylate)–poly(benzyl methacrylate) worms at 13% w/w solids in water by polymerization...

  17. Transient instability upon temperature quench in weakly ordered block copolymers

    OpenAIRE

    Qi, Shuyan; Wang, Zhen-Gang

    1999-01-01

    We report a novel transient instability upon temperature quench in weakly ordered block copolymer microphases possessing a soft direction or directions, such as the lamellar and hexagonal cylinder (HEX) phases. We show that reequilibration of the order parameter is accompanied by transient long wavelength undulation of the layers or cylinders—with an initial wavelength that depends on the depth of the temperature quench—that eventually disappears as the structure reaches its equilibrium at th...

  18. Host-Guest Self-assembly in Block Copolymer Blends

    OpenAIRE

    Woon Ik Park; YongJoo Kim; Jae Won Jeong; Kyungho Kim; Jung-Keun Yoo; Yoon Hyung Hur; Jong Min Kim; Thomas, Edwin L.; Alfredo Alexander-Katz; Yeon Sik Jung

    2013-01-01

    Ultrafine, uniform nanostructures with excellent functionalities can be formed by self-assembly of block copolymer (BCP) thin films. However, extension of their geometric variability is not straightforward due to their limited thin film morphologies. Here, we report that unusual and spontaneous positioning between host and guest BCP microdomains, even in the absence of H-bond linkages, can create hybridized morphologies that cannot be formed from a neat BCP. Our self-consistent field theory (...

  19. Block and Graft Copolymers Containing Carboxylate or Phosphonate Anions

    OpenAIRE

    Hu, Nan

    2014-01-01

    This dissertation focuses on synthesis and characterization of graft and block copolymers containing carboxylate or phosphonate anions that are potential candidates for biomedical applications such as drug delivery and dental adhesives. Ammonium bisdiethylphosphonate (meth)acrylate and acrylamide phosphonate monomers were synthesized based on aza-Michael addition reactions. Free radical copolymerizations of these monomers with an acrylate-functional poly(ethylene oxide) (PEO) macromonomer...

  20. Electrically Tunable Soft-Solid Block Copolymer Structural Color.

    Science.gov (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

    2015-12-22

    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. PMID:26505787

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

    Directory of Open Access Journals (Sweden)

    Kazuhiro Nakabayashi

    2014-04-01

    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.

  2. Supramolecular Routes to Hierarchical Structures : Comb-Coil Diblock Copolymers Organized with Two Length Scales

    NARCIS (Netherlands)

    Ruokolainen, J.; Saariaho, M.; Ikkala, O.; Brinke, G. ten; Thomas, E.L.; Torkkeli, M.; Serimaa, R.

    1999-01-01

    We show that polymeric materials characterized by two length scales are obtained if diblock copolymers are mixed with amphiphilic selective solvents, leading to self-organization which combines the “block copolymer length scale” with a much shorter “nanoscale”. In this work, the amphiphilic compound

  3. Preparation and icephobic properties of polymethyltrifluoropropylsiloxane–polyacrylate block copolymers

    Energy Technology Data Exchange (ETDEWEB)

    Li, Xiaohui; Zhao, Yunhui [School of Materials Science and Engineering, and Tianjin Key Laboratory of Composite and Functional Materials, Tianjin University, Tianjin 300072 (China); Li, Hui [School of Chemistry and Chemical Engineering, Shandong Key Laboratory of Fluorine Chemistry and Chemical Engineering Materials, University of Jinan, Jinan 250022 (China); Yuan, Xiaoyan, E-mail: xyuan28@yahoo.com [School of Materials Science and Engineering, and Tianjin Key Laboratory of Composite and Functional Materials, Tianjin University, Tianjin 300072 (China)

    2014-10-15

    Highlights: • PMTFPS–b-polyacrylate copolymers in five different compositions were synthesized. • Enrichment of PMTFPS amounts at the surface made high F/Si value. • Icing delay time was related to the surface roughness. • Ice shear strength was decreased by the synergistic effect of silicone and fluorine. - Abstract: Five polymethyltrifluoropropylsiloxane (PMTFPS)–polyacrylate block copolymers (PMTFPS–b-polyacrylate) were synthesized by free radical polymerization of methyl methacrylate, n-butyl acrylate and hydroxyethyl methacrylate using PMTFPS macroazoinitiator (PMTFPS-MAI) in range of 10–50 mass percentages. The morphology, surface chemical composition and wettability of the prepared copolymer films were investigated by transmission electron microscopy, atomic force microscopy, X-ray photoelectron spectroscopy, and water contact angle measurement. Delayed icing time and ice shear strength of the films were also detected for the icephobic purpose. The surface morphologies of the copolymers were different from those of the bulk because of the migration of the PMTFPS segments to the air interface during the film formation. Maximal delayed icing time (186 s at −15 °C) and reduction of the ice shear strength (301 ± 10 kPa) which was significantly lower than that of polyacrylates (804 ± 37 kPa) were achieved when the content of PMTFPS-MAI was 20 wt%. The icephobicity of the copolymers was attributed primarily to the enrichment of PMTFPS on the film surface and synergistic effect of both silicone and fluorine. Thus, the results show that the PMTFPS–b-polyacrylate copolymer can be used as icephobic coating materials potentially.

  4. Nanostructured assemblies from amphiphilic ABC multiblock polymers

    Science.gov (United States)

    Hillmyer, Marc A.

    2012-02-01

    Amphiphilic AB diblock copolymers containing a water compatible segment can self-assemble in aqueous media to give supramolecular structures that include simple spherical micelles and macromolecular vesicles termed polymersomes. Amphiphilic ABA triblocks with hydrophobic end blocks can adopt analogous structures but can also form gels at high polymer concentrations. The structural and chemical diversity demonstrated in block copolymer micelles and gels makes them attractive for applications ranging from drug delivery to personal care products to nanoreactors. The inclusion of a third block in amphiphilic ABC triblock systems can lead to a much wider array of self-assembled structures that depend not only on composition but also on block sequence, architecture and incompatibility considerations. I will present our recent efforts on tuning micelle and gel structure and behavior using controlled architecture ABC triblocks. The combination of diverse polymer segments into a single macromolecule is a powerful method for development of self-assembled structures with both new form and new function.

  5. Metal Nanoparticle/Block Copolymer Composite Assembly and Disassembly

    OpenAIRE

    Li, Zihui; Sai, Hiroaki; Warren, Scott C.; Kamperman, Marleen; Arora, Hitesh; Gruner, Sol M.; Wiesner, Ulrich

    2009-01-01

    Ligand-stabilized platinum nanoparticles (Pt NPs) were self-assembled with poly(isoprene-block-dimethylaminoethyl methacrylate) (PI-b-PDMAEMA) block copolymers to generate organic-inorganic hybrid materials. High loadings of NPs in hybrids were achieved through usage of N,N-di-(2-(allyloxy)ethyl)-N-3-mercaptopropyl-N-3-methylammonium chloride as the ligand, which provided high solubility of NPs in various solvents as well as high affinity to PDMAEMA. From NP synthesis, existence of sub-1 nm P...

  6. Redox-controlled micellization of organometallic block copolymers.

    Science.gov (United States)

    Rider, David A; Winnik, Mitchell A; Manners, Ian

    2007-11-21

    Polystyrene-block-polyferrocenylsilane (PS-b-PFS) diblock copolymers were stoichiometrically oxidized in solution using salts of the one-electron oxidant tris(4-bromophenyl)ammoniumyl. Due to a redox-induced polarity change for the PFS block, self-assembly into well-defined spherical micelles occurs. The micelles are composed of a core of partially oxidized PFS segments and a corona of PS. When the micellar solutions were treated with the reducing agent decamethylcobaltocene, the spherical micelles disassemble and regenerate unassociated and pristine PS-b-PFS free chains. PMID:17971963

  7. Photoresponsive Block Copolymers Containing Azobenzenes and Other Chromophores

    Directory of Open Access Journals (Sweden)

    Takaomi Kobayashi

    2010-01-01

    Full Text Available Photoresponsive block copolymers (PRBCs containing azobenzenes and other chromophores can be easily prepared by controlled polymerization. Their photoresponsive behaviors are generally based on photoisomerization, photocrosslinking, photoalignment and photoinduced cooperative motions. When the photoactive block forms mesogenic phases upon microphase separation of PRBCs, supramolecular cooperative motion in liquid-crystalline PRBCs enables them to self-organize into hierarchical structures with photoresponsive features. This offers novel opportunities to photocontrol microphase-separated nanostructures of well-defined PRBCs and extends their diverse applications in holograms, nanotemplates, photodeformed devices and microporous films.

  8. Bioreducible unimolecular micelles based on amphiphilic multiarm hyperbranched copolymers for triggered drug release

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    A novel type of bioreducible amphiphilic multiarm hyperbranched copolymer (H40-star-PLA-SS-PEG) based on Boltorn H40 core,poly(L-lactide) (PLA) inner-shell,and poly(ethylene glycol) (PEG) outer-shell with disulfide-linkages between the hydrophobic and hydrophilic moieties was developed as unimolecular micelles for controlled drug release triggered by reduction.The obtained H40-star-PLA-SS-PEG was characterized in detail by nuclear magnetic resonance (NMR),Fourier transform infrared (FTIR),gel permeation chromatography (GPC),differential scanning calorimeter (DSC),and thermal gravimetric analysis (TGA).Transmission electron microscopy (TEM) and dynamic light scattering (DLS) analyses suggested that H40-star-PLA-SS-PEG formed stable unimolecular micelles in aqueous solution with an average diameter of 19 nm.Interestingly,these micelles aggregated into large particles rapidly in response to 10 mM dithiothreitol (DTT),most likely due to shedding of the hydrophilic PEG outer-shell through reductive cleavage of the disulfide bonds.As a hydrophobic anticancer model drug,doxorubicin (DOX) was encapsulated into these reductive unimolecular micelles.In vitro release studies revealed that under the reduction-stimulus,the detachment of PEG outer-shell in DOX-loaded micelles resulted in a rapid drug release.Flow cytometry and confocal laser scanning microscopy (CLSM) measurements indicated that these DOX-loaded micelles were easily internalized by living cells.Methyl tetrazolium (MTT) assay demonstrated a markedly enhanced drug efficacy of DOX-loaded H40-star-PLA-SS-PEG micelles as compared to free DOX.All of these results show that these bioreducible unimolecular micelles are promising carriers for the triggered intracellular delivery of hydrophobic anticancer drugs.

  9. Responsive block copolymer photonics triggered by protein-polyelectrolyte coacervation.

    Science.gov (United States)

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

    2014-11-25

    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. PMID:25393374

  10. Block copolymers for alkaline fuel cell membrane materials

    Science.gov (United States)

    Li, Yifan

    Alkaline fuel cells (AFCs) using anion exchange membranes (AEMs) as electrolyte have recently received considerable attention. AFCs offer some advantages over proton exchange membrane fuel cells, including the potential of non-noble metal (e.g. nickel, silver) catalyst on the cathode, which can dramatically lower the fuel cell cost. The main drawback of traditional AFCs is the use of liquid electrolyte (e.g. aqueous potassium hydroxide), which can result in the formation of carbonate precipitates by reaction with carbon dioxide. AEMs with tethered cations can overcome the precipitates formed in traditional AFCs. Our current research focuses on developing different polymer systems (blend, block, grafted, and crosslinked polymers) in order to understand alkaline fuel cell membrane in many aspects and design optimized anion exchange membranes with better alkaline stability, mechanical integrity and ionic conductivity. A number of distinct materials have been produced and characterized. A polymer blend system comprised of poly(vinylbenzyl chloride)-b-polystyrene (PVBC-b-PS) diblock copolymer, prepared by nitroxide mediated polymerization (NMP), with poly(2,6-dimethyl-1,4-phenylene oxide) (PPO) or brominated PPO was studied for conversion into a blend membrane for AEM. The formation of a miscible blend matrix improved mechanical properties while maintaining high ionic conductivity through formation of phase separated ionic domains. Using anionic polymerization, a polyethylene based block copolymer was designed where the polyethylene-based block copolymer formed bicontinuous morphological structures to enhance the hydroxide conductivity (up to 94 mS/cm at 80 °C) while excellent mechanical properties (strain up to 205%) of the polyethylene block copolymer membrane was observed. A polymer system was designed and characterized with monomethoxy polyethylene glycol (mPEG) as a hydrophilic polymer grafted through substitution of pendent benzyl chloride groups of a PVBC

  11. Biodegradable PELA block copolymers: in vitro degradation and tissue reaction.

    Science.gov (United States)

    Younes, H; Nataf, P R; Cohn, D; Appelbaum, Y J; Pizov, G; Uretzky, G

    1988-01-01

    Degradation of, and tissue reaction elicited by a series of polyethylene oxide (PEO)/polylactic acid (PLA) PELA block copolymers were studied in vitro and in vivo. In particular, the effect of pH, temperature and enzymatic activity was addressed. The mass loss was faster, the more basic the media, while, expectedly, PELA copolymers degraded faster with the higher temperature. The addition of an enzyme (carboxylic ester hydrolase) had no effect. The degradation process strongly affected the mechanical properties of the materials under investigation, the elongation at break dropping drastically after two days of degradation. After seven days, only gross observation of the extensively degraded samples was possible. The in vivo studies compared the tissue reaction elicited by various PELA copolymers to that evoked by PLA. Evaluation of tissue reaction observed with a PELA sample after sterilization with gamma radiation showed acute inflammation with considerable dispersion of the material, 12 days after implantation. The granulomatous reaction observed with PELA copolymers after ethylene oxide sterilization was identical to the reaction observed with PLA. PMID:3064826

  12. Diamond-Forming Block Copolymers and Diamond-like Morphologies: a New Route towards efficient Block Copolymer Membranes?

    Science.gov (United States)

    Erukhimovich, Igor; Kriksin, Yury

    2014-03-01

    Formation of ordered (microphase separated) block copolymer nanostructures is a promising route towards creating isoporous membranes suitable for technological applications. We propose a new route to achieve this target: to choose such block copolymer architectures, which would provide a practically isotropic permeability both in the bulk and in thin films. Basing both on the weak segregation theory extension into the thin films and the self-consistent field theory numerical procedure we present the results concerning the effects of the wall confinement both with neutral, selective and patterned walls on the structure and stability of the block copolymer ordered films. The diamond-like morphology is found to be the most promising one as to optimizing the permeability of thin films. A new effect of the diamond morphology stability enhancement in the presence of a properly designed lamellar-like wall pattern is discovered and the corresponding phase diagram demonstrating the effect of the pattern scale and film width on the diamond morphology stability is presented. The financial support was provided by Ministry of Science and Education of Russian Federation (State Contract No. 02.740.11.0858) and European Commission (FP7 project NMP3-SL-2009- 228652 (SELFMEM)).

  13. Morphology and Proton Transport in Humidified Phosphonated Peptoid Block Copolymers

    Science.gov (United States)

    2016-01-01

    Polymers that conduct protons in the hydrated state are of crucial importance in a wide variety of clean energy applications such as hydrogen fuel cells and artificial photosynthesis. Phosphonated and sulfonated polymers are known to conduct protons at low water content. In this paper, we report on the synthesis phosphonated peptoid diblock copolymers, poly-N-(2-ethyl)hexylglycine-block-poly-N-phosphonomethylglycine (pNeh-b-pNpm), with volume fractions of pNpm (ϕNpm) values ranging from 0.13 to 0.44 and dispersity (Đ) ≤ 1.0003. The morphologies of the dry block copolypeptoids were determined by transmission electron microscopy and in both the dry and hydrated states by synchrotron small-angle X-ray scattering. Dry samples with ϕNpm > 0.13 exhibited a lamellar morphology. Upon hydration, the lowest molecular weight sample transitioned to a hexagonally packed cylinder morphology, while the others maintained their dry morphologies. Water uptake of all of the ordered samples was 8.1 ± 1.1 water molecules per phosphonate group. In spite of this, the proton conductivity of the ordered pNeh-b-pNpm copolymers ranged from 0.002 to 0.008 S/cm. We demonstrate that proton conductivity is maximized in high molecular weight, symmetric pNeh-b-pNpm copolymers. PMID:27134312

  14. P(HPMA)-block-P(LA) copolymers in paclitaxel formulations: polylactide stereochemistry controls micellization, cellular uptake kinetics, intracellular localization and drug efficiency.

    Science.gov (United States)

    Barz, Matthias; Armiñán, Ana; Canal, Fabiana; Wolf, Florian; Koynov, Kaloian; Frey, Holger; Zentel, Rudolf; Vicent, María J

    2012-10-10

    In order to explore the influence of polymer microstructure and stereochemistry in biological settings, the synthesis, micellization, cellular fate and the use in paclitaxel formulations of poly(N-(2-hydroxypropyl)-methacrylamide)-block-poly(L-lactide) (P(HPMA)-block-P(LLA)) and poly(N-(2-hydroxypropyl)-methacrylamide)-block-poly(DL-lactide) block copolymers (P(HPMA)-block-P(DLLA)) were studied. To this end, P(HPMA)-block-P(lactide) block copolymers and their fluorescently labeled analogues were synthesized. The polymers exhibited molecular weights M(n) around 20,000 g/mol with dispersities (D=M(w)/M(n)) below 1.3. In addition, the solution conformation of this new type of partially degradable amphiphilic block copolymers was studied with and without paclitaxel loading in PBS buffer (pH 7.2), employing fluorescence correlation spectroscopy (FCS). We observed polymeric micelles with a hydrodynamic diameter of 17.0 nm for a fluorescently labeled P(HPMA)-block-P(LLA) block copolymer (P2*) and 20.4 nm for a P(HPMA)-block-P(DLLA) block copolymer (P3*). For the corresponding loaded block copolymers aggregates with a diameter of 40.0 nm (P2*) and 41.4 nm (P3*) in formulations containing 17 wt.% paclitaxel were observed, respectively. While the block copolymer itself showed non-toxic behavior up to a concentration of 3 mg/mL in HeLa (human cervix adenocarcinoma) cells, the paclitaxel containing formulations showed IC 50 values in the range of 10-100 nM. The P(HPMA)-block-P(DLLA) polymer (P3*) enters the cells more efficiently than stereo regular polymer (P2*) via an energy-dependent uptake mechanism. Thus, differences in the IC(50) value are--most likely--attributed to significant changes in cellular uptake. Polymer tacticity and stereoregularity appear to represent a key feature determining cellular uptake and efficiency for the PLA block copolymer drug formulations. This work demonstrates the importance of the microstructure of polymers used in drug delivery systems (DDS

  15. Metal Nanoparticle/Block Copolymer Composite Assembly and Disassembly.

    Science.gov (United States)

    Li, Zihui; Sai, Hiroaki; Warren, Scott C; Kamperman, Marleen; Arora, Hitesh; Gruner, Sol M; Wiesner, Ulrich

    2009-01-01

    Ligand-stabilized platinum nanoparticles (Pt NPs) were self-assembled with poly(isoprene-block-dimethylaminoethyl methacrylate) (PI-b-PDMAEMA) block copolymers to generate organic-inorganic hybrid materials. High loadings of NPs in hybrids were achieved through usage of N,N-di-(2-(allyloxy)ethyl)-N-3-mercaptopropyl-N-3-methylammonium chloride as the ligand, which provided high solubility of NPs in various solvents as well as high affinity to PDMAEMA. From NP synthesis, existence of sub-1 nm Pt NPs was confirmed by high-angle annular dark field scanning transmission electron microscopy (HAADF-STEM) images. Estimations of the Pt NP ligand head group density based on HAADF-STEM images and thermogravimetric analysis (TGA) data yielded results comparable to what has been found for alkanethiol self-assembled monolayers (SAMs) on flat Pt {111} surfaces. Changing the volume fraction of Pt NPs in block copolymer-NP composites yielded hybrids with spherical micellar, wormlike micellar, lamellar and inverse hexagonal morphologies. Disassembly of hybrids with spherical, wormlike micellar, and lamellar morphologies generated isolated metal-NP based nano-spheres, cylinders and sheets, respectively. Results suggest the existence of powerful design criteria for the formation of metal-based nanostructures from designer blocked macromolecules. PMID:21103025

  16. Synthesis of segmented PB(SMA-block-PB)(n) block copolymers through a polymeric iniferter technique

    NARCIS (Netherlands)

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

    1997-01-01

    A technique is described for the synthesis of segmented block copolymers of polybutadiene and poly(styrene-co-maleic anhydride) through a polymeric therma iniferter based on polybutadiene, which was used as an initiator for the thermal copolymerization of styrene and maleic anhydride. The polymeric

  17. Mucoadhesive Amphiphilic Methacrylic Copolymer-Functionalized Poly(ε-caprolactone) Nanocapsules for Nose-to-Brain Delivery of Olanzapine.

    Science.gov (United States)

    Fonseca, Francisco N; Betti, Andresa H; Carvalho, Flávia C; Gremião, Maria P D; Dimer, Frantiescoli A; Guterres, Sílvia S; Tebaldi, Marli L; Rates, Stela M K; Pohlmann, Adriana R

    2015-08-01

    Nose-to-brain drug delivery has been proposed to overcome the low absorption of drugs in central nervous system due to the absence of brain-blood barrier in the olfactory nerve pathway. However, the presence of a mucus layer and quick clearance limit the use of this route. Herein, amphiphilic methacrylic copolymer-functionalized poly(ε-caprolactone) nanocapsules were proposed as a mucoadhesive system to deliver olanzapine after intranasal administration. In vitro evaluations showed that these nanocapsules were able to interact with mucin (up to 17% of increment in particle size and 30% of reduction of particle concentration) and nasal mucosa (2-fold higher force for detaching), as well as to increase the retention of olanzapine (about 40%) on the nasal mucosa after continuous wash. The olanzapine-loaded amphiphilic methacrylic copolymer-functionalized PCL nanocapsules enhanced the amount of drug in the brain of rats (1.5-fold higher compared to the drug solution). In accordance with this finding, this formulation improved the prepulse inhibition impairment induced by apomorphine, which is considered as an operational measure of pre-attentive sensorimotor gating impairment present in schizophrenia. Besides, nanoencapsulated olanzapine did not affect the nasal mucosa integrity after repeated doses. These data evidenced that the designed nanocapsules are a promising mucoadhesive system for nose-to-brain delivery of drugs. PMID:26295147

  18. 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;

    2013-01-01

    PEG and charged PAA buoyant blocks with all other conditions identical, the former showed superior adsorption onto nonpolar, hydrophobic PDMS surfaces from a neutral aqueous solution. PEGbased copolymers showed substantial adsorption for both PS and PMEA as the anchoring block, whereas PAA......-based copolymers showed 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......, hindering the facile formation of the lubricating layer under cyclic tribological stress at the sliding PDMS−PDMS interface. © American Chemical Society...

  19. Hybrid - block copolymer nanocomposites. characterization of nanostructure by small-angle X-ray scattering (SAXS)

    OpenAIRE

    A. Romo-Uribe

    2007-01-01

    The nanoscopic order of a series of block copolymer-inorganic nanocomposites was characterized using small-angle X-ray scattering (SAXS). The nanostructures were obtained via a diblock copolymer directed sol-gel synthesis. The copolymer consists of blocks of poly(isoprene) -PI- and blocks of poly(ethylene oxide) -PEO. The inorganic material consists of a crosslinked sol of 3-glycidoxypropyltrimethoxysilane and aluminum-tri-sec-butoxide in a 4:1 mole ratio, to generate an aluminosilicate ceram...

  20. High aspect ratio sub-15 nm silicon trenches from block copolymer templates.

    Science.gov (United States)

    Gu, Xiaodan; Liu, Zuwei; Gunkel, Ilja; Chourou, S T; Hong, Sung Woo; Olynick, Deirdre L; Russell, Thomas P

    2012-11-01

    High-aspect-ratio sub-15-nm silicon trenches are fabricated directly from plasma etching of a block copolymer mask. A novel method that combines a block copolymer reconstruction process and reactive ion etching is used to make the polymer mask. Silicon trenches are characterized by various methods and used as a master for subsequent imprinting of different materials. Silicon nanoholes are generated from a block copolymer with cylindrical microdomains oriented normal to the surface. PMID:22903820

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

    OpenAIRE

    Shvets, Violetta; Schulte, Lars; Ndoni, Sokol

    2014-01-01

    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-linked phase are sliced with microtome and pattern is transfered from flakes to substrate by plasma etching.Experimental Section. Group of Self-organized Nanoporous Materials in Technical University of Denm...

  2. Enhanced Photophysical Properties of Nanopatterned Titania Nanodots/Nanowires upon Hybridization with Silica via Block Copolymer Templated Sol-Gel Process

    OpenAIRE

    Dinakaran Kannaiyan; Saji Thomas Kochuveedu; Yoon Hee Jang; Juyon Lee; Jooyong Kim; Jieun Lee; Ji Yong Lee; Dong Ha Kim; Yu Jin Jang

    2010-01-01

    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 stepw...

  3. Designing block copolymer architectures for targeted membrane performance

    KAUST Repository

    Dorin, Rachel Mika

    2014-01-01

    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.

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

    Directory of Open Access Journals (Sweden)

    Wenyuan Xie

    2015-08-01

    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.

  5. Self-assembly of block copolymers on topographically patterned polymeric substrates

    Energy Technology Data Exchange (ETDEWEB)

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

    2016-05-10

    Highly-ordered block copolymer films are prepared by a method that includes forming a polymeric replica of a topographically patterned crystalline surface, forming a block copolymer film on the topographically patterned surface of the polymeric replica, and annealing the block copolymer film. The resulting structures can be used in a variety of different applications, including the fabrication of high density data storage media. The ability to use flexible polymers to form the polymeric replica facilitates industrial-scale processes utilizing the highly-ordered block copolymer films.

  6. Characterization and micellization of a poloxamer block copolymer

    DEFF Research Database (Denmark)

    Hvidt, S.; Pedersen, Walther Batsberg

    2007-01-01

    Several poloxamers that are symmetrical EPE block copolymers (E and P are ethylene and propylene oxide, respectively) have been characterized by size exclusion chromatography on Superose columns in water. The poloxamers contain between 12 and 26 wt% of smaller-size UV-absorbing impurities....... Poloxamer P94 (E28P48E28) forms micelles with increasing temperature, and micellization was investigated by eluent gel permeation chromatography (EGPC). EGPC results demonstrate that P94 impurities are not incorporated into the micelles up to 38°C. The importance of poloxamer heterogeneity for thermodynamic...

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

    KAUST Repository

    Marques, Debora S.

    2013-01-01

    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.

  8. Perspective: Evolutionary design of granular media and block copolymer patterns

    Science.gov (United States)

    Jaeger, Heinrich M.; de Pablo, Juan J.

    2016-05-01

    The creation of new materials "by design" is a process that starts from desired materials properties and proceeds to identify requirements for the constituent components. Such process is challenging because it inverts the typical modeling approach, which starts from given micro-level components to predict macro-level properties. We describe how to tackle this inverse problem using concepts from evolutionary computation. These concepts have widespread applicability and open up new opportunities for design as well as discovery. Here we apply them to design tasks involving two very different classes of soft materials, shape-optimized granular media and nanopatterned block copolymer thin films.

  9. Synthesis and Characterization of Cleavable Core-Cross-Linked Micelles Based on Amphiphilic Block Copolypeptoids as Smart Drug Carriers.

    Science.gov (United States)

    Li, Ang; Zhang, Donghui

    2016-03-14

    Amphiphilic block copolypeptoids consisting of a hydrophilic poly(N-ethyl glycine) segment and a hydrophobic poly[(N-propargyl glycine)-r-(N-decyl glycine)] random copolymer segment [PNEG-b-P(NPgG-r-NDG), EPgD] have been synthesized by sequential primary amine-initiated ring-opening polymerization (ROP) of the corresponding N-alkyl N-carboxyanhydride monomers. The block copolypeptoids form micelles in water and the micellar core can be cross-linked with a disulfide-containing diazide cross-linker by copper-mediated alkyne-azide cycloaddition (CuAAC) in aqueous solution. Transmission electron microscopy (TEM) and dynamic light scattering (DLS) analysis revealed the formation of spherical micelles with uniform size for both the core-cross-linked micelles (CCLMs) and non-cross-linked micelles (NCLMs) precursors for selective block copolypeptoid polymers. The CCLMs exhibited increased dimensional stability relative to the NCLMs in DMF, a nonselective solvent for the core and corona segments. Micellar dissociation of CCLMs can be induced upon addition of a reducing agent (e.g., dithiothreitol) in dilute aqueous solutions, as verified by a combination of fluorescence spectroscopy, size exclusion chromatography (SEC), and (1)H NMR spectroscopic measurement. Doxorubicin (DOX), an anticancer drug, can be loaded into the hydrophobic core of CCLMs with a maximal 23% drug loading capacity (DLC) and 37% drug loading efficiency (DLE). In vitro DOX release from the CCLMs can be triggered by DTT (10 mM), in contrast to significantly reduced DOX release in the absence of DTT, attesting to the reductively responsive characteristic of the CCLMs. While the CCLMs exhibited minimal cytotoxicity toward HepG2 cancer cells, DOX-loaded CCLMs inhibited the proliferation of the HepG2 cancer cells in a concentration and time dependent manner, suggesting the controlled release of DOX from the DOX-loaded CCLMS in the cellular environment. PMID:26866458

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

    KAUST Repository

    Bukhryakov, Konstantin V.

    2015-02-09

    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.

  11. (Electro)Mechanical Properties of Olefinic Block Copolymers

    Science.gov (United States)

    Spontak, Richard

    2014-03-01

    Conventional styrenic triblock copolymers (SBCs) swollen with a midblock-selective oil have been previously shown to exhibit excellent electromechanical properties as dielectric elastomers. In this class of electroactive polymers, compliant electrodes applied as active areas to opposing surfaces of an elastomer attract each other, and thus compress the elastomer due to the onset of a Maxwell stress, upon application of an external electric field. This isochoric process is accompanied by an increase in lateral area, which yields the electroactuation strain (measuring beyond 300% in SBC systems). Performance parameters such as the Maxwell stress, transverse strain, dielectric breakdown, energy density and electromechanical efficiency are determined directly from the applied electric field and resulting electroactuation strain. In this study, the same principle used to evaluate SBC systems is extended to olefinic block copolymers (OBCs), which can be described as randomly-coupled multiblock copolymers that consist of crystallizable polyethylene hard segments and rubbery poly(ethylene-co-octene) soft segments. Considerations governing the development of a methodology to fabricate electroresponsive OBC systems are first discussed for several OBCs differing in composition and bulk properties. Evidence of electroactuation in selectively-solvated OBC systems is presented and performance metrics measured therefrom are quantitatively compared with dielectric elastomers derived from SBC and related materials.

  12. Interaction between Albumin and Pluronic F127 Block Copolymer Revealed by Global and Local Physicochemical Profiling.

    Science.gov (United States)

    Neacsu, Maria Victoria; Matei, Iulia; Micutz, Marin; Staicu, Teodora; Precupas, Aurica; Popa, Vlad Tudor; Salifoglou, Athanasios; Ionita, Gabriela

    2016-05-12

    The interaction of human serum albumin (HSA) with amphiphilic block copolymer Pluronic F127 has been investigated by several physical methods. Interest in studying this system stems from a broad range of bioactivities involving both macromolecules. Serum albumins constitute a significant class of proteins in the circulatory system, acting as carriers for a wide spectrum of compounds or assemblies. Pluronic block copolymers have revealed their capacity to ferry a variety of biologically active compounds. Circular dichroism, rheological measurements, and differential scanning microcalorimetry (μDSC) were employed to get insight into the interaction betweeen the two macromolecules. The results reveal that Pluronic F127 induces conformational changes to albumin if it is organized in a micellar form, while albumin influences the self-assembly of Pluronic F127 into micelles or gels. F127 micelles, however, induce smaller conformational changes compared to ionic surfactants. The μDSC thermograms obtained for HSA and/or F127 show that HSA shifts the critical micellar temperature (cmt) to lower values, while concurrently the HSA denaturation behavior is influenced by F127, depending on its concentration. Rheological measurements on solutions of F127 17% have shown that a sol-to-gel transition occurs at higher temperatures in the presence of HSA and the resulting gel is weaker. The global profile on HSA/F127 systems was complemented by local information provided by EPR measurements. A series of X-band EPR experiments was performed with spin probes 4-(N,N'-dimethyl-N-hexadecyl)ammonium-2,2',6,6'-tetramethylpiperidine-1-oxyl iodide (CAT16) and 5-doxyl stearic acid (5-DSA). These spin probes bind to albumin sites and are sensitive to phase transformations in Pluronic block copolymer solutions. For a given F127 concentration, the spin probe binds only to HSA below cmt and migrates to the F127 micelles above cmt. The collective data suggest soft interactions between the

  13. Tough Block Copolymer Organogels and Elastomers as Short Fiber Composites

    Science.gov (United States)

    Kramer, Edward J.

    2012-02-01

    The origins of the exceptional toughness and elastomeric properties of gels and elastomers from block copolymers with semicrystalline syndiotactic polypropylene blocks will be discussed. Using synchrotron X-radiation small angle (SAXS) and wide angle X-ray scattering (WAXS) experiments were simultaneously performed during step cycle tensile deformation of these elastomers and gels. From these results the toughness can be attributed to the formation, orientation and elongation of the crystalline fibrils along the tensile direction. The true stress and true strain ɛH during each cycle were recorded, including the true strain at zero load ɛH,p after each cycle that resulted from the plastic deformation of the sPP crystals in the gel or elastomer. The initial Young's modulus Einit and maximum tangent modulus Emax in each cycle undergo dramatic changes as a function of ɛH,p, with Einit decreasing for ɛH,p 100 to 1000 at the highest maximum (nominal) strain. Based on SAXS patterns from the deformed and relaxed gels, as well as on previous results on deformation of semicrystalline random copolymers by Strobl and coworkers, we propose that the initial decrease in Einit and increase in Emax with ɛH,p are due to a breakup of the network of the original sPP crystal lamellae and the conversion of the sPP lamellae into fibrils whose aspect ratio increases with further plastic deformation, respectively. The gel elastic properties can be understood quantitatively as those of a short fiber composite with a highly deformable matrix. At zero stress the random copolymer midblock chains that connect the fibrils cause these to make all angles to the tensile axis (low Einit), while at the maximum strain the stiff, crystalline sPP fibrils align with the tensile axis producing a strong, relatively stiff gel. The evolution of the crystalline structure during deformation is confirmed by WAXS and FTIR measurements.

  14. Silver-enhanced block copolymer membranes with biocidal activity

    KAUST Repository

    Madhavan, Poornima

    2014-11-12

    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.

  15. Controlling thermochromism in a photonic block copolymer gel.

    Science.gov (United States)

    Walish, Joseph J; Fan, Yin; Centrone, Andrea; Thomas, Edwin L

    2012-09-26

    The tunable properties of stimulus-responsive materials attract great interest in a variety of technological applications. Photonic gels are a new class of these materials, which can be tuned to reflect different wavelengths of light. Controlling this reflected color via temperature-induced changes of self-assembled photonic materials is important for their application in sensors and displays. In this work, the thermochromic behavior of a PS-P2VP photonic gel was found to originate from a temperature-induced change in the pK(a) of the P2VP blocks. Control was obtained through the manipulation of the solution pH. The findings of this work provide the basis for understanding and controlling the properties of thermochromic block copolymers fostering their use in technologically relevant applications. PMID:22763921

  16. Chirality in block copolymer melts: mesoscopic helicity from intersegment twist.

    Science.gov (United States)

    Zhao, Wei; Russell, Thomas P; Grason, Gregory M

    2013-02-01

    We study the effects of chirality at the segment scale on the thermodynamics of block copolymer melts using self-consistent field theory. In linear diblock melts where segments of one block prefer a twisted, or cholesteric, texture, we show that melt assembly is critically sensitive to the ratio of random coil size to the preferred pitch of cholesteric twist. For weakly chiral melts (large pitch), mesophases remain achiral, while below a critical value of pitch, two mesoscopically chiral phases are stable: an undulated lamellar phase and a phase of hexagonally ordered helices. We show that the nonlinear sensitivity of mesoscale chiral order to preferred pitch derives specifically from the geometric and thermodynamic coupling of the helical mesodomain shape to the twisted packing of chiral segments within the core, giving rise to a second-order cylinder-to-helix transition. PMID:23414052

  17. Characterizing the interfaces of block copolymers with high χ

    Science.gov (United States)

    Sunday, Daniel; Maher, Michael; Blachut, Gregory; Asano, Yusuke; Tein, Summer; Willson, C. Grant; Ellison, Christopher; Kline, R. Joseph

    In order for block copolymer (BCP) directed self-assembly (DSA) to be able to pattern features below 10 nm there must be materials which can spontaneously assembly at the required length scales. For the smallest features this will require phase separation where the total chain lengths are under 50 monomer units, demanding very large interaction parameters (χ) to have an order-disorder transition. One of the key parameters for DSA will be the interfacial width between the blocks, which is expected to be correlated to the interaction parameter and will help determine the line edge roughness (LER). We have used resonant soft X-ray reflectivity to investigate a series of high χ BCPs with different compositions and molecular weights to determine the interfacial width and degree of phase separation. We use these results to estimate the value of χ and determine relationships between χ and the interfacial mixing.

  18. Hollow ZIF-8 Nanoworms from Block Copolymer Templates

    KAUST Repository

    Yu, Haizhou

    2015-10-16

    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.

  19. Amphiphilic graft copolymer based on poly(styrene-co-maleic anhydride with low molecular weight polyethylenimine for efficient gene delivery

    Directory of Open Access Journals (Sweden)

    Duan XP

    2012-09-01

    Full Text Available Xiaopin Duan,1,2 Jisheng Xiao,2 Qi Yin,2 Zhiwen Zhang,2 Shirui Mao,1 Yaping Li21School of Pharmacy, Shenyang Pharmaceutical University, Shenyang, 2Center of Pharmaceutics, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, ChinaBackground and methods: A new amphiphilic comb-shaped copolymer (SP was synthesized by conjugating poly(styrene-co-maleic anhydride with low molecular weight polyethyleneimine for gene delivery. Fourier transform infrared spectrum, 1H nuclear magnetic resonance, and gel permeation chromatography were used to characterize the graft copolymer.Results: The buffering capability of SP was similar to that of polyethyleneimine within the endosomal pH range. The copolymer could condense DNA effectively to form complexes with a positive charge (13–30 mV and a small particle size (130–200 nm at N/P ratios between 5 and 20, and protect DNA from degradation by DNase I. In addition, SP showed much lower cytotoxicity than polyethyleneimine 25,000. Importantly, the gene transfection activity and cellular uptake of SP-DNA complexes were all markedly higher than that of complexes of polyethyleneimine 25,000 and DNA in MCF-7 and MCF-7/ADR cell lines.Conclusion: This work highlights the promise of SP as a safe and efficient synthetic vector for DNA delivery.Keywords: poly(styrene-co-maleic anhydride, polyethylenimine, DNA, gene delivery

  20. In-situ formation of silver nanoparticles stabilized by amphiphilic star-shaped copolymer and their catalytic application

    Science.gov (United States)

    Huang, Xiujuan; Xiao, Yan; Zhang, Wei; Lang, Meidong

    2012-01-01

    Silver nanoparticles (Ag NPs) were prepared via in situ reduction of silver nitrate (AgNO3) using polymeric micelles as nanoreactors without any additional reductant. The micelles were constructed from the amphiphilic star-shaped copolymer composed of poly(ɛ-caprolactone) (PCL) segment, 2-(dimethylamino)ethyl methacrylate (DMAEMA or DMA) units and oligo(ethylene glycol)monomethyl ether methacrylate (OEGMA or OEG) units. The Ag NPs stabilized by those star-shaped copolymers were characterized using UV-vis spectrum, DLS, TEM and FTIR. It confirmed that PDMAEMA exhibited the reducing property unless pH was above 7. The Ag NPs were sphere-like with a diameter of 10-20 nm, which was independent of the architecture of the copolymer and AgNO3 concentration. Furthermore, the catalytic activity of these Ag NPs was investigated by monitoring the reduction of p-nitrophenol (4-NP) by NaBH4. The result showed that the Ag NPs formed by coordination reduction can be effectively applied in catalytic reaction.

  1. Synthesis and self-organization of ion-containing amphiphilic diblock copolymers in bulk and in solutions

    Czech Academy of Sciences Publication Activity Database

    Gromadzki, Daniel; Štěpánek, Petr; Janata, Miroslav; Lokaj, Jan; Černoch, Peter; Kůdela, Vlastimil; Diat, O.; Nallet, F.

    Warwick: University of Warwick, 2007. P45-P45. [International Conference on Polymer Colloids. 16.089.2007-18.09.2007, Warwick] R&D Projects: GA ČR GESON/03/E001 Institutional research plan: CEZ:AV0Z40500505 Keywords : ion-containing block copolymers * ionomers * TEMPO Subject RIV: CF - Physical ; Theoretical Chemistry

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

    KAUST Repository

    Moreno, Nicolas

    2015-10-27

    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.

  3. PRECISE SYNTHESIS OF OLEFIN BLOCK COPOLYMERS USING A SYNDIOSPECIFIC LIVING POLYMERIZATION SYSTEM

    Institute of Scientific and Technical Information of China (English)

    Zheng-guo Cai; Hai-hui Su; Takeshi Shiono

    2013-01-01

    This feature article summarizes the synthesis of novel olefin block copolymers using fast syndiospecific living homo-and copolymerization of propylene,higher 1-alkene,and norbomene with ansa-fluorenylamidodimethyltitaniumbased catalyst according to the authors' recent results.The catalytic synthesis of monodisperse polyolefin and olefin block copolymer was also described using this living system.

  4. 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.

    1994-01-01

    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

  5. 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

    2010-01-01

    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

  6. Block copolymer self-assembly : homopolymer additives and multiple length scales

    NARCIS (Netherlands)

    Klymko, Tetyana Romanivna

    2008-01-01

    This thesis is devoted to a theoretical study of self-assembly in specific block-copolymer systems. The ability of block copolymer-based systems to organize at the nanoscale level depends on several parameters, such as volume fraction of the different components, their molar masses and the strength

  7. Dilute gels with exceptional rigidity from self-assembling silk-collagen-like block copolymers

    NARCIS (Netherlands)

    Martens, A.A.; Gucht, van der J.; Eggink, G.; Wolf, de F.A.; Cohen Stuart, M.A.

    2009-01-01

    Rheological data on monodisperse block copolymer hydrogels are rare because the amounts produced with various methods usually are not sufficient for materials testing. By biotechnological means, expression of a block copolymer encoding gene in the yeast Pichia pastoris, we produced enough protein bl

  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.

    1999-01-01

    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 homopol

  9. Enhanced gene expression promoted by hybrid magnetic/cationic block copolymer micelles.

    Science.gov (United States)

    Haladjova, E; Rangelov, S; Tsvetanov, Ch B; Posheva, V; Peycheva, E; Maximova, V; Momekova, D; Mountrichas, G; Pispas, S; Bakandritsos, A

    2014-07-15

    We report on novel gene delivery vector systems based on hybrid polymer-magnetic micelles. The hybrid micelles were prepared by codissolution of hydrophobically surface modified iron oxide and amphiphilic polystyrene-b-poly(quaternized 2-vinylpyridine) block copolymer (PS-b-P2QVP) in organic solvent. After extensive dialysis against water, micelles with positively charged hydrophilic corona of PQVP and hydrophobic PS core were prepared, in which magnetic nanoparticles were randomly distributed. The hybrid micelles were used to form complexes with linear (salmon sperm, 2000 bp, corresponding to M(w) of 1.32 × 10(6) Da) and plasmid (pEGFP-N1, 4730 bp, corresponding to M(w) of 3.12 × 10(6) Da) DNA. The resulting magnetopolyplexes of phosphate:amine (P/N) ratios in the 0.05-20 range were characterized by light scattering, ζ-potential measurements, and transmission electron microscopy as well as cytotoxicity and gel retardation assays. The investigated systems displayed a narrow size distribution, particle dimensions below 360 nm, whereas their ζ-potential values varied from positive to negative depending of the P/N ratio. The resulting vector nanosystems exhibited low toxicity. They were able to introduce pEGFP-N1 molecules into the cells. The application of a magnetic field markedly boosted the transgene expression efficiency of the magnetopolyplexes, which was even superior to those of commercial transfectants such as Lipofectamine and dendritic polyethylenimine. PMID:24945823

  10. Understanding the ordering mechanisms of self-assembled nanostructures of block copolymers during zone annealing.

    Science.gov (United States)

    Cong, Zhinan; Zhang, Liangshun; Wang, Liquan; Lin, Jiaping

    2016-03-21

    A theoretical method based on dynamic version of self-consistent field theory is extended to investigate directed self-assembly behaviors of block copolymers subjected to zone annealing. The ordering mechanisms and orientation modulation of microphase-separated nanostructures of block copolymers are discussed in terms of sweep velocity, wall preference, and Flory-Huggins interaction parameter. The simulated results demonstrate that the long-range ordered nanopatterns are achieved by lowering the sweep velocity of zone annealing due to the incorporation of templated ordering of block copolymers. The surface enrichment by one of the two polymer species induces the orientation modulation of defect-free nanostructures through finely tuning the composition of block copolymers and the preference of walls. Additionally, the Flory-Huggins interaction parameters of block copolymers in the distinct regions are main factors to design the zone annealing process for creating the highly ordered nanostructures with single orientation. PMID:27004895

  11. Phase behavior of multi-arm star-shaped polystyrene-block-poly(methyl methacrylate) copolymer

    Science.gov (United States)

    Jang, Sangshin; Moon, Hong Chul; Bae, Dusik; Kwak, Jonghen; Kim, Jin Kon

    2013-03-01

    We synthesized star-shaped polystyrene-block-poly(methyl methacrylate) copolymer (PS- b-PMMA) by utilizing α-cyclodextrin (α-CD) as a core of the star-shaped block copolymer. Eighteen hydroxyl groups on α-CD were transformed to bromine by the reaction with α-bromoisobutyryl bromide. We found that the number of bromine substituted arms per one α-CD was higher than 16, which was determined by nuclear magnetic resonance and Matrix-assisted laser desorption/ionization. We could control molecular weight of block copolymers by changing polymerization times. The block copolymers were characterized by gel permeation chromatography and nuclear magnetic resonance. Phase behaviors of these star-shaped block copolymers were investigated by small angle X-ray scattering and transmission electron microscopy.

  12. Understanding the ordering mechanisms of self-assembled nanostructures of block copolymers during zone annealing

    Science.gov (United States)

    Cong, Zhinan; Zhang, Liangshun; Wang, Liquan; Lin, Jiaping

    2016-03-01

    A theoretical method based on dynamic version of self-consistent field theory is extended to investigate directed self-assembly behaviors of block copolymers subjected to zone annealing. The ordering mechanisms and orientation modulation of microphase-separated nanostructures of block copolymers are discussed in terms of sweep velocity, wall preference, and Flory-Huggins interaction parameter. The simulated results demonstrate that the long-range ordered nanopatterns are achieved by lowering the sweep velocity of zone annealing due to the incorporation of templated ordering of block copolymers. The surface enrichment by one of the two polymer species induces the orientation modulation of defect-free nanostructures through finely tuning the composition of block copolymers and the preference of walls. Additionally, the Flory-Huggins interaction parameters of block copolymers in the distinct regions are main factors to design the zone annealing process for creating the highly ordered nanostructures with single orientation.

  13. Application of poly(ethylene glycol)-distearoylphosphatidylethanolamine (PEG-DSPE) block copolymers and their derivatives as nanomaterials in drug delivery.

    Science.gov (United States)

    Wang, Rongrong; Xiao, Renzhong; Zeng, Zhaowu; Xu, Lili; Wang, Junjie

    2012-01-01

    Poly(ethylene glycol)-distearoylphosphatidylethanolamine (PEG-DSPE) block copolymers are biocompatible and amphiphilic polymers that can be widely utilized in the preparation of liposomes, polymeric nanoparticles, polymer hybrid nanoparticles, solid lipid nanoparticles, lipid-polymer hybrid nanoparticles, and microemulsions. Particularly, the terminal groups of PEG can be activated and linked to various targeting ligands, which can prolong the circulation time, improve the drug bioavailability, reduce undesirable side effects, and especially target specific cells, tissues, and even the intracellular localization in organelles. This review herein aims to describe recent developments in drug carriers exploiting PEG-DSPE block copolymers and their derivatives, and the incorporation of different ligands to the end groups of PEG-DSPE to target delivery, focusing on their modification approaches, advantages, applications, and the probable associated drawbacks. PMID:22904628

  14. Water distributions in PS-b-P(S-g-PEO) block grafted copolymer system in aqueous solutions revealed by contrast variation SANS study

    International Nuclear Information System (INIS)

    In this report, we present a contrast variation small angle neutron scattering (SANS) study of PS-b-P(S-g-PEO) block graft copolymers in aqueous media at a concentration of 10 mg/ml. Through varying the solvent D2O/H2O ratio, the scattering contributions from the water molecules and the micellar constituent components can be determined. Based on the commonly used core-shell model, a theoretical coherent scattering cross section incorporating the effect of water penetration is developed and used to analyze the SANS I(Q), we have successfully quantified the micellar structure and the number of - water molecules associated with the core and corona. We have found that the overall micellar hydration level increase with the increase in the molecular weight of hydrophilic PEO side chains. This study provides key information in understanding solvent distributions within self-assembled amphiphilic block grafted copolymers.

  15. Calorimetric study on pH-responsive block copolymer grafted lipid bilayers: rational design and development of liposomes.

    Science.gov (United States)

    Pippa, Natassa; Chountoulesi, Maria; Kyrili, Aimilia; Meristoudi, Anastasia; Pispas, Stergios; Demetzos, Costas

    2016-09-01

    This study is focused on chimeric advanced drug delivery nanosystems and specifically on pH-sensitive liposomes, combining lipids and pH-responsive amphiphilic block copolymers. Chimeric liposomes composed of 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) and two different forms of block copolymers, i.e. poly(n-butylacrylate)-b-poly(acrylic acid) (PnBA-b-PAA) at 70 and 85% content of PAA at six different molar ratios, each form respectively. PAA block exhibits pH-responsiveness, because of the regulative group of -COOH. -COOH is protonated under acidic pH (pKa ca. 4.2), while remains ionized under basic or neutral pH, leading to liposomes repulse and eventually stability. Lipid bilayers were prepared composed of DPPC and PnBA-b-PAA. Experiments were carried out using differential scanning calorimetry (DSC) in order to investigate their thermotropic properties. DSC indicated disappearance of pre-transition at all chimeric lipid bilayers and slight thermotropic changes of the main transition temperature. Chimeric liposomes have been prepared and their physicochemical characteristics have been explored by measuring the size, size distribution and ζ-potential, owned to the presence of pH-responsive polymer. At percentages containing medium to high amounts of the polymer, chimeric liposomes were found to retain their size during the stability studies. These results were well correlated with those indicated in the DSC measurements of lipid bilayers incorporating polymers in order to explain their physicochemical behavior. The incorporation of the appropriate amount of these novel pH-responsive block copolymers affects thus the cooperativity, the liposomal stabilization and imparts pH-responsiveness. PMID:26364717

  16. Nanowire polarizers by guided self-assembly of block copolymers

    Science.gov (United States)

    Roberts, Philip M. S.; Baum, Alexandra; Karamath, James; Evans, Allan; Shibata, Satoshi; Walton, Harry

    2014-01-01

    Wire-grid polarizers (WGPs) are currently limited by their wafer-scale manufacturing methods to sizes of approximately 12 to 18 in. For large-size displays, a new method for the production of large-area WGPs is required. Large-area WGPs were simulated using the finite-difference-time-domain method, and a scaleable method for their production based on a block copolymer (BCP)-nanostructured template was implemented. The nanostructured template is globally aligned through the use of a cylinder-forming liquid crystal (LC) diblock copolymer, which is first aligned on a rubbed polyimide substrate. A surface-relief template is produced using the differential dry etch rates of the cylinder-forming component and LC polymer matrix component of the BCP. The template is metalized to produce a WGP. Polarizers of arbitrary size with polarization efficiency up to 0.6 have been made in close agreement with calculated values for idealized structures. The choice of the cylinder-forming polymer is critical to the degree of alignment of the template, and the thermal stability of the LC polymer matrix is critical to the stability of the template during etching.

  17. Ultrathin and Micellar Block Copolymer Films for Nanopatterning

    Science.gov (United States)

    Möller, Martin

    1998-03-01

    The formation of A-B functionalized surfaces, where nanometer sized A and B patches are distinguished for their different physical and chemical properties, represent a rather virgin field of research. We will present a technology for generating nanosized chemical heterogeneous surfaces by combination of self-organization of metal particle containing diblock copolymer micelles and conventional semiconductor etching techniques. Polystrene-block-poly(2-vinylpyridine) diblock copolymers form reverse micelles in toluene, i.e., a core of P2VP is protected by a shell of PS. Such nanocompartments are used for generating metal or semiconductor particles of equal size in each single micelle in solution. The micelle stabilized particles can be cast to mono micellar films, forming quasi hexagonal arranged lattices. The particle to particle distance (10 to 200nm) is controlled by the polymer shell and the particles size (1 to 20nm) by the micellar compartment. After film formation the polymer shell can be removed comp letely by using an oxygen plasma technique resulting in the deposition of the naked clusters on different substrates without destroying the former particle organization. These highly regular metal or semiconducting nanopatches can cover macroscopic areas (5cm x 5cm). The metal patterns are used for binding single makromolecules or as masks for nanolithography. Epitaxially grown semiconductors like GaAs, InGaAs or InP have been structured by islands or holes and their quantisized band structure has been in vestigated.

  18. Control of hyperbranched structure of polycaprolactone/poly(ethylene glycol) polyurethane block copolymers by glycerol and their hydrogels for potential cell delivery.

    Science.gov (United States)

    Li, Zibiao; Li, Jun

    2013-11-27

    A series of biodegradable amphiphilic polyurethane block copolymers with hyperbranched structure were synthesized by copolymerizing poly(ε-caprolactone) (PCL) and poly(ethylene glycol) (PEG) together with glycerol. The copolymers were characterized, and their composition and branch length were varied with the feeding ratio between PCL, PEG, and glycerol used. Hydrogels were formed from these copolymers by swelling of water at low polymer concentrations. The hydrogels were thixotropic, and their dynamic viscoelastic properties were dependent on the copolymer composition, branch length, and polymer concentration. Hydrolytic degradation of the hydrogels was evaluated by mass loss and changes in molecular structures. The porous morphology of the hydrogels provided good permeability for gas and nutrition. Together with the tunable rheological properties, the hydrogels were found to be suitable for 3D living cell encapsulation and delivery. The morphology of the solid copolymers was semicrystalline, while the hydrogels were totally amorphous without crystallinity, providing a mild aqueous environment for living cells. When the encapsulated cells were recovered from the hydrogels followed by subculture, they showed good cell viability and proliferation ability. The results indicate that the hyperbranched copolymers hydrogels developed in this work may be promising candidates for potential injectable cell delivery application. PMID:24175974

  19. Synthesis and gas permeability of block copolymers composed of poly(styrene-co-acrylonitrile) and polystyrene blocks

    Czech Academy of Sciences Publication Activity Database

    Lokaj, Jan; Brožová, Libuše; Holler, Petr; Pientka, Zbyněk

    2002-01-01

    Roč. 67, č. 2 (2002), s. 267-278. ISSN 0010-0765 R&D Projects: GA ČR GA203/99/0572 Institutional research plan: CEZ:AV0Z4050913 Keywords : azeotropic styrene- acrylonitrile copolymers * block copolymers * nitroxide-mediated copolymerization Subject RIV: CD - Macromolecular Chemistry Impact factor: 0.848, year: 2002

  20. Aligned nanowires and nanodots by directed block copolymer assembly

    Energy Technology Data Exchange (ETDEWEB)

    Xiao Shuaigang; Yang Xiaomin; Lee, Kim Y; Ver der Veerdonk, Rene J M; Kuo, David [Seagate Technology, 47010 Kato Road, Fremont, CA 94538 (United States); Russell, Thomas P, E-mail: shuaigang.xiao@seagate.com [Department of Polymer Science and Engineering, University of Massachusetts, 120 Governors Drive, Amherst, MA 01003 (United States)

    2011-07-29

    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.

  1. Correlative infrared nanospectroscopic and nanomechanical imaging of block copolymer microdomains.

    Science.gov (United States)

    Pollard, Benjamin; Raschke, Markus B

    2016-01-01

    Intermolecular interactions and nanoscale phase separation govern the properties of many molecular soft-matter systems. Here, we combine infrared vibrational scattering scanning near-field optical microscopy (IR s-SNOM) with force-distance spectroscopy for simultaneous characterization of both nanoscale optical and nanomechanical molecular properties through hybrid imaging. The resulting multichannel images and correlative analysis of chemical composition, spectral IR line shape, modulus, adhesion, deformation, and dissipation acquired for a thin film of a nanophase separated block copolymer (PS-b-PMMA) reveal complex structural variations, in particular at domain interfaces, not resolved in any individual signal channel alone. These variations suggest that regions of multicomponent chemical composition, such as the interfacial mixing regions between microdomains, are correlated with high spatial heterogeneity in nanoscale material properties. PMID:27335750

  2. Aligned nanowires and nanodots by directed block copolymer assembly

    International Nuclear Information System (INIS)

    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.

  3. Microstructural organization of polydimethylsiloxane based polyurethane block copolymers

    Science.gov (United States)

    Hernandez, Rebeca; Weksler, Jadwiga; Padsalgikar, Ajay; Runt, James

    2007-03-01

    Microphase separation was investigated for polyurethane block copolymers synthesized from MDI and 1,4 butanediol as the hard segments, and poly(hexamethyleneoxide) (MW ˜ 700) and bis(6-hydroxyethoxypropyl) poly(dimethylsiloxane) as soft segments (MW ˜ 1000). The neat PDMS-based diol presents two segmental relaxations corresponding to the principle siloxane repeat unit and to the hydroxyethoxypropyl end group segments, respectively. When incorporated in the polyurethane, the siloxane units form a phase without intermixing with hard segments and the polyether end group segments are mixed with the second macrodiol and some short hard segment sequences. The microdomain morphology was characterized by atomic force microscopy and small-angle X-ray scattering, and the scattering data were analyzed using an approach based on a modified core-shell model. The model includes core hard segment particles (MDI-BDO), surrounded by a mixed polyether shell (PHMO and hydroxyethoxypropyl end group segments), and a matrix composed of the siloxane units.

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

    KAUST Repository

    Nunes, Suzana Pereira

    2010-10-12

    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.

  5. Fluorinated polyphenylenevinylene (PPV) block co-polymers for nanophotonics

    Science.gov (United States)

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

    2013-09-01

    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.

  6. Effects of stiffness and polydispersity on the phase behaviour of block copolymers

    OpenAIRE

    Jager, Pieter Menno

    2006-01-01

    In this thesis the phase behaviour of melts of chain-like molecules, also known as polymers, is studied. Polymers are built from monomers. These monomers are connected consecutively to form chains. If all monomers are of the same kind the chain is called a homopolymer. The polymers studied in this thesis are block copolymers. In a block copolymer different kinds of homopolymers or so-called blocks are connected. For example a diblock copolymer consists of two different kinds of blocks A and B...

  7. Novel pH-sensitive polyacetal-based block copolymers for controlled drug delivery

    OpenAIRE

    Kim, Jin-Ki; Garripelli, Vivek Kumar; Jeong, Ui-Hyeon; Park, Jeong-Sook; Repka, Michael A.; Jo, Seongbong

    2010-01-01

    The principal aim of this study was to synthesize and characterize pH-sensitive biodegradable triblock copolymers containing a hydrophobic polyacetal segment for controlled drug delivery. Poly(ethylene glycol)-poly(ethyl glyoxylate)-poly(ethylene glycol) (PEG-PEtG-PEG) triblock copolymers with PEG molecular weights 500 (PEtG-PEG500) and 750 (PEtG-PEG750) were synthesized by PEtG end-capping with methoxy PEG via a carbamate linkage. Synthesized amphiphilic PEG-PEtG-PEG was characterized by 1H-...

  8. Poly(lactide)-block-poly([epsilon]-caprolactone-co-[epsilon]-decalactone)-block-poly(lactide) copolymer elastomers

    Energy Technology Data Exchange (ETDEWEB)

    Schneiderman, Deborah K.; Hill, Erin M.; Martello, Mark T.; Hillmyer, Marc A. (UMM)

    2015-08-28

    Batch ring opening transesterification copolymerization of ε-caprolactone and ε-decalactone was used to generate statistical copolymers over a wide range of compositions and molar masses. Reactivity ratios determined for this monomer pair, rCL = 5.9 and rDL = 0.03, reveal ε-caprolactone is added preferentially regardless of the propagating chain end. Relative to poly(ε-caprolactone) the crystallinity and melting point of these statistical copolymers were depressed by the addition of ε-decalactone; copolymers containing greater than 31 mol% (46 wt%) ε-decalactone were amorphous. Poly(lactide)-block-poly(ε-caprolactone-co-ε-decalactone)-block-poly(lactide) triblock polymers were also prepared and used to explore the influence of midblock composition on the temperature dependent Flory-Huggins interaction parameter (χ). In addition, uniaxial extension tests were used to determine the effects of midblock composition, poly(lactide) content, and molar mass on the mechanical properties of these new elastomeric triblocks.

  9. Using click chemistry to modify block copolymers and their morphologies

    Science.gov (United States)

    Wollbold, Johannes

    Microphase separated block copolymers (BCPs) are emerging as promising templates and scaffolds for the fabrication of nanostructured materials. To achieve the desired nanostructures, it is necessary to establish convenient approaches to control the morphology of BCPs. It remains challenging to induce morphological transitions of BCPs via external fields. Click chemistry, especially alkyne/azide click chemistry, has been widely used to synthesize novel functionalized materials. Here, we demonstrate that alkyne/azide click chemistry can be used as an efficient approach to chemically modify BCPs and therefore induce morphological transitions. Alkyne-functionalized diblock copolymers (di-BCPs) poly(ethylene oxide)- block-poly(n-butyl methacrylate-random-propargyl methacrylate) (PEO-b-P(nBMA-r-PgMA)) have been successfully synthesized. When the di-BCP is blended with an azide additive Rhodamine B azide and annealed at elevated temperatures, click reaction occurs between the two components. With the Rhodamine B structure attached to the polymer backbone, the di-BCP shows dramatic change in the interactions between the two blocks and the volume fraction of each block. As a result, morphological transitions, such as disorder-to-order transitions (DOTs) and order-to-order transitions (OOTs), are observed. The reaction kinetics and morphology evolution during the click chemistry induced DOTs have been investigated by in-situ and ex-situ characterizations, and fast kinetics properties are observed. Microphase separated morphologies after the DOTs or OOTs are dictated by the composition of neat di-BCPs and the mole ratio between the alkyne and azide groups. The DOTs of PEO-b-P(nBMA-r-PgMA) di-BCPs induced by alkyne/azide click chemistry have also been achieved in thin film geometries, with comparable kinetics to bulk samples. The orientation of the microdomains is dependent on the grafting density of Rhodamine B structure as well as film thickness. At higher grafting densities

  10. Amine-containing block copolymers: long-term adhesion promoters and corrosion resistant coatings

    Energy Technology Data Exchange (ETDEWEB)

    Small, J.H.; Saunders, R.S.; Kent, M.S.

    1996-07-01

    Arylamine-containing diblock copolymers were prepared via ring- opening metathesis polymerization (ROMP) to afford well-defined phase- separated materials. Alteration of the functionaity in a block, as well as the size of the blocks, allowed for the synthesis of self- assembled monolayers on a copper surface. The arylamine-containing block exhibited a strong binding affinity for the copper surface as seen by neutron reflectivity experiments. In addition, neutron reflectivity data verifies the self-assembly of block copolymer monolayers normal to the copper surface. Block copolymers prepared in this manner allow for the preparation of a wide range of adhesives and corrosion resistant materials. The use of ring-opening metathesis polymerization is important because it permits the synthesis of a variety of functionalized block copolymers.

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

    Science.gov (United States)

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

    2015-08-19

    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. PMID:26222398

  12. Liquid crystal alignment in electro-responsive nanostructured thermosetting materials based on block copolymer dispersed liquid crystal

    International Nuclear Information System (INIS)

    Novel well-defined nanostructured thermosetting systems were prepared by modification of a diglicydylether of bisphenol-A epoxy resin (DGEBA) with 10 or 15 wt% amphiphilic poly(styrene-b-ethylene oxide) block copolymer (PSEO) and 30 or 40 wt% low molecular weight liquid crystal 4'-(hexyl)-4-biphenyl-carbonitrile (HBC) using m-xylylenediamine (MXDA) as a curing agent. The competition between well-defined nanostructured materials and the ability for alignment of the liquid crystal phase in the materials obtained has been studied by atomic and electrostatic force microscopy, AFM and EFM, respectively. Based on our knowledge, this is the first time that addition of an adequate amount (10 wt%) of a block copolymer to 40 wt% HBC-(DGEBA/MXDA) leads to a well-organized nanostructured thermosetting system (between a hexagonal and worm-like ordered structure), which is also electro-responsive with high rate contrast. This behavior was confirmed using electrostatic force microscopy (EFM), by means of the response of the HBC liquid crystal phase to the voltage applied to the EFM tip. In contrast, though materials containing 15 wt% PSEO and 30 wt% HBC also form a well-defined nanostructured thermosetting system, they do not show such a high contrast between the uncharged and charged surface

  13. Application of poly(ethylene glycol– distearoylphosphatidylethanolamine (PEG-DSPE block copolymers and their derivatives as nanomaterials in drug delivery

    Directory of Open Access Journals (Sweden)

    Wang R

    2012-08-01

    Full Text Available Rongrong Wang,1 Renzhong Xiao,2 Zhaowu Zeng,2 Lili Xu,2 Junjie Wang21Campus Hospital of Zhejiang University, 2Research Center for Biomedicine and Health, Hangzhou Normal University, Hangzhou, ChinaAbstract: Poly(ethylene glycol–distearoylphosphatidylethanolamine (PEG-DSPE block copolymers are biocompatible and amphiphilic polymers that can be widely utilized in the preparation of liposomes, polymeric nanoparticles, polymer hybrid nanoparticles, solid lipid nanoparticles, lipid–polymer hybrid nanoparticles, and microemulsions. Particularly, the terminal groups of PEG can be activated and linked to various targeting ligands, which can prolong the circulation time, improve the drug bioavailability, reduce undesirable side effects, and especially target specific cells, tissues, and even the intracellular localization in organelles. This review herein aims to describe recent developments in drug carriers exploiting PEG-DSPE block copolymers and their derivatives, and the incorporation of different ligands to the end groups of PEG-DSPE to target delivery, focusing on their modification approaches, advantages, applications, and the probable associated drawbacks.Keywords: PEG-DSPE, PEG-lipid, Mal-PEG-DSPE, targeting delivery

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

    International Nuclear Information System (INIS)

    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

  15. 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: zhaoyunhui@tju.edu.cn; Yuan, Xiaoyan

    2015-08-30

    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.

  16. 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

    2002-01-01

    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.)

  17. RAFT polymerization kinetics and polymer characterization of P3HT rod-coil block copolymers and their uses to prepare hybrid nanocomposites

    Science.gov (United States)

    Kern, Melissa Robin

    group reactions result in P3HT homopolymer in the final sample. Therefore accurate characterization requires molecular weight determination of the block copolymer and quantification of the sample composition. Also presented in this work is the synthesis of amphiphilic rod-coil block copolymers of P3HT with poly(4-vinyl pyridine) (4VP) and poly(acrylic acid) (AA). Here, P3HT-b-PAA is prepared by the direct synthesis of acrylic acid with the macroRAFT agent using a binary solvent system of trichlorobenzene and dioxane to maintain polymer solubility throughout the polymerization. The micelle formation of the resulting block copolymer is detailed as the transparent micelle solution of P3HT-b-PAA exhibits the optical behavior of solid-state P3HT. Finally, the preparation of various nanocomposites from the synthesized P3HT homopolymer and block copolymers is presented. In the first method, the RAFT end group of the P3HT macroRAFT agent and the P3HT block copolymers is reduced to a thiol to allow for attachment to Au nanoparticles. While Au nanoparticles are not useful for photovoltaic applications, the surface modification demonstrates the utility of the P3HT macroRAFT agent, which is used to modify the surface with P3HT homopolymer and P3HT block copolymers. The second method to prepare P3HT hybrid nanocomposites is in-situ growth of CdS in P3HT-b-P4VP. With analysis by dynamic light scattering (DLS), Fourier-transform infrared (FT-IR) spectroscopy and transmission electron microscopy (TEM), it is concluded that a majority of the CdS growth in the P3HT-b-P4VP was confined to the P4VP block.

  18. How to Place Block Copolymer Molecules at the Interface of a Binary Blend

    Science.gov (United States)

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

    2015-03-01

    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.

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

    Directory of Open Access Journals (Sweden)

    Omotunde Olubi

    2014-08-01

    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.

  20. Inducing an Order-Order Morphological Transition via Chemical Degradation of Amphiphilic Diblock Copolymer Nano-Objects

    OpenAIRE

    Ratcliffe, L.P.; Couchon, C.; Armes, S. P.; Paulusse, J.M.

    2016-01-01

    The disulfide-based cyclic monomer, 3-methylidene-1,9-dioxa-5,12,13-trithiacyclopentadecane-2,8-dione (MTC), is statistically copolymerized with 2-hydroxypropyl methacrylate to form a range of diblock copolymer nano-objects via reversible addition-fragmentation chain transfer (RAFT) polymerization. Poly(glycerol monomethacrylate) (PGMA) is employed as the hydrophilic stabilizer block in this aqueous polymerization-induced self-assembly (PISA) formulation, which affords pure spheres, worms or ...

  1. Surface Modification of Block Copolymer Through Sulfur Containing Plasma Treatment.

    Science.gov (United States)

    Choi, Sang Wook; Shin, Jae Hee; Jeon, Min Hwan; Mun, Jeong Ho; Kim, Sang Ouk; Yeom, Geun Young; Kim, Kyong Nam

    2015-10-01

    Some of the important issues of block copolymer (BCP) as an application to the potential low cost next generation lithography are thermal stability and deformation during pattern transfer process in addition to defect density, line edge/width roughness, etc. In this study, sulfur containing plasma treatment was used to modify the BCP and the effects of the plasma on the properties of plasma treated BCP were investigated. The polystyrene hole pattern obtained from polystyrene polystyrene-block-poly(methyl methacrylate) (PS-b-PMMA) was initially degraded when the polystyrene hole was annealed at 190 °C for 15 min. However, when the hole pattern was treated using sulfur containing plasmas using H2S or SF6 up to 2 min, possibly due to the sulfurization of the polystyrene hole surface, no change in the hole pattern was observed after the annealing even though there is a slight change in hole shapes during the plasma treatment. The optimized plasma treated polystyrene pattern showed the superior characteristics as the mask layer by showing better thermal stability, higher chemical inertness, and higher etch selectivity during plasma etching. PMID:26726468

  2. Bicontinuous ceramics with high surface area from block copolymer templates.

    Science.gov (United States)

    Hsueh, Han-Yu; Ho, Rong-Ming

    2012-06-01

    Mesoporous polymers with gyroid nanochannels can be fabricated from the self-assembly of degradable block copolymer, polystyrene-b-poly(L-lactide) (PS-PLLA), followed by hydrolysis of PLLA block. Well-defined polymer/ceramic nanohybrid materials with inorganic gyroid nanostructures in a PS matrix can be obtained by using the mesoporous PS as a template for sol-gel reaction. Titanium tetraisopropoxide (TTIP) is used as a precursor to give a model system for the fabrication of metal oxide nanostructures from reactive transition metal alkoxides. By controlling the rates of capillary-driven pore filling and sol-gel reaction, the templated synthesis can be well-developed. Also, by taking advantage of calcination, bicontinuous TiO(2) with controlled crystalline phase (i.e., anatase phase) can be fabricated after removal of the PS template and crystallization of TiO(2) by calcination leading to high photocatalytic efficiency. This new approach provides an easy way to fabricate high-surface-area and high-porosity ceramics with self-supporting structure and controlled crystalline phase for practical applications. As a result, a platform technology to fabricate precisely controlled polymer/ceramic nanohybrids and mesoporous ceramic materials can be established. PMID:22530553

  3. Flexible Battery Cathodes Enabled by Conductive Block Copolymers

    Science.gov (United States)

    Lutkenhaus, Jodie; Verduzco, Rafael; An, Hyosung; Lin, Yen-Hao; Lutkenhaus Laboratory Collaboration; Verduzco Laboratory Collaboration

    2015-03-01

    Alone, or as part of hybrid electrodes, conductive polymers are poised to play an integral role in the new and growing field of flexible or ``plastic'' power. Here we demonstrate that even small amounts of a poly(3-hexylthiophene)-block-poly(ethylene oxide) (P3HT-b-PEO) block copolymer, acting as an ion and electron conductor, can bring about significant improvements in energy storage and mechanical flexibility for V2O5 hybrid cathodes for Li-ion batteries. By following this approach, traditional inert polymer binders and carbon black additives are not needed. V2O5 alone has a high theoretical capacity that is limited in practical application by low conductivity. Further, V2O5 alone is brittle and breaks upon repeated flexure. P3HT-b-PEO serves to address both these issues. This presentation will cover how these hybrid electrodes are formed and the resulting physicochemical properties that lead to its enhanced flexibility and energy storage.

  4. Controlling sub-microdomain structure in microphase-ordered block copolymers and their nanocomposites

    Science.gov (United States)

    Bowman, Michelle Kathleen

    Block copolymers exhibit a wealth of morphologies that continue to find ubiquitous use in a diverse variety of mature and emergent (nano)technologies, such as photonic crystals, integrated circuits, pharmaceutical encapsulents, fuel cells and separation membranes. While numerous studies have explored the effects of molecular confinement on such copolymers, relatively few have examined the sub-microdomain structure that develops upon modification of copolymer molecular architecture or physical incorporation of nanoscale objects. This work will address two relevant topics in this vein: (i) bidisperse brushes formed by single block copolymer molecules and (ii) copolymer nanocomposites formed by addition of molecular or nanoscale additives. In the first case, an isomorphic series of asymmetric poly(styrene-b -isoprene-b-styrene) (S1IS2) triblock copolymers of systematically varied chain length has been synthesized from a parent SI diblock copolymer. Small-angle x-ray scattering, coupled with dynamic rheology and self-consistent field theory (SCFT), reveals that the progressively grown S2 block initially resides in the I-rich matrix and effectively reduces the copolymer incompatibility until a critical length is reached. At this length, the S2 block co-locates with the S1 block so that the two blocks generate a bidisperse brush (insofar as the S1 and S2 lengths differ). This single-molecule analog to binary block copolymer blends affords unique opportunities for materials design at sub-microdomain length scales and provides insight into the transition from diblock to triblock copolymer (and thermoplastic elastomeric nature). In the second case, I explore the distribution of molecular and nanoscale additives in microphase-ordered block copolymers and demonstrate via SCFT that an interfacial excess, which depends strongly on additive concentration, selectivity and relative size, develops. These predictions are in agreement with experimental findings. Moreover, using a

  5. Comparison of Facially Amphiphilic versus Segregated Monomers in the Design of Antibacterial Copolymers

    OpenAIRE

    Gabriel, Gregory J.; Maegerlein, Janet A.; Nelson, Christopher F.; Dabkowski, Jeffrey M.; Eren, Tarik; Nüsslein, Klaus; Tew, Gregory N.

    2009-01-01

    A direct comparison of two strategies for designing antimicrobial polymers is presented. Previously, we published several reports on the use of facially amphiphilic (FA) monomers which led to polynorbornenes with excellent antimicrobial activities and selectivities. Our polymers obtained by copolymerization of structurally similar segregated monomers, in which cationic and non-polar moieties reside on separate repeat units, led to polymers with less pronounced activities. A wide range of poly...

  6. Bottlebrush Copolymer Morphology Transition: Influence of Side Chain Length and Block Volume Fraction

    Science.gov (United States)

    Gai, Yue; Song, Dong-Po; Watkins, James

    Brush block copolymers synthesized via living ring-opening metathesis polymerization (ROMP) offer unique advantages as templates for functional hybrid materials. Unlike linear block copolymer, the bottlebrush polymer phase transition not only depends on volume fractions of the two blocks but also on side chain length. Here we report the morphology transitions of PS-b-PEO bottlebrush copolymer (BBCP) as a function of PEO side chain length and block volume fraction. For the BBCPs with similar side chain lengths, highly ordered lamellar morphologies were observed with PEO volume fractions in a wide range from 32 vol% to 72 vol%, which is significantly different from that of traditional linear block copolymers. This study will lay the groundwork for nanostructure fabrications using the BBCPs and provides new insights into the phase behavior of the new type of materials. This work was supported by NSF center for Hierarchical Manufacturing at the University of Massachusetts, Amherst.

  7. Amphiphilic poly{[α-maleic anhydride-ω-methoxypoly(ethylene glycol)]-co-(ethyl cyanoacrylate)} graft copolymer nanoparticles as carriers for transdermal drug delivery

    OpenAIRE

    Dong, Anjie

    2009-01-01

    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 b...

  8. Phase behavior of miscible block copolymer blends and baraplastic property

    International Nuclear Information System (INIS)

    The phase behavior of the multi-component polymer systems such as blends and block copolymers (BCPs) has been studied extensively, as it determines the chemical and physical properties of the polymeric materials in practical applications. Above all, polymer baroplasticity is a desirable property for the recycling and regenerating industries, since it allows the polymers to flow at relatively mild pressure. Particularly, the compressibility issue on the enhanced miscibility with pressure has been an attractive topic, because an ordered state of the baroplastic BCPs becomes a phase-mixed state (or disordered phase) between the two dissimilar blocks upon pressurizing. This is in contrast to the incompressibility that was dictated by the enthalpic effect arising from the increased unfavorable contacts between the two blocks by increasing pressure. The phase behaviors of BCP blends composed of the weakly interacting (with no specific interaction) polystyrene-b-poly(n-butyl methacrylate) (PS-b-PnBMA) and deuterated polystyreneb- poly-(n-hexyl methacrylate) (dPS-b-PnHMA) were investigated by Small-Angle Neutron Scattering(SANS) and Depolarized Light Scattering (DPLS) measurements. Interestingly, pressure dependence of various phase transitions for the miscible BCP blends was significantly changed, in which the blends consist of a PS-b-PnBMA and a deuterated dPS-b-PnHMA. To elucidate the origin and difference in baroplasticity of weakly interacting BCP blends, the pressure dependence of transition temperatures was evaluated using enthalpic and volumetric changes at phase transitions. We also demonstrate that the entropic compressibility for the miscible BCP blends is a baroplastic indicator, which was characterized by the negative volume change on mixing (ΔVmix) at transitions.

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

    DEFF Research Database (Denmark)

    Jankova, Katja; Hvilsted, Søren

    2005-01-01

    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-...

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

    Science.gov (United States)

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

    2015-08-01

    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.

  11. STUDY ON STYRENE-BUTADIENE BLOCK COPOLYMER FOR THE MODIFICATION OF TIRE TREAD

    Institute of Scientific and Technical Information of China (English)

    WANG Yan; CHEN Weijie; MU Ruifeng; WANG Yongwei; YU Fengnian; LIU Qing

    1996-01-01

    This paper mainly deals with the design and synthesis of a novel styrene-butadiene block copolymer. When this copolymer is used in the tread portion of tyres, it can improve wet skid resistance and reduce rolling resistance without sacrificing its general physicalmechanical properties. The visco-elastic curve of tire tread using the novel copolymer as its rubber portion was showed. Reactivity ratios for two monomers in the polymerizing system were calculated. The diagrams of differential, integral and finite difference calculi throughout the whole molecular chain were presented. The influence of the micro- and macro-structure of the copolymer chain on wet skid resistance and rolling resistance was discussed.

  12. Phase Behavior of Star-shaped polystyrene-block-poly(methyl methacrylate) Copolymers

    Science.gov (United States)

    Jang, Sangshin; Moon, Hongchul; Lee, Youngmin; Kim, Jin Kon

    2012-02-01

    Star-shaped polystyrene-block-poly(methyl methacrylate) copolymer (PS-b-PMMA) was synthesized by utilizing α-cyclodextrin (α-CD) as a junction point of the star-shaped block copolymer. Eighteen hydroxyl groups on α-CD were substituted with bromine by the reaction with α-bromoisobutyryl bromide for atom transfer radical polymerization. We found that the number of bromine substituted arms per one α-CD was higher than 16 measured by nuclear magnetic resonance and Matrix-assisted laser desorption/ionization. We could control molecular weight of this unusual kind of block copolymer depending on polymerization times. Those polymers were characterized by gel permeation chromatography and nuclear magnetic resonance. Phase behavior of these star-shaped block copolymers were investigated.

  13. Complexation-tailored morphology of asymmetric block copolymer membranes

    KAUST Repository

    Madhavan, Poornima

    2013-08-14

    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.

  14. Silicon crystallization in nanodot arrays organized by block copolymer lithography

    Energy Technology Data Exchange (ETDEWEB)

    Perego, Michele, E-mail: michele.perego@mdm.imm.cnr.it; Andreozzi, Andrea; Seguini, Gabriele [IMM-CNR, Laboratorio MDM (Italy); Schamm-Chardon, Sylvie; Castro, Celia; BenAssayag, Gerard [Université de Toulouse, nMat Group, CEMES-CNRS (France)

    2014-12-15

    Asymmetric polystyrene-b-polymethylmethacrylate (PS-b-PMMA) block copolymers are used to fabricate nanoporous PS templates with different pore diameter depending on the specific substrate neutralization protocol. The resulting polymeric templates are used as masks for the subsequent deposition of a thin (h = 5 nm) amorphous Si layer by electron beam evaporation. After removal of the polymeric film and of the silicon excess, well-defined hexagonally packed amorphous Si nanodots are formed on the substrate. Their average diameter (d < 20 nm), density (1.2 × 10{sup 11} cm{sup −2}), and lateral distribution closely mimic the original nanoporous template. Upon capping with SiO{sub 2} and high temperature annealing (1050 °C, N{sub 2}), each amorphous Si nanodot rearranges in agglomerates of Si nanocrystals (d < 4 nm). The average diameter and shape of these Si nanocrystals strongly depend on the size of the initial Si nanodot.

  15. Defect motion and annihilation in block copolymer thin films

    Science.gov (United States)

    Mueller, Marcus; Li, Weihua

    2015-03-01

    Using self-consistent field theory and computer simulation of a soft, coarse-grained particle model we study defect motion and annihilation in thin films of lamella-forming block copolymers on neutral and chemically patterned substrates. By virtue of the strain-field mediated interactions, dislocation defects with opposite orientation move towards each other. This motion depends both on the thermodynamic, strain-field mediated driving force and the single-chain dynamics that is required to alter the morphology and reduce the distance between the defect cores. This interplay results in a qualitative dependence of the time evolution on the topology of the defect morphology. Upon collision of the defects, they either spontaneously annihilate or form a metastable, tight defect pair. In the latter case, a free-energy barrier has to be overcome to finally produce a defect-free structure. Computing the minimum free-energy path within self-consistent field theory we investigate the dependence of the free-energy barriers of defect motion and annihilation on incompatibility, strength of the chemical surface pattern, and defect morphology. European Union FP7 / GA No. 619793 CoLiSA.MMP.

  16. Direct Immersion Annealing (DIA) of Block Copolymer Thin Film

    Science.gov (United States)

    Modi, Arvind; Karim, Alamgir

    2014-03-01

    Solvent Vapor Annealing (SVA) methodologies of block copolymer (BCP) films have demonstrated excellent potential for control of nanostructures and morphologies. However, SVA designs require sophisticated instrumentation, and fine control of system parameters in batch processing mode which is relatively complex and limits its feasibility. We developed a faster and robust solvent immersion strategy for microphase separation and nanostructure control of as-cast BCP thin films with minimal sophistication. Our Direct Immersion Annealing (DIA) method requires immersion in a mixture of non-solvent and good solvent (for BCP) for annealing. A non-solvent component prevents dissolution of the film resting on substrate while a good solvent percolates through the film, plasticizes it, and shifts glass-transition below room temperature leading to microphase separation and ordering. Our study of PS-PMMA system demonstrates that a robust control over thin film ordering and transient swelling could be achieved through a fine control of solubility parameter of solvent mixture and temperature with no dead-time. Further, we exhibit the utility of DIA for alignment of BCP domains on topographically patterned substrates. University of Akron Research Foundation (UARF).

  17. Silicon crystallization in nanodot arrays organized by block copolymer lithography

    International Nuclear Information System (INIS)

    Asymmetric polystyrene-b-polymethylmethacrylate (PS-b-PMMA) block copolymers are used to fabricate nanoporous PS templates with different pore diameter depending on the specific substrate neutralization protocol. The resulting polymeric templates are used as masks for the subsequent deposition of a thin (h = 5 nm) amorphous Si layer by electron beam evaporation. After removal of the polymeric film and of the silicon excess, well-defined hexagonally packed amorphous Si nanodots are formed on the substrate. Their average diameter (d < 20 nm), density (1.2 × 1011 cm−2), and lateral distribution closely mimic the original nanoporous template. Upon capping with SiO2 and high temperature annealing (1050 °C, N2), each amorphous Si nanodot rearranges in agglomerates of Si nanocrystals (d < 4 nm). The average diameter and shape of these Si nanocrystals strongly depend on the size of the initial Si nanodot

  18. Host-guest self-assembly in block copolymer blends.

    Science.gov (United States)

    Park, Woon Ik; Kim, Yongjoo; Jeong, Jae Won; Kim, Kyungho; Yoo, Jung-Keun; Hur, Yoon Hyung; Kim, Jong Min; Thomas, Edwin L; Alexander-Katz, Alfredo; Jung, Yeon Sik

    2013-01-01

    Ultrafine, uniform nanostructures with excellent functionalities can be formed by self-assembly of block copolymer (BCP) thin films. However, extension of their geometric variability is not straightforward due to their limited thin film morphologies. Here, we report that unusual and spontaneous positioning between host and guest BCP microdomains, even in the absence of H-bond linkages, can create hybridized morphologies that cannot be formed from a neat BCP. Our self-consistent field theory (SCFT) simulation results theoretically support that the precise registration of a spherical BCP microdomain (guest, B-b-C) at the center of a perforated lamellar BCP nanostructure (host, A-b-B) can energetically stabilize the blended morphology. As an exemplary application of the hybrid nanotemplate, a nanoring-type Ge2Sb2Te5 (GST) phase-change memory device with an extremely low switching current is demonstrated. These results suggest the possibility of a new pathway to construct more diverse and complex nanostructures using controlled blending of various BCPs. PMID:24217036

  19. 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;

    2013-01-01

    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...... superior properties over random copolymers P(3HP-co-4HB). The block copolymers had two glass transition temperatures (Tg) and two melting temperatures (Tm). In comparison to the homopolymers P3HP and P4HB, incorporation of block microstructure resulted in the lowering of Tm, block copolymers were revealed...

  20. Enhancing ordering dynamics in solvent-annealed block-copolymer films by lithographic hard masks supports

    OpenAIRE

    Stenbock-Fermor, Anja; Knoll, Armin W.; Böker, Alexander; Tsarkova, Larisa

    2014-01-01

    We studied solvent-driven ordering dynamics of block copolymer films supported by a densely cross-linked polymer network designed as organic hard mask (HM) for lithographic fabrications. The ordering of microphase separated domains at low degrees of swelling corresponding to intermediate/strong segregation regimes was found to proceed significantly faster in films on a HM layer as compared to similar block copolymer films on silicon wafers. The ten-fold enhancement of the chain mobility was e...

  1. Synthesis and Characterization of Proton Conducting, Fluorine-Containing Block Copolymers

    OpenAIRE

    Shi, Zhi Qing

    2004-01-01

    Fuel cells are being investigated as environmental-friendly, highly efficient alternative power sources. Proton conducting membranes play a central role in proton exchange membrane fuel cells (PEMFCs), serving as both electrolyte and fuel separator. This thesis addresses the design, synthesis and characterization of novel fluorinecontaining block copolymers, and the preparation and investigation of sulfonated block copolymers as model proton exchange membranes (PEMs). Poly([vinylidene difluor...

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

    KAUST Repository

    Madhavan, Poornima

    2015-04-30

    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.

  3. Release kinetics of an amphiphilic photosensitizer by block-polymer nanoparticles.

    Science.gov (United States)

    Kerdous, Rachid; Sureau, Franck; Bour, Aurélien; Bonneau, Stéphanie

    2015-11-30

    Block-polymer nanoparticles are now well-known candidates for the delivery of various non-soluble drugs to cells. The release of drugs from these nanoparticles is a major concern related to their efficiency as nanovectors and is still not completely deciphered. Various processes have been identified, depending of both the nature of the block-polymer and those of the drugs used. We focused our interest on an amphiphilic photosensitizer studied for photodynamic treatments of cancer, Pheophorbide-a (Pheo). We studied the transfer of Pheo from poly(ethyleneglycol-b-ϵ-caprolactone) nanoparticles (I) to MCF-7 cancer cells and (II) to models of membranes. Altogether, our results suggest that the delivery of the major part of the Pheo by the nanoparticles occurs via a direct transfer of Pheo from the nanoparticles to the membrane, by collision. A minor process may involve the internalization of a small amount of the nanoplatforms by the cells. So, this research illustrates the great care necessary to address the question of the choice of such nanocarriers, in relation with the properties - in particular the relative hydrophobicity - of the drugs encapsulated, and gives elements to predict the mechanism and the efficiency of the delivery. PMID:26387620

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

    Energy Technology Data Exchange (ETDEWEB)

    Gratzl, Günther, E-mail: guenther.gratzl@jku.at [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)

    2014-05-01

    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.

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

    International Nuclear Information System (INIS)

    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

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

    Directory of Open Access Journals (Sweden)

    2011-02-01

    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.

  7. Self-organization on multiple length scales in "hairy rod"-coil block copolymer supramolecular complexes

    OpenAIRE

    Hammond, Matthew R.; Klok, Harm-Anton; Mezzenga, Raffaele

    2008-01-01

    A peptide-synthetic hybrid block copolymer, poly(ethylene oxide)-block-poly(L-glutamic acid), is shown to form supramolecular complexes with primary alkylamines of varying alkyl chain lengths (8 to 18 methylene units) in organic solvents via acid-base proton transfer and subsequent ionic bonding. The peptidic block being in the α-helical conformation, these materials behave as coil-"hairy rod" block copolymers, and show hierarchically self-organized nanostructures in the solid state. X-ray sc...

  8. Effect of Hydrogen-Bonding Junctions on Microphase Separation in Block Copolymers

    Science.gov (United States)

    Stone, Greg; Hedrick, Jim; Nederberg, Fredrik; Balsara, Nitash

    2008-03-01

    The morphology of poly(styrene-block- trimethylene carbonate) (PS-PTMC) copolymers with and without thiourea groups at the junction between the blocks was studied by a combination of small angle X-ray scattering (SAXS) and transmission electron microscopy (TEM). The thiourea groups are known to exhibit inter-molecular hydrogen bonding. We demonstrate that the presence of thiourea groups results in increased segregation between PS and PTMC blocks. We focus on symmetric systems with total molecular weights in the 5 kg/mol range. In conventional block copolymers without hydrogen bonding groups it is difficult to obtain strong segregation in low molecular weight systems because the product chi*N controls segregation (chi is the Flory-Huggins interaction parameter and N is the number of monomers per chain). The incorporation of hydrogen bonding groups may provide a route for the generation of patterns with small, sharply defined features using block copolymers.

  9. Interactions between plasma and block copolymers used in directed self-assembly patterning

    Science.gov (United States)

    Sirard, Stephen; Azarnouche, Laurent; Gurer, Emir; Durand, William; Maher, Michael; Mori, Kazunori; Blachut, Gregory; Janes, Dustin; Asano, Yusuke; Someya, Yasunobu; Hymes, Diane; Graves, David; Ellison, Christopher J.; Willson, C. Grant

    2016-03-01

    The directed self-assembly (DSA) of block copolymers offers a promising route for scaling feature sizes below 20 nm. At these small dimensions, plasmas are often used to define the initial patterns. It is imperative to understand how plasmas interact with each block in order to design processes with sufficient etch contrast and pattern fidelity. Symmetric lamella forming block copolymers including, polystyrene-b-poly(methyl methacrylate) and several high-χ silicon-containing and tin-containing block copolymers were synthesized, along with homopolymers of each block, and exposed to various oxidizing, reducing, and fluorine-based plasma processes. Etch rate kinetics were measured, and plasma modifications of the materials were characterized using XPS, AES, and FTIR. Mechanisms for achieving etch contrast were elucidated and were highly dependent on the block copolymer architecture. For several of the polymers, plasma photoemissions were observed to play an important role in modifying the materials and forming etch-resistant protective layers. Furthermore, it was observed for the silicon- and tin-containing polymers that an initial transient state exists, where the polymers exhibit an enhanced etch rate, prior to the formation of the etch-resistant protective layer. Plasma developed patterns were demonstrated for the differing block copolymer materials with feature sizes ranging from 20 nm down to approximately 5 nm.

  10. Control of Crystallization to Promote Microphase Separation in Fully Conjugated Block Copolymers

    Science.gov (United States)

    Lee, Youngmin; Le, Thinh P.; Seibers, Zach; Kilbey, S. Michael, II; Wang, Qing; Gomez, Enrique D.

    Donor -acceptor fully conjugated block copolymers, where donor and acceptor conjugated polymers are covalently bonded together, are interesting as single-component active-layer materials for photovoltaics because it can adopt mesoscale microphase separated structures with length scales comparable to the exciton diffusion length. Nevertheless, due to the strong crystallization of poly(3-hexylthiophene-2,5-diyl) (P3HT), morphologies of fully conjugated block copolymers containing P3HT are predominantly driven by crystallization as opposed to microphase separation. We control the crystallization in block copolymers to promote microphase separation in fully conjugated block copolymers through the addition of small amounts of 3-octylthiophene to the polymerization of P3HT. Poly(3-hexylthiophene-2,5-diyl- r-3-octylthiophene-2,5-diyl)-block-poly((9,9-dioctylfluorene-2,7-diyl)-alt-(4,7-di(thiophene-2-yl)-2,1,3-benzothiadiazole)-5',5''-diyl) (P3HT- b-PFTBT) copolymers were prepared by Grignard metathesis for the alkylthiophene block followed by chain extension through a Suzuki-Miyaura polycondensation. We compare the crystallization, self-assembly and performance in devices of P3HT-b-PFTBT with a few mole percent of 3-octylthiophene in the P3HT block. Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, TN 37831.

  11. Preparation of Pickering double emulsions using block copolymer worms.

    Science.gov (United States)

    Thompson, Kate L; Mable, Charlotte J; Lane, Jacob A; Derry, Mathew J; Fielding, Lee A; Armes, Steven P

    2015-04-14

    The rational formulation of Pickering double emulsions is described using a judicious combination of hydrophilic and hydrophobic block copolymer worms as highly anisotropic emulsifiers. More specifically, RAFT dispersion polymerization was utilized to prepare poly(lauryl methacrylate)-poly(benzyl methacrylate) worms at 20% w/w solids in n-dodecane and poly(glycerol monomethacrylate)-poly(2-hydroxypropyl methacrylate)-poly(benzyl methacrylate) worms at 13% w/w solids in water by polymerization-induced self-assembly (PISA). Water-in-oil-in-water (w/o/w) double emulsions can be readily prepared with mean droplet diameters ranging from 30 to 80 μm using a two-stage approach. First, a w/o precursor emulsion comprising 25 μm aqueous droplets is prepared using the hydrophobic worms, followed by encapsulation within oil droplets stabilized by the hydrophilic worms. The double emulsion droplet diameter and number of encapsulated water droplets can be readily varied by adjusting the stirring rate employed during the second stage. For each stage, the droplet volume fraction is relatively high at 0.50. The double emulsion nature of the final formulation was confirmed by optical and fluorescence microscopy studies. Such double emulsions are highly stable to coalescence, with little or no change in droplet diameter being detected over storage at 20 °C for 10 weeks as judged by laser diffraction. Preliminary experiments indicate that the complementary o/w/o emulsions can also be prepared using the same pair of worms by changing the order of homogenization, although somewhat lower droplet volume fractions were required in this case. Finally, we demonstrate that triple and even quadruple emulsions can be formulated using these new highly anisotropic Pickering emulsifiers. PMID:25834923

  12. Surface affinity role in graphoepitaxy of lamellar block copolymers

    Science.gov (United States)

    Claveau, G.; Quemere, P.; Argoud, M.; Hazart, J.; Pimenta Barros, P.; Sarrazin, A.; Posseme, N.; Tiron, R.; Chevalier, X.; Nicolet, C.; Navarro, C.

    2016-03-01

    Overcoming the optical limitations of 193nm immersion lithography can be achieved using Directed Self Assembly (DSA) of block-copolymers (BCPs) as a low-cost and versatile complementary technique. The goal of this paper is to investigate the potential of DSA to address line and space (L/S) high resolution patterning by performing the density multiplication of lines with the graphoepitaxy approach. As surface affinity is a key parameter in self-assembly, three variations, or "flavors", of DSA template affinity are investigated regarding several success criteria such as morphology control or defectivity. More precisely, both the methodology to register DSA defects and the impact of process parameters on defectivity are detailed. Using the 300mm pilot line available in LETI and Arkema's advanced materials, we investigate process optimization of DSA line/space patterning of a 38nm period lamellar PS-b-PMMA BCP (L38). For this study, our integration scheme, depicted in figure 2-1, is based on BCP self-assembly inside organic hard mask guiding patterns obtained using 193i nm lithography. Defect analysis coupled with the fine tuning of process parameters (annealing, brush material) provided the optimum conditions for the L38 self-assembly. Using such conditions, DSA using the three affinity flavors is investigated by means of SEM top-view and cross-section review. Lithographic performances of one selected flavor are then evaluated with the comparison of Process Windows (PWs) function of either commensurability, morphology or LWR. This work is a first step in finding the best process for an industrial graphoepitaxy approach.

  13. Lysine-tagged peptide coupling onto polylactide nanoparticles coated with activated ester-based amphiphilic copolymer: a route to highly peptide-functionalized biodegradable carriers.

    Science.gov (United States)

    Handké, Nadège; Ficheux, Damien; Rollet, Marion; Delair, Thierry; Mabrouk, Kamel; Bertin, Denis; Gigmes, Didier; Verrier, Bernard; Trimaille, Thomas

    2013-03-01

    Efficient biomolecule conjugation to the surface of biodegradable colloidal carriers is crucial for their targeting efficiency in drug/vaccine delivery applications. We here propose a potent strategy to drastically improve peptide immobilization on biodegradable polylactide (PLA) nanoparticles (NPs). Our approach particularly relies on the use of an amphiphilic block copolymer PLA-b-poly(N-acryloxysuccinimide-co-N-vinylpyrrolidone) (PLA-b-P(NAS-co-NVP)) as NP surface modifier, whose the N-succinimidyl (NS) ester functions of the NAS units along the polymer chain ensure N-terminal amine peptide coupling. The well-known immunostimulatory peptide sequence derived from the human interleukin 1β (IL-1β), VQGEESNDK, was coupled on the NPs of 169 nm mean diameter in phosphate buffer (pH 8, 10 mM). A maximum amount of 2 mg immobilized per gram of NPs (i.e. 0.042 peptidenm(-2)) was obtained. Introduction of a three lysine tag at the peptide N-terminus (KKKVQGEESNDK) resulted in a dramatic improvement of the immobilized peptide amounts (27.5 mg/g NP, i.e. 0.417 peptidenm(-2)). As a comparison, the density of tagged peptide achievable on surfactant free PLA NPs of similar size (140 nm), through classical EDC or EDC/NHS activation of the surface PLA carboxylic end-groups, was found to be 6 mg/g NP (i.e. 0.075 peptidenm(-2)), showing the decisive impact of the P(NAS-co-NVP)-based hairy corona for high peptide coupling. These results demonstrate that combined use of lysine tag and PLA-b-P(NAS-co-NVP) surfactant represents a valuable platform to tune and optimize surface bio-functionalization of PLA-based biodegradable carriers. PMID:23277324

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

    OpenAIRE

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

    1988-01-01

    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 styrene in dimethylformamide, using 2-aminoethanethiol as a chain transfer agent. This amino group was used in the coupling reaction with amino-telechelic poly(ethylene oxide) to produce an AB type...

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

    OpenAIRE

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

    1990-01-01

    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 in cyclohexane, using sec-butyllithium as initiator and N-(benzylidene)trimethylsilylamide as terminator. After purification using preparative column chromatography, polystyrene with one amino gro...

  16. 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: jonghak@yonsei.ac.kr [Department of Chemical and Biomolecular Engineering, Yonsei University, 262 Seongsanno, Seodaemun-gu, Seoul 120-749 (Korea, Republic of); Sung, Jung-Suk, E-mail: sungjs@dongguk.edu [Department of Life Science, Dongguk University-Seoul, 3–26 Phil-dong, Chung-gu, Seoul 100-715 (Korea, Republic of)

    2013-04-01

    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.

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

    International Nuclear Information System (INIS)

    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

  18. A Solution-Processable (Tetraaniline-b-Polyethylene Glycol)3 Star-Shaped Rod-Coil Block Copolymer with Enhanced Electrochromic Properties.

    Science.gov (United States)

    Cao, Linyu; Gong, Chen; Yang, Jiping

    2016-02-01

    A novel electroactive star-shaped rod-coil copolymer composed of a benzene core and three symmetrically positioned tetraaniline-b-poly(ethylene glycol) arms, (TAni-b-PEG)3 rod-coil block copolymer, is synthesized successfully and characterized using Fourier transform infrared spectroscopy (FTIR), UV-vis, (1)H NMR, and matrix-assisted laser desorption/ionization (MALDI) mass spectrometry. Uniform and high-quality (TAni-b-PEG)3 thin films onto indium tin oxide-coated glass surface are fabricated simply from its DMF solution. Resulting (TAni-b-PEG)3 copolymer thin films possess excellent electrochromic properties with a high optical contrast of 73.3%, superb coloration efficiency of 318.5 cm(2) C(-1) at 750 nm. Very short switching times, that is, 2.11 s and 2.14 s for coloring and bleaching times, respectively, are observed as well. The mechanism of these impressive electrochromic properties of (TAni-b-PEG)3 thin films possessed is proposed based on the atomic force microscopy investigation, star-shaped molecular geometry, synergetic electronic and ionic conductivity and amphiphilic self-assembly feature of (TAni-b-PEG)3 copolymer, which can self-assemble to form cylinder pattern consisting of quick pathways for electronic charges and ionic species, respectively. PMID:26663524

  19. Multicompartment micellar aggregates of linear ABC amphiphiles in solvents selective for the C block: A Monte Carlo simulation

    KAUST Repository

    Zhu, Yutian

    2012-01-01

    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

  20. Hybrid organic/inorganic nanostructured systems obtained by self-assembly of block-copolymers

    OpenAIRE

    Chieffi, Gianpaolo

    2013-01-01

    An amphiphilic polystyrene-b-poly(ethylene-oxide) (PS-b-PEO) diblock copolymer (BCP) was used as template for the incorporation of metal oxide nanoparticles, namely TiO2 or Nb2O5 using the sol-gel method. This study was aimed to the preparation of neat BCP and hybrid thin films by spin-coating. The hydrophilic sol–gel precursor of the metal oxides was selectively incorporated into hydrophilic PEO domains of BCP organized in a hexagonal array of vertical cylinders embedded in the PS matrix. Re...

  1. 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

    2015-01-01

    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 polymerizati

  2. 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.

    1999-01-01

    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.

  3. Ethyl cellulose amphiphilic graft copolymers with LCST-UCST transition: Opposite self-assembly behavior, hydrophilic-hydrophobic surface and tunable crystalline morphologies.

    Science.gov (United States)

    Yuan, Hua; Chi, Hai; Yuan, Weizhong

    2016-08-20

    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. PMID:27178932

  4. Paclitaxel-incorporated nanoparticles using block copolymers composed of poly(ethylene glycol)/poly(3-hydroxyoctanoate)

    OpenAIRE

    Kim, Hyun Yul; Ryu, Je Ho; Chu, Chong Woo; Son, Gyung Mo; Jeong, Young-IL; Kwak, Tae-Won; Kim, Do Hyung; Chung, Chung-Wook; Rhee, Young Ha; Kang, Dae Hwan; Kim, Hyung Wook

    2014-01-01

    Block copolymers composed of poly(3-hydroxyoctanoate) (PHO) and methoxy poly(ethylene glycol) (PEG) were synthesized to prepare paclitaxel-incorporated nanoparticle for antitumor drug delivery. In a 1H-NMR study, chemical structures of PHO/PEG block copolymers were confirmed and their molecular weight (M.W.) was analyzed with gel permeation chromatography (GPC). Paclitaxel as a model anticancer drug was incorporated into the nanoparticles of PHO/PEG block copolymer. They have spherical shapes...

  5. Analytic Structure of the SCFT Energy Functional of Multicomponent Block Copolymers

    CERN Document Server

    Jiang, Kai; Zhang, Pingwen

    2013-01-01

    This paper concerns the analytic structure of the self-consistent field theory (SCFT) energy functional of multicomponent block copolymer systems which contain more than two chemically distinct blocks. The SCFT has enjoyed considered success and wide usage in investigation of the complex phase behavior of block copolymers. It is well-known that the physical solutions of the SCFT equations are saddle points, however, the analytic structure of the SCFT energy functional has received little attention over the years. A recent work by Fredrickson and collaborators [see the monograph by Fredrickson, The Equilibrium Theory of Inhomogeneous Polymers, (2006), pp. 203-209] has analysed the mathematical structure of the field energy functional for polymeric systems, and clarified the index-1 saddle point nature of the problem produced by the incompressibility constraint. In this paper, our goals are to draw further attention to multicomponent block copolymers utilizing the Hubbard-Stratonovich transformation used by Fre...

  6. The Organization of Nanoporous Structure Using Controlled Micelle Size from MPEG-b-PDLLA Block Copolymers

    International Nuclear Information System (INIS)

    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 m2/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 13C and 29Si 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

  7. 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

    2002-01-01

    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

  8. Multi-block sulfonated poly(phenylene) copolymer proton exchange membranes

    Science.gov (United States)

    Fujimoto, Cy H.; Hibbs, Michael; Ambrosini, Andrea

    2012-02-07

    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.

  9. Polymer Segmental Cross-Correlations from Dielectric Relaxation Spectra of Block Copolymers

    OpenAIRE

    Phillies, George D. J.

    2011-01-01

    Dielectric relaxation spectra of block polymers containing sequential type-A dipoles are considered. Spectra of a specific set of block copolymers can be combined to isolate the dynamic cross-correlation between the motions of two distinct parts of the same polymer chain. Unlike past treatments of this problem, no model is assumed for the underlying polymer dynamics.

  10. Photocatalytic Nanostructuring of Graphene Guided by Block Copolymer Self-Assembly

    DEFF Research Database (Denmark)

    Wang, Zhongli; Li, Tao; Schulte, Lars;

    2016-01-01

    graphene nanomesh was fabricated by photocatalysis of single-layer graphene suspended on top of TiO2-covered nanopillars, which were produced by combining block copolymer nanolithography with atomic layer deposition. Graphene nanoribbons were also prepared by the same method applied to a line-forming block...

  11. 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

    2010-10-01

    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.

  12. Melt and Solid-State Structures of Polydisperse Polyolefin Block Copolymers

    Science.gov (United States)

    Register, Richard; Li, Sheng

    2013-03-01

    Recent developments in coordinative chain transfer polymerization have enabled the synthesis of ethylene-co-octene block copolymers, where the blocks are either crystallizable (an ethylene-co-octene random copolymer block with low octene content) or amorphous (analogous block with high octene content). With a suitable choice of catalyst type(s) and reactor train configuration, accessible chain architectures include diblock, where each block ideally has the most-probable distribution of chain lengths, and multiblock, where both the individual blocks and the number of blocks per chain follow the most-probable distribution. With a sufficiently large interblock octene differential, block copolymers of both architectures, containing roughly equal masses of the two types of block, self-assemble in the melt into well-ordered lamellar structures, despite the large polydispersity. Interblock mixing, induced by the modest Flory interaction parameter and the broad distribution of block lengths, yields an enormous domain spacing (> 100 nm) despite the relatively low average block molecular weights (< 50 kg/mol). Extensive interblock mixing also allows the polyethylene crystals to grow freely and nearly isotropically across the domain interfaces, while preserving the domain structure present in the melt; in the solid state, the optical and x-ray contrasts between dissimilar domains are greatly enhanced due to their different levels of crystallinity. (Work conducted in collaboration with Jeffrey Weinhold, Philip Hustad, and Brian Landes of Dow Chemical Core R&D.) Support from the NSF Polymers Program (DMR-1003942).

  13. Improved conductivity in dye-sensitised solar cells through block-copolymer confined TiO 2 crystallisation

    KAUST Repository

    Guldin, Stefan

    2011-01-01

    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.

  14. DETERMINATION OF THE CRYSTALLINITY IN DIFFERENT TYPE POLY (OXYETHYLENE -STYRENE )BLOCK COPOLYMERS BY X- RAY DIFFRACTION METHOD

    Institute of Scientific and Technical Information of China (English)

    YAO Ning

    1989-01-01

    By means of the intensity theory of X- ray scattering and the two - phase concept of high polymer, the basic formula of the crystallinity in block copolymers has been proposed after the corrections of atomic, temperature, absorption, Lorentz and polarization factor. Application of this method to different type poly (oxyethylene - styrene) block copolymers and the same type block copolymers with different EO contents indicates that the crystallinity in poly (oxyethylene - styrene) block copolymers increases with the increase of the EO content and decreases in the order: PEO - PS - PEO > PEO - PS > PS - PEO - PS.

  15. 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: laurence.bois@univ-lyon1.fr [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)

    2015-01-15

    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.

  16. Epitaxial relationships for hexagonal-to-cubic phase transition in a block copolymer mixture

    DEFF Research Database (Denmark)

    Schulz, M.F.; Bates, F.S.; Almdal, K.;

    1994-01-01

    Small-angle neutron scattering experiments have revealed an epitaxial relationship between the hexagonal cylinder phase, and a bicontinuous cubic phase with Ia3dBAR space group symmetry, in a poly(styrene)-poly(2-vinylpyridine) diblock copolymer mixture. Proximity to the order-disorder transition...... and an inelastic low frequency rheological response suggest that the cubic phase is stabilized by fluctuations. These results identify block copolymers as model compounds for investigating the thermodynamics and dynamics of complex ''soft'' condensed matter....

  17. An Observation on the Microphase Separation of Poly(methyl methacrylate)-block-Polystyrene Copolymer

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The phase behavior of a well-defined poly(methyl methacrylate)-b-polystyrene block copolymer was studied by transmission electron microscope.The results show that a microphase transition may have occurred in the copolymer film.A kind of lamellae and an ordered bicontinuous double-diamond morphology are observed clearly.The lamellar morphology reveals a larger period of about 400 nm.

  18. Magnetic properties and morphology of block copolymer-cobalt oxide nanocomposites

    International Nuclear Information System (INIS)

    The morphology and magnetic properties of diblock copolymer templated ferrimagnetic cobalt oxide nanoparticles are reported. Ring opening metathesis polymerization (ROMP) was used to synthesize a novel cobalt diblock copolymer, where cobalt is directly attached to the polymer chain. Gel permeation chromatography (GPC) was performed to determine molecular weight distribution. Transmission electron microscope (TEM), UV-Vis, FTIR, and vibrating sample magnetometer (VSM) were used to characterize the block copolymer nanocomposite. The nanocomposite films were weakly ferrimagnetic at room temperature. The cobalt oxide nanoparticles were uniformly dispersed within the polymer matrix with an average radius of 4.9+/-0.9nm

  19. Magnetic properties and morphology of block copolymer-cobalt oxide nanocomposites

    Energy Technology Data Exchange (ETDEWEB)

    Ahmed, Sufi R. [Department of Chemical Engineering, University of Maryland, College Park, MD 20742-2111 (United States); Kofinas, Peter [Department of Chemical Engineering, University of Maryland, College Park, MD 20742-2111 (United States)]. E-mail: kofinas@umd.edu

    2005-03-01

    The morphology and magnetic properties of diblock copolymer templated ferrimagnetic cobalt oxide nanoparticles are reported. Ring opening metathesis polymerization (ROMP) was used to synthesize a novel cobalt diblock copolymer, where cobalt is directly attached to the polymer chain. Gel permeation chromatography (GPC) was performed to determine molecular weight distribution. Transmission electron microscope (TEM), UV-Vis, FTIR, and vibrating sample magnetometer (VSM) were used to characterize the block copolymer nanocomposite. The nanocomposite films were weakly ferrimagnetic at room temperature. The cobalt oxide nanoparticles were uniformly dispersed within the polymer matrix with an average radius of 4.9+/-0.9nm.

  20. First observation of an ordered microphase in melts of poly(oxyethylene)-poly(oxypropylene) block copolymers

    DEFF Research Database (Denmark)

    Patrick, J.; Fairclough, J.P.A.; Yu, G.E.;

    2000-01-01

    The first observation of ordered microphase structures in poly(oxyethylene)-poly(oxypropylene) diblock copolymers melts is reported. Two diblock copolymers were synthesised by anionic polymerisation, i.e. E130P58 and E107P69 where E represents an oxyethylene unit, OCH2CH2, and P an oxypropylene...... triblock copolymer with perdeuterated P blocks, E(33)dP(42)E(33), was synthesised and studied in the melt phase by small-angle neutron scattering. This allowed determination of the temperature dependence of the Flory-Huggins interaction parameter for the poly(oxyethylene)-poly(oxypropylene) system, i...

  1. Self-Assembly and Critical Aggregation Concentration Measurements of ABA Triblock Copolymers with Varying B Block Types: Model Development, Prediction, and Validation.

    Science.gov (United States)

    Aydin, Fikret; Chu, Xiaolei; Uppaladadium, Geetartha; Devore, David; Goyal, Ritu; Murthy, N Sanjeeva; Zhang, Zheng; Kohn, Joachim; Dutt, Meenakshi

    2016-04-21

    simulations, and used these results to predict the CAC values of triblock copolymers with higher molecular weights by extrapolation. In parallel, a PEG5K-b-oligo(DTO-SA)-b-PEG5K block copolymer was synthesized, and the CAC value was determined experimentally using the pyrene method. The experimental CAC value agreed well with the CAC value predicted by simulation. These results validate our CG models, and demonstrate an avenue to simulate and predict aggregation characteristics of ABA amphiphilic triblock copolymers with complex structures. PMID:27031284

  2. Studies on microphase-separated structures of block copolymers by neutron reflectivity measurement

    International Nuclear Information System (INIS)

    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)

  3. Structure and ionic conductivity of block copolymer electrolytes over a wide salt concentration range

    Science.gov (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

  4. Polydimethylsiloxane-polymethacrylate block copolymers tethering quaternary ammonium salt groups for antimicrobial coating

    International Nuclear Information System (INIS)

    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+ 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+ content presented better antimicrobial activity. The functionalized copolymers based PDMS and quaternary ammonium salts materials have the potential applications as antimicrobial coatings

  5. 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: zhaoyunhui@tju.edu.cn; Yuan, Xiaoyan

    2015-02-15

    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.

  6. Thermosensitive PNIPAM-b-HTPB block copolymer micelles: molecular architectures and camptothecin drug release.

    Science.gov (United States)

    Luo, Yan-Ling; Yang, Xiao-Li; Xu, Feng; Chen, Ya-Shao; Zhang, Bin

    2014-02-01

    Two kinds of thermo-sensitive poly(N-isoproplacrylamide) (PNIPAM) block copolymers, AB4 four-armed star multiblock and linear triblock copolymers, were synthesized by ATRP with hydroxyl-terminated polybutadiene (HTPB) as central blocks, and characterization was performed by (1)H NMR, FT-IR and SEC. The multiblock copolymers could spontaneously assemble into more regular spherical core-shell nanoscale micelles than the linear triblock copolymer. The physicochemical properties were detected by a surface tension technique, nano particle analyzer, TEM, DLS and UV-vis measurements. The multiblock copolymer micelles had lower critical micelle concentration than the linear counterpart, TEM size from 100 to 120 nm and the hydrodynamic diameters below 150 nm. The micelles exhibited thermo-dependent size change, with low critical solution temperature about 33-35 °C. The characteristic parameters were affected by the composition ratios, length of PNIPAM blocks and molecular architectures. The camptothecin release demonstrated that the drug release was thermo-responsive, accompanied by the temperature-induced structural changes of the micelles. MTT assays were performed to evaluate the biocompatibility or cytotoxicity of the prepared copolymer micelles. PMID:24184534

  7. Thermoresponsive and Redox Behaviors of Poly(N-isopropylacrylamide)-Based Block Copolymers Having TEMPO Groups as Their Side Chains

    OpenAIRE

    Toru Uemukai; Tomoya Hioki; Manabu Ishifune

    2013-01-01

    Thermoresponsive and redox-active block copolymers having 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO) moieties have been synthesized by using the reversible addition-fragmentation chain transfer (RAFT) polymerization technique. N-Isopropylacrylamide (NIPAAm) and 2,2,6,6-tetramethylpiperidyl methacrylate (TEMPMA) monomers were copolymerized stepwise under RAFT polymerization conditions to afford the thermoresponsive block copolymers, PNIPAAm-block-PTEMPMA and PNIPAAm-block-PTEMPMA-block-PNIPA...

  8. Silk-collagen-like block copolymers with charged blocks : self-assembly into nanosized ribbons and macroscopic gels

    NARCIS (Netherlands)

    Martens, A.A.

    2008-01-01

    The research described in this thesis concerns the design, biotechnological production, and physiochemical study of large water-soluble (monodisperse) protein triblock-copolymers with sequential blocks, some of which are positively or negatively charged and self-assemble in response to a change in p

  9. Manipulating Interfaces through Surface Confinement of Poly(glycidyl methacrylate)-block-poly(vinyldimethylazlactone), a Dually Reactive Block Copolymer

    International Nuclear Information System (INIS)

    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.

  10. Synthesis of Carboxylic Block Copolymers via Reversible Addition Fragmentation Transfer Polymerization for Tooth Erosion Prevention

    OpenAIRE

    Lei, Y.; Wang, T.; Mitchell, J. W.; Qiu, J.; Kilpatrick-Liverman, L.

    2014-01-01

    Dental professionals are seeing a growing population of patients with visible signs of dental erosion. The approach currently being used to address the problem typically leverages the enamel protection benefits of fluoride. In this report, an alternative new block copolymer with a hydrophilic polyacrylic acid (PAA) block and a hydrophobic poly(methyl methacrylate) (PMMA) block was developed to similarly reduce the mineral loss from enamel under acidic conditions. This series of PMMA-b-PAA blo...

  11. A functionalizable reverse thermal gel based on a polyurethane/PEG block copolymer

    OpenAIRE

    Park, Daewon; Wu, Wei; Wang, Yadong

    2011-01-01

    Injectable reverse thermal gels have great potentials as biomaterials for tissue engineering and drug delivery. However, most existing gels lack functional groups that can be modified with biomolecules that can guide cell/material interactions. We created an amine-functionalized ABA block copolymer, poly(ethylene glycol)-poly(serinol hexamethylene urethane), or ESHU. This reverse thermal gel consists of a hydrophobic block (B): poly(serinol hexamethylene urethane) and a hydrophilic block (A):...

  12. Pattern Transfer of Sub-10 nm Features via Tin-Containing Block Copolymers

    OpenAIRE

    Maher, Michael J.; Mori, Kazunori; Sirard, Stephen M.; Dinhobl, Andrew M.; Bates, Christopher M.; Gurer, Emir; Blachut, Gregory; Lane, Austin P.; Durand, William J.; Carlson, Matthew C.; Strahan, Jeffrey R.; Ellison, Christopher J.; Willson, C. Grant

    2016-01-01

    Tin-containing block copolymers were investigated as materials for nanolithographic applications. Poly(4-trimethylstannylstyrene-block-styrene) (PSnS-PS) and poly(4-trimethylstannylstyrene-block-4-methoxystyrene) (PSnS-PMOST) synthesized by reversible addition–fragmentation chain transfer polymerization form lamellar domains with periodicities ranging from 18 to 34 nm. Thin film orientation control was achieved by thermal annealing between a neutral surface treatment and a top coat. Incorpora...

  13. Selective Semiconductor Nanocluster Deposition on Eptaxially Patterned Semicrystalline Block Copolymer Film

    Science.gov (United States)

    Park, Cheolmin; Lee, Jinwook; Jensen, Klavs F.; Bawendi, Moungi G.; Thomas, Edwin L.

    2001-03-01

    Monodisperse ZnS encapsulated CdSe semiconductor nanoclusters are sequestered in between the crystalline polyethylene (PE) lamellae of poly (ethylene-b-ethylene-alt-propylene-b ethylene) semicrystalline triblock copolymer epitaxially crystallized on single crystal of anthracene (AN). Epitaxy between PE block and An created a cross oriented texture of the edge-on crystalline PE lamellae in the thin film. At the same time, the nanoclusters, initially dissolved in the mixture of block copolymer and AN, were rejected out of the crystalline lamellae during epitaxial crystallization and selectively deposited in the amorphous region of the block copolymer. Selective distribution of nanoclusters on the cross oriented pattern structure is clearly evidenced by selected area diffraction (SAD) and bright field transmission electron microscope (TEM).

  14. Three-dimensional inverse design of nanopatterns with block copolymers and homopolymers

    Science.gov (United States)

    Xu, Dan; Liu, Hong; Zhu, You-Liang; Lu, Zhong-Yuan

    2016-02-01

    We propose a facile inverse design strategy to generate three-dimensional (3D) nanopatterns by using either block copolymers or a binary homopolymer blend via dissipative particle dynamics simulations. We find that the composition window of block copolymers to form a specific 3D morphology can be expanded when the self-assembly of block copolymers is directed by templates. We also find that a binary homopolymer blend can serve as a better candidate in the inverse templating design, since they have similar performances on recovering the target pattern, with much lower cost. This strategy is proved efficient for fabricating templates with desired topographical configuration, and the inverse design idea sheds lights on better control and design of materials with complex nanopatterns.

  15. Three-dimensional inverse design of nanopatterns with block copolymers and homopolymers.

    Science.gov (United States)

    Xu, Dan; Liu, Hong; Zhu, You-Liang; Lu, Zhong-Yuan

    2016-03-01

    We propose a facile inverse design strategy to generate three-dimensional (3D) nanopatterns by using either block copolymers or a binary homopolymer blend via dissipative particle dynamics simulations. We find that the composition window of block copolymers to form a specific 3D morphology can be expanded when the self-assembly of block copolymers is directed by templates. We also find that a binary homopolymer blend can serve as a better candidate in the inverse templating design, since they have similar performances on recovering the target pattern, with much lower cost. This strategy is proved efficient for fabricating templates with desired topographical configuration, and the inverse design idea sheds lights on better control and design of materials with complex nanopatterns. PMID:26880143

  16. Selective directed self-assembly of coexisting morphologies using block copolymer blends

    Science.gov (United States)

    Stein, A.; Wright, G.; Yager, K. G.; Doerk, G. S.; Black, C. T.

    2016-08-01

    Directed self-assembly (DSA) of block copolymers is an emergent technique for nano-lithography, but is limited in the range of structures possible in a single fabrication step. Here we expand on traditional DSA chemical patterning. A blend of lamellar- and cylinder-forming block copolymers assembles on specially designed surface chemical line gratings, leading to the simultaneous formation of coexisting ordered morphologies in separate areas of the substrate. The competing energetics of polymer chain distortions and chemical mismatch with the substrate grating bias the system towards either line/space or dot array patterns, depending on the pitch and linewidth of the prepattern. This is in contrast to the typical DSA, wherein assembly of a single-component block copolymer on chemical templates generates patterns of either lines/spaces (lamellar) or hexagonal dot arrays (cylinders). In our approach, the chemical template encodes desired local spatial arrangements of coexisting design motifs, self-assembled from a single, sophisticated resist.

  17. Tuning of Block Copolymer Membrane Morphology through Water Induced Phase Inversion Technique

    KAUST Repository

    Madhavan, Poornima

    2016-06-01

    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

  18. Micellization kinetics in block copolymer solutions : Scaling model

    NARCIS (Netherlands)

    Dormidontova, EE

    1999-01-01

    The kinetics of micelle evolution of diblock copolymers from unimers toward the equilibrium state is studied analytically on the basis of consideration of the kinetic equations. The association/dissociation rate constants for unimer insertion/expulsion and micelle fusion/fission are calculated by ap

  19. Collapse transitions in thermosensitive multi-block copolymers: A Monte Carlo study

    International Nuclear Information System (INIS)

    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 (AnBn)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. Collapse transitions in thermosensitive multi-block copolymers: A Monte Carlo study

    Energy Technology Data Exchange (ETDEWEB)

    Rissanou, Anastassia N., E-mail: rissanou@tem.uoc.gr [Department of Mathematics and Applied Mathematics, University of Crete, GR-71003 Heraklion Crete, Greece and Archimedes Center for Analysis, Modeling and Computation, University of Crete, P.O. Box 2208, GR-71003 Heraklion Crete (Greece); Tzeli, Despoina S. [Department of Materials Science and Technology, University of Crete, GR-71003 Heraklion Crete (Greece); Anastasiadis, Spiros H. [Department of Chemistry, University of Crete, P.O. Box 2208, 710 03 Heraklion Crete (Greece); Institute of Electronic Structure and Laser, Foundation for Research and Technology-Hellas, GR-71110 Heraklion Crete (Greece); Bitsanis, Ioannis A. [Institute of Electronic Structure and Laser, Foundation for Research and Technology-Hellas, GR-71110 Heraklion Crete (Greece)

    2014-05-28

    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{sub n}B{sub n}){sub 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.

  1. Formation of Nonclassical Ordered Phases of A B -Type Multiarm Block Copolymers

    Science.gov (United States)

    Gao, Ya; Deng, Hanlin; Li, Weihua; Qiu, Feng; Shi, An-Chang

    2016-02-01

    The formation of ordered phases from block copolymers is driven by a delicate balance between the monomer-monomer interaction and chain configurational entropy. The configurational entropy can be regulated by designed chain architecture, resulting in a new entropy-driven mechanism to control the self-assembly of ordered phases from block copolymers. An effective routine to regulate the configurational entropy is to utilize multiarm architecture, in which the entropic contribution to the free energy could be qualitatively controlled by the fraction of bridging configurations. As an illustration of this mechanism, the phase behavior of two A B -type multiarm block copolymers, B0-(Bi-Ai) m and (B1-Ai-B2) m where the minority A blocks form cylindrical or spherical domains, are examined using the self-consistent field theory (SCFT). The SCFT results demonstrate that the packing symmetry of the cylinders or spheres can be controlled by the length of the bridging B blocks. Several nonclassical ordered phases, including a novel square array cylinder with p 4 m m symmetry, are predicted to form from the A B -type multiarm block copolymers.

  2. Hierarchical nanoparticle topography in amphiphilic copolymer films controlled by thermodynamics and dynamics.

    Science.gov (United States)

    Caporizzo, M A; Ezzibdeh, R M; Composto, R J

    2015-03-17

    This study systematically investigates how polymer composition changes nanoparticle (NP) grafting and diffusion in solvated random copolymer thin films. By thermal annealing from 135 to 200 °C, thin films with a range of hydrophobicity are generated by varying acrylic acid content from 2% (SAA2) to 29% (SAA29). Poly(styrene-random-tert butyl acrylate) films, 100 nm thick, that are partially converted to poly(styrene-random-acrylic acid), SAA, reversibly swell in ethanol solutions containing amine-functionalized SiO2 nanoparticles with a diameter of 45 nm. The thermodynamics and kinetics of NP grafting are directly controlled by the AA content in the SAA films. At low AA content, namely SAA4, NP attachment saturates at a monolayer, consistent with a low solubility of NPs in SAA4 due to a weakly negative χ parameter. When the AA content exceeds 4%, NPs sink into the film to form multilayers. These films exhibit hierarchical surface roughness with a RMS roughness greater than the NP size. Using a quartz crystal microbalance, NP incorporation in the film is found to saturate after a mass equivalence of about 3 close-packed layers of NPs have been incorporated within the SAA. The kinetics of NP grafting is observed to scale with AA content. The surface roughness is greatest at intermediate times (5-20 min) for SAA13 films, which also exhibit superhydrophobic wetting. Because clustering and aggregation of the NPs within SAA29 films reduce film transparency, SAA13 films provide both maximum hydrophobicity and transparency. The method in this study is widely applicable because it can be applied to many substrate types, can cover large areas, and retains the amine functionality of the particles which allows for subsequent chemical modification. PMID:25689222

  3. Copolymers containing 4-vinylpyridine, acrylonitrile and styrene units by controlled radical polymerization

    Czech Academy of Sciences Publication Activity Database

    Poláková, Lenka; Lokaj, Jan; Holler, Petr; Starovoytova, Larisa; Štěpánek, Petr; Diat, O.

    Prague : Institute of Macromolecular Chemistry AS CR, 2006. s. 47. [SONS Networking Activity Workshop: Structure and properties of self-organized amphiphilic copolymers. 04.10.2006-07.10.2006, Prague] R&D Projects: GA ČR GESON/03/E001 Keywords : block copolymers * nitroxide-mediated radical polymerization * 4-vinylpyridine Subject RIV: CD - Macromolecular Chemistry

  4. Synthesis of Dextran/Methoxy Poly(ethylene glycol) Block Copolymer

    OpenAIRE

    Young-Il Jeong; Dong-Gon Kim; Dae-Hwan Kang

    2013-01-01

    We synthesized a block copolymer composed of dextran and methoxy poly(ethylene glycol) (mPEG). To accomplish this, the end group of dextran was modified by reductive amination. The aminated dextran (Dextran-NH2) showed the intrinsic peaks of both dextran at 3~5.5 ppm and hexamethylene diamine at 1~2.6 ppm at 1H nuclear magnetic resonance (NMR) spectrum. The amino end group of dextran was conjugated with mPEG to make the block copolymer consisting of dextran/mPEG (abbre...

  5. Data on macrophage mediated muscle transfection upon delivery of naked plasmid DNA with block copolymers.

    Science.gov (United States)

    Mahajan, Vivek; Gaymalov, Zagit; Alakhova, Daria; Gupta, Richa; Zucker, Irving H; Kabanov, Alexander V

    2016-06-01

    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. PMID:27222845

  6. Azidated Ether-Butadiene-Ether Block Copolymers as Binders for Solid Propellants

    Science.gov (United States)

    Cappello, Miriam; Lamia, Pietro; Mura, Claudio; Polacco, Giovanni; Filippi, Sara

    2016-07-01

    Polymeric binders for solid propellants are usually based on hydroxyl-terminated polybutadiene (HTPB), which does not contribute to the overall energy output. Azidic polyethers represent an interesting alternative but may have poorer mechanical properties. Polybutadiene-polyether copolymers may combine the advantages of both. Four different ether-butadiene-ether triblock copolymers were prepared and azidated starting from halogenated and/or tosylated monomers using HTPB as initiator. The presence of the butadiene block complicates the azidation step and reduces the storage stability of the azidic polymer. Nevertheless, the procedure allows modifying the binder properties by varying the type and lengths of the energetic blocks.

  7. 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...

  8. Inducing an Order-Order Morphological Transition via Chemical Degradation of Amphiphilic Diblock Copolymer Nano-Objects.

    Science.gov (United States)

    Ratcliffe, Liam P D; Couchon, Claudie; Armes, Steven P; Paulusse, Jos M J

    2016-06-13

    The disulfide-based cyclic monomer, 3-methylidene-1,9-dioxa-5,12,13-trithiacyclopentadecane-2,8-dione (MTC), is statistically copolymerized with 2-hydroxypropyl methacrylate to form a range of diblock copolymer nano-objects via reversible addition-fragmentation chain transfer (RAFT) polymerization. Poly(glycerol monomethacrylate) (PGMA) is employed as the hydrophilic stabilizer block in this aqueous polymerization-induced self-assembly (PISA) formulation, which affords pure spheres, worms or vesicles depending on the target degree of polymerization for the core-forming block. When relatively low levels (99%) are achieved and high blocking efficiencies are observed, as judged by (1)H NMR spectroscopy and gel permeation chromatography (GPC), respectively. However, the side reactions that are known to occur when cyclic allylic sulfides such as MTC are statistically copolymerized with methacrylic comonomers lead to relatively broad molecular weight distributions. Nevertheless, the worm-like nanoparticles obtained via PISA can be successfully transformed into spherical nanoparticles by addition of excess tris(2-carboxyethyl)phosphine (TCEP) at pH 8-9. Surprisingly, DLS and TEM studies indicate that the time scale needed for this order-order transition is significantly longer than that required for cleavage of the disulfide bonds located in the worm cores indicated by GPC analysis. This reductive degradation pathway may enable the use of these chemically degradable nanoparticles in biomedical applications, such as drug delivery systems and responsive biomaterials. PMID:27228898

  9. Inducing an Order–Order Morphological Transition via Chemical Degradation of Amphiphilic Diblock Copolymer Nano-Objects

    Science.gov (United States)

    2016-01-01

    The disulfide-based cyclic monomer, 3-methylidene-1,9-dioxa-5,12,13-trithiacyclopentadecane-2,8-dione (MTC), is statistically copolymerized with 2-hydroxypropyl methacrylate to form a range of diblock copolymer nano-objects via reversible addition–fragmentation chain transfer (RAFT) polymerization. Poly(glycerol monomethacrylate) (PGMA) is employed as the hydrophilic stabilizer block in this aqueous polymerization-induced self-assembly (PISA) formulation, which affords pure spheres, worms or vesicles depending on the target degree of polymerization for the core-forming block. When relatively low levels (99%) are achieved and high blocking efficiencies are observed, as judged by 1H NMR spectroscopy and gel permeation chromatography (GPC), respectively. However, the side reactions that are known to occur when cyclic allylic sulfides such as MTC are statistically copolymerized with methacrylic comonomers lead to relatively broad molecular weight distributions. Nevertheless, the worm-like nanoparticles obtained via PISA can be successfully transformed into spherical nanoparticles by addition of excess tris(2-carboxyethyl)phosphine (TCEP) at pH 8–9. Surprisingly, DLS and TEM studies indicate that the time scale needed for this order–order transition is significantly longer than that required for cleavage of the disulfide bonds located in the worm cores indicated by GPC analysis. This reductive degradation pathway may enable the use of these chemically degradable nanoparticles in biomedical applications, such as drug delivery systems and responsive biomaterials. PMID:27228898

  10. Mesoscopic multiphase structures and the interfaces of block and graft copolymers in bulk

    International Nuclear Information System (INIS)

    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, φs, 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)

  11. Characterization of high performance randomly segmented poly(urethane siloxane) and poly(imide siloxane) block copolymers

    Science.gov (United States)

    Doǧan, Türkan; Baydoǧan, Nilgün; Köken, Nesrin

    2016-03-01

    Poly(imide siloxane) block copolymers with the same polydimethlysiloxane(APPS) were prepared by using 4,4'-oxydianiline (ODA) and Benzofenon-3,3,4,4-tetrakarboksilik dianhydride(BTDA) to compose the polyimide hard block. APPS and BTDA composed the polysiloxane soft block. The length of polysiloxane soft blocks increased with increasing the length of polyimide hard block. Copolymerization of soft and hard segments were determined by using this method. Copolymer structures could be obtained by holding constant hard block segments and by adjusting and increasing soft block segments. Thus, more flexible randomly segmented poly(imide siloxane) block copolymers can be obtained. These composed structure as flexible and high performance copolymers were characterized by FT-IR and evaluated. The structures were tested mechanically to detect their elastic recovery property as flexible material. The characterization of the samples enabled to examine flexible substrates in order to use in solar cell, aerospace applications and microelectronic devices.

  12. A simple pathway to ordered silica nanopattern from self-assembling of block copolymer containing organic silicon block

    International Nuclear Information System (INIS)

    Self-assembly of block copolymer is an effective strategy to prepare periodic structures at nanoscale. In this paper an unique and very simple method to prepare inorganic silica nanopattern is demonstrated from self-assembling of poly(styrene-block-dimethylsiloxane) (PS-b-PDMS) on the surface of silicon wafer. To simplify the patterning process, at first we obtain highly ordered PDMS microdomains, which are covered with PS layer by controlling solvent vapor annealing conditions. Following exposure to UV/O3 irradiation, nanopatterned surface consisting of silicon oxide is fabricated directly via selectively etching PS phase and converting PDMS phase into silicon oxide. As tuning the composition of the block copolymer, hexagonally packing dot and straight stripe pattern can be obtained. Finally, the time evolution from spheres morphology to aligned long cylinders is discussed. These results hold promise for nanolithography and the fabrication of nanodevices.

  13. Topcoat approaches for directed-assembly of copolymer films with blocks exhibiting differences in surface energy

    Science.gov (United States)

    Suh, Hyo Seon; in Lee, Jeong; Ramirez-Hernandez, Abelardo; Tada, Yasuhiko; Yoshida, Hiroshi; Wan, Lei; Ruiz, Ricardo; de Pablo, Juan; Nealey, Paul

    2013-03-01

    Fabricating patterns with feature dimensions smaller than 10 nm scale using block copolymer lithography requires the use of materials with large Flory-Huggins interaction parameters. Because such block copolymers (BCPs) typically show the large differences in surface energy between the blocks, one block (with lower surface energy) tends to segregate to the free surface of films and precludes the assembly of the desired through-film perpendicularly oriented structures. Here we describe a generalizable strategy to overcome this limitation. By coating the BCP film with an additional layer, a topcoat, thermodynamically favorable boundary conditions at the top surface of the film can be engineered for directed self-assembly. The allowable properties of the topcoats depend on the interfacial energies of the layer with the blocks of the copolymer, and the block-block interfacial energy. The strategy is demonstrated experimentally by directing the assembly of polystyrene-block-poly-2-vinylpyridine (PS- b-P2VP) films on chemically nanopatterned substrates with different topcoat materials.

  14. Living cationic polymerization and polyhomologation: an ideal combination to synthesize functionalized polyethylene–polyisobutylene block copolymers

    KAUST Repository

    Zhang, Hefeng

    2015-12-17

    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).

  15. Structure-property relationships in multilayered polymeric system and olefinic block copolymers

    Science.gov (United States)

    Khariwala, Devang

    Chapter 1. The effect of tie-layer thickness on delamination behavior of polypropylene/tie-layer/Nylon-6 multilayers is examined in this study. Various maleated polypropylene resins were compared for their effectiveness as tie-layers. Delamination failure occurred cohesively in all the multilayer systems. Two adhesion regimes were defined based on the change in slope of the linear relationship between the delamination toughness and the tie-layer thickness. The measured delamination toughness of the various tie-layers was quantitatively correlated to the damage zone length formed at the crack tip. In addition, the effect of tie-layer thickness on the multilayer tensile properties was correlated with the delamination behavior. The fracture strain of the multilayers decreased with decreasing tie-layer thickness. Examination of the prefracture damage mechanism of stretched multilayers revealed good correlation with the delamination toughness of the tie-layers. In thick tie-layers (>2microm) the delamination toughness of the tie-layers was large enough to prevent delamination of multilayers when they were stretched. In the thin tie-layers (block copolymers with properties typical of thermoplastic elastomers. The block copolymers synthesized by chain shuttling technology consist of crystallizable ethylene-octene blocks with low comonomer content and high melting temperature (hard blocks), alternating with amorphous ethylene-octene blocks with high comonomer content and low glass transition temperature (soft blocks). This study describes the material science of these unique polymers as characterized by thermal analysis, X-ray diffraction, microscopy, and tensile deformation. The crystallizable blocks are long enough to form well-organized lamellar crystals with the orthorhombic unit cell and high melting temperature. The lamellae are organized into space-filling spherulites in all compositions even in copolymers with only 18 wt% hard block. The morphology is consistent

  16. SYNTHESIS AND CHARACTERIZATION OF HYDROPHOBIC-HYDROPHILIC MULTIBLOCK COPOLYMERS FOR BIOMEDICAL APPLICATIONS

    Institute of Scientific and Technical Information of China (English)

    Yong Kiel Sung; Yong Joo Kim; Sung Wan Kim

    1999-01-01

    The synthesis and characterization of amphiphilic copolymers of poly(dimethyl siloxane)(PDMS),poly(ethylene oxide)(PEO), and heparin(Hep) were investigated. These multiblock copolymers were identified using 1H-NMR, FTIR, end group analysis, and sulfur elemental analysis. The multiblock copolymers were characterized by using DSC and X-ray diffractometry. The glass transition temperature,crystalline melting characteristics, annealing effect, and cold crystallization of the block copolymers were determined by DSC. The crystallinity of the block copolymers was also determined by X-ray diffraction method.

  17. Enantiomeric PLA-PEG block copolymers and their stereocomplex micelles used as rifampin delivery

    International Nuclear Information System (INIS)

    A novelty approach to self-assembling stereocomplex micelles by enantiomeric PLA-PEG block copolymers as a drug delivery carrier was described. The particles were encapsulated by enantiomeric PLA-PEG stereocomplex to form nanoscale micelles different from the microspheres or the single micelles by PLLA or PDLA in the reported literatures. First, the block copolymers of enantiomeric poly(l-lactide)-poly(ethylene-glycol) (PLLA-PEG) and poly(D-lactide)-poly(ethylene-glycol) (PDLA-PEG) were synthesized by the ring-opening polymerization of l-lactide and d-lactide in the presence of monomethoxy PEG, respectively. Second, the stereocomplex block copolymer micelles were obtained by the self-assembly of the equimolar mixtures of enantiomeric PLA-PEG copolymers in water. These micelles possessed partially the crystallized hydrophobic cores with the critical micelle concentrations (cmc) in the range of 0.8-4.8 mg/l and the mean hydrodynamic diameters ranging from 40 to 120 nm. The micelle sizes and cmc values obviously depended on the hydrophobic block PLA content in the copolymer. Compared with the single PLLA-PEG or PDLA-PEG micelles, the cmc values of the stereocomplex micelles became lower and the sizes of the stereocomplex micelles formed smaller. And lastly, the stereocomplex micelles encapsulated with rifampin were tested for the controlled release application. The rifampin loading capacity and encapsulation efficiency by the stereocomplex micelles were higher than those by the single polymer micelles, respectively. The drug release time in vitro was depending on the composites of the block copolymers and also could be controlled by the polymer molecular weight and the morphology of the polymer micelles

  18. Dissipative Particle Dynamics Simulation of Onion Phase in Star-block Copolymer

    Institute of Scientific and Technical Information of China (English)

    WU Shao-gui; DU Ting-ting

    2013-01-01

    A dissipative particle dynamics simulation technique was used to investigate the effect of molecular architecture of star-block copolymer on the patterned structure in a nanodroplet.With increasing the ratio of solvophilic to block length to solvophobic block length(RH/T),solvophobic sphere,ordered hexagonal phase,onion phase,perforated onion phase and flocculent phase are formed,respectively.Since onion phase has potential application in controlled drug release,it has received wide attention experimentally and theoretically.Our simulation indicates onion phase forms at a certain RH/T(close to but less than 1).A star-block copolymer molecule has two conformations in onion phase:either fully located in a shell or shared by two neighboring shells.Central structure affects onion's final shape.The molecular number of the copolymer in each shell is a quadratic function of the shell's radius.The arm number of star-block copolymer has little influence on onion's structure,but slightly affects the solvent content.Additionally,we studied the influence of arm length on onion's structure.

  19. PS-b-PDMS Block Copolymer Thin Film: Pattern Formation and Phase Behavior

    Science.gov (United States)

    Hsieh, I.-Fan; Cheng, Stephen Z. D.; Department of Polymer Science, The University of Akron Team

    2011-03-01

    Recently, block copolymer thin films attract great attention due to their potential applications in surface nano-lithography. In our work, PS- b -PDMS with cylinder morphology is chosen due to extremely large χ value between two blocks. Besides, PS- b -PDMS can be transformed into silicon oxide under UV/O3 exposure and a layer of silicon oxide with the self-assembled block copolymer patterns can be made. By utilizing the PGMEA as solvent, we can easily obtain sphere morphology in cylindrical composition block copolymer by preserved block copolymer solution morphology during film formation. Furthermore, in thermal annealing process, the phase behavior of the PS- b -PDMS thin film is strongly affects by molecular weight, film thickness and annealing temperature. In larger-molecular-weight PS- b -PDMS, we only observed spherical domains rearrangement and without morphology transition between sphere and cylinder due to high energy barrier, whereas, in the case of smaller-molecular-weight polymer, depending on the film thickness and annealing temperature, its thin film morphology transits between sphere and cylinder alternatively, which is similar to what we found in solvent annealing.

  20. Block copolymer modified surfaces for conjugation of biomacromolecules with control of quantity and activity.

    Science.gov (United States)

    Li, Xin; Wang, Mengmeng; Wang, Lei; Shi, Xiujuan; Xu, Yajun; Song, Bo; Chen, Hong

    2013-01-29

    Polymer brush layers based on block copolymers of poly(oligo(ethylene glycol) methacrylate) (POEGMA) and poly(glycidyl methacrylate) (PGMA) were formed on silicon wafers by activators generated by electron transfer atom transfer radical polymerization (AGET ATRP). Different types of biomolecule can be conjugated to these brush layers by reaction of PGMA epoxide groups with amino groups in the biomolecule, while POEGMA, which resists nonspecific protein adsorption, provides an antifouling environment. Surfaces were characterized by water contact angle, ellipsometry, and Fourier transform infrared spectroscopy (FTIR) to confirm the modification reactions. Phase segregation of the copolymer blocks in the layers was observed by AFM. The effect of surface properties on protein conjugation was investigated using radiolabeling methods. It was shown that surfaces with POEGMA layers were protein resistant, while the quantity of protein conjugated to the diblock copolymer modified surfaces increased with increasing PGMA layer thickness. The activity of lysozyme conjugated on the surface could also be controlled by varying the thickness of the copolymer layer. When biotin was conjugated to the block copolymer grafts, the surface remained resistant to nonspecific protein adsorption but showed specific binding of avidin. These properties, that is, well-controlled quantity and activity of conjugated biomolecules and specificity of interaction with target biomolecules may be exploited for the improvement of signal-to-noise ratio in sensor applications. More generally, such surfaces may be useful as biological recognition elements of high specificity for functional biomaterials. PMID:23265296

  1. Double stimuli-responsive ultrafiltration membranes from polystyrene-block-poly(N,N-dimethylaminoethyl methacrylate) diblock copolymers.

    Science.gov (United States)

    Schacher, Felix; Rudolph, Tobias; Wieberger, Florian; Ulbricht, Mathias; Müller, Axel H E

    2009-07-01

    We report on the formation of self-supporting, double stimuli-responsive ultrafiltration membranes via the non-solvent-induced phase separation (NIPS) process. The polymers, polystyrene-block-poly(N,N-dimethylaminoethyl methacrylate) (PS-b-PDMAEMA), were synthesized via living anionic polymerization in THF using sec-butyllithium as initiator. Two amphiphilic diblock copolymers were used, S(81)D(19)(75) and S(68)D(32)(100). The membranes were cast from mixtures of THF and DMF. The influence of the solvent composition, the "open-time" before immersion into the coagulation bath, and the casting film thickness onto the membrane morphology were thoroughly investigated, and flux values obtained for the different membrane systems were compared. The higher content in hydrophilic polymer for S(68)D(32)(100) resulted in a better compatibility with the nonsolvent bath consisting of water, leading to a slower precipitation and thus an improved control of the phase separation occurring. Under certain conditions, ordered microphase-separated porous morphologies were observed in parts of the membrane cross-section. Further, the "smart" properties of those novel materials are shown for two representative systems. It could be demonstrated that both stimuli for PDMAEMA, pH and temperature, can be reversibly and independently applied in order to significantly change the transmembrane water flux. PMID:20355953

  2. Supramolecular block copolymers by kinetically controlled co-self-assembly of planar and core-twisted perylene bisimides

    Science.gov (United States)

    Görl, Daniel; Zhang, Xin; Stepanenko, Vladimir; Würthner, Frank

    2015-05-01

    New synthetic methodologies for the formation of block copolymers have revolutionized polymer science within the last two decades. However, the formation of supramolecular block copolymers composed of alternating sequences of larger block segments has not been realized yet. Here we show by transmission electron microscopy (TEM), 2D NMR and optical spectroscopy that two different perylene bisimide dyes bearing either a flat (A) or a twisted (B) core self-assemble in water into supramolecular block copolymers with an alternating sequence of (AmBB)n. The highly defined ultralong nanowire structure of these supramolecular copolymers is entirely different from those formed upon self-assembly of the individual counterparts, that is, stiff nanorods (A) and irregular nanoworms (B), respectively. Our studies further reveal that the as-formed supramolecular block copolymer constitutes a kinetic self-assembly product that transforms into thermodynamically more stable self-sorted homopolymers upon heating.

  3. Humidity-Induced Phase Transitions in Ion-Containing Block Copolymer Membranes

    Energy Technology Data Exchange (ETDEWEB)

    Park, Moon Jeong; Nedoma, Alisyn J.; Geissler, Phillip L.; Balsara, Nitash P.; Jackson, Andrew; Cookson, David (UCB); (NIST); (Aust. Synch.); (LBNL)

    2008-08-21

    The phase behavior of ion-containing block copolymer membranes in equilibrium with humidified air is studied as a function of the relative humidity (RH) of the surrounding air, ion content of the copolymer, and temperature. Increasing RH at constant temperature results in both disorder-to-order and order-to-order transitions. In-situ small-angle neutron scattering experiments on the open block copolymer system, when combined with water uptake measurement, indicate that the disorder-to-order transition is driven by an increase in the partial molar entropy of the water molecules in the ordered phase relative to that in the disordered phase. This is in contrast to most systems wherein increasing entropy results in stabilization of the disordered phase.

  4. Self-Assembled Asymmetric Block Copolymer Membranes: Bridging the Gap from Ultra- to Nanofiltration

    KAUST Repository

    Yu, Haizhou

    2015-09-21

    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.

  5. Self-Assembled Asymmetric Block Copolymer Membranes: Bridging the Gap from Ultra- to Nanofiltration.

    Science.gov (United States)

    Yu, Haizhou; Qiu, Xiaoyan; Moreno, Nicolas; Ma, Zengwei; Calo, Victor Manuel; Nunes, Suzana P; Peinemann, Klaus-Viktor

    2015-11-16

    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. PMID:26388216

  6. Effects of copolymer composition, film thickness, and solvent vapor annealing time on dewetting of ultrathin block copolymer films.

    Science.gov (United States)

    Huang, Changchun; Wen, Gangyao; Li, Jingdan; Wu, Tao; Wang, Lina; Xue, Feifei; Li, Hongfei; Shi, Tongfei

    2016-09-15

    Effects of copolymer composition, film thickness, and solvent vapor annealing time on dewetting of spin-coated polystyrene-block-poly(methyl methacrylate) (PS-b-PMMA) films (annealed for different times were performed using X-ray photoelectron spectroscopy and contact angle measurement. With the annealing of acetone vapor, dewetting of the films with different thicknesses occur via the spinodal dewetting and the nucleation and growth mechanisms, respectively. The PS-b-PMMA films rupture into droplets which first coalesce into large ones to reduce the surface free energy. Then the large droplets rupture into small ones to increase the contact area between PMMA blocks and acetone molecules resulting from ultimate migration of PMMA blocks to droplet surface, which is a novel dewetting process observed in spin-coated films for the first time. PMID:27309943

  7. Synthesis of tri-block copolymers through reverse atom transfer radical polymerization of methyl methacrylate using polyurethane macroiniferter

    Directory of Open Access Journals (Sweden)

    2008-08-01

    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.

  8. Block Copolymer Electrolytes: Thermodynamics, Ion Transport, and Use in Solid- State Lithium/Sulfur Cells

    Science.gov (United States)

    Teran, Alexander Andrew

    Nanostructured block copolymer electrolytes containing an ion-conducting block and a modulus-strengthening block are of interest for applications in solid-state lithium metal batteries. These materials can self-assemble into well-defined microstructures, creating conducting channels that facilitate ion transport. The overall objective of this dissertation is to gain a better understanding of the behavior of salt-containing block copolymers, and evaluate their potential for use in solid-state lithium/sulfur batteries. Anionically synthesized polystyrene-b-poly(ethylene oxide) (SEO) copolymers doped with lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) salt were used as a model system. This thesis investigates the model system on several levels: from fundamental thermodynamic studies to bulk characterization and finally device assembly and testing. First, the thermodynamics of neat and salt-containing block copolymers was studied. The addition of salt to these materials is necessary to make them conductive, however even small amounts of salt can have significant effects on their phase behavior, and consequently their iontransport and mechanical properties. As a result, the effect of salt addition on block copolymer thermodynamics has been the subject of significant interest over the last decade. A comprehensive study of the thermodynamics of block copolymer/salt mixtures over a wide range of molecular weights, compositions, salt concentrations and temperatures was conducted. Next, the effect of molecular weight on ion transport in both homopolymer and copolymer electrolytes were studied over a wide range of chain lengths. Homopolymer electrolytes show an inverse relationship between conductivity and chain length, with a plateau in the infinite molecular weight limit. This is due to the presence of two mechanisms of ion conduction in homopolymers; the first mechanism is a result of the segmental motion of the chains surrounding the salt ions, 2 creating a liquid

  9. SYNTHESIS AND CHARACTERIZATION OF NOVEL CHIRAL SMECTIC C(Sc*) PHASE SHISH-KEBAB TYPE LIQUID CRYSTALLINE BLOCK COPOLYMERS

    Institute of Scientific and Technical Information of China (English)

    Shi-jun Zheng; Zi-fa Li; Shu-yuan Zhang; Shao-kui Cao; Ming-sheng Tang; Qiu-jun Fen; Qi-feng Zhou

    1999-01-01

    A new series of chiral shish-kebab type liquid crystal block copolymers that form the smectic C(Sc*) phase was synthesized by solution polycondensation. The copolymers were characterized by GPC,DSC, TG, POM, X-ray diffraction and polarimeter. The copolymers 7 entered into liquid crystal phase when they were heated to their melting temperatures (Tm) and the copolymers 8 were in liquid crystal phase at room temperature with low viscosities. The smectic sanded texture or focal-conic texture were observed on POM.All the chiral block copolymers showed high optical activity. No racemization has happened. Temperaturevariable X-ray diffraction study together with POM and polarimetric analysis realized that they are chiral smectic C(Sc*) phase. Thus we offer in this report the first example of shish-kebab type liquid crystal block copolymers that form a chiral smectic C(Sc*) phase. The variation of melting and isotropization temperatures with molecular structure was also discussed.

  10. Fluorinated Amphiphilic Polymers and Their Blends for Fouling-Release Applications: The Benefits of a Triblock Copolymer Surface

    KAUST Repository

    Sundaram, Harihara S.

    2011-09-28

    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.

  11. Synthesis of (meth)acrylate block copolymers by ligated anionic polymerization

    Czech Academy of Sciences Publication Activity Database

    Vlček, Petr; Čadová, Eva; Janata, Miroslav; Látalová, Petra; Toman, Luděk; Kříž, Jaroslav; Kurková, Dana

    Goa : International Union of Pure and Applied Chemistry, 2005. s. 20-21. [International Symposium on Ionic Polymerization. 23.10.2005-28.10.2005, Goa ] R&D Projects: GA MŠk 1P05ME753 Institutional research plan: CEZ:AV0Z40500505 Keywords : block copolymers * anionic polymerization * tert-alkoxides Subject RIV: CD - Macromolecular Chemistry

  12. Complexes of block copolymers in solution: a graph-theoretical approach

    NARCIS (Netherlands)

    Damme, van Ruud; Geurts, Bernard J.

    1989-01-01

    We determine the statistical properties of block copolymers in solution. These complexes are assumed to have the topological structure of connected graphs with “nonnested” loops and cycles. The generating function method is used to determine the number of topologically different complexes containing

  13. 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

    2006-01-01

    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

  14. Thin block copolymer films : film formation and corrugation under the AFM tip

    NARCIS (Netherlands)

    Maas, J.H.; Cohen Stuart, M.A.; Fleer, G.J.

    2000-01-01

    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 b

  15. 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.

    2013-01-01

    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, elect

  16. Water vapor and gas transport through a poly (butylene terephthalate) poly (ethylene oxide) block copolymer

    NARCIS (Netherlands)

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

    2002-01-01

    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 wat

  17. Synthesis of Dendritic-Linear Block Copolymers by Atom Transfer Radical Polymerization

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The dendritic polyarylether 2-bromoisobutyrate as the macromolecular initiator for the controlled free radical polymerization of styrene was investigated. The polymerization was carried out with CuBr/2,2′-bipyridine catalyst at 110℃. It is found that the hybrid dendritic-linear block copolymers possess well-defined molecular weights and low polydispersities.

  18. 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

    2014-01-01

    Roč. 55, č. 1 (2014), s. 126-136. ISSN 0032-3861 R&D Projects: GA ČR GAP108/12/1459 Grant ostatní: 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

  19. Effect of Electric Field Alignment on Morphology and Ionic Conductivity of Polymerized Ionic Liquid Block Copolymers

    Science.gov (United States)

    Sharick, Sharon; Nykaza, Jacob; Elabd, Yossef A.; Winey, Karen I.

    2014-03-01

    Polymerized ionic liquid (PIL) block copolymers are appealing for numerous electrochemical applications, including solid polymer electrolyte membranes for batteries and anion exchange membranes for fuel cells. The extent to which the reduced segmental motion caused by the non-conducting polymer segments and grain boundaries between block copolymer microdomains are detrimental to ionic conductivity is unknown. Increased long-range morphological order and connectivity of PIL microdomains are key to understanding the ion transport mechanism and may improve the ionic conductivity of PIL block copolymers. The effect of electric field on the morphology and ionic conductivity of poly(styrene- b-1-[2-(methacryloyloxy)ethyl]-3-butylimidazolium-bis(trifluoromethanesulfonyl)imide)) (PS- b-PMEBIm-TFSI) will be discussed as a function of microdomain orientation. Electric field is used to increase the perpendicular orientation of ion-conducting pathways with respect to the electrodes. The morphology and ionic conductivity were characterized by small-angle X-ray scattering and electrochemical impedance spectroscopy, respectively. The ionic conductivity of unoriented and oriented block copolymers will be compared to the PIL homopolymer, PMEBIm-TFSI, using the Sax and Ottino model.

  20. DYNAMIC DENSITY-FUNCTIONAL THEORY FOR MICROPHASE SEPARATION KINETICS OF BLOCK-COPOLYMER MELTS

    NARCIS (Netherlands)

    FRAAIJE, JGEM

    1993-01-01

    In this paper, we describe a numerical method for the calculation of collective diffusion relaxation mechanisms in quenched block copolymer melts. The method entails the repeated calculation of two opposing fields-an external potential field U, conjugate to the density field rho, and an energetic in

  1. 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.

    2014-01-01

    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

  2. Self-assembled block copolymer membranes: From basic research to large-scale manufacturing

    KAUST Repository

    Nunes, Suzana Pereira

    2013-09-24

    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.

  3. Multiscale Control of Hierarchical Structure in Crystalline Block Copolymer Nanoparticles Using Microfluidics.

    Science.gov (United States)

    Bains, Aman; Cao, Yimeng; Moffitt, Matthew G

    2015-11-01

    Hierarchical semicrystalline block copolymer nanoparticles are produced in a segmented gas-liquid microfluidic reactor with top-down control of multiscale structural features, including nanoparticle morphologies, sizes, and internal crystallinities. Control of multiscale structure on disparate length scales by a single control variable (flow rate) enables tailoring of drug delivery nanoparticle function including release rates. PMID:26305569

  4. Anionic polymerization and polyhomologation: An ideal combination to synthesize polyethylene-based block copolymers

    KAUST Repository

    Zhang, H.

    2013-08-07

    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.

  5. Composition and solution properties of fluorinated block copolymers and their surface structures in the solid state

    Institute of Scientific and Technical Information of China (English)

    NI HuaGang; XUE DongWu; WANG XiaoFang; ZHANG Wei; WANG XinPing; SHEN ZhiQuan

    2009-01-01

    A series of diblock copolymers composed of methyl methacrylate and 2-perfluorooctylethyl methacry-late (PMMA144-b-PFMAn) with various PFMA block lengths were prepared by atom transfer radical po-lymerization (ATRP). The surface structures and properties of these polymers in the solid state and in solution were investigated using contact angle measurement, X-ray photoelectron spectroscopy (XPS), sum frequency generation (SFG) vibrational spectroscopy, surface tension and dynamic laser light scattering (DLS). It was found that with increasing PFMA block length, water and oil repellency de-creased, the ratio of F/C increased with increasing film depth, and the degree of ordered packing of the perfluoroalkyl side chains at the surface decreased. When the number of PFMA block units reached 10, PMMA segments were detected at the copolymer surface, which was attributed to the PFMA block length affecting molecular aggregation structure of the copolymer in the solution and the interfacial structure at the air/liquid interface, which in turn affects surface structure formation during solution solidification. The results suggest that copolymer solution properties play an important role in struc-ture formation on the solid surface.

  6. Wafer-Scale Nanopillars Derived from Block Copolymer Lithography for Surface-Enhanced Raman Spectroscopy

    DEFF Research Database (Denmark)

    Li, Tao; Wu, Kaiyu; Rindzevicius, Tomas;

    2016-01-01

    ). 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...

  7. Morphology-controlled growth of perylene derivative induced by double-hydrophilic block copolymers

    OpenAIRE

    Minghua Huang; Markus Antonietti; Helmut Cölfen

    2016-01-01

    Controlled growth of technically relevant perylene derivative 3, 4, 9, 10-perylenetetracarboxylic acid potassium salt (PTCAPS), with tuneable morpologies, has been successfully realized by a recrystallization method using a double-hydrophilic block copolymer poly (ethylene glycol)-block poly (ethyleneimine) (PEG-b-PEI) as the structure directing agent. The {001} faces of PTCAPS are most polar and adsorb the oppositively charged polymer additive PEG-b-PEI well by electrostatic attraction. By s...

  8. Ligand switch in photoinduced copper-mediated polymerization: synthesis of methacrylate-acrylate block copolymers

    OpenAIRE

    CHUANG, Ya-Mi; Wenn, Benjamin; Gielen, Sam; Ethirajan, Anitha; Junkers, Thomas

    2015-01-01

    The use of photo-induced copper-mediated radical polymerization (photoCMP) to synthesize mixed acrylate/methacrylate (methyl acrylate, MA and methyl methacrylate, MMA) block copolymers is investigated. Reactions in which only one type of ligand (Me6TREN) is used lead to unsuccessful outcomes of polymerization due to a mismatch in reactivity of the two monomers. A ligand exchange to PMDETA for methacrylate is required to obtain good block structures. Due to insufficient re-initiation of polyac...

  9. Photoinitiated Crosslinking and Grafting of Methylmethacrylate Using N,N-Dimethyl Amino Functional Polystyrene Block Copolymers

    OpenAIRE

    MÜFTÜOĞLU, Ali Ekrem; YAĞCI, Yusuf; SE, Kazunori

    2004-01-01

    Monodisperse poly(N,N-dimethyl-4-vinylphenethylamine)-block-polystyrene was synthesized via anionic living polymerization carried out at -78 °C under a pressure of 10-6 torr using cumyl potassium as the initiator. Subsequent photoinduced radical polymerization of styrene through side chain-functional N,N-dimethyl amino groups yielded a crosslinked polymer and a brush type block-graft copolymer to a lesser extent. Upon irradiation at a wavelength of 350 nm, macroradicals were generate...

  10. Sub-15nm Silicon Lines Fabrication via PS-b-PDMS Block Copolymer Lithography

    OpenAIRE

    Sozaraj Rasappa; Lars Schulte; Dipu Borah; Morris, Michael A.; Sokol Ndoni

    2013-01-01

    This paper describes the fabrication of nanodimensioned silicon structures on silicon wafers from thin films of a poly(styrene)-block-poly(dimethylsiloxane) (PS-b-PDMS) block copolymer (BCP) precursor self-assembling into cylindrical morphology in the bulk. The structure alignment of the PS-b-PDMS (33 k–17 k) was conditioned by applying solvent and solvothermal annealingtechniques. BCP nanopatterns formed after the annealing process have been confirmed by scanning electron microscope (SEM) af...

  11. Chirality in Block Copolymer Melts: Mesoscopic Helicity from Inter-Segment Twist

    OpenAIRE

    Zhao, Wei; Russell, Thomas P.; Grason, Gregory M.

    2012-01-01

    We study the effects of chirality at the segment scale on the thermodynamics of block copolymer melts using self consistent field theory. In linear diblock melts where segments of one block prefer a twisted, or cholesteric, texture, we show that melt assembly is critically sensitive to the ratio of random coil size to the preferred pitch of cholesteric twist. For weakly-chiral melts (large pitch), mesophases remain achiral, while below a critical value of pitch, two mesocopically chiral phase...

  12. Evaluation of Isoprene Chain Extension from PEO Macromolecular Chain Transfer Agents for the Preparation of Dual, Invertible Block Copolymer Nanoassemblies

    OpenAIRE

    Bartels, Jeremy W.; Cauët, Solène I.; Billings, Peter L.; Lin, Lily Yun; Zhu, Jiahua; Fidge, Christopher; Pochan, Darrin J.; Wooley, Karen L.

    2010-01-01

    Two RAFT-capable PEO macro-CTAs, 2 and 5 kDa, were prepared and used for the polymerization of isoprene which yielded well-defined block copolymers of varied lengths and compositions. GPC analysis of the PEO macro-CTAs and block copolymers showed remaining unreacted PEO macro-CTA. Mathematical deconvolution of the GPC chromatograms allowed for the estimation of the blocking efficiency, about 50% for the 5 kDa PEO macro-CTA and 64% for the 2 kDa CTA. Self assembly of the block copolymers in bo...

  13. Phase behavior of ABC-type triple-hydrophilic block copolymers in aqueous solutions.

    Science.gov (United States)

    Zheng, Lingfei; Wu, Jianqi; Wang, Zheng; Yin, Yuhua; Jiang, Run; Li, Baohui

    2016-07-01

    The phase behavior of symmetric ABC triple-hydrophilic triblock copolymers in concentrated aqueous solutions is investigated using a simulated annealing technique. Two typical cases, in which the hydrophilicity of the middle B-block is either stronger or weaker than that of the end A- and C-blocks, are studied. In these two cases, a variety of phase diagrams are constructed as a function of the volume fraction of the B-block and the copolymer concentration ([Formula: see text] for both non-frustrated and frustrated copolymers. Structures, such as two-color alternatingly packed cylinders or gyroid, and lamellae-in-lamellae etc. that do not occur in the melt system, are obtained in solutions. Rich phase transition sequences, especially re-entrant phase transitions involving complex continuous networks of alternating gyroid and alternating diamond are observed for a given copolymer with decreasing [Formula: see text] . The difference in hydrophilicity among different blocks can result in inhomogeneous distribution of solvent molecules in the morphology, and with the decrease of [Formula: see text] , the distribution of solvent molecules presents a non-monotonic variation. This results in a non-monotonic variation of the effective volume fraction of each domain with the decrease of [Formula: see text] , which induces the re-entrant phase transitions. The presence of a good solvent for all the blocks can cause changes in the effective segregation strengths between different blocks and also in chain conformations, hence can alter the bulk phases and results in the occurrence of new structures and phase transitions. Especially, structures having A-C interfaces or A-C mixed domains can be obtained even in the non-frustrated copolymer systems, and structures obtained in the frustrated systems may be similar to those obtained in the non-frustrated systems. The window of the alternating gyroid structures may occupy a large part of the phase diagram for non

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

    OpenAIRE

    Tong, Jing; Luxenhofer, Robert; Yi, Xiang; Jordan, Rainer; Kabanov, Alexander V.

    2010-01-01

    Several homo-, random and block copolymers based on poly(2-oxazoline)s (POx) were synthesized and conjugated to horseradish peroxidase (HRP) using biodegradable and non-biodegradable 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...

  15. Time-resolved GISAXS and cryo-microscopy characterization of block copolymer membrane formation

    KAUST Repository

    Marques, Debora S.

    2014-03-01

    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.

  16. Block copolymer micelle nanolithography on non-conductive substrates

    International Nuclear Information System (INIS)

    A new lithographic technique has been developed and applied to cell adhesion studies and electro-optical material development. Attachment of 6 nm Au particles, in periodic and non-periodic pattern, onto non-conductive substrates has been achieved. This was performed via a combination of diblock copolymer self-assembly and electron beam lithographic techniques. To optimize e-beam resolution on non-conductive materials, an additional carbon layer was thread-coated onto the substrates. This carbon coating and the diblock copolymer used in the self-assembly step were simultaneously removed by a final hydrogen plasma treatment to reveal Au nanodot patterns of unprecedented pattern quality. These optically transparent substrates (glass cover slips) were bio-functionalized via the Au-dot patterns to yield a platform for unique cell adhesion studies. The same Au-dot patterning technique was applied to sapphire substrates, which were subsequently employed to nucleate electro-optically active ZnO nanopost growth

  17. Theory for dynamical self arrest and gelation in microemulsions and the block copolymer systems

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Sangwook

    2005-05-01

    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| = q{sub m}) 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 q{sub m}, but with random orientations and phases, i.e. just the ones which form the metastable states of our microemulsion and block copolymer glass. (38)

  18. Silk-collagen-like block copolymers with charged blocks : self-assembly into nanosized ribbons and macroscopic gels

    OpenAIRE

    Martens, A.A.

    2008-01-01

    The research described in this thesis concerns the design, biotechnological production, and physiochemical study of large water-soluble (monodisperse) protein triblock-copolymers with sequential blocks, some of which are positively or negatively charged and self-assemble in response to a change in pH or co-assemble in response to oppositely charged polyelectrolytes (including each other). Such molecules displaying controlled self-assembly may lead to new biocompatible nano-structured material...

  19. SYNTHESIS OF POLY(ETHYLENE TEREPHTHALATE)-POLYCAPROLACTONE BLOCK COPOLYMER BY DIRECT COPOLYMERIZATION

    Institute of Scientific and Technical Information of China (English)

    Shen-guo Wang; Kai Tang

    1999-01-01

    Poly(ethylene terephthalate)-polycaprolactone block copolymer (PCL-b-PET) is a polyester with improved biodegradability. In the present paper, a new direct copolymerization method of ε-caprolactone (ε-CL) and bishydroxyethylene terephthalate (BHET) in the presence of Ti(OBu)4 was proposed for the synthesis of PCL-b-PET. The PCL-b-PET copolymer was characterized by IR, GPC and 1H-NMR techniques, and the effects of synthesis conditions, such as temperature, reaction time and concentration of catalyst on the copolymerization were discussed.

  20. Reversible Micro- and Nano- Phase Programming of Anthraquinone Thermochromism Using Blended Block Copolymers.

    Science.gov (United States)

    Zhang, Yumiao; Lovell, Jonathan F

    2015-12-22

    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. PMID:26626998