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Sample records for copolymer incorporating electroactive

  1. Ductile electroactive biodegradable hyperbranched polylactide copolymers enhancing myoblast differentiation.

    Science.gov (United States)

    Xie, Meihua; Wang, Ling; Guo, Baolin; Wang, Zhong; Chen, Y Eugene; Ma, Peter X

    2015-12-01

    Myotube formation is crucial to restoring muscular functions, and biomaterials that enhance the myoblast differentiation into myotubes are highly desirable for muscular repair. Here, we report the synthesis of electroactive, ductile, and degradable copolymers and their application in enhancing the differentiation of myoblasts to myotubes. A hyperbranched ductile polylactide (HPLA) was synthesized and then copolymerized with aniline tetramer (AT) to produce a series of electroactive, ductile and degradable copolymers (HPLAAT). The HPLA and HPLAAT showed excellent ductility with strain to failure from 158.9% to 42.7% and modulus from 265.2 to 758.2 MPa. The high electroactivity of the HPLAAT was confirmed by UV spectrometer and cyclic voltammogram measurements. These HPLAAT polymers also showed improved thermal stability and controlled biodegradation rate compared to HPLA. Importantly, when applying these polymers for myotube formation, the HPLAAT significantly improved the proliferation of C2C12 myoblasts in vitro compared to HPLA. Furthermore, these polymers greatly promoted myogenic differentiation of C2C12 cells as measured by quantitative analysis of myotube number, length, diameter, maturation index, and gene expression of MyoD and TNNT. Together, our study shows that these electroactive, ductile and degradable HPLAAT copolymers represent significantly improved biomaterials for muscle tissue engineering compared to HPLA. Copyright © 2015 Elsevier Ltd. All rights reserved.

  2. Fluorinated ethylene propylene copolymer coating for the stability enhancement of electroactive and photoactive systems

    Science.gov (United States)

    Zhao, Luping; Neoh, K. G.; Zhang, Yan; Kang, E. T.

    2003-11-01

    The effectiveness of radio frequency sputtered fluorinated ethylene propylene copolymer (FEP) for the stability enhancement of electroactive and photoactive systems was investigated. Two kinds of electroactive polymer systems, polyaniline (PANI) coated low density polyethylene (LDPE) film and PANI-viologen assembly, were tested. In both cases, a sputtered FEP coating of coating of 40-50 nm in thickness. The deposition of a FEP coating on the photoactive viologen system (viologen grafted on LDPE film) prolonged its photochromic effect by inhibiting the diffusion of oxygen, and hence the reoxidation of the highly colored viologen radical cations to the dication state.

  3. (Phenylen-carbazolylenes) copolymers: new soluble electroactive materials

    Energy Technology Data Exchange (ETDEWEB)

    Faid, K. (Lab. de Recherches sur les Macromolecules, Univ. Paris-Nord, 93 - Villetaneuse (France)); Ades, D. (Lab. de Recherches sur les Macromolecules, Univ. Paris-Nord, 93 - Villetaneuse (France)); Chevrot, C. (Lab. de Recherches sur les Macromolecules, Univ. Paris-Nord, 93 - Villetaneuse (France)); Siove, A. (Lab. de Recherches sur les Macromolecules, Univ. Paris-Nord, 93 - Villetaneuse (France))

    1993-03-22

    (Phenylen-Carbazolylenes) copolymers with tunable compositions and properties have been prepared by electrocatalyzed dehalogenative polycondensation of 4,4' dihalobiphenyl and 3,6-dibromo-N-alkylcarbazole mixtures in the presence of zero valent nickel catalyst. The polymers are partly soluble in polar solvents and this solubility depends on the proportion of carbazolylen units in the materials. For a given composition, it increases with the length of the aliphatic substituent on the nitrogen. The conductivity upon doping varies between those of the homopolymers and is a function of the length of the alkyl substituents. Thin films of these materials can be prepared either by solvent casting or by direct electrodeposition on various supports. The electrochemical behavior is strongly dependent on the copolymer composition and reveals the existence of two distinct electronic states (two quantum-wells). The first one is related to the presence of the carbazolylen units while the second shows the presence of phenylen moieties. (orig.)

  4. 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.

  5. Influence of Zwitterions on Thermomechanical Properties and Morphology of Acrylic Copolymers: Implications for Electroactive Applications

    Science.gov (United States)

    2011-09-30

    properties of ethyl acrylate and n-butyl acrylate ( nBA )-based sulfobetaine-containing copolymers.10,11 They found that the incorporation of...ammonio]-1-propanesulfonate (SBMA), a zwitterionic mono- mer. Copolymerization of both charge-containing monomers with nBA elucidates the influence of...3-[[2-(methacryloyloxy)ethyl]- (dimethyl)ammonio]-1-propanesulfonate (SBMA), was generously provided by Raschig GmbH. n-Butyl acrylate ( nBA , Alfa

  6. Electroactive Film of Myoglobin Incorporated in a 3D-porous Calcium Alginate Film with Polyvinyl Alcohol, Glycerin and Gelatin.

    Science.gov (United States)

    Zheng, Xueqin; Sun, Hong; Hou, Shifeng

    2015-01-01

    In this work, an electroactive porous Mb-CA's composite film was fabricated by incorporating myoglobin (Mb) in a three-dimension (3D) porous calcium alginate (CA) film with polyvinyl alcohol, glycerol, and gelatin. The porous Mb-CA's film modified electrodes exhibited a pair of well-defined, quasi-reversible cyclic voltammetric (CV) peaks at about -0.37 V vs. SCE in pH 7.0 buffers, characteristic of Mb heme Fe((III))/Fe((II)) redox couples. The electrochemical parameters, such as formal potentials (E(o')) and apparent heterogeneous electron-transfer rate constants (ks), were estimated by square-wave voltammetry with nonlinear regression analysis. The porous CA's composite film could form hydrogel in aqueous solution. The positions of the Soret absorbance band suggest that Mb in the CA's composite film kept its native states in the medium pH range. Hydrogen peroxide, oxygen, and nitrite were electrochemically catalyzed by the Mb-CA's composite film with significant lowering of the reduction overpotential.

  7. Temperature-Responsive Biocompatible Copolymers Incorporating Hyperbranched Polyglycerols for Adjustable Functionality

    Directory of Open Access Journals (Sweden)

    Alan J. House

    2011-08-01

    Full Text Available Temperature-triggered copolymers are proposed for a number of bio-applications but there is no ideal material platform, especially for injectable drug delivery. Options are needed for degradable biomaterials that not only respond to temperature but also easily accommodate linkage of active molecules. A first step toward realizing this goal is the design and synthesis of the novel materials reported herein. A multifunctional macromer, methacrylated hyperbranched polyglycerol (HPG-MA with an average of one acrylate unit per copolymer, was synthesized and copolymerized with N-isopropylacrylamide (NIPAAm, hydroxyethyl methacrylate-polylactide (HEMAPLA and acrylic acid (AAc. The potential to fully exploit the copolymers by modification of the multiple HPG hydroxyl groups will not be discussed here. Instead, this report focuses on the thermoresponsive, biocompatible, and degradation properties of the material. Poly(NIPAAm-co-HEMAPLA-co-AAc-co-HPG-MA displayed increasing lower critical solution temperatures (LCST as the HPG content increased over a range of macromer ratios. For the copolymer with the maximum HPG incorporation (17%, the LCST was ~30 °C. In addition, this sample showed no toxicity when human uterine fibroid cells were co-cultured with the copolymer for up to 72 h. This copolymer lost approximately 92% of its mass after 17 hours at 37 °C. Thus, the reported biomaterials offer attractive properties for the design of drug delivery systems where orthogonally triggered mechanisms of therapeutic release in relatively short time periods would be attractive.

  8. Multilayer Electroactive Polymer Composite Material

    Science.gov (United States)

    Ounaies, Zoubeida (Inventor); Park, Cheol (Inventor); Harrison, Joycelyn S. (Inventor); Holloway, Nancy M. (Inventor); Draughon, Gregory K. (Inventor)

    2011-01-01

    An electroactive material comprises multiple layers of electroactive composite with each layer having unique dielectric, electrical and mechanical properties that define an electromechanical operation thereof when affected by an external stimulus. For example, each layer can be (i) a 2-phase composite made from a polymer with polarizable moieties and an effective amount of carbon nanotubes incorporated in the polymer for a predetermined electromechanical operation, or (ii) a 3-phase composite having the elements of the 2-phase composite and further including a third component of micro-sized to nano-sized particles of an electroactive ceramic incorporated in the polymer matrix.

  9. Coated electroactive materials

    Energy Technology Data Exchange (ETDEWEB)

    Amine, Khalil; Abouimrane, Ali

    2016-08-30

    A process includes suspending an electroactive material in a solvent, suspending or dissolving a carbon precursor in the solvent; and depositing the carbon precursor on the electroactive material to form a carbon-coated electroactive material. Compositions include a graphene-coated electroactive material prepared from a solution phase mixture or suspension of an electroactive material and graphene, graphene oxide, or a mixture thereof.

  10. Cisplatin-incorporated nanoparticles of poly(acrylic acid-co-methyl methacrylate copolymer

    Directory of Open Access Journals (Sweden)

    Lee KD

    2013-08-01

    Full Text Available Kyung Dong Lee,1,* Young-Il Jeong,2,* Da Hye Kim,3,4 Gyun-Taek Lim,2 Ki-Choon Choi5 1Department of Oriental Medicine Materials, Dongshin University, Naju, South Korea; 2Department of Polymer Engineering, Chonnam National University, Gwangju, South Korea; 3Faculty of Life and Environmental Science, Shimane University, Matsue, Japan; 4United Graduate School of Agricultural Sciences, Tottori University, Tottori, Japan; 5Grassland and Forages Division, National Institute of Animal Science, Rural Development Administration, Cheonan, South Korea *These authors contributed equally to this work Background: Although cisplatin is extensively used in the clinical field, its intrinsic toxicity limits its clinical use. We investigated nanoparticle formations of poly(acrylic acid-co-methyl methacrylate (PAA-MMA incorporating cisplatin and their antitumor activity in vitro and in vivo. Methods: Cisplatin-incorporated nanoparticles were prepared through the ion-complex formation between acrylic acid and cisplatin. The anticancer activity of cisplatin-incorporated nanoparticles was assessed with CT26 colorectal carcinoma cells. Results: Cisplatin-incorporated nanoparticles have small particle sizes of less than 200 nm with spherical shapes. Drug content was increased according to the increase of the feeding amount of cisplatin and acrylic acid content in the copolymer. The higher acrylic acid content in the copolymer induced increase of particle size and decrease of zeta potential. Cisplatin-incorporated nanoparticles showed a similar growth-inhibitory effect against CT26 tumor cells in vitro. However, cisplatin-incorporated nanoparticles showed improved antitumor activity against an animal tumor xenograft model. Conclusion: We suggest that PAA-MMA nanoparticles incorporating cisplatin are promising carriers for an antitumor drug-delivery system. Keywords: cisplatin, nanoparticle, poly(acrylic acid-co-methyl methacrylate, ion complexes

  11. An in vitro study of anticariogenic compounds incorporated into Bis-GMA/TEGDMA copolymer

    Science.gov (United States)

    Pilly Yadaiah, Vinay Kumar

    Composite resins continue to evolve and are increasingly favoured by the people. However, drawbacks such as decreased longevity, secondary caries and costs make choosing composites a dilemma. This study evaluated drug release, inhibitory growth against Streptococcus mutans and drug stability of epigallocatechin-gallate (EGCg) incorporated into dental copolymer compared to resins containing chlorhexidine (CHX). Resin discs (5mm x 3mm) were prepared from 70 mol% Bis-GMA and 30 mol% TEGDMA comonomers containing: placebo, CHX and EGCg. Two corresponding concentrations in weight% of each drug for 0.5 and 1.0 x MIC were incorporated into paste resins and tested at time points: 24 hours, 7 days, 30 days, 60 days and 90 days. There is a significant difference in the 90 days drug delivery and bacterial inhibition among different drugs and drug ratios, which showed stability after 90 days. The results indicate that drug-based composites may reduce bacterial growth, which may improve its longevity.

  12. Electroactivity in Polymeric Materials

    CERN Document Server

    2012-01-01

    Electroactivity in Polymeric Materials provides an in-depth view of the theory of electroactivity and explores exactly how and why various electroactive phenomena occur. The book explains the theory behind electroactive bending (including ion-polymer-metal-composites –IPMCs), dielectric elastomers, electroactive contraction, and electroactive contraction-expansion cycles.  The book also balances theory with applications – how electroactivity can be used – drawing inspiration from the manmade mechanical world and the natural world around us.  This book captures: A complete introduction to electroactive materials including examples and recent developments The theory and applications of numerous topics like electroactive bending of dielectric elastomers and electroactive contraction and expansion New topics, such as biomimetic applications and energy harvesting This is a must-read within the electroactive community, particularly for professionals and graduate students who are interested in the ...

  13. Multifunctional e-spun colloidal nanofiber structures from various dispersed blends of PVA/ODA-MMT with PVP/ODA-MMT, poly(VP-alt-MA and AgNPs incorporated polymer complexes as electro-active platforms

    Directory of Open Access Journals (Sweden)

    U. Bunyatova

    2016-07-01

    Full Text Available This work presented a new approach to fabricate polymer nanocomposites films with nanofiber structures from solution blends of poly(vinyl alcohol + octadecyl amine-montmorillonite (ODA-MMT (matrix with poly(N-vinylpyrrolidone + ODA-MMT (partner-1, poly(N-vinylpyrrolidone-alt-maleic anhydride ((poly(VP-alt-MA + (ODA-MMT (partner-2 and their silver (Ag-carrying polymer complexes by electrospinning. Chemical and physical structures, surface morphologies, thermal behaviors, electrical conductivity and thermal resistance parameters of nanofiber structures were investigated. Poly(VP-alt-MA was used both as a crosslinker and a donor of the hydrophilic groups such as ‒COOH and ‒NH–C=O amide from pyrrolidone ring. Reactive poly(VP-alt-MA, in situ generated Ag nanoparticles (AgNPs and original partner polymer had an significant effect on the morphology and diameter distribution of nanofibers. High and excellent conductive behaviors were observed for the homopolymer and copolymer of VP based fiber structures, respectively. Upon successive chemical cross-linking of the nanofiber structures by reactive partner copolymer, the conductivity of nanofiber films as electro-active platforms dramatically increased to 3.90·10–2 S·cm–1 at room temperature. Comparative analysis results also indicated that electrical properties strongly depended on the loaded reactive organoclay and in situ generated AgNPs.

  14. Platinum-Incorporating Poly(N-vinylpyrrolidone)-poly(aspartic acid) Pseudoblock Copolymer Nanoparticles for Drug Delivery.

    Science.gov (United States)

    Yao, Xikuang; Xie, Chen; Chen, Weizhi; Yang, Chenchen; Wu, Wei; Jiang, Xiqun

    2015-07-13

    Cisplatin-incorporating pseudoblock copolymer nanoparticles with high drug loading efficiency (ca. 50%) were prepared built on host-guest inclusion complexation between β-cyclodextrin end-capped poly(N-vinylpyrrolidone) block and admantyl end-capped poly(aspartic acid) block, followed by the coordination between cisplatin and carboxyl groups in poly(aspartic acid). The host-guest interaction between the two polymer blocks was examined by two-dimensional nuclear overhauser effect spectroscopy. The size and morphology of nanoparticles formed were characterized by dynamic light scattering, zeta potential, transmission electron microscopy, and atomic force microscopy. The size control of nanoparticles was carried out by varying the ratio of poly(N-vinylpyrrolidone) to poly(aspartic acid). The nanoparticles were stable in the aqueous medium with different pH values but disintegrated in the medium containing Cl(-) ions. The in vitro and in vivo antitumor effects of cisplatin-loaded nanoparticles were evaluated. The biodistribution of the nanoparticles in vivo was studied by noninvasive near-infrared fluorescence imaging and ion-coupled plasma mass spectrometry. It was found that cisplatin-loaded nanoparticles could effectively accumulate in the tumor site and exhibited significant superior in vivo antitumor activity to the commercially available free cisplatin by combining the tumor volume, body weight, and survival rate measurements.

  15. Biocompatible, Biodegradable, and Electroactive Polyurethane-Urea Elastomers with Tunable Hydrophilicity for Skeletal Muscle Tissue Engineering.

    Science.gov (United States)

    Chen, Jing; Dong, Ruonan; Ge, Juan; Guo, Baolin; Ma, Peter X

    2015-12-30

    It remains a challenge to develop electroactive and elastic biomaterials to mimic the elasticity of soft tissue and to regulate the cell behavior during tissue regeneration. We designed and synthesized a series of novel electroactive and biodegradable polyurethane-urea (PUU) copolymers with elastomeric property by combining the properties of polyurethanes and conducting polymers. The electroactive PUU copolymers were synthesized from amine capped aniline trimer (ACAT), dimethylol propionic acid (DMPA), polylactide, and hexamethylene diisocyanate. The electroactivity of the PUU copolymers were studied by UV-vis spectroscopy and cyclic voltammetry. Elasticity and Young's modulus were tailored by the polylactide segment length and ACAT content. Hydrophilicity of the copolymer films was tuned by changing DMPA content and doping of the copolymer. Cytotoxicity of the PUU copolymers was evaluated by mouse C2C12 myoblast cells. The myogenic differentiation of C2C12 myoblasts on copolymer films was also studied by analyzing the morphology of myotubes and relative gene expression during myogenic differentiation. The chemical structure, thermal properties, surface morphology, and processability of the PUU copolymers were characterized by NMR, FT-IR, gel permeation chromatography (GPC), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), X-ray diffraction (XRD), scanning electron microscopy (SEM), atomic force microscopy (AFM), and solubility testing, respectively. Those biodegradable electroactive elastic PUU copolymers are promising materials for repair of soft tissues such as skeletal muscle, cardiac muscle, and nerve.

  16. Electroactive functional hybrid layered nanocomposites

    Energy Technology Data Exchange (ETDEWEB)

    Destri, Giovanni Li; Torrisi, Vanna; Marletta, Giovanni [Laboratory for Molecular Surfaces and Nanotechnology (LAMSUN) - University of Catania and CSGI - Catania (Italy)

    2012-07-11

    Two methodologies to build new nanostructured hybrid layered nanocomposites are presented. The first one involves the preparation of hybrid metal/polymer nanolayers (NLs) by combining two monolayer preparation techniques: Horizontal Precipitation Langmuir Blodgett method (HP-ML), for copolymer monolayers and sputter deposition technique, for Au NLs deposition. The second methodology is aimed to prepare regular arrays of nanopores, with diameter ranging between 40-100 nm, in ultra-thin films of electroactive polymers, to obtain embedded regular arrays of nanopores filled by a further electroactive organic component. The produced hybrid MLs have been characterized by means of X-ray Photoelectron Spectroscopy (XPS), Atomic Force Microscopy (AFM) and Grazing Incidence X-ray Diffraction (GI-XRD). In the first case, current-voltage (I-V) measurements demonstrate that the multilayers exhibit a bipolar conduction behaviour (electrons and holes carriers), with a peculiar transition in the nature of the majority carriers (from holes to electrons) above a threshold number of bilayers. In the second case, it is found that the degree of pore filling, as well as the polymer crystallinity can be easily modulated, prompting the tuning of the photoresponse of the nanocomposites.

  17. 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

    a possibility for substantial improvement of properties such as high permittivity, stretchability and non-conductivity – if carefully designed. The objective is to synthesize PDMS-PEG multiblock copolymer assembling into discontinuous morphologies in PEG based on variation of volume fractions of PDMS...

  18. Incorporation of Amphipathic Diblock Copolymer in Lipid Bilayer for Improving pH Responsiveness

    Directory of Open Access Journals (Sweden)

    Tian Xia

    2016-01-01

    Full Text Available Diblock copolymers (mPEG-b-PDPA, which were designed to possess pH-sensitivity as well as amphipathy, were used as an intelligent lock in the liposomal membrane. The so-called pH-sensitive liposomes were prepared by simple mixing of the synthesized mPEG-b-PDPA with phospholipids and cholesterol. Fluorescence polarization at pH 7.4 showed that the membrane stability of the hybrid liposome was significantly increased compared with the pure liposome. Therefore, in the neutral environment, the leakage of doxorubicin (DOX was inhibited. However, when pH decreased to 6.0, DOX release rate increased by 60% due to the escape of copolymer. The effects of the membrane composition and the PDPA segment length on bilayer membrane functions were investigated. These results revealed that the synthesized copolymers increased the difference in DOX cumulative release between pH 7.4 and 6.0, that is, improved the pH-controllability of the drug release from hybrid liposomes.

  19. Multilayer Electroactive Polymer Composite Material Comprising Carbon Nanotubes

    Science.gov (United States)

    Ounaies, Zoubeida (Inventor); Park, Cheol (Inventor); Harrison, Joycelyn S. (Inventor); Holloway, Nancy M. (Inventor); Draughon, Gregory K. (Inventor)

    2009-01-01

    An electroactive material comprises multiple layers of electroactive composite with each layer having unique dielectric, electrical and mechanical properties that define an electromechanical operation thereof when affected by an external stimulus. For example, each layer can be (i) a 2-phase composite made from a polymer with polarizable moieties and an effective amount of carbon nanotubes incorporated in the polymer for a predetermined electromechanical operation, or (ii) a 3-phase composite having the elements of the 2-phase composite and further including a third component of micro-sized to nano-sized particles of an electroactive ceramic incorporated in the polymer matrix.

  20. Anthocyanin Incorporated Dental Copolymer: Bacterial Growth Inhibition, Mechanical Properties, and Compound Release Rates and Stability by 1H NMR

    Directory of Open Access Journals (Sweden)

    Halyna Hrynash

    2014-01-01

    Full Text Available Objective. To evaluate bacterial growth inhibition, mechanical properties, and compound release rate and stability of copolymers incorporated with anthocyanin (ACY; Vaccinium macrocarpon. Methods. Resin samples were prepared (Bis-GMA/TEGDMA at 70/30 mol% and incorporated with 2 w/w% of either ACY or chlorhexidine (CHX, except for the control group. Samples were individually immersed in a bacterial culture (Streptococcus mutans for 24 h. Cell viability (n=3 was assessed by counting the number of colony forming units on replica agar plates. Flexural strength (FS and elastic modulus (E were tested on a universal testing machine (n=8. Compound release and chemical stability were evaluated by UV spectrophotometry and 1H NMR (n=3. Data were analyzed by one-way ANOVA and Tukey’s test (α = 0.05. Results. Both compounds inhibited S. mutans growth, with CHX being most effective (P<0.05. Control resin had the lowest FS and E values, followed by ACY and CHX, with statistical difference between control and CHX groups for both mechanical properties (P<0.05. The 24 h compound release rates were ACY: 1.33 μg/mL and CHX: 1.92 μg/mL. 1H NMR spectra suggests that both compounds remained stable after being released in water. Conclusion. The present findings indicate that anthocyanins might be used as a natural antibacterial agent in resin based materials.

  1. P(MMA-EMA Random Copolymer Electrolytes Incorporating Sodium Iodide for Potential Application in a Dye-Sensitized Solar Cell

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    Nurul Akmaliah Dzulkurnain

    2015-02-01

    Full Text Available Polymer electrolytes based on 90 wt% of methyl methacrylate and 10 wt% of ethyl methacrylate (90MMA-co-10EMA incorporating different weight ratios of sodium iodide were prepared using the solution casting method. The complexation between salt and copolymer host has been investigated using Fourier transform infrared spectroscopy. The ionic conductivity and thermal stability of the electrolytes were measured using impedance spectroscopy and differential scanning calorimetry, respectively. Scanning electron microscopy was used to study the morphology of the polymer electrolytes. The ionic conductivity and glass transition temperature increased up to 20 wt% of sodium iodide (5.19 × 10−6 S·cm−1 and decreased with the further addition of salt concentration, because of the crosslinked effect. The morphology behavior of the highest conducting sample also showed smaller pores compared to the other concentration. The total ionic transference number proved that this system was mainly due to ions, and the electrochemical stability window was up to 2.5 V, which is suitable for a dye-sensitized solar cell application. This sample was then tested in a dye-sensitized solar cell and exhibited an efficiency of 0.62%.

  2. Electroactive polymers for sensing

    Science.gov (United States)

    2016-01-01

    Electromechanical coupling in electroactive polymers (EAPs) has been widely applied for actuation and is also being increasingly investigated for sensing chemical and mechanical stimuli. EAPs are a unique class of materials, with low-moduli high-strain capabilities and the ability to conform to surfaces of different shapes. These features make them attractive for applications such as wearable sensors and interfacing with soft tissues. Here, we review the major types of EAPs and their sensing mechanisms. These are divided into two classes depending on the main type of charge carrier: ionic EAPs (such as conducting polymers and ionic polymer–metal composites) and electronic EAPs (such as dielectric elastomers, liquid-crystal polymers and piezoelectric polymers). This review is intended to serve as an introduction to the mechanisms of these materials and as a first step in material selection for both researchers and designers of flexible/bendable devices, biocompatible sensors or even robotic tactile sensing units. PMID:27499846

  3. Anthracycline antibiotics non-covalently incorporated into the block copolymer micelles: in vivo evaluation of anti-cancer activity.

    Science.gov (United States)

    Batrakova, E V; Dorodnych, T Y; Klinskii, E Y; Kliushnenkova, E N; Shemchukova, O B; Goncharova, O N; Arjakov, S A; Alakhov, V Y; Kabanov, A V

    1996-11-01

    The chemosensitising effects of poly(ethylene oxide)-poly(propylene oxide)-poly-(ethylene oxide) (PEO-PPO-PEO) block copolymers (Pluronic) in multidrug-resistant cancer cells has been described recently (Alakhov VY, Moskaleva EY, Batrakova EV, Kabanov AV 1996, Biocon. Chem., 7, 209). This paper presents initial studies on in vivo evaluation of Pluronic copolymers in the treatment of cancer. The anti-tumour activity of epirubicin (EPI) and doxorubicin (DOX), solubilised in micelles of Pluronic L61, P85 and F108, was investigated using murine leukaemia P388 and daunorubicin-sensitive Sp2/0 and -resistant Sp2/0(DNR) myeloma cells grown subcutaneously (s.c.). The study revealed that the lifespan of the animals and inhibition of tumour growth were considerably increased in mice treated with drug/copolymer compositions compared with animals treated with the free drugs. The anti-tumour activity of the drug/copolymer compositions depends on the concentration of the copolymer and its hydrophobicity, as determined by the ratio of the lengths of hydrophilic PEO and hydrophobic PPO segments. The data suggest that higher activity is associated with more hydrophobic copolymers. In particular, a significant increase in lifespan (T/C> 150%) and tumour growth inhibition (> 90%) was observed in animals with Sp2/0 tumours with EPI/P85 and DOX/L61 compositions. The effective doses of these compositions caused inhibition of Sp2/0 tumour growth and complete disappearance of tumour in 33-50% of animals. Future studies will focus on the evaluation of the activity of Pluronic-based compositions against human drug-resistant tumours.

  4. Unusual Emission of Polystyrene-Based Alternating Copolymers Incorporating Aminobutyl Maleimide Fluorophore-Containing Polyhedral Oligomeric Silsesquioxane Nanoparticles

    Directory of Open Access Journals (Sweden)

    Mohamed Gamal Mohamed

    2017-03-01

    Full Text Available In this study, we synthesized an unusual 2-aminobutyl maleimide isobutyl polyhedral oligomeric silsesquioxane (MIPOSS-NHBu monomer lacking conventional fluorescent groups. We then prepared poly(styrene-alt-2-aminobutyl maleimide isobutyl POSS [poly(S-alt-MIPOSS-NHBu] and poly(4-acetoxystyrene-alt-2-aminobutyl maleimide isobutyl POSS [poly(AS-alt-MIPOSS-NHBu] copolymers through facile free radical copolymerizations using azobisisobutyronitrile as the initiator and tetrahydrofuran as the solvent. A poly(4-hydroxystyrene-alt-2-aminobutyl maleimide isobutyl POSS [poly(HS-alt-MIPOSS-NHBu] copolymer was prepared through acetoxyl hydrazinolysis of poly(AS-alt-MIPOSS-NHBu. We employed 1H, 13C, and 29Si nuclear magnetic resonance spectroscopy; Fourier transform infrared spectroscopy; differential scanning calorimetry; and photoluminescence spectroscopy to investigate the structures and the thermal and optical properties of the monomers and novel POSS-containing alternating copolymers. Intramolecular hydrogen bonding between the amino and dihydrofuran-2,5-dione group and clustering of the locked C=O groups from the POSS nanoparticles in the MIPOSS-NHBu units restricted the intramolecular motion of the polymer chain, causing it to exhibit strong light emission. As a result, the MIPOSS-NHBu monomer and the poly(AS-alt-MIPOSS-NHBu copolymer both have potential applicability in the detection of metal ions with good selectivity.

  5. EDITORIAL: Electroactive polymer materials

    Science.gov (United States)

    Bar-Cohen, Yoseph; Kim, Kwang J.; Ryeol Choi, Hyouk; Madden, John D. W.

    2007-04-01

    Imitating nature's mechanisms offers enormous potential for the improvement of our lives and the tools we use. This field of the study and imitation of, and inspiration from, nature's methods, designs and processes is known as biomimetics. Artificial muscles, i.e. electroactive polymers (EAPs), are one of the emerging technologies enabling biomimetics. Polymers that can be stimulated to change shape or size have been known for many years. The activation mechanisms of such polymers include electrical, chemical, pneumatic, optical and magnetic. Electrical excitation is one of the most attractive stimulators able to produce elastic deformation in polymers. The convenience and practicality of electrical stimulation and the continual improvement in capabilities make EAP materials some of the most attractive among activatable polymers (Bar-Cohen Y (ed) 2004 Electroactive Polymer (EAP) Actuators as Artificial Muscles—Reality, Potential and Challenges 2nd edn, vol PM136 (Bellingham, WA: SPIE Press) pp 1-765). As polymers, EAP materials offer many appealing characteristics that include low weight, fracture tolerance and pliability. Furthermore, they can be configured into almost any conceivable shape and their properties can be tailored to suit a broad range of requirements. These capabilities and the significant change of shape or size under electrical stimulation while being able to endure many cycles of actuation are inspiring many potential possibilities for EAP materials among engineers and scientists in many different disciplines. Practitioners in biomimetics are particularly excited about these materials since they can be used to mimic the movements of animals and insects. Potentially, mechanisms actuated by EAPs will enable engineers to create devices previously imaginable only in science fiction. For many years EAP materials received relatively little attention due to their poor actuation capability and the small number of available materials. In the last fifteen

  6. Electroactive Polymers With Anti-Counterfeiting Feature

    Science.gov (United States)

    2010-09-28

    for security documents comprising two layers of High Density Polyethylene (HDPE) polymer encapsulating a layer of oriented polypropylene (OPP...of a capacitor separated by the banknote in question). 11 PIEZOELECTRIC MATERIALS [0035] Some electroactive polymers are piezoelectric

  7. Electroactive polymers for healthcare and biomedical applications

    Science.gov (United States)

    Bauer, Siegfried

    2017-04-01

    Electroactivity was noticed early in biological substances, including proteins, polynucleotides and enzymes, even piezoand pyroelectricity were found in wool, hair, wood, bone and tendon. Recently, ferroelectricity has been identified in a surprisingly large number of biologically relevant materials, including hydroxyapatite, aortic walls and elastin. Inspired by the variety of natural electroactive materials, a wealth of new elastomers and polymers were designed recently, including an all organic elastomer electret and self-healing dielectric elastomers. Let's further draw inspiration from nature and widen the utilization of electroactive polymers towards (mobile) healthcare and biomedical applications. Ferroelectrets, internally charged polymer foams with a strong piezoelectric thickness coefficient are employed in biomedical sensing, for example as blood pressure and pulse sensor, as vital signs monitor or for the detection of tonicclonic seizures. Piezo- and pyroelectric polymers are booming in printed electronics research. They provide electronic skin the ability to "feel" pressure and temperature changes, or to generate electrical energy from vibrations and motions, even from contractile and relaxation motions of the heart and lung. Dielectric elastomers are pioneered by StretchSense as wearable motion capture sensors, monitoring pressure, stretch, bend and shear, quantifying comfort in sports and healthcare. On the cellular level, electroactive polymer arrays are used to study mechanotransduction of individual cells. Ionic electroactive polymers show potential to be used in implantable electroactive biomedical devices. Already with the currently available science and technology, we are at the verge of witnessing the demonstration of truly complex bionic systems.

  8. Method of Making an Electroactive Sensing/Actuating Material for Carbon Nanotube Polymer Composite

    Science.gov (United States)

    Ounaies, Zoubeida (Inventor); Park, Cheol (Inventor); Harrison, Joycelyn S. (Inventor); Holloway, Nancy M. (Inventor); Draughon, Gregory K. (Inventor)

    2009-01-01

    An electroactive sensing or actuating material comprises a composite made from a polymer with polarizable moieties and an effective amount of carbon nanotubes incorporated in the polymer for a predetermined electromechanical operation of the composite when such composite is affected by an external stimulus. In another embodiment, the composite comprises a, third component of micro -sized to nano-sized particles of an electroactive ceramic that is also incorporated in the polymer matrix. The method for making the three-phase composite comprises either incorporating the carbon nanotubes in the polymer matrix before incorporation of the particles of ceramic or mixing the carbon nanotubes and particles of ceramic together in a solution before incorporation in the polymer matrix.

  9. 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.

  10. Considerations for Contractile Electroactive Materials and Actuators

    Energy Technology Data Exchange (ETDEWEB)

    Lenore Rasmussen, David Schramm, Lewis D. Meixler, Charles A. Gentile, George Ascione, Carl Tilson, and Kelsey Pagdon

    2010-02-19

    Ras Labs produces electroactive polymer (EAP) based materials and actuators that bend, swell, ripple, and now contract (new development) with low electric input. In addition, Ras Labs produces EAP materials that quickly contract and expand, repeatedly, by reversing the polarity of the electric input. These recent developments are important attributes in the field of electroactivity because of the ability of contraction and contraction-expansion to produce biomimetric motion. The mechanism of contraction is not well understood. Radionuclide-labeled experiments were conducted to determine the mechanisms during contraction of these EAPs.

  11. Ion Modulated Electroactivity in Thin Film Metallopolymers

    Science.gov (United States)

    1994-04-18

    5 to 11 - but essentially no dependance for nf0 to 4. Interestingly, the break in the plot at n=4 is parallelled in the electroactivity attenuation... dependance . In particular, transient measurements (chronoamperometry) of charge transport diffusion coefficients (Dcr) during polymer oxidation show that DT

  12. Comparative study of aluminum phthalocyanine incorporating into two types of block copolymer: photo-physical property, size, and in vitro photodynamic therapy efficacy

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Yide [Fujian Normal University, College of Life Sciences (China); Ma, Dongdong; Pan, Sujuan; Lin, Pingping [Fujian Normal University, College of Chemistry & Engineering, Fujian Provincial Key Laboratory of Polymer Materials (China); Lin, Yao [Fujian Normal University, College of Life Sciences (China); Yang, Hongqin [Fujian Normal University, College of Photonic & Electronic Engineering (China); Peng, Yiru, E-mail: yirupeng@fjnu.edu.cn [Fujian Normal University, College of Chemistry & Engineering, Fujian Provincial Key Laboratory of Polymer Materials (China)

    2015-01-15

    Nanoparticles of amphiphilic triblock copolymer poly(l-lysine)-b-poly(ethylene glycol)-b-poly(l-lysine) and diblock copolymer methoxy-poly(ethylene glycol)-b-poly(l-lysine) were developed to encapsulate tetra(4-sulfoazophenyl-4′-aminosulfonyl) chloride aluminum phthalocyanine, a new photosensitizer used in photodynamic therapy. The mean nanoparticle sizes varied from 10 to 70 nm, and the encapsulation efficacy ranged from 56 to 73 % due to electrostatic self-assembly induced by two types of polymer. The characteristic photophysical parameters including the absorption spectrum profile, fluorescence quantum yield, and fluorescence decay curves for free and encapsulated phthalocyanine were analyzed. The cellular uptake amount and photoactivity of S-AlPc were improved by encapsulation. The aluminum phthalocyanine loaded with poly(l-lysine)-b-poly(ethylene glycol)-b-poly(l-lysine) presented suitable physical stability, improved photophysical properties, and enhanced phototoxicity in vitro, suggesting it may be considered as a promising formulation for PDT.

  13. Simultaneous determination of electroactive and non-electroactive food preservatives by novel capillary electrophoresis with amperometric detection.

    Science.gov (United States)

    Wang, Weiyu; Wang, Yiping; Zhang, Junbo; Chu, Qingcui; Ye, Jiannong

    2010-09-23

    A novel capillary electrophoresis and amperometric detection method was achieved by adding an electroactive additive (3,4-dihydroxybenzylamine, 3,4-DHBA) to the running buffer, so that both electroactive and non-electroactive food preservatives were simultaneously determined. Under the selected optimum conditions, four electroactive preservatives (methylparaben, ethylparaben, propylparaben and butylparaben) and two non-electroactive preservatives (potassium sorbate and sodium lactate) were well separated and sensitively detected with detection limits (S/N=3) ranging from 1.06×10(-8) to 2.73×10(-6) g mL(-1). This method has been successfully employed for the determination of both electroactive and non-electroactive preservatives in several food commodities.

  14. Remarkably enhanced thermal stability of an irradiation-crosslinked ethylene-octene copolymer by incorporation of a novel organic/inorganic hybrid nano-sensitizer

    Science.gov (United States)

    Zhang, Sideng; Sun, Bin; Jiang, Xiaoze; Li, Lili; Meng, Zhouqi; Zhu, Meifang

    2015-01-01

    We report a novel method to improve the anti-thermal-deformation performance of an ethylene-octene copolymer (POE) using vinyl functionalized silica nanoparticles (M-SiO2) as a sensitizer to enhance radiation-induced crosslinking. The M-SiO2 nanoparticles were prepared by coupling commercially available silica nanoparticles with KH570 (γ-methacryloxypropyl-trimethoxysilane, γ-MPS) and were blended with POE by melt blending. Then, the mixture was irradiated with γ-rays under a nitrogen atmosphere to form the crosslinked POE/M-SiO2 nanocomposite. The novel nanocomposites were characterized, and the results showed that the gel fraction was proportional to the content of M-SiO2 in the loading range studied in this work. When the content of M-SiO2 was 10 wt%, the gel fraction of POE was increased by approximately 50%, and the softening temperature (T0.5D) increased from 104.4 °C to 224.6 °C after a 120 kGy dose of radiation. The tensile strength of the POE/M-SiO2-10 nanocomposite was better than that of the neat POE copolymer irradiated with an absorption dose up to 100 kGy. In contrast, the elongation of the POE/M-SiO2-10 nanocomposite was lower than that of the neat POE irradiated under the same conditions, due to the increased degree of crosslinking by radiation. These results clearly demonstrated that the use of M-SiO2 as an irradiation sensitizer effectively enhanced the radiation-induced crosslinking of POE.

  15. Stereocomplexation in Copolymer Networks Incorporating Enantiomeric Glycerol-Based 3-Armed Lactide Oligomers and a 2-Armed ɛ-Caprolactone Oligomer

    Directory of Open Access Journals (Sweden)

    Ayaka Shibita

    2016-07-01

    Full Text Available The reactions of enantiomeric glycerol-based 3-armed lactide oligomers (H3DLAO and H3LLAO and a diethylene glycol-based 2-armed ɛ-caprolactone oligomer (H2CLO with hexamethylene diisocyanate (HDI produced polyesterurethane copolymer networks (PEU-3scLAO/2CLOs 100/0, 75/25, 50/50, 25/75 and 0/100 with different feed ratios of stereocomplex (sc lactide oligomer (H3scLAO = H3DLAO + H3LLAO, H3DLAO/H3LLAO = 1/1 and H2CLO. Thermal and mechanical properties of the copolymer networks were compared with those of a simple homochiral (hc network (PEU-3DLAO produced by the reaction of H3DLAO and HDI. X-ray diffraction and differential scanning calorimetric analyses revealed that sc crystallites are formed without any hc crystallization for PEU-3scLAO/2CLOs, and that PEU-3DLAO is amorphous. The melting temperatures of sc crystallites for PEU-3scLAO/2CLOs were much higher than that of hc crystallites of H3DLAO. The polarized optical microscopic analysis revealed that the nucleation efficiency is enhanced with increasing feed of H3scLAO fraction, whereas the spherulite growth rate is accelerated with increasing feed H2CLO fraction over 100/0-50/50 networks. PEU-3scLAO/2CLO 100/0 (i.e., PEU-3scLAO exhibited a higher tensile strength and modulus than PEU-3DLAO. The elongation at break and tensile toughness for PEU-3scLAO/2CLOs increased with an increasing feed amount of H2CLO.

  16. 3D Printing of Aniline Tetramer-Grafted-Polyethylenimine and Pluronic F127 Composites for Electroactive Scaffolds.

    Science.gov (United States)

    Dong, Shi-Lei; Han, Lu; Du, Cai-Xia; Wang, Xiao-Yu; Li, Lu-Hai; Wei, Yen

    2017-02-01

    Electroactive hydrogel scaffolds are fabricated by the 3D-printing technique using composites of 30% Pluronic F127 and aniline tetramer-grafted-polyethylenimine (AT-PEI) copolymers with various contents from 2.5% to 10%. The synthesized AT-PEI copolymers can self-assemble into nanoparticles with the diameter of ≈50 nm and display excellent electroactivity due to AT conjugation. The copolymers are then homogeneously distributed into 30% Pluronic F127 solution by virtue of the thermosensitivity of F127, denoted as F/AT-PEI composites. Macroscopic photographs of latticed scaffolds elucidate their excellent printability of F/AT-PEI hydrogels for the 3D-printing technique. The conductivities of the printed F/AT-PEI scaffolds are all higher than 2.0 × 10(-3) S cm(-1) , which are significantly improved compared with that of F127 scaffold with only 0.94 × 10(-3) S cm(-1) . Thus, the F/AT-PEI scaffolds can be considered as candidates for application in electrical stimulation of tissue regeneration such as repair of muscle and cardiac nerve tissue. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  17. Drug governs the morphology of polyalkylated block copolymer aggregates.

    Science.gov (United States)

    Le Dévédec, F; Her, S; Vogtt, K; Won, A; Li, X; Beaucage, G; Yip, C; Allen, C

    2017-02-16

    Polyalkylated copolymers based on mPEG-b-(AGE-C6,12 or 18)25 have been used to formulate clinically relevant concentrations of doxorubicin (DOX) and the impact of drug incorporation on copolymer aggregation behaviour was examined. The copolymer aggregates were analyzed by various microscopy techniques (TEM, cryo-TEM and AFM) and scattering methods (SANS, DLS). In the absence of the drug, the copolymers formed largely non-spherical aggregates (i.e. cylinders, vesicles). Drug incorporation during copolymer aggregate formation directed the formation of only spherical aggregates. As well, the nature of the core-forming block was found to influence drug release and cytotoxicity of the formulations.

  18. Electroactive and Optoelectronically Active Graphene Nanofilms

    DEFF Research Database (Denmark)

    Chi, Qijin

    As an atomic-scale-thick two-dimensional material, graphene has emerged as one of the most miracle materials and has generated intensive interest in physics, chemistry and even biology in the last decade [1, 2]. Nanoscale engineering and functionalization of graphene is a crucial step for many...... applications ranging from catalysis, electronic devices, sensors to advanced energy conversion and storage [3]. This talk highlights our recent studies on electroactive and optoelectronically active graphene ultrathin films for chemical sensors and energy technology. The presentation includes a general theme...... for functionalization of graphene nanosheets, followed by showing several case studies. Our systems cover redox-active nanoparticles, electroactive supramolecular ensembles and redox enzymes which are integrated with graphene nanosheets as building blocks for the construction of functional thin films or graphene papers....

  19. Electroactive Bisiminopyridine Ligands: Synthesis and Complexation Studies

    Directory of Open Access Journals (Sweden)

    Narcis Avarvari

    2012-04-01

    Full Text Available The condensation reaction of (4-(6,7-dimethyldithio-tetrathiafulvalene-aniline with 2,6-diformylpyridine afforded an electroactive Schiff base (N,N,N pincer (3. This pincer was reacted with Zn(II cation to yield the corresponding Zinc chloride complex (4. The crystal structure of the newly prepared electroactive zinc complex reveals that the tetrathiafulvalene (TTF is neutral and the zinc cation is pentacoordinated. The two chlorines are involved in a set of hydrogen bonds giving rise to a 2D supramolecular grid arrangement. The electronic absorption properties and the electrochemical behavior have been elucidated. These two compounds are promising for the construction of crystalline radical cation salts.

  20. Volatile organic compound detection using nanostructured copolymers.

    Science.gov (United States)

    Li, Bo; Sauvé, Genevieve; Iovu, Mihaela C; Jeffries-El, Malika; Zhang, Rui; Cooper, Jessica; Santhanam, Suresh; Schultz, Lawrence; Revelli, Joseph C; Kusne, Aaron G; Kowalewski, Tomasz; Snyder, Jay L; Weiss, Lee E; Fedder, Gary K; McCullough, Richard D; Lambeth, David N

    2006-08-01

    Regioregular polythiophene-based conductive copolymers with highly crystalline nanostructures are shown to hold considerable promise as the active layer in volatile organic compound (VOC) chemresistor sensors. While the regioregular polythiophene polymer chain provides a charge conduction path, its chemical sensing selectivity and sensitivity can be altered either by incorporating a second polymer to form a block copolymer or by making a random copolymer of polythiophene with different alkyl side chains. The copolymers were exposed to a variety of VOC vapors, and the electrical conductivity of these copolymers increased or decreased depending upon the polymer composition and the specific analytes. Measurements were made at room temperature, and the responses were found to be fast and appeared to be completely reversible. Using various copolymers of polythiophene in a sensor array can provide much better discrimination to various analytes than existing solid state sensors. Our data strongly indicate that several sensing mechanisms are at play simultaneously, and we briefly discuss some of them.

  1. A free-standing, sheet-shaped, "hydrophobic" biomaterial containing polymeric micelles formed from poly(ethylene glycol)-poly(lactic acid) block copolymer for possible incorporation/release of "hydrophilic" compounds.

    Science.gov (United States)

    Moroishi, Hitomi; Yoshida, Chikara; Murakami, Yoshihiko

    2013-02-01

    Sheet-shaped materials with a large contact area relative to the drug targeting site lead to advantages over conventional particle-shaped drug carriers and have several advantages for their biomedical applications. The present study proposes a methodology for preparing a novel sheet-shaped "hydrophobic" and biocompatible biomaterial in which polymeric micelles are uniformly dispersed for the incorporation of "hydrophilic" compounds into the sheet. The methoxy-terminated poly(ethylene glycol)-block-poly(lactic acid) block copolymer (CH(3)O-PEG-b-PLA) was successfully synthesized by means of the anionic ring-opening polymerization of both ethylene oxide and dl-lactide. CH(3)O-PEG-b-PLA was self-assembled and formed stable micelle-like w/o emulsion with a hydrophilic inner core in organic solvents. A sheet-shaped material containing a hydrophilic inner space for incorporating hydrophilic compounds was obtained by spin-coating both the micelle solution and a sheet-forming polymer. Fluorescent images of the sheet proved that polymeric micelles providing hydrophilic spaces were uniformly dispersed in the hydrophobic sheet. The facile technique presented in this paper can be a tool for fabricating sheet-shaped biomaterials that have a hydrophilic inner core and, consequently, that are suitable for the sustained release of hydrophilic compounds.

  2. Adjustable solitary waves in electroactive rods

    Science.gov (United States)

    Wang, Y. Z.; Zhang, C. L.; Dai, H.-H.; Chen, W. Q.

    2015-10-01

    This paper presents an asymptotic analysis of solitary waves propagating in an incompressible isotropic electroactive circular rod subjected to a biasing longitudinal electric displacement. Several asymptotic expansions are introduced to simplify the rod governing equations. The boundary conditions on the lateral surface of the rod are satisfied from the asymptotic point of view. In the limit of finite-small amplitude and long wavelength, a set of ten simplified one-dimensional nonlinear governing equations is established. To validate our approach and the derivation, we compare the linear dispersion relation with the one directly derived from the three-dimensional linear theory in the limit of long wavelength. Then, by the reductive perturbation method, we deduce the far-field equation (i.e. the KdV equation). Finally, the leading order of the electroelastic solitary wave solution is presented. Numerical examples are provided to show the influences of the biasing electric displacement and material constants on the solitary waves. It is found that the biasing electric displacement can modulate the velocity of solitary waves with a prescribed amplitude in the electroactive rod, a very interesting result which may promote the particular application of solitary waves in solids with multi-field coupling.

  3. MWCNTs-reinforced epoxidized linseed oil plasticized polylactic acid nanocomposite and its electroactive shape memory behaviour.

    Science.gov (United States)

    Alam, Javed; Alam, Manawwer; Raja, Mohan; Abduljaleel, Zainularifeen; Dass, Lawrence Arockiasamy

    2014-10-31

    A novel electroactive shape memory polymer nanocomposite of epoxidized linseed oil plasticized polylactic acid and multi-walled carbon nanotubes (MWCNTs) was prepared by a combination of solution blending, solvent cast technique, and hydraulic hot press moulding. In this study, polylactic acid (PLA) was first plasticized by epoxidized linseed oil (ELO) in order to overcome the major limitations of PLA, such as high brittleness, low toughness, and low tensile elongation. Then, MWCNTs were incorporated into the ELO plasticized PLA matrix at three different loadings (2, 3 and 5 wt. %), with the aim of making the resulting nanocomposites electrically conductive. The addition of ELO decreased glass transition temperature, and increased the elongation and thermal degradability of PLA, as shown in the results of differential scanning calorimetry (DSC), tensile test, and thermo gravimetric analysis (TGA). Scanning electron microscopy (SEM) and atomic force microscopy (AFM) were used to observe surface morphology, topography, and the dispersion of MWCNTs in the nanocomposite. Finally, the electroactive-shape memory effect (electroactive-SME) in the resulting nanocomposite was investigated by a fold-deploy "U"-shape bending test. As per the results, the addition of both ELO and MWCNTs to PLA matrix seemed to enhance its overall properties with a great deal of potential in improved shape memory. The 3 wt. % MWCNTs-reinforced nanocomposite system, which showed 95% shape recovery within 45 s at 40 DC voltage, is expected to be used as a preferential polymeric nanocomposite material in various actuators, sensors and deployable devices.

  4. MWCNTs-Reinforced Epoxidized Linseed Oil Plasticized Polylactic Acid Nanocomposite and Its Electroactive Shape Memory Behaviour

    Directory of Open Access Journals (Sweden)

    Javed Alam

    2014-10-01

    Full Text Available A novel electroactive shape memory polymer nanocomposite of epoxidized linseed oil plasticized polylactic acid and multi-walled carbon nanotubes (MWCNTs was prepared by a combination of solution blending, solvent cast technique, and hydraulic hot press moulding. In this study, polylactic acid (PLA was first plasticized by epoxidized linseed oil (ELO in order to overcome the major limitations of PLA, such as high brittleness, low toughness, and low tensile elongation. Then, MWCNTs were incorporated into the ELO plasticized PLA matrix at three different loadings (2, 3 and 5 wt. %, with the aim of making the resulting nanocomposites electrically conductive. The addition of ELO decreased glass transition temperature, and increased the elongation and thermal degradability of PLA, as shown in the results of differential scanning calorimetry (DSC, tensile test, and thermo gravimetric analysis (TGA. Scanning electron microscopy (SEM and atomic force microscopy (AFM were used to observe surface morphology, topography, and the dispersion of MWCNTs in the nanocomposite. Finally, the electroactive-shape memory effect (electroactive-SME in the resulting nanocomposite was investigated by a fold-deploy “U”-shape bending test. As per the results, the addition of both ELO and MWCNTs to PLA matrix seemed to enhance its overall properties with a great deal of potential in improved shape memory. The 3 wt. % MWCNTs-reinforced nanocomposite system, which showed 95% shape recovery within 45 s at 40 DC voltage, is expected to be used as a preferential polymeric nanocomposite material in various actuators, sensors and deployable devices.

  5. Incorporation of Hexa-peri-hexabenzocoronene (HBC) into Carbazole-Benzo-2,1,3-thiadiazole Copolymers to Improve Hole Mobility and Photovoltaic Performance.

    Science.gov (United States)

    Gao, Chen; Jiang, Pei; Shi, Keli; Ma, Di; Li, Yongfang; Yu, Gui; Li, Xiaoyu; Wang, Haiqiao

    2016-03-04

    Hexa-peri-hexabenzocoronene (HBC) is a discotic-shaped conjugated molecule with strong π-π stacking property, high intrinsic charge mobility, and good self-assembly properties. For a long time, however, organic photovoltaic (OPV) solar cells based on HBC demonstrated low power conversion efficiencies (PCEs). In this study, two conjugated terpolymers, poly[N-9'-heptadecanyl-2,7-carbazole-alt-5,5'-(4',7'-di-2-thienyl-2',1',3'-benzothiadiazole)] (PCDTBT)-5 HBC and PCDTBT-10 HBC, were synthesized by incorporating different amounts of HBC as the third component into poly[N-9'-heptadecanyl-2,7-carbazole-alt-5,5'-(4',7'-di-2-thienyl-2',1',3'-benzothiadiazole)] (PCDTBT) through Suzuki coupling polymerization. For comparison, the donor-acceptor (D-A) conjugated dipolymer PCDTBT was also synthesized to investigate the effect of HBC units on conjugated polymers. The HBC-containing polymers exhibited higher thermal stabilities, broader absorption spectra, and lower highest-occupied molecular orbital (HOMO) energy levels. In particular, the field-effect mobilities were enhanced by more than one order of magnitude after the incorporation of HBC into the conjugated polymer backbone on account of increased interchain π-π stacking interactions. The bulk heterojunction (BHJ) polymer solar cells (PSCs) fabricated with the polymers as donor and PC71 BM as acceptor demonstrated gradual improvement of open-circuit voltage (VOC ) and short-circuit current (JSC ) with the increase in HBC content. As a result, the PCEs were improved from 3.21 % for PCDTBT to 3.78 % for PCDTBT-5 HBC and then to 4.20 % for PCDTBT-10 HBC.

  6. In vitro biocompatibility and antibacterial efficacy of a degradable poly(L-lactide-co-epsilon-caprolactone) copolymer incorporated with silver nanoparticles.

    Science.gov (United States)

    Samberg, Meghan E; Mente, Peter; He, Ting; King, Martin W; Monteiro-Riviere, Nancy A

    2014-07-01

    Silver nanoparticles (Ag-nps) are currently used as a natural biocide to prevent undesired bacterial growth in clothing, cosmetics and medical products. The objective of the study was to impart antibacterial properties through the incorporation of Ag-nps at increasing concentrations to electrospun degradable 50:50 poly(L-lactide-co-epsilon-caprolactone) scaffolds for skin tissue engineering applications. The biocompatibility of the scaffolds containing Ag-nps was evaluated with human epidermal keratinocytes (HEK); cell viability and proliferation were evaluated using Live/Dead and alamarBlue viability assays following 7 and 14 days of cell culture on the scaffolds. Significant decreases in cell viability and proliferation were noted for the 1.0 mg(Ag) g(scaffold)(-1) after 7 and 14 days on Ag-nps scaffolds. After 14 days, scanning electron microscopy revealed a confluent layer of HEK on the surface of the 0.0 and 0.1 mg(Ag) g(scaffold)(-1). Both 0.5 and 1.0 mg(Ag) g(scaffold)(-1) were capable of inhibiting both Gram positive and negative bacterial strains. Uniaxial tensile tests revealed a significant (p < 0.001) decrease in the modulus of elasticity following Ag-nps incorporation compared to control. These findings suggest that a scaffold containing between 0.5 and 1.0 mg(Ag) g(scaffold)(-1) is both biocompatible and antibacterial, and is suitable for skin tissue engineering graft scaffolds.

  7. Multifunctional Electroactive Nanocomposites Based on Piezoelectric Boron Nitride Nanotubes.

    Science.gov (United States)

    Kang, Jin Ho; Sauti, Godfrey; Park, Cheol; Yamakov, Vesselin I; Wise, Kristopher E; Lowther, Sharon E; Fay, Catharine C; Thibeault, Sheila A; Bryant, Robert G

    2015-12-22

    Space exploration missions require sensors and devices capable of stable operation in harsh environments such as those that include high thermal fluctuation, atomic oxygen, and high-energy ionizing radiation. However, conventional or state-of-the-art electroactive materials like lead zirconate titanate, poly(vinylidene fluoride), and carbon nanotube (CNT)-doped polyimides have limitations on use in those extreme applications. Theoretical studies have shown that boron nitride nanotubes (BNNTs) have strength-to-weight ratios comparable to those of CNTs, excellent high-temperature stability (to 800 °C in air), large electroactive characteristics, and excellent neutron radiation shielding capability. In this study, we demonstrated the experimental electroactive characteristics of BNNTs in novel multifunctional electroactive nanocomposites. Upon application of an external electric field, the 2 wt % BNNT/polyimide composite was found to exhibit electroactive strain composed of a superposition of linear piezoelectric and nonlinear electrostrictive components. When the BNNTs were aligned by stretching the 2 wt % BNNT/polyimide composite, electroactive characteristics increased by about 460% compared to the nonstretched sample. An all-nanotube actuator consisting of a BNNT buckypaper layer between two single-walled carbon nanotube buckypaper electrode layers was found to have much larger electroactive properties. The additional neutron radiation shielding properties and ultraviolet/visible/near-infrared optical properties of the BNNT composites make them excellent candidates for use in the extreme environments of space missions.

  8. Multifunctional Electroactive Nanocomposites Based on Piezoelectric Boron Nitride Nanotubes

    Science.gov (United States)

    Kang, Jin Ho; Sauti, Godfrey; Park, Cheol; Yamakov, Vesselin I.; Wise, Kristopher E.; Lowther, Sharon E.; Fay, Catharine C.; Thibeault, Sheila A.; Bryant, Robert G.

    2015-01-01

    Space exploration missions require sensors and devices capable of stable operation in harsh environments such as those that include high thermal fluctuation, atomic oxygen, and high-energy ionizing radiation. However, conventional or state-of-the-art electroactive materials like lead zirconate titanate, poly(vinylidene fluoride), and carbon nanotube (CNT)-doped polyimides have limitations on use in those extreme applications. Theoretical studies have shown that boron nitride nanotubes (BNNTs) have strength-to-weight ratios comparable to those of CNTs, excellent high-temperature stability (to 800 C in air), large electroactive characteristics, and excellent neutron radiation shielding capability. In this study, we demonstrated the experimental electroactive characteristics of BNNTs in novel multifunctional electroactive nanocomposites. Upon application of an external electric field, the 2 wt % BNNT/polyimide composite was found to exhibit electroactive strain composed of a superposition of linear piezoelectric and nonlinear electrostrictive components. When the BNNTs were aligned by stretching the 2 wt % BNNT/polyimide composite, electroactive characteristics increased by about 460% compared to the nonstretched sample. An all-nanotube actuator consisting of a BNNT buckypaper layer between two single-walled carbon nanotube buck-paper electrode layers was found to have much larger electroactive properties. The additional neutron radiation shielding properties and ultraviolet/visible/near-infrared optical properties of the BNNT composites make them excellent candidates for use in the extreme environments of space missions. utilizing the unique characteristics of BNNTs.

  9. Multifunctional Electroactive Nanocomposites Based on Piezoelectric Boron Nitride Nanotubes

    Science.gov (United States)

    Kang, Jin Ho; Sauti, Godfrey; Park, Cheol; Yamakov, Vesselin I.; Wise, Kristopher E.; Lowther, Sharon E.; Fay, Catharine C.; Thibeault, Sheila A.; Bryant, Robert G.

    2015-01-01

    Space exploration missions require sensors and devices capable of stable operation in harsh environments such as those that include high thermal fluctuation, atomic oxygen, and high-energy ionizing radiation. However, conventional or state-of-the-art electroactive materials like lead zirconate titanate, poly(vinylidene fluoride), and carbon nanotube (CNT)-doped polyimides have limitations on use in those extreme applications. Theoretical studies have shown that boron nitride nanotubes (BNNTs) have strength-to-weight ratios comparable to those of CNTs, excellent high-temperature stability (to 800 C in air), large electroactive characteristics, and excellent neutron radiation shielding capability. In this study, we demonstrated the experimental electroactive characteristics of BNNTs in novel multifunctional electroactive nanocomposites. Upon application of an external electric field, the 2 wt % BNNT/polyimide composite was found to exhibit electroactive strain composed of a superposition of linear piezoelectric and nonlinear electrostrictive components. When the BNNTs were aligned by stretching the 2 wt % BNNT/polyimide composite, electroactive characteristics increased by about 460% compared to the nonstretched sample. An all-nanotube actuator consisting of a BNNT buckypaper layer between two single-walled carbon nanotube buck-paper electrode layers was found to have much larger electroactive properties. The additional neutron radiation shielding properties and ultraviolet/visible/near-infrared optical properties of the BNNT composites make them excellent candidates for use in the extreme environments of space missions. utilizing the unique characteristics of BNNTs.

  10. Considerations for contractile electroactive materials and actuators

    Science.gov (United States)

    Rasmussen, Lenore; Schramm, David; Rasmussen, Paul; Mullally, Kevin; Meixler, Lewis D.; Pearlman, Daniel; Kirk, Alice

    2011-04-01

    Ras Labs produces contractile electroactive polymer (EAP) based materials and actuators that bend, swell, ripple, and contract (new development) with low electric input. In addition, Ras Labs produces EAP materials that quickly contract and expand, repeatedly, by reversing the polarity of the electric input, which can be cycled. This phenomenon was explored using molecular modeling, followed by experimentation. Applied voltage step functions were also investigated. High voltage steps followed by low voltage steps produced a larger contraction followed by a smaller contraction. Actuator control by simply adjusting the electric input is extremely useful for biomimetic applications. Muscles are able to partially contract. If muscles could only completely contract, nobody could hold an egg, for example, without breaking it. A combination of high and low voltage step functions could produce gross motor function and fine manipulation within the same actuator unit. Plasma treated electrodes with various geometries were investigated as a means of providing for more durable actuation.

  11. Considerations for Contractile Electroactive Materials and Actuators

    Energy Technology Data Exchange (ETDEWEB)

    Lenore Rasmussen, David Schramm, Paul Rasmussen, Kevin Mullaly, Ras Labs, LLC, Intelligent Materials for Prosthetics & Automation, Lewis D. Meixler, Daniel Pearlman and Alice Kirk

    2011-05-23

    Ras Labs produces contractile electroactive polymer (EAP) based materials and actuators that bend, swell, ripple, and contract (new development) with low electric input. In addition, Ras Labs produces EAP materials that quickly contract and expand, repeatedly, by reversing the polarity of the electric input, which can be cycled. This phenomenon was explored using molecular modeling, followed by experimentation. Applied voltage step functions were also investigated. High voltage steps followed by low voltage steps produced a larger contraction followed by a smaller contraction. Actuator control by simply adjusting the electric input is extremely useful for biomimetic applications. Muscles are able to partially contract. If muscles could only completely contract, nobody could hold an egg, for example, without breaking it. A combination of high and low voltage step functions could produce gross motor function and fine manipulation within the same actuator unit. Plasma treated electrodes with various geometries were investigated as a means of providing for more durable actuation.

  12. Considerations For Contractile Electroactive Materials and Actuators

    Energy Technology Data Exchange (ETDEWEB)

    Lenore Rasmussen, Lewis D. Meixler and Charles A. Gentile

    2012-02-29

    Electroactive polymers (EAPs) that bend, swell, ripple (first generation materials), and now contract with low electric input (new development) have been produced. The mechanism of contraction is not well understood. Radionuclide-labeled experiments, molecular modeling, electrolyte experiments, pH experiments, and an ionic concentration experiment were used to determine the chain of events that occur during contraction and, reciprocally, expansion when the polarity is reversed, in these ionic EAPs. Plasma treatment of the electrodes, along with other strategies, allows for the embedded electrodes and the EAP material of the actuator to work and move as a unit, with no detachment, by significantly improving the metal-polymer interface, analogous to nerves and tendons moving with muscles during movement. Challenges involved with prototyping actuation using contractile EAPs are also discussed.

  13. Structural health monitoring system/method using electroactive polymer fibers

    Science.gov (United States)

    Scott-Carnell, Lisa A. (Inventor); Siochi, Emilie J. (Inventor)

    2013-01-01

    A method for monitoring the structural health of a structure of interest by coupling one or more electroactive polymer fibers to the structure and monitoring the electroactive responses of the polymer fiber(s). Load changes that are experienced by the structure cause changes in the baseline responses of the polymer fiber(s). A system for monitoring the structural health of the structure is also provided.

  14. Morphology and Ionic Conductivity of Block Copolymer Electrolytes Containing Ionic Liquids

    Science.gov (United States)

    Park, Moon Jeong

    2015-03-01

    The global energy crisis and an increase in environmental pollution in the recent years have drawn the attention of the scientific community towards the development of efficient electrochemical devices. Polymers containing charged species have the potential to serve as electrolytes in next-generation devices and achieving high ion transport properties in these electrolytes is the key to improving their efficiency. Although the synthesis and characterization of a wide variety of ion-containing polymers have been extensively reported over the last decade, quantitative understanding of the factors governing the ion transport properties of these materials is in its infancy. In this talk, I will present the current understanding of the diverse factors affecting the thermodynamics, morphologies and ion transport of ion-containing polymers by focusing on the use of ionic liquids (ILs). Various strategies for accessing improved transport properties of IL-containing polymers are elucidated by focusing on the role of IL-polymer interactions. The major accomplishment of obtaining well-defined morphologies for these IL-containing polymers by the use of block copolymer is particularly emphasized as a novel means of controlling the transport properties. The application of IL-incorporated polymer electrolytes in high temperature fuel cells and electro-active actuators is also enclosed.

  15. Considerations for Contractile Electroactive Materials and Actuators

    Energy Technology Data Exchange (ETDEWEB)

    Rasmussen, Lenore; Erickson, Carl J.; Meixler, Lewis D.; Ascione, George; Gentile, Charles A.; Tilson, Carl; Bernasek, Stephen L.; Abelev, Esta

    2010-02-19

    Ras Labs produces electroactive polymer (EAP) based materials and actuators that bend, swell, ripple and now contract (new development) with low electric input. This is an important attribute because of the ability of contraction to produce life-like motion. The mechanism of contraction is not well understood. Radionuclide-labeled experiments were conducted to follow the movement of electrolytes and water in these EAPs when activated. Extreme temperature experiments were performed on the contractile EAPs with very favorable results. One of the biggest challenges in developing these actuators, however, is the electrode-EAP interface because of the pronounced movement of the EAP. Plasma treatments of metallic electrodes were investigated in order to improve the attachment of the embedded electrodes to the EAP material. Surface analysis, adhesive testing, and mechanical testing were conducted to test metal surfaces and metal-polymer interfaces. The nitrogen plasma treatment of titanium produced a strong metal-polymer interface; however, oxygen plasma treatment of both stainless steel and titanium produced even stronger metal-polymer interfaces. Plasma treatment of the electrodes allows for the embedded electrodes and the EAP material of the actuator to work and move as a unit, with no detachment, by significantly improving the metal-polymer interface.

  16. Constitutive equations for an electroactive polymer

    Science.gov (United States)

    Tixier, Mireille; Pouget, Joël

    2016-07-01

    Ionic electroactive polymers can be used as sensors or actuators. For this purpose, a thin film of polyelectrolyte is saturated with a solvent and sandwiched between two platinum electrodes. The solvent causes a complete dissociation of the polymer and the release of small cations. The application of an electric field across the thickness results in the bending of the strip and vice versa. The material is modeled by a two-phase continuous medium. The solid phase, constituted by the polymer backbone inlaid with anions, is depicted as a deformable porous media. The liquid phase is composed of the free cations and the solvent (usually water). We used a coarse grain model. The conservation laws of this system have been established in a previous work. The entropy balance law and the thermodynamic relations are first written for each phase and then for the complete material using a statistical average technique and the material derivative concept. One deduces the entropy production. Identifying generalized forces and fluxes provides the constitutive equations of the whole system: the stress-strain relations which satisfy a Kelvin-Voigt model, generalized Fourier's and Darcy's laws and the Nernst-Planck equation.

  17. Electroactive graphene nanofluids for fast energy storage

    Science.gov (United States)

    Dubal, Deepak P.; Gomez-Romero, Pedro

    2016-09-01

    Graphenes have been extensively studied as electrode materials for energy storage in supercapacitors and batteries, but always as solid electrodes. The conception and development of graphene electroactive nanofluids (ENFs) reported here for the first time provides a novel way to ‘form’ graphene electrodes and demonstrates proof of concept for the use of these liquid electrodes for energy storage in novel flow cells. A stabilized dispersion of reduced graphene oxide (rGO) in aqueous sulfuric acid solution was shown to have capacitive energy storage capabilities parallel to those of solid electrode supercapacitors (169 F g-1(rGO)) but working up to much faster rates (from 1 mV s-1 to the highest scan rate of 10 V s-1) in nanofluids with 0.025, 0.1 and 0.4 wt% rGO, featuring viscosities very close to that of water, thus being perfectly suitable for scalable flow cells. Our results provide proof of concept for this technology and include preliminary flow cell performance of rGO nanofluids under static and continuous flow conditions. Graphene nanofluids effectively behave as true liquid electrodes with very fast capacitive storage mechanism and herald the application not only of graphenes but also other 2D materials like MoS2 in nanofluids for energy storage and beyond.

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

    DEFF Research Database (Denmark)

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

    2014-01-01

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

  19. Extruded electroactive fibers: preferred crystallographic orientation

    Science.gov (United States)

    Strock, Harold B.; Pascucci, Marina R.; Bystricky, Pavel

    2001-07-01

    Electroactive fibers of preferred macro crystalline orientation and ultimately single crystal structure are goals of the research discussed in this paper. Four compositions are under evaluation; lead magnesium niobate- lead titanate solid solution, PMN-31PT, an incongruently melting near-morphotropic phase boundary piezoelectric composition; PMN-10PT, an electrostrictor composition; and two lead free compositions in the sodium bismuth titanate- barium titanate solid solution, NbiT-BaT, family, both congruently melting, one electrostrictor and one piezoelectric. The efficacy of seed crystals in stimulating oriented crystal growth is being evaluated in the lead-based PMN-31PT system. Sub-micron reactive precursor powders of high chemical potential are being evaluated as matrix material. Direct fiber and ribbon extrusion have been shown to orient high chemical potential are being evaluated as matrix material. Direct fiber and ribbon extrusion have been shown to orient high chemical potential are being evaluated as matrix material. Direct fiber and ribbon extrusion have been shown to orient prismatic, needle and platelet shaped seed crystals. Extrusion orifice, seed and initial matrix particle size have not influenced the degree of seed orientation within the tested bounds of our experimental parameters. Non-equilibrium sintering conditions near the melting points of all four compositions noted above will be used to generate exaggerated grain growth under seeded and self-seeding conditions. In the PMN-31PT system, an as yet uncharacterized melt phase appears to stimulate rapid crystal growth, the orientation of which shall be determined by x-ray back reflection Laue methods. Analyses of fiber composition and grain orientation are ongoing. Results to-date will be reported. Analyses of fiber quality and performance, measured using single fiber P-E loop testing, are presented. Loops of sufficient quality to warrant fiber evaluation in active fiber composite packs have

  20. Additive-driven assembly of block copolymers

    Science.gov (United States)

    Lin, Ying; Daga, Vikram; Anderson, Eric; Watkins, James

    2011-03-01

    One challenge to the formation of well ordered hybrid materials is the incorporation of nanoscale additives including metal, semiconductor and dielectric nanoparticles at high loadings while maintaining strong segregation. Here we describe the molecular and functional design of small molecule and nanoparticle additives that enhance phase segregation in their block copolymer host and enable high additive loadings. Our approach includes the use of hydrogen bond interactions between the functional groups on the additive or particle that serve as hydrogen bond donors and one segment of the block copolymer containing hydrogen bond acceptors. Further, the additives show strong selectively towards the targeted domains, leading to enhancements in contrast between properties of the phases. In addition to structural changes, we explore how large changes in the thermal and mechanical properties occur upon incorporation of the additives. Generalization of this additive-induced ordering strategy to various block copolymers will be discussed.

  1. Polypyrrole-Based Implantable Electroactive Pump for Controlled Drug Microinjection.

    Science.gov (United States)

    Yan, Bingxi; Li, Boyi; Kunecke, Forest; Gu, Zhen; Guo, Liang

    2015-07-15

    Implantable devices for long-lasting controlled insulin microinjection are of great value to diabetic patients. To address this need, we develop a flexible electroactive pump based on a biocompatible polypyrrole composite film that comprises a polypyrrole matrix and a macromolecular dopant of polycaprolactone-block-polytetrahydrofuran-block-polycaprolactone. Using phosphate-buffered saline as the electrolyte, this film demonstrates much higher electroactivity and reproducibility than conventional Cl--doped polypyrrole, making it an excellent actuator for driving an implantable pump. At a driving current density of 1 mA/cm2, the pump demonstrates a consistent output capacity of 10.5 at 0.35 μL/s over 20 cycles. This work paves the way for the development of an implantable electroactive pump to improve the quality of life of diabetics.

  2. Redox properties of extracellular polymeric substances (EPS) from electroactive bacteria

    Science.gov (United States)

    Li, Shan-Wei; Sheng, Guo-Ping; Cheng, Yuan-Yuan; Yu, Han-Qing

    2016-12-01

    Although the capacity for electroactive bacteria to convert environmental metallic minerals and organic pollutants is well known, the role of the redox properties of microbial extracellular polymeric substances (EPS) in this process is poorly understood. In this work, the redox properties of EPS from two widely present electroactive bacterial strains (Shewanella oneidensis and Pseudomonas putida) were explored. Electrochemical analysis demonstrates that the EPS extracted from the two strains exhibited redox properties. Spectroelectrochemical and protein electrophoresis analyses indicate that the extracted EPS from S. oneidensis and P. putida contained heme-binding proteins, which were identified as the possible redox components in the EPS. The results of heme-mediated behavior of EPS may provide an insight into the important roles of EPS in electroactive bacteria to maximize their redox capability for biogeochemical cycling, environmental bioremediation and wastewater treatment.

  3. Electrochemical performance of electroactive poly(amic acid)-Cu2+ composites

    Science.gov (United States)

    Yan, Ying; Li, Fangfei; Hanlon, Ashley M.; Berda, Erik B.; Liu, Xincai; Wang, Ce; Chao, Danming

    2017-01-01

    Electroactive poly(amic acid)-Cu2+ (EPAA-Cu) composites on substrates were successfully prepared via nucleophilic polycondensation followed by the use of an immersing method. Analysis of the structure properties of EPAA-Cu composites was performed using scanning electron microscopy (SEM), X-ray photoelectron spectra (XPS) and Fourier-transform infrared spectra (FTIR). A significant current enhancement phenomenon of EPAA-Cu/ITO electrodes was found as evident from cyclic voltammetry (CV) measurements. In addition, Cu2+ ions were incorporated into the composites and had a positive effect on their electrochromic behaviors decreasing their switching times. The anticorrosive performance of EPAA-Cu composites coatings on the carbon steel in 3.5 wt% NaCl solution were also investigated in detail using tafel plots analysis and electrochemical impedance spectroscopy. The anticorrosive ability of these coatings significantly enhanced through the incorporation of Cu2+ ions.

  4. High Temperature, Low Relative Humidity, Polymer-type Membranes Based on Disulfonated Poly(arylene ether) Block and Random Copolymers Optionally Incorporating Protonic Conducting Layered Water insoluble Zirconium Fillers

    Energy Technology Data Exchange (ETDEWEB)

    McGrath, James E.; Baird, Donald G.

    2010-06-03

    Our research group has been engaged in the past few years in the synthesis of biphenol based partially disulfonated poly(arylene ether sulfone) random copolymers as potential PEMs. This series of polymers are named as BPSH-xx, where BP stands for biphenol, S stands for sulfonated, H stands for acidified and xx represents the degree of disulfonation. All of these sulfonated copolymers phase separate to form nano scale hydrophilic and hydrophobic morphological domains. The hydrophilic phase containing the sulfonic acid moieties causes the copolymer to absorb water. Water confined in hydrophilic pores in concert with the sulfonic acid groups serve the critical function of proton (ion) conduction and water transport in these systems. Both Nafion and BPSH show high proton conductivity at fully hydrated conditions. However proton transport is especially limited at low hydration level for the BPSH random copolymer. It has been observed that the diffusion coefficients of both water and protons change with the water content of the pore. This change in proton and water transport mechanisms with hydration level has been attributed to the solvation of the acid groups and the amount of bound and bulk-like water within a pore. At low hydration levels most of the water is tightly associated with sulfonic groups and has a low diffusion coefficient. This tends to encourage isolated domain morphology. Thus, although there may be significant concentrations of protons, the transport is limited by the discontinuous morphological structure. Hence the challenge lies in how to modify the chemistry of the polymers to obtain significant protonic conductivity at low hydration levels. This may be possible if one can alter the chemical structure to synthesize nanophase separated ion containing block copolymers. Unlike the BPSH copolymers, where the sulfonic acid groups are randomly distributed along the chain, the multiblock copolymers will feature an ordered sequence of hydrophilic and

  5. Injectable, degradable, electroactive nanocomposite hydrogels containing conductive polymer nanoparticles for biomedical applications.

    Science.gov (United States)

    Wang, Qinmei; Wang, Qiong; Teng, Wei

    2016-01-01

    Injectable electroactive hydrogels (eGels) are promising in regenerative medicine and drug delivery, however, it is still a challenge to obtain such hydrogels simultaneously possessing other properties including uniform structure, degradability, robustness, and biocompatibility. An emerging strategy to endow hydrogels with desirable properties is to incorporate functional nanoparticles in their network. Herein, we report the synthesis and characterization of an injectable hydrogel based on oxidized alginate (OA) crosslinking gelatin reinforced by electroactive tetraaniline-graft-OA nanoparticles (nEOAs), where nEOAs are expected to impart electroactivity besides reinforcement without significantly degrading the other properties of hydrogels. Assays of transmission electron microscopy, (1)H nuclear magnetic resonance, and dynamic light scattering reveal that EOA can spontaneously and quickly self-assemble into robust nanoparticles in water, and this nanoparticle structure can be kept at pH 3~9. Measurement of the gel time by rheometer and the stir bar method confirms the formation of the eGels, and their gel time is dependent on the weight content of nEOAs. As expected, adding nEOAs to hydrogels does not cause the phase separation (scanning electron microscopy observation), but it improves mechanical strength up to ~8 kPa and conductivity up to ~10(-6) S/cm in our studied range. Incubating eGels in phosphate-buffered saline leads to their further swelling with an increase of water content <6% and gradual degradation. When growing mesenchymal stem cells on eGels with nEOA content ≤14%, the growth curves and morphology of cells were found to be similar to that on tissue culture plastic; when implanting these eGels on a chick chorioallantoic membrane for 1 week, mild inflammation response appeared without any other structural changes, indicating their good in vitro and in vivo biocompatibility. With injectability, uniformity, degradability, electroactivity, relative

  6. Anisotropy of Electroactive Strain in Textured Polypyrrole Actuators

    Science.gov (United States)

    Pytel, Rachel; Thomas, Edwin; Hunter, Ian

    2006-03-01

    Polypyrrole has been extensively studied as an electroactive material, but these studies have provided little insight to the influence that morphology has on actuation at the nanoscale. By discovering and exploiting the connection between nanoscale transport events and macroscale active strain, we can learn how to process polypyrrole and other conducting polymers for improved electroactive device performance. We show that by controlling polymer chain configuration and packing, a conducting polymer actuator can be engineered that shows a significantly larger macroscopic electroactive response for a given set of driving conditions. We utilize different modes of deformation to impart orientation textures that can be observed via synchrotron x-ray diffraction and electronic and ionic resistance measurements. Certain textures enhance pathways for ion transport between polymer chains, resulting in an anisotropic electroactive strain response that can be harnessed when making polypyrrole-driven devices. This response provides valuable insight to the mechanism of polypyrrole actuation on the nanoscale, supporting a mechanism where counterions migrate to locations between the oriented polymer chains.

  7. Microactuators based on ion implanted dielectric electroactive polymer (EAP) membranes

    NARCIS (Netherlands)

    Dubois, Philippe; Rosset, Samuel; Koster, Sander; Stauffer, Johann; Mikhailov, Serguei; Dadras, Massoud; de Rooij, Nico-F.; Shea, Herbert

    2006-01-01

    We report on the first successfully microfabricated and tested ion implanted dielectric electroactive polymer (DEAP) actuators. Dielectric EAP (DEAP) actuators combine exceptionally high energy-density with large amplitude displacements [S. Ashley, Artificial muscles, Sci. Am. 289 (2003) 52-59: R. P

  8. Innovative approach for the electrochemical detection of non-electroactive organophosphorus pesticides using oxime as electroactive probe

    Energy Technology Data Exchange (ETDEWEB)

    Dong, Jing; Hou, Juying; Jiang, Jianxia; Ai, Shiyun, E-mail: ashy@sdau.edu.cn

    2015-07-23

    Highlights: • Novel approach for electrochemical detection of non-electroactive OPs was proposed. • PAM was used as electroactive probe for the first time. • The detection system displayed high sensitivity and promptness. • The developed sensor was used in real samples with satisfactory results. - Abstract: An innovative approach for sensitive and simple electrochemical detection of non-electroactive organophosphorus pesticides (OPs) was described in this report. The novel strategy emphasized the fabrication of an oxime-based sensor via attaching pralidoxime (PAM) on graphene quantum dots (GQDs) modified glassy carbon electrode. The introduction of GQDs significantly increased the effective electrode area, and then enlarged the immobilization quantity of PAM. Thus, the oxidation current of PAM was obviously increased. Relying on the nucleophilic substitution reaction between oxime and OPs, fenthion was detected using PAM as the electroactive probe. Under optimum conditions, the difference of oxidation current of PAM was proportional to fenthion concentration over the range from 1.0 × 10{sup −11} M to 5.0 × 10{sup −7} M with a detection limit of 6.8 × 10{sup −12} M (S/N = 3). Moreover, the favorable detection performance in water and soil samples heralded the promising applications in on-site OPs detection.

  9. Silicon containing copolymers

    CERN Document Server

    Amiri, Sahar; Amiri, Sanam

    2014-01-01

    Silicones have unique properties including thermal oxidative stability, low temperature flow, high compressibility, low surface tension, hydrophobicity and electric properties. These special properties have encouraged the exploration of alternative synthetic routes of well defined controlled microstructures of silicone copolymers, the subject of this Springer Brief. The authors explore the synthesis and characterization of notable block copolymers. Recent advances in controlled radical polymerization techniques leading to the facile synthesis of well-defined silicon based thermo reversible block copolymers?are described along with atom transfer radical polymerization (ATRP), a technique utilized to develop well-defined functional thermo reversible block copolymers. The brief also focuses on Polyrotaxanes and their great potential as stimulus-responsive materials which produce poly (dimethyl siloxane) (PDMS) based thermo reversible block copolymers.

  10. Significant enhancement of dielectric and conducting properties of electroactive polymer polyvinylidene fluoride films: An innovative use of Ferrum metallicum at different concentrations

    OpenAIRE

    B K Paul; Kar, S.; Bandyopadhyay, P.; R. Basu; Das, S.; D S Bhar; Raj K Manchanda; Anil Khurana; Nayak, D.; Papiya Nandy

    2016-01-01

    Background: There are experimental evidences of nanoparticle aspect of homoeopathic medicine. It has also been established that the size of these nanoparticles (NPs) decrease with increase in potency. Aim: We have used this aspect of homoeopathic medicines in some technical applications. Here, to improve the electrical properties of an electroactive polymer, poly (vinylidene fluoride-hexa-fluoropropylene) (PVDF-HFP), we have incorporated in the polymer film, a very novel and unique probe F...

  11. 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.

  12. Electroactive bacteria--molecular mechanisms and genetic tools.

    Science.gov (United States)

    Sydow, Anne; Krieg, Thomas; Mayer, Florian; Schrader, Jens; Holtmann, Dirk

    2014-10-01

    In nature, different bacteria have evolved strategies to transfer electrons far beyond the cell surface. This electron transfer enables the use of these bacteria in bioelectrochemical systems (BES), such as microbial fuel cells (MFCs) and microbial electrosynthesis (MES). The main feature of electroactive bacteria (EAB) in these applications is the ability to transfer electrons from the microbial cell to an electrode or vice versa instead of the natural redox partner. In general, the application of electroactive organisms in BES offers the opportunity to develop efficient and sustainable processes for the production of energy as well as bulk and fine chemicals, respectively. This review describes and compares key microbiological features of different EAB. Furthermore, it focuses on achievements and future prospects of genetic manipulation for efficient strain development.

  13. Dielectric electroactive polymers comprising an ionic supramolecular structure

    DEFF Research Database (Denmark)

    2014-01-01

    The present invention relates to an ionic interpenetrating polymer network comprising at least one elastomer and an ionic supramolecular structure comprising the reaction product of at least two chemical compounds wherein each of said compounds has at least two functional groups and wherein said ...... compounds are able to undergo Lewis acid-base reactions. The interpenetrating polymer network may be used as dielectric electroactive polymers (DEAPs) having a high dielectric permittivity....

  14. Electroactive Reactive Oligomers and Polymers as Device Components

    Science.gov (United States)

    2009-02-03

    development of conjugated. conducting and electroactive oligomers, polymers and multi-component materials is proposed for application to photovoltaic...characteristics. Intense research has focused on oligo- and polythiophenes , as such materials early showed high hole mobilities. While vapor deposited a...to atmospheric oxygen, air stability now becomes an issue. The research conducted in this project focuses on the study of a soluble polymer consisting

  15. Electro-active elastomer composite based on doped titanium dioxide Electro-active elastomer composite based on doped titanium dioxide

    OpenAIRE

    Kossi, Alaedine; Bossis, Georges; Persello, Jacques

    2015-01-01

    International audience; Recently, electro-active composites have been considered by several researchers because they exhibit an interesting change in their viscoelastic properties under an applied electric field. However, their relative elastic modulus change ΔG'=G'(E)-G'(0) is still low and rarely exceed 100 kPa. In this article, we demonstrated that, by synthesizing mesoporous aggregates of titanium dioxide (TiO2) and by adsorbing acetylacetone dipolar molecule (Acac) onto the TiO2 surface,...

  16. Thermal conductivity and multiferroics of electroactive polymers and polymer composites

    Science.gov (United States)

    Jin, Jiezhu

    Electronically conducting polymers and electromechanical polymers are the two important branches of the cutting-edge electroactive polymers. They have shown significant impact on many modern technologies such as flat panel display, energy transport, energy conversion, sensors and actuators. To utilize conducting polymers in microelectronics, optoelectronics and thermoelectrics, it is necessary to have a comprehensive study of their thermal conductivity since thermal conductivity is a fundamental materials property that is particularly important and sometimes a determining factor of the device performance. For electromechanical polymers, larger piezoelectric effect will contribute to the improvement of magnetoelectric (ME) coupling efficiency in their multiferroic composites. This dissertation is devoted to characterizing electronically conducting polymers for their electrical and thermal conductivity, and developing new classes of electromechanical polymers and strain-mediated electromechanical polymer-based multiferroic ME composites. Conducting polymers opened up new possibilities for devices combining novel electrical and thermal properties, but there has been limited understanding of the length-scale effect of the electrical and thermal conductivity, and the mechanism underlying the electricity and heat transport behavior. In this dissertation, the analytical model and experimental technique are presented to measure the in-plane thermal conductivity of polyaniline thin films. For camphorsulfonic acid doped polyaniline patterned on silicon oxide/silicon substrate using photolithography and reactive ion etching, the thermal conductivity of the film with thickness of 20 nm is measured to be 0.0406 W/m˙K, which significantly deviates from their bulk (> 0.26 W/m˙K). The size effect on thermal conductivity at this scale is attributed to the significant phonon boundary scattering. When the film goes up to 130 nm thick, the thermal conductivity increases to 0.166 W

  17. Advanced Electroactive Single Crystal and Polymer Actuator Concepts for Passive Optics Project

    Data.gov (United States)

    National Aeronautics and Space Administration — TRS Technologies proposes large stroke and high precision piezoelectric single crystal and electroactive polymer actuator concepts?HYBrid Actuation System (HYBAS)...

  18. Energy Harvesting Cycles of Dielectric ElectroActive Polymer Generators

    DEFF Research Database (Denmark)

    Dimopoulos, Emmanouil; Trintis, Ionut; Munk-Nielsen, Stig

    2012-01-01

    Energy harvesting via Dielectric ElectroActive Polymer (DEAP) generators has attracted much of the scientific interest over the past few years, mainly due to the advantages that these smart materials offer against competing technologies, as electromagnetic generators and piezoelectrics....... Their higher energy density, superior low-speed performance, light-weighted nature as well as their shapely structure have rendered DEAPs candidate solutions for various actuation and energy harvesting applications. In this paper, a thoroughly analysis of all energy harvesting operational cycles of a DEAP...

  19. Fabrication and characterization of cellulose nanocrystal based transparent electroactive polyurethane

    Science.gov (United States)

    Ko, Hyun-U.; Kim, Hyun Chan; Kim, Jung Woong; Zhai, Lindong; Jayaramudu, Tippabattini; Kim, Jaehwan

    2017-08-01

    This paper reports cellulose nanocrystal (CNC) based transparent and electroactive polyurethane (CPPU), suitable for actively tunable optical lens. CNC is used for high dielectric filler to improve electromechanical behavior of CPPU. For high transparency and homogeneous distribution of CNC in polyurethane, CNC-poly[di(ethylene glycol) adipate] is used to play a role of polyol and isocyanate salt. The fabricated CPPU exhibits high transparency (>90%) and 10% of electromechanical strain under 3 V μm-1 electric field. Mechanical, dielectric properties as well as physical and chemical characteristics are investigated to prove the electromechanical behavior of CPPU.

  20. Biomimetic actuators using electroactive polymers (EAP) as artificial muscles

    Science.gov (United States)

    Bar-Cohen, Yoseph

    2006-01-01

    Evolution has resolved many of nature's challenges leading to lasting solutions with maximal performance and effective use of resources. Nature's inventions have always inspired human achievements leading to effective materials, structures, tools, mechanisms, processes, algorithms, methods, systems and many other benefits. The field of mimicking nature is known as Biomimetics and one of its topics includes electroactive polymers that gain the moniker artificial muscles. Integrating EAP with embedded sensors, self-repair and many other capabilities that are used in composite materials can add greatly to the capability of smart biomimetic systems. Such development would enable fascinating possibilities potentially turning science fiction ideas into engineering reality.

  1. Novel Electroactive Polymers as Environmentally Compliant Coatings for Corrosion Control

    Science.gov (United States)

    2006-02-03

    and Corrosion Inhibition of Poly(bis(dialkylamino)phenylene vinylenes),” ACS PMSE Preprints, 86, 7 (2002). 22. D. J. Irvin, N. Anderson, C. Webber, S...Fallis, and P. Zarras, “New Synthetic Routes to Poly(bis(dialkylamino)phenylene vinylenes)”, ACS PMSE Preprints, 86, 61 (2002). 23. N. Anderson...of Electroactive Polymers with Oligoaniline Side Chains,” ACS PMSE Preprints, 86, 42 (2002). 144 25. N. Anderson, J. D. Stenger-Smith, D.J. Irvin

  2. STUDY ON SOME PROPERTIES OF Si-CONTAINING POLYESTER-POLYETHER MULTIBLOCK COPOLYMERS

    Institute of Scientific and Technical Information of China (English)

    LI Zhenyi; ZHU Jin

    1997-01-01

    Some physical properties of the polyester-polyether multiblock copolymers with Si-containing hard segment were further examined by a series of physical methods. The hydrophobicity of the copolymers was improved with the incorporation of increasing amount of orgauosilicone, XPS test proved that silicon element was enriched at the surface of the Si-containing polyester-polyether copolymers. It was also found that their heat resistance and gas permeability for O2 and N2 were greatly improved. The study on semipermeability of films made of the Si-containing copolymers was also followed with interest.

  3. Recent Progress on Cellulose-Based Electro-Active Paper, Its Hybrid Nanocomposites and Applications

    Science.gov (United States)

    Khan, Asif; Abas, Zafar; Kim, Heung Soo; Kim, Jaehwan

    2016-01-01

    We report on the recent progress and development of research into cellulose-based electro-active paper for bending actuators, bioelectronics devices, and electromechanical transducers. The cellulose electro-active paper is characterized in terms of its biodegradability, chirality, ample chemically modifying capacity, light weight, actuation capability, and ability to form hybrid nanocomposites. The mechanical, electrical, and chemical characterizations of the cellulose-based electro-active paper and its hybrid composites such as blends or coatings with synthetic polymers, biopolymers, carbon nanotubes, chitosan, and metal oxides, are explained. In addition, the integration of cellulose electro-active paper is highlighted to form various functional devices including but not limited to bending actuators, flexible speaker, strain sensors, energy harvesting transducers, biosensors, chemical sensors and transistors for electronic applications. The frontiers in cellulose paper devices are reviewed together with the strategies and perspectives of cellulose electro-active paper and cellulose nanocomposite research and applications. PMID:27472335

  4. Recent Progress on Cellulose-Based Electro-Active Paper, Its Hybrid Nanocomposites and Applications

    Directory of Open Access Journals (Sweden)

    Asif Khan

    2016-07-01

    Full Text Available We report on the recent progress and development of research into cellulose-based electro-active paper for bending actuators, bioelectronics devices, and electromechanical transducers. The cellulose electro-active paper is characterized in terms of its biodegradability, chirality, ample chemically modifying capacity, light weight, actuation capability, and ability to form hybrid nanocomposites. The mechanical, electrical, and chemical characterizations of the cellulose-based electro-active paper and its hybrid composites such as blends or coatings with synthetic polymers, biopolymers, carbon nanotubes, chitosan, and metal oxides, are explained. In addition, the integration of cellulose electro-active paper is highlighted to form various functional devices including but not limited to bending actuators, flexible speaker, strain sensors, energy harvesting transducers, biosensors, chemical sensors and transistors for electronic applications. The frontiers in cellulose paper devices are reviewed together with the strategies and perspectives of cellulose electro-active paper and cellulose nanocomposite research and applications.

  5. Finite element analysis of electroactive polymer and magnetoactive elastomer based actuation for origami folding

    Science.gov (United States)

    Zhang, Wei; Ahmed, Saad; Masters, Sarah; Ounaies, Zoubeida; Frecker, Mary

    2017-10-01

    The incorporation of smart materials such as electroactive polymers and magnetoactive elastomers in origami structures can result in active folding using external electric and magnetic stimuli, showing promise in many origami-inspired engineering applications. In this study, 3D finite element analysis (FEA) models are developed using COMSOL Multiphysics software for three configurations that incorporate a combination of active and passive material layers, namely: (1) a single-notch unimorph folding configuration actuated using only external electric field, (2) a double-notch unimorph folding configuration actuated using only external electric field, and (3) a bifold configuration which is actuated using multi-field (electric and magnetic) stimuli. The objectives of the study are to verify the effectiveness of the FEA models to simulate folding behavior and to investigate the influence of geometric parameters on folding quality. Equivalent mechanical pressure and surface stress are used as external loads in the FEA to simulate electric and magnetic fields, respectively. Compared quantitatively with experimental data, FEA captured the folding performance of electric actuation well for notched configurations and magnetic actuation for a bifold structure, but underestimated electric actuation for the bifold structure. By investigating the impact of geometric parameters and locations to place smart materials, FEA can be used in design, avoiding trial-and-error iterations of experiments.

  6. Estudo da recuperação das propriedades de poliestireno de alto impacto (HIPS através da incorporação de borracha termoplástica tipo estireno-butadieno-estireno (SBS Recovering properties of recycled HIPS through incorporation of SBS triblock copolymer

    Directory of Open Access Journals (Sweden)

    Vanda F. Ribeiro

    2012-01-01

    Full Text Available A tenacificação de termoplásticos vítreos através da adição de partículas de borracha na matriz polimérica é um processo amplamente estudado. Neste trabalho foi avaliada a recuperação das propriedades de poliestireno de alto impacto (HIPS reciclado através da incorporação de copolímeros estireno-butadieno-estireno (SBS de estrutura linear e radial. As blendas foram processadas em uma extrusora dupla rosca. Os copolímeros foram adicionados em teores de 5, 10 e 15% em massa. As propriedades avaliadas foram o índice de fluidez, a morfologia e o comportamento frente a ensaios de tração, flexão e resistência ao impacto das blendas formuladas. Em todos os casos, o SBS radial foi mais eficiente na recuperação das propriedades do poliestireno de alto impacto que o SBS linear quando comparadas às propriedades do HIPS reciclado.Toughening glassy thermoplastics by blending a rubbery material to the polymeric matrix has been extensively studied. In this work, we evaluated the resulting properties of recycled high impact polystyrene (HIPS, after the incorporation of either radial or linear SBS triblock copolymers. The blends were melt mixed using a twin-screw extruder. The copolymers were added at 5, 10 and 15% weight percent. The investigated properties included the determination of the melt flow index, the morphology and the mechanical behavior according to standard tension, flexion and impact methods of all formulated blends. In all cases, the radial SBS was more efficient in recovering the HIPS properties than the linear SBS, when comparing the properties of the blends with the properties of recycled HIPS.

  7. Electro-active material (EAM) based bend sensors

    Science.gov (United States)

    LaComb, Ronald; LaComb, Julie

    2010-04-01

    The capability to accurately estimate strain and orientation of cables in an undersea environment is important for a multitude of applications. One way to estimate the positional location of a submersed cable is to utilize a network of distributed bend sensors providing inputs to a curve fitting algorithm. In this work commercially available bend sensors are characterized for small deflections. In addition proto-type devices are presented which can potentially improve device sensitivity. Commercially available bend sensors are based upon electro-active materials and variable resistance materials. Electro-active materials (EAM) are known for their actuator functionality but certain EAMs are capable of sensing as well. New advances in materials such as Ionic Polymer Metal Composites (IPMC) are proving suitable for quasi-static sensor applications. These sensors are low power, conformal and produce directionally dependent output voltages which are linearly proportional to deflection, with voltage polarity representative of the deflection direction. IPMCs are capable of being morphed for increased sensitivity. Variable resistivity sensors are based on smart epoxy polymer and carbon loaded inks. These sensors are inexpensive and conformal and unlike EAMs provide static measurements.

  8. Electroactive 3D materials for cardiac tissue engineering

    Science.gov (United States)

    Gelmi, Amy; Zhang, Jiabin; Cieslar-Pobuda, Artur; Ljunngren, Monika K.; Los, Marek Jan; Rafat, Mehrdad; Jager, Edwin W. H.

    2015-04-01

    By-pass surgery and heart transplantation are traditionally used to restore the heart's functionality after a myocardial Infarction (MI or heart attack) that results in scar tissue formation and impaired cardiac function. However, both procedures are associated with serious post-surgical complications. Therefore, new strategies to help re-establish heart functionality are necessary. Tissue engineering and stem cell therapy are the promising approaches that are being explored for the treatment of MI. The stem cell niche is extremely important for the proliferation and differentiation of stem cells and tissue regeneration. For the introduction of stem cells into the host tissue an artificial carrier such as a scaffold is preferred as direct injection of stem cells has resulted in fast stem cell death. Such scaffold will provide the proper microenvironment that can be altered electronically to provide temporal stimulation to the cells. We have developed an electroactive polymer (EAP) scaffold for cardiac tissue engineering. The EAP scaffold mimics the extracellular matrix and provides a 3D microenvironment that can be easily tuned during fabrication, such as controllable fibre dimensions, alignment, and coating. In addition, the scaffold can provide electrical and electromechanical stimulation to the stem cells which are important external stimuli to stem cell differentiation. We tested the initial biocompatibility of these scaffolds using cardiac progenitor cells (CPCs), and continued onto more sensitive induced pluripotent stem cells (iPS). We present the fabrication and characterisation of these electroactive fibres as well as the response of increasingly sensitive cell types to the scaffolds.

  9. Electroactive-Zone Extension in Flow-Battery Stacks

    Energy Technology Data Exchange (ETDEWEB)

    Smith, KC; Brunini, VE; Dong, YJ; Chiang, YM; Carter, WC

    2014-11-20

    Flowable suspensions that conduct both electrons and ions can enable the use of energy-dense electroactive species in flow batteries [M. Duduta et al., Adv. Energy Mater., 1, 511 (2011); Z. Li et al., Phys. Chem. Chem. Phys., 15, 15,833 (2013); F. Fan et al., Nano Lett., 14, 2210 (2014)]. In comparison with conventional flow batteries where electrochemical reactions are confined to a fixed current-collector region, electronically conductive flow electrodes permit electrochemical reactions to extend outside of the physical confines of the stack. We have measured and modeled how mixed-conduction enables an electroactive zone (EAZ, in which electrochemical reactions occur) that is of greater spatial extent than current collectors, the extension being termed side zone, SZ. Electrochemical reactions in SZs can reduce coulombic and energetic efficiency. Here we show that for realistic suspension properties and operating conditions, the added inefficiency is small in practice, and can be further mitigated by using appropriate operating conditions and/or materials choices. For the specific example of a non-aqueous Li4Ti5O12 suspension, we show that EAZ extension contributes less than 1% additional efficiency loss at C/10 rates for current collectors greater than 20 mm long. (C) 2014 Elsevier Ltd. All rights reserved.

  10. Inkjet printing of electroactive polymer actuators on polymer substrates

    Science.gov (United States)

    Pabst, O.; Perelaer, J.; Beckert, E.; Schubert, U. S.; Eberhardt, R.; Tünnermann, A.

    2011-04-01

    Electroactive polymers (EAP) are promising materials for actuators in different application areas. This paper reports inkjet printing as a versatile tool for manufacturing EAP actuators. Drop-on-demand inkjet printing can be used for additive deposition of functional materials onto substrates. Cantilever bending actuators with lateral dimensions in the mm range are described here. A commercially available solution of electroactive polymers is dispensed onto metalized polycarbonate substrates using inkjet printing. These polymers exhibit piezoelectric behavior. Multiple layers are printed resulting in a film thickness of 5 to 10 μm. After printing, the polymer layers are annealed thermally at 130 °C. Top electrodes are deposited onto the EAP layer by inkjet printing a silver nanoparticle ink. The as-printed silver layers are sintered using an argon plasma - a recently developed sintering technique that is compatible with low TG polymer foils. After printing the EAP layers are poled. When applying an electric field across the polymer layer, piezoelectric strain in the EAP leads to a bending deflection of the structures. With driving voltages of 200 V the actuators generate displacements of 20 μm and blocking forces of approximately 3 mN. The first resonance frequency occurs at 230 Hz.

  11. Electrochemical behavior and conductivity measurements of electropolymerized selenophene-based copolymers

    Directory of Open Access Journals (Sweden)

    Alakhras Fadi

    2015-03-01

    Full Text Available Electrochemical copolymerization of selenophene and thiophene was performed at a constant electrode potential. The obtained homopolymer films and copolymers were studied and characterized with cyclic voltammetry and conductivity measurements, from which conductivity values around 13.35 S · cm-1 were determined. The influence of the applied electropolymerization potential and the monomer feed ratio of selenophene and thiophene on the copolymers properties was investigated. The obtained copolymers showed good stability of the redox activity in an acetonitrile-based electrolyte solution. At higher polymerization potentials and at higher concentrations of thiophene in the feed, more thiophene units were incorporated into the copolymer chain. The conductivities of the copolymers were between those of homopolymers, implying that oxidation of both monomers was possible and the copolymer chains might accordingly be composed of both selenophene and thiophene units.

  12. 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...... functional nanoporous polymers based on nanoporous 1,2- polybuatdiene 1,2-PB, which is derived from a 1,2-PB-b-PDMS diblock copolymer precursor. As a result, nanoporous 1,2-PB with pores decorated of polyacrylates, sulfonated polymers and poly(ethylene glycol) are created. A method of vapor phase deposition...... has also been generated to obtain nanoporous polymers with functional coatings on pore walls. Vapor phase polymerization of pyrrole is performed to incorporate an ultra thin film of polypyrrole into nanoporous 1,2-PB. The preliminary test shows that nanoporous 1,2-PB gains conductivity. Generally...

  13. Photothermal degradation of ethylene/vinylacetate copolymer

    Science.gov (United States)

    Liang, R. H.; Chung, S.; Clayton, A.; Di Stefano, S.; Oda, K.; Hong, S. D.; Gupta, A.

    1983-01-01

    Photothermal degradation studies were conducted on a 'stabilized' formulation of ethylene/vinyl acetate copolymer (EVA) in the temperature range 25-105 C under three different oxygen environments (in open air, with limited access to O2, and in a dark closed stagnant oven). These studies were performed in order to evaluate the utility of EVA as an encapsulation material for photovoltaic modules. Results showed that at low temperature (25 C), slow photooxidation of the polymer occurred via electronic energy transfer involving the UV absorber incorporated in the polymer. However, no changes in the physical properties of the bulk polymer were detected up to 1500 hours of irradiation. At elevated temperatures, leaching and evaporation of the additives occurred, which ultimately resulted in the chemical crosslinking of the copolymer and the formation of volatile photoproducts such as acetic acid.

  14. 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.

  15. Behavior of polymer-based electroactive actuator incorporated with mild hydrothermally treated CNTs

    Science.gov (United States)

    Melvin, Gan Jet Hong; Ni, Qing-Qing; Natsuki, Toshiaki

    2014-12-01

    We fabricated an actuator that was made from polyurethane (PU) with carbon nanotubes (CNTs) as the filler. To improve the dispersion of the CNTs, a mild hydrothermal treatment was carried out. Carboxyl and hydroxyl groups were introduced to the surface of the CNTs, and they were found to be highly dispersed in polar solvents such as dimethylformamide. To evaluate these films, we mainly focused on electrical properties, such as dielectric spectroscopy, space charge measurements, and actuator behavior. We found that the PU/CNTs film bents toward the cathode when an electric field was applied, and it reverted to its original position when the electric field was removed. Upon the inclusion of the CNTs as the filler for the polymer, the electrical properties of the films improved significantly. The highly polarized films had a high relative permittivity, and this produced a higher Maxwell pressure, which assisted the actuation. A high accumulated charge density was observed from space charge measurements in some of the films, and this explains the bending direction and the actuation mechanism.

  16. New Polytetrahydrofuran Graft Copolymers.

    Science.gov (United States)

    1979-03-15

    chioroprene) , chiorobutyl - ~~~~~ rubber , bromobutyl rubber , chlorinated EPDM , chlorinated poly(buta— diene) and chlorinated butadiene styrene copolymer...for initial detailed studies (3 ,4 , 6 , 7 — 9 ) . Many soluble metal salts with cations capable of stabilizing an on].um ion polymerization (SO3CF 3

  17. Block coordination copolymers

    Science.gov (United States)

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

    2012-11-13

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

  18. Field-theoretic simulations of random copolymers with structural rigidity.

    Science.gov (United States)

    Mao, Shifan; MacPherson, Quinn; Qin, Jian; Spakowitz, Andrew J

    2017-04-12

    Copolymers play an important role in a range of soft-materials applications and biological phenomena. Prevalent works on block copolymer phase behavior use flexible chain models and incorporate interactions using a mean-field approximation. However, when phase separation takes place on length scales comparable to a few monomers, the structural rigidity of the monomers becomes important. In addition, concentration fluctuations become significant at short length scales, rendering the mean-field approximation invalid. In this work, we use simulation to address the role of finite monomer rigidity and concentration fluctuations in microphase segregation of random copolymers. Using a field-theoretic Monte-Carlo simulation of semiflexible polymers with random chemical sequences, we generate phase diagrams for random copolymers. We find that the melt morphology of random copolymers strongly depends on chain flexibility and chemical sequence correlation. Chemically anti-correlated copolymers undergo first-order phase transitions to local lamellar structures. With increasing degree of chemical correlation, this first-order phase transition is softened, and melts form microphases with irregular shaped domains. Our simulations in the homogeneous phase exhibit agreement with the density-density correlation from mean-field theory. However, conditions near a phase transition result in deviations between simulation and mean-field theory for the density-density correlation and the critical wavemode. Chain rigidity and sequence randomness lead to frustration in the segregated phase, introducing heterogeneity in the resulting morphologies.

  19. Meter-long multiblock copolymer microfibers via interfacial bioorthogonal polymerization.

    Science.gov (United States)

    Liu, Shuang; Zhang, Han; Remy, Roddel A; Deng, Fei; Mackay, Michael E; Fox, Joseph M; Jia, Xinqiao

    2015-05-01

    High-molecular-weight multiblock copolymers are synthesized as robust polymer fibers via interfacial bioorthogonal polymerization employing the rapid cycloaddition of s-tetrazines with strained trans-cyclooctenes. When cell-adhesive peptide is incorporated in the tetrazine monomer, the resulting protein-mimetic polymer fibers provide guidance cues for cell attachment and elongation.

  20. Electroactive Polymer (EAP) Actuators for Future Humanlike Robots

    Science.gov (United States)

    Bar-Cohen, Yoseph

    2009-01-01

    Human-like robots are increasingly becoming an engineering reality thanks to recent technology advances. These robots, which are inspired greatly by science fiction, were originated from the desire to reproduce the human appearance, functions and intelligence and they may become our household appliance or even companion. The development of such robots is greatly supported by emerging biologically inspired technologies. Potentially, electroactive polymer (EAP) materials are offering actuation capabilities that allow emulating the action of our natural muscles for making such machines perform lifelike. There are many technical issues related to making such robots including the need for EAP materials that can operate as effective actuators. Beside the technology challenges these robots also raise concerns that need to be addressed prior to forming super capable robots. These include the need to prevent accidents, deliberate harm, or their use in crimes. In this paper, the potential EAP actuators and the challenges that these robots may pose will be reviewed.

  1. A compact electroactive polymer actuator suitable for refreshable Braille display

    Science.gov (United States)

    Ren, Kailiang; Liu, Sheng; Lin, Minren; Wang, Yong; Zhang, Q. M.

    2007-04-01

    The large strain, high elastic modulus, and easy processing of P(VDF-TrFE-CFE) electrostrictive terpolymer make it very attractive to replace low strain piezoceramics and piezopolymers in many applications with much improved performance. In this paper, a compact polymer actuator is developed utilizing the electrostrictive terpolymer, which is suitable for full page Braille Display and graphic display. Key issues related to the reliability of electroactive polymers used in the compact actuators and for the mass fabrication of these polymer actuators are investigated. Making use of a recently developed conductive polymer, a screen printing deposition method was developed which enables direct deposition very thin conductive polymer electrode layer (Braille actuator was designed and fabricated with these terpolymer films wound on a spring core. The test results demonstrate that the EAP Braille actuator meets all the functional requirements of actuators for refreshable full Braille display, which offers compact size, reduced cost and weight.

  2. Comparison of the dielectric electroactive polymer generator energy harvesting cycles

    DEFF Research Database (Denmark)

    Dimopoulos, Emmanouil; Trintis, Ionut; Munk-Nielsen, Stig

    2013-01-01

    The Dielectric ElectroActive Polymer (DEAP) generator energy harvesting cycles have been in the spotlight of the scientific interest for the past few years. Indeed, several articles have demonstrated thorough and comprehensive comparisons of the generator fundamental energy harvesting cycles......, namely Constant Charge (CC), Constant Voltage (CV) and Constant E-field (CE), based on averaged theoretical models. Yet, it has not been possible until present to validate the outcome of those comparisons via respective experimental results. In this paper, all three primary energy harvesting cycles...... are experimentally compared, based upon the coupling of a DEAP generator with a bidirectional non-isolated power electronic converter, by means of energy gain, energy harvesting efficiency and energy conversion efficiency....

  3. Water-soluble, electroactive, and photoluminescent quaterthiophene-dinucleotide conjugates.

    Science.gov (United States)

    Alesi, Silvia; Brancolini, Giorgia; Melucci, Manuela; Capobianco, Massimo Luigi; Venturini, Alessandro; Camaioni, Nadia; Barbarella, Giovanna

    2008-01-01

    Quaterthiophene-dinucleotide conjugates 5'TA3'-t4-3'AT5', 5'AA3'-t4-3'AA5', and 5'TT3'-t4-3'TT5' (TA: thymidine-adenosine, AA: adenosine-adenosine, TT: thymidine-thymidine) were synthesized and analyzed by a combination of spectroscopy and microscopy, electrical characterization, and theoretical calculations. Circular dichroism (CD) experiments demonstrated a transfer of chirality from the dinucleotides to quaterthiophene at high ionic strength and in cast films. The films were photoluminescent and electroactive. CD and photoluminescence spectra and current density/voltage plots (measured under dynamic vacuum) displayed significant variation on changing the dinucleotide scaffold. Molecular mechanics and molecular dynamics calculations indicated that the conformation and packing modes of the conjugates are the result of a balance between intra- and intermolecular nucleobase-thiophene stacking interactions and intramolecular hydrogen bonding between the nucleobases.

  4. A Review on Electroactive Polymers for Waste Heat Recovery

    Directory of Open Access Journals (Sweden)

    Ewa Kolasińska

    2016-06-01

    Full Text Available This paper reviews materials for thermoelectric waste heat recovery, and discusses selected industrial and distributed waste heat sources as well as recovery methods that are currently applied. Thermoelectric properties, especially electrical conductivity, thermopower, thermal conductivity and the thermoelectric figures of merit, are considered when evaluating thermoelectric materials for waste heat recovery. Alloys and oxides are briefly discussed as materials suitable for medium- and high-grade sources. Electroactive polymers are presented as a new group of materials for low-grade sources. Polyaniline is a particularly fitting polymer for these purposes. We also discuss types of modifiers and modification methods, and their influence on the thermoelectric performance of this class of polymers.

  5. 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.

  6. Encapsulation of ionic electroactive polymers: reducing the interaction with environment

    Science.gov (United States)

    Jaakson, P.; Aabloo, A.; Tamm, T.

    2016-04-01

    Ionic electro-active polymer (iEAP) actuators are composite materials that change their mechanical properties in response to external electrical stimulus. The interest in these devices is mainly driven by their capability to generate biomimetic movements, and their potential use in soft robotics. The driving voltage of an iEAP-actuator (0.5… 3 V) is at least an order of magnitude lower than that needed for other types of electroactive polymers. To apply iEAP-actuators in potential real-world applications, the capability of operating in different environments (open air, different solvents) must be available. In their natural form, the iEAP-actuators are capable of interacting with the surrounding environment (evaporation of solvent from the electrolyte solution, ion or solvent exchange, humidity effects), therefore, for prevention of unpredictable behavior of the actuator and the contamination of the environment, encapsulation of the actuator is needed. The environmental contamination aspect of the encapsulation material is substantial when selecting an applicable encapsulant. The suitable encapsulant should form thin films, be light in weight, elastic, fit tightly, low cost, and easily reproducible. The main goal of the present study is to identify and evaluate the best potential encapsulation techniques for iEAPactuators. Various techniques like thin film on liquid coating, dip coating, hot pressing, hot rolling; and several materials like polydimethylsiloxane, polyurethane, nitrocellulose, paraffin-composite-films were investigated. The advantages and disadvantages of the combinations of the above mentioned techniques and materials are discussed. Successfully encapsulated iEAP-actuators gained durability and were stably operable for long periods of time under ambient conditions. The encapsulation process also increased the stability of the iEAP-actuator by minimizing the environment effects. This makes controlling iEAP-actuators more straight-forward and

  7. Effect of porosity of the electrodes on ionic electroactive polymer actuators

    Science.gov (United States)

    Nakshatharan, S. Sunjai; Johanson, Urmas; Punning, Andres; Aabloo, Alvo

    2017-04-01

    Ionic electroactive polymer (IEAP) actuators with carbon based porous electrodes and ionic liquid electrolyte are attractive alternatives compared to the actuators composed of noble metal electrodes. Besides of numerous other parameters, the porosity of the electrode matrix has high influence on the electrochemical behavior and mechanical response of these actuators. Porosity has direct influence on the tortuosity, electronic conductivity, ionic conductivity, ion diffusivity, mobility, as well as the specific area and specific capacitance of electrode. It can also influence directly the mechanical properties of the IEAP laminate: durability, stiffness, etc. In this study, a detailed physical model that incorporates porosity of electrodes and its relation to the electrochemical, transport and mechanical behavior of the IEAP actuator is developed. The behavior of the actuator under different porosity values is investigated through finite elements simulation. The outputs of the simulation are cation concentration, current consumed and deformation of the actuator etc. Altering porosity and determining its optimum value help to comprehend the occurring physical and electrochemical processes, as well as to design actuators capable of delivering optimum electrical and mechanical response.

  8. Evaluation of electron beam radiation effects in the incorporation of Piassava fibers (Attalea funifera Mart.) on ethylene vinyl alcohol copolymer (EVOH); Avaliacao dos efeitos da radiacao ionizante por feixe de eletrons na incorporacao de fibra de Piacava (Attalea funifera Mart.) no copolimero de etileno e alcool vinilico (EVOH)

    Energy Technology Data Exchange (ETDEWEB)

    Nogueira, Beatriz Ribeiro

    2012-07-01

    The aim of this work is to explore the contribution of ionizing radiation in the incorporation of piassava fibers (derived from wastes from broom factories) in the ethylene vinyl alcohol copolymer (EVOH), to obtain a composite material, {sup E}VOH-Piassava{sup ,} for packaging applications. The interest in this fiber is due to its inherent properties and morphology as well as being biodegradable. The EVOH composite reinforced with 5% or 10%, by weight of piassava fiber powder with a particle size equal to or less than 125 {mu}m, untreated or treated with 1% silane, were obtained by extrusion, using a twin screw extruder. For carrying out the tensile tests and oxygen barrier of the materials obtained, films were produced from composite materials and EVOH resin was obtained using the process of flat extrusion. Samples of EVOH and the composites were irradiated using an electron accelerator, at doses from 0 to 500 kGy. The results of SEM analysis and X-ray diffraction of composites suggest a good fiber-matrix adhesion, which can be also confirmed by its higher tensile strength at break, compared to that of neat EVOH. The results showed that the incorporation of piassava fibers can promote better oxygen barrier compared to the neat EVOH, in conditions of high humidity. It was observed that, after irradiation, the EVOH film showed better oxygen barrier in high humidity condition, when compared to the non-irradiated EVOH under the same condition, indicating radiation as an effective treatment to improve oxygen barrier in the studied conditions. (author)

  9. Advanced Electroactive Single Crystal and Polymer Actuators for Passive Optics Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Large stroke and high precision electroactive single crystal and polymer actuators are desired for cryogenic passive optics such as Fabry-Perot Interferometer (FPI)...

  10. Aligned Electroactive TMV Nanofibers as Enabling Scaffold for Neural Tissue Engineering.

    Science.gov (United States)

    Wu, Yehong; Feng, Sheng; Zan, Xingjie; Lin, Yuan; Wang, Qian

    2015-11-09

    Electroactive nanofibers were fabricated by in situ polymerization of aniline on the surface of tobacco mosaic virus (TMV) using sodium poly(styrenesulfonate) (PSS) as dopant. These electroactive TMV/PANi/PSS nanofibers were employed to support growth of neuronal cells, resulting in augmentation of the length of neurites. In addition, the percentage of cells with neurites was increased in comparison to cells cultured on TMV-derived nonconductive nanofibers. The TMV-based electroactive nanofibers could be aligned in capillaries that could guide the outgrowth direction of neurites, increase the percentage of cells with neurites, and lead to a bipolar cellular morphology. Our results demonstrate that the electroactivity and topographical cues provided by TMV/PANi/PSS nanofibers can synergistically stimulate neural cells differentiation and neurites outgrowth, which make it a promising scaffolding material for neural tissue engineering.

  11. STUDY ON PET-PA66 COPOLYMER

    Institute of Scientific and Technical Information of China (English)

    WU Rongrui; SHI Weitong

    1992-01-01

    In this work the PET-PA66 copolymers are obtained. The characterization of chemical structure of copolymer chain by NMR method is also given . It is shown that when the 66 Nylon salt is added in the copolycondensation, the adipic acid and hexamethylenediamine reacted mainly by itself and the obtained copolymer is a random copolymer, and when the Nylon 66 oligomer is added, the obtained copolymer is a block copolymer. The result of NMR analysis is demonstrated by properties investigation.

  12. 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.

  13. Block copolymer battery separator

    Science.gov (United States)

    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.

  14. Electroactivity of PVDF electrospun fiber mats and ZNO-PVDF composites

    OpenAIRE

    Öğüt, Erdem; Ogut, Erdem

    2007-01-01

    Poly (vinylidene fluoride) (PVDF), an electroactive polymer, has great distinctions for its mechanical properties compared to highly brittle electroceramics. Its piezoelectricity however is not immediately utilizable after being cast in film form, and the cast PVDF film requires additional processes, such as mechanical stretching and poling. In this thesis, alternative to cast PVDF film, electroactive characteristics of PVDF fibrous mats produced by electrospinning are investigated to seek wh...

  15. Block copolymer adhesion promoters via ring-opening metathesis polymerization

    Science.gov (United States)

    Kent, M.S.; Saunders, R.

    1997-02-18

    Coupling agents are disclosed based on functionalized block copolymers for bonding thermoset polymers to solid materials. These are polymers which possess at least two types of functional groups, one which is able to attach to and react with solid surfaces, and another which can react with a thermoset resin, which are incorporated as pendant groups in monomers distributed in blocks (typically two) along the backbone of the chain. The block copolymers in this invention are synthesized by living ring-opening metathesis polymerization. 18 figs.

  16. Electroactive biomimetic collagen-silver nanowire composite scaffolds

    Science.gov (United States)

    Wickham, Abeni; Vagin, Mikhail; Khalaf, Hazem; Bertazzo, Sergio; Hodder, Peter; Dånmark, Staffan; Bengtsson, Torbjörn; Altimiras, Jordi; Aili, Daniel

    2016-07-01

    Electroactive biomaterials are widely explored as bioelectrodes and as scaffolds for neural and cardiac regeneration. Most electrodes and conductive scaffolds for tissue regeneration are based on synthetic materials that have limited biocompatibility and often display large discrepancies in mechanical properties with the surrounding tissue causing problems during tissue integration and regeneration. This work shows the development of a biomimetic nanocomposite material prepared from self-assembled collagen fibrils and silver nanowires (AgNW). Despite consisting of mostly type I collagen fibrils, the homogeneously embedded AgNWs provide these materials with a charge storage capacity of about 2.3 mC cm-2 and a charge injection capacity of 0.3 mC cm-2, which is on par with bioelectrodes used in the clinic. The mechanical properties of the materials are similar to soft tissues with a dynamic elastic modulus within the lower kPa range. The nanocomposites also support proliferation of embryonic cardiomyocytes while inhibiting the growth of both Gram-negative Escherichia coli and Gram-positive Staphylococcus epidermidis. The developed collagen/AgNW composites thus represent a highly attractive bioelectrode and scaffold material for a wide range of biomedical applications.Electroactive biomaterials are widely explored as bioelectrodes and as scaffolds for neural and cardiac regeneration. Most electrodes and conductive scaffolds for tissue regeneration are based on synthetic materials that have limited biocompatibility and often display large discrepancies in mechanical properties with the surrounding tissue causing problems during tissue integration and regeneration. This work shows the development of a biomimetic nanocomposite material prepared from self-assembled collagen fibrils and silver nanowires (AgNW). Despite consisting of mostly type I collagen fibrils, the homogeneously embedded AgNWs provide these materials with a charge storage capacity of about 2.3 mC cm-2

  17. Polyether/Polyester Graft Copolymers

    Science.gov (United States)

    Bell, Vernon L., Jr.; Wakelyn, N.; Stoakley, D. M.; Proctor, K. M.

    1986-01-01

    Higher solvent resistance achieved along with lower melting temperature. New technique provides method of preparing copolymers with polypivalolactone segments grafted onto poly (2,6-dimethyl-phenylene oxide) backbone. Process makes strong materials with improved solvent resistance and crystalline, thermally-reversible crosslinks. Resulting graft copolymers easier to fabricate into useful articles, including thin films, sheets, fibers, foams, laminates, and moldings.

  18. Temperature and humidity dependence of ionic electroactive polymer actuators

    Science.gov (United States)

    Nakshatharan, S. Sunjai; Punning, Andres; Aabloo, Alvo

    2017-04-01

    The ionic electroactive polymer (IEAP) actuators with carbonaceous electrodes and ionic liquid electrolytes are distinguished by their ability for operation in open air. Nevertheless, their behavior is influenced by at least two parameters of the ambient environment - temperature and humidity. Both parameters affect many factors of the IEAP materials: viscosity and ionic conductivity of the electrolyte, specific capacitance of the electrodes, stiffness of the polymer, etc. This circumstance makes it difficult to comprehend the actual physical and electrochemical processes occurring in the IEAP materials as well as hinders the control of the actuators in the possible applications. This work is focused on characterizing the temperature and humidity-dependence of the electromechanical and electrochemical response of IEAP actuators. An extensive experiment was performed with several types of IEAP actuators in a temperature- and humidity-controlled environment. The characterization of electrical and electromechanical response measurements were carried out at temperatures ranging from 0°C to +60°C and relative humidity ranging from 0% to 90%. The result showing that impact of both parameters on IEAP actuators is easily recognizable.

  19. Considerations for Contractile Electroactive Polymeric Materials and Actuators

    Energy Technology Data Exchange (ETDEWEB)

    Rasmussen, Lenore; Erickson, Carl J.; Meixler, Lewis D.; Ascione, George; Gentile, Charles A.; Tilson, Charles; Bernasek, Stephen L.; Abelev, Esta

    2009-06-16

    Ras Labs produces electroactive polymer (EAP) based materials and actuators that bend, swell, ripple and now contract (new development) with low electric input. This is an important attribute because of the ability of contraction to produce life-like motion. The mechanism of contraction is not well understood. Radionuclide-labeled experiments were conducted to follow the movement of electrolytes and water in these EAPs when activated. Extreme temperature experiments were performed on the contractile EAPs with very favorable results. One of the biggest challenges in developing these actuators, however, is the electrode-EAP interface because of the pronounced movement of the EAP. Plasma treatments of metallic electrodes were investigated in order to improve the attachment of the embedded electrodes to the EAP material. Surface analysis, adhesive testing, and mechanical testing were conducted to test metal surfaces and metal-polymer interfaces. The nitrogen plasma treatment of titanium produced a strong metal-polymer interface; however, oxygen plasma treatment of both stainless steel and titanium produced even stronger metal-polymer interfaces. Plasma treatment of the electrodes allows for the embedded electrodes and the EAP material of the actuator to work and move as a unit, with no detachment, by significantly improving the metal-polymer interface.

  20. Bio-kinetic energy harvesting using electroactive polymers

    Science.gov (United States)

    Slade, Jeremiah R.; Bowman, Jeremy; Kornbluh, Roy

    2012-06-01

    In hybrid vehicles, electric motors are used on each wheel to not only propel the car but also to decelerate the car by acting as generators. In the case of the human body, muscles spend about half of their time acting as a brake, absorbing energy, or doing what is known as negative work. Using dielectric elastomers it is possible to use the "braking" phases of walking to generate power without restricting or fatiguing the Warfighter. Infoscitex and SRI have developed and demonstrated methods for using electroactive polymers (EAPs) to tap into the negative work generated at the knee during the deceleration phase of the human gait cycle and convert it into electrical power that can be used to support wearable information systems, including display and communication technologies. The specific class of EAP that has been selected for these applications is termed dielectric elastomers. Because dielectric elastomers dissipate very little mechanical energy into heat, greater amounts of energy can be converted into electricity than by any other method. The long term vision of this concept is to have EAP energy harvesting cells located in components of the Warfighter ensemble, such as the boot uppers, knee pads and eventually even the clothing itself. By properly locating EAPs at these sites it will be possible to not only harvest power from the negative work phase but to actually reduce the amount of work done by the Warfighter's muscles during this phase, thereby reducing fatigue and minimizing the forces transmitted to the joints.

  1. High-Force Dielectric Electroactive Polymer (DEAP) membrane actuator

    Science.gov (United States)

    Hau, Steffen; York, Alexander; Seelecke, Stefan

    2016-04-01

    Energy efficiency, lightweight and scalability are key features for actuators in applications such as valves, pumps or any portable system. Dielectric electroactive Polymer (DEAP) technology is able to fulfill these requirements1 better than commonly used technology e.g. solenoids, but has limitations concerning force and stroke. However, the circular DEAP membrane actuator shows a potential increase in stroke in the mm range, when combined with an appropriate biasing mechanism2. Although, thus far, their force range is limited to the single-digit Newton range, or less3,4. This work describes how this force limit of DEAP membrane actuators can be pushed to the high double-digit Newton range and beyond. The concept for such an actuator consists of a stack of double-layered DEAPs membrane actuator combined with a biasing mechanism. These two components are combined in a novel way, which allows a compact design by integrating the biasing mechanism into the DEAP membrane actuator stack. Subsequently, the single components are manufactured, tested, and their force-displacement characteristic is documented. Utilizing this data allows assembling them into actuator systems for different applications. Two different actuators are assembled and tested (dimensions: 85x85x30mm3 (LxWxH)). The first one is able to lift 7.5kg. The second one can generate a force of 66N while acting against a spring load.

  2. Antimicrobial applications of electroactive PVK-SWNT nanocomposites.

    Science.gov (United States)

    Ahmed, Farid; Santos, Catherine M; Vergara, Regina Aileen May V; Tria, Maria Celeste R; Advincula, Rigoberto; Rodrigues, Debora F

    2012-02-07

    The antibacterial properties of a nanocomposite containing an electroactive polymer, polyvinyl-N-carbazole (PVK) (97 wt %), and single-walled carbon nanotubes (SWNT) (3 wt %) was investigated as suspensions in water and as thin film coatings. The toxic effects of four different PVK-SWNT (97:3 wt %) nanocomposite concentrations (1, 0.5, 0.05, and 0.01 mg/mL) containing 0.03, 0.015, 0.0015, and 0.0003 mg/mL of SWNT, respectively, were determined for planktonic cells and biofilms of Escherichia coli (E. coli) and Bacillus subtilis (B. subtilis). The results showed that the nanocomposite PVK-SWNT had antibacterial activity on planktonic cells and biofilms at all concentration levels. Higher bacterial inactivation (94% for E. coli and 90% for B. subtilis) were achieved in planktonic cells at a PVK-SWNT concentration of 1 mg/mL. Atomic force microscopy (AFM) imaging showed significant reduction of biofilm growth on PVK-SWNT coated surfaces. This study established for the first time that the improved dispersion of SWNTs in aqueous solutions in the presence of PVK enhances the antimicrobial effects of SWNTs at very low concentrations. Furthermore, PVK-SWNT can be used as an effective thin film coating material to resist biofilm formation.

  3. Piezoelectric sensor characteristics of electro-active paper

    Science.gov (United States)

    Lee, Ho Cheol; Kim, Heung Soo; Yun, Gyu Young; Kim, Jaehwan

    2009-03-01

    The possibility as a vibration sensor of Electro-Active paper (EAPap) based on piezoelectricity was investigated in the present paper. The EAPap was fabricated by regenerating and tape casting cellulose. The sample was coated by thin laminating film for packaging. The capacitance of EAPap was measured and compared with commercial PVDF. Relative permittivity of EAPap was 12, which was same as commercially available PVDF. This reveals that EAPap has similar sensing potential of synthetic piezo polymer film. The simple aluminum cantilevered beam was used for the vibration testing and EAPap was attached on the beam. The original EAPap sensor without grounding and shielding has greatly affected by the surrounding noise such as power noise especially. The power noise reduced dramatically with grounding and shielding of EAPap. The impulsive response of EAPap provided correct dynamic characteristics of the beam. Especially, twisting mode of the beam was clearly observed even though the EAPap was attached at the center of the beam. This is because the sensing capability of EAPap is based on piezoelectricity which is bidirectional strain characteristics. EAPap sensor based on piezoelectricity provided a great potential as a vibration sensor.

  4. Structure-Property Relationships of Poly(lactide)-based Triblock and Multiblock Copolymers

    Science.gov (United States)

    Panthani, Tessie Rose

    Replacing petroleum-based plastics with alternatives that are degradable and synthesized from annually renewable feedstocks is a critical goal for the polymer industry. Achieving this goal requires the development of sustainable analogs to commodity plastics which have equivalent or superior properties (e.g. mechanical, thermal, optical etc.) compared to their petroleum-based counterparts. This work focuses on improving and modulating the properties of a specific sustainable polymer, poly(lactide) (PLA), by incorporating it into triblock and multiblock copolymer architectures. The multiblock copolymers in this work are synthesized directly from dihydroxy-terminated triblock copolymers by a simple step-growth approach: the triblock copolymer serves as a macromonomer and addition of stoichiometric quantities of either an acid chloride or diisocyanate results in a multiblock copolymer. This work shows that over wide range of compositions, PLA-based multiblock copolymers have superior mechanical properties compared to triblock copolymers with equivalent chemical compositions and morphologies. The connectivity of the blocks within the multiblock copolymers has other interesting consequences on properties. For example, when crystallizable poly(L-lactide)-based triblock and multiblock copolymers are investigated, it is found that the multiblock copolymers have much slower crystallization kinetics. Additionally, the total number of blocks connected together is found to effect the linear viscoelastic properties as well as the alignment of lamellar domains under uniaxial extension. Finally, the synthesis and characterization of pressure-sensitive adhesives based upon renewable PLA-containing triblock copolymers and a renewable tackifier is detailed. Together, the results give insight into the effect of chain architecture, composition, and morphology on the mechanical behavior, thermal properties, and rheological properties of PLA-based materials.

  5. Formation of nanophases in epoxy thermosets containing amphiphilic block copolymers with linear and star-like topologies.

    Science.gov (United States)

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

    2013-07-11

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

  6. Electrically and chemically tunable soft-solid block copolymer structural color (Conference Presentation)

    Science.gov (United States)

    Park, Cheolmin

    2016-09-01

    1D photonic crystals based on the periodic stacking of two different dielectric layers have been widely studied due to their potential use in low-power reflective mode displays, e-books and sensors, but the fabrication of mechanically flexible polymer structural color (SC) films, with electro-active color switching, remains challenging. Here, we demonstrate free-standing electric field tunable ionic liquid swollen block copolymer films. Placement of a polymer/ionic liquid (IL) film-reservoir adjacent to a self-assembled poly(styrene-block-quaternized 2vinyl pyridine) (PS-b-QP2VP) copolymer SC film allowed the development of R, G and B full-color SC block copolymer films by swelling of the QP2VP domains by the ionic liquid associated with water molecules. The IL-polymer/BCP SC film is mechanically flexible with excellent color stability over several days at ambient conditions. The selective swelling of the QP2VP domains could be controlled by both the ratio of the IL to a polymer in the gel-like IL reservoir layer and by an applied voltage in the range of -3V to +6V using a metal/IL reservoir/SC film/IL reservoir/metal capacitor type device.

  7. Polyhydroxyalkanoate copolymers from forest biomass.

    Science.gov (United States)

    Keenan, Thomas M; Nakas, James P; Tanenbaum, Stuart W

    2006-07-01

    The potential for the use of woody biomass in poly-beta-hydroxyalkanoate (PHA) biosynthesis is reviewed. Based on previously cited work indicating incorporation of xylose or levulinic acid (LA) into PHAs by several bacterial strains, we have initiated a study for exploring bioconversion of forest resources to technically relevant copolymers. Initially, PHA was synthesized in shake-flask cultures of Burkholderia cepacia grown on 2.2% (w/v) xylose, periodically amended with varying concentrations of levulinic acid [0.07-0.67% (w/v)]. Yields of poly(beta-hydroxybutyrate-co-beta-hydroxyvalerate) [P(3HB-co-3HV)] from 1.3 to 4.2 g/l were obtained and could be modulated to contain from 1.0 to 61 mol% 3-hydroxyvalerate (3HV), as determined by 1H and 13C NMR analyses. No evidence for either the 3HB or 4HV monomers was found. Characterization of these P(3HB-co-3HV) samples, which ranged in molecular mass (viscometric, Mv) from 511-919 kDa, by differential scanning calorimetry and thermogravimetric analyses (TGA) provided data which were in agreement for previously reported P(3HB-co-3HV) copolymers. For these samples, it was noted that melting temperature (Tm) and glass transition temperature (Tg) decreased as a function of 3HVcontent, with Tm demonstrating a pseudoeutectic profile as a function of mol% 3HV content. In order to extend these findings to the use of hemicellulosic process streams as an inexpensive carbon source, a detoxification procedure involving sequential overliming and activated charcoal treatments was developed. Two such detoxified process hydrolysates (NREL CF: aspen and CESF: maple) were each fermented with appropriate LA supplementation. For the NREL CF hydrolysate-based cultures amended with 0.25-0.5% LA, P(3HB-co-3HV) yields, PHA contents (PHA as percent of dry biomass), and mol% 3HV compositions of 2.0 g/l, 40% (w/w), and 16-52 mol% were obtained, respectively. Similarly, the CESF hydrolysate-based shake-flask cultures yielded 1.6 g/l PHA, 39% (w

  8. 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

  9. Mechanically compliant electrodes and dielectric elastomers from PEG-PDMS copolymers

    DEFF Research Database (Denmark)

    A Razak, Aliff Hisyam; Madsen, Frederikke Bahrt; Skov, Anne Ladegaard

    2016-01-01

    Soft conducting elastomers have been prepared from polydimethylsiloxane-polyethyleneglycol (PDMS-PEG) copolymer and surfactant-stabilized multi-walled carbon nanotubes (MWCNTs). The copolymer was chain-extended with PDMS of molecular weight 17.2 kg mol-1 in order to obtain a crosslinkable PDMS...... showed high conductivity combined with inherent softness. The high conductivity and softness, PDMS-PEG copolymers with incorporated MWCNTs hold great promises as compliant and highly stretchable electrodes for stretchable devices such as electro-mechanical transducers....

  10. An Electrochemical Study of Two Self-Dopable Water-Soluble Aniline Derivatives: Electrochemical Deposition of Copolymers

    Directory of Open Access Journals (Sweden)

    Loredana Vacareanu

    2012-01-01

    Full Text Available An electrochemical study of two water-soluble aniline derivatives, N-(3-sulfopropyl aniline (AnPS and N-(3-sulfopropyl p-aminodiphenylamine (DAnPS, in aqueous acidic electrolytic solutions containing different kinds of doping anions (Cl −, SO4 2−, and ClO4 − was carried out. At sufficiently high anodic potential, the sulfonated aniline derivatives undergo oxidation processes yielding cation-radical and dimer intermediates, but no polymer deposition was observed on the working electrode surface. Experimental results showed that both aniline derivatives are electroactive compounds exhibiting redox behaviour in the range of potential of −0.2 V–1.6 V. Due to the self-doping effect induced by sulfonic groups, AnPS and DAnPS compounds have good electroactivity even in neat water solution. By adding a small amount of aniline into electrolytic system, thin layers of copolymers were deposited on the working electrode surface. The copolymer layers formed on the electrodes show a highly orientational and positional order, confirmed by AFM and XRD spectroscopic techniques. During the anodic oxidation processes some distinct colour changes were observed.

  11. Synthesis, characterization, and applications of electroactive polymeric nanostructures for organic coatings

    Science.gov (United States)

    Suryawanshi, Abhijit Jagnnath

    Electroactive polymers (EAP) such as polypyrrole (PPy) and polyaniline (PANI) are being explored intensively in the scientific community. Nanostructures of EAPs have low dimensions and high surface area enabling them to be considered for various useful applications. These applications are in several fields including corrosion inhibition, capacitors, artificial muscles, solar cells, polymer light emitting diodes, and energy storage devices. Nanostructures of EAPs have been synthesized in different morphologies such as nanowires, nanorods, nanotubes, nanospheres, and nanocapsules. This variety in morphology is traditionally achieved using soft templates, such as surfactant micelles, or hard templates, such as anodized aluminum oxide (AAO). Templates provide stability and groundwork from which the polymer can grow, but the templates add undesirable expense to the process and can change the properties of the nanoparticles by integrating its own properties. In this study a template free method is introduced to synthesize EAP nanostructures of PPy and PANI utilizing ozone oxidation. The simple techniques involve ozone exposure to the monomer solution to produce aqueous dispersions of EAP nanostructures. The synthesized nanostructures exhibit uniform morphology, low particle size distribution, and stability against agglomeration. Ozone oxidation is further explored for the synthesis of silver-PPy (Ag-PPy) core-shell nanospheres (CSNs). Coatings containing PPy nanospheres were formulated to study the corrosion inhibition efficiency of PPy nanospheres. Investigation of the coatings using electrochemical techniques revealed that the PPy nanospheres may provide corrosion inhibition against filiform corrosion by oxygen scavenging mechanism. Finally, organic corrosion inhibitors were incorporated in PPy to develop efficient corrosion inhibiting systems, by using the synergistic effects from PPy and organic corrosion inhibitors.

  12. On the Use of Self-Assembling Block Copolymers to Toughen A Model Epoxy

    Science.gov (United States)

    Chen, Yilin

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

  13. Electroactive Polymer (EAP) Actuators as Artificial Muscles Reality, Potential, and Challenges

    CERN Document Server

    Bar-Cohen, Yoseph

    2004-01-01

    In concept and execution, this book covers the field of EAP with careful attention to all its key aspects and full infrastructure, including the available materials, analytical models, processing techniques, and characterization methods. In this second edition the reader is brought current on promising advances in EAP that have occurred in electric EAP, electroactive polymer gels, ionomeric polymer-metal composites, carbon nanotube actuators, and more. "'Electroactive Polymer (EAP) Actuators as Artificial Muscles' is a delightful book dealing with one of the hottest topics in biomedical e

  14. An Electromechanical Model for a Dielectric ElectroActive Polymer Generator

    DEFF Research Database (Denmark)

    Dimopoulos, Emmanouil; Trintis, Ionut; Munk-Nielsen, Stig;

    2013-01-01

    Smart electroactive materials have attracted much of the scientific interest over the past few years, as they reflect a quite promising alternative to conservative approaches used nowadays in various transducer applications. Especially Dielectric ElectroActive Polymers (DEAPs), which are constantly...... gaining momentum due to their superior low-speed performance, light-weighted nature and higher energy density when compared with competing technologies. In this paper an electromechanical model for a DEAP generator is presented, accounting for both the visco-hyperelastic characteristics of the polymer...

  15. Synthesis and characterization of a novel PNIPAAm-based copolymer with hydrolysis-dependent thermosensitivity.

    Science.gov (United States)

    Rosellini, Elisabetta; Cristallini, Caterina; Guerra, Giulio D; Barbani, Niccoletta; Giusti, Paolo

    2010-06-01

    The aim of this work was the synthesis and characterization of a novel poly(N-isopropylacrylamide)-based copolymer, with hydrolysis-dependent thermosensitivity, for bioengineering applications. For this purpose, N-isopropylacrylamide (NIPAAm) and 2-hydroxyethylmethacrylate-6-hydroxyhexanoate (HEMAHex) monomers were chosen. The poly(NIPAAm-co-HEMAHex) copolymer was synthesized by radical polymerization. The physicochemical, mechanical, functional and biological properties of the copolymer were investigated. The physicochemical characterization confirmed that the copolymerization was successfully carried out. In addition, the newly synthesized poly(NIPAAm-co-HEMAHex) copolymer showed temperature sensitivity, with a phase separation temperature under body temperature (at 23 °C). Fourier transform infrared spectroscopy and differential scanning calorimetry results after hydrolysis tests indicated that the incorporation of the HEMAHex ester groups provides the cleavage of the lateral chain, which leads to an increase in the hydrophilicity of the copolymer and, consequently, to an increase in the lower critical solution temperature (LCST) with time. Since the LCST increases above body temperature (up to 40.4 °C), the copolymer becomes soluble again and diffuses away. It was also demonstrated that the hydrolysis occurred on the peripheral ester bond of the lateral chain, with the release of 6-hydroxyhexanoic acid, whose bioresorbibility has been reported in the literature. Therefore, the properties of this copolymer are very interesting and make it particularly attractive for biomedical applications.

  16. Synthesis and properties of acrylic copolymers for ocular implants

    Science.gov (United States)

    Reboul, Adam C.

    There is a need for flexible polymers with higher refractive index and extended UV absorbing properties for improved intraocular lenses (IOLs). This research was devoted to the synthesis of new acrylic copolymers for foldable IOLs and to studies concerning IOL polymer properties. New polymers were synthesized from phenylated acrylates copolymerized with N-vinyl carbazole derivatives using bulk free radical addition methods. The copolymers had low Tg values, high refractive index, and were flexible. The N-vinyl carbazole derivatives were characterized by NMR and copolymers were characterized by DSC, UV-Vis, and refractometry. New phenothiazine based UV absorbers with high extinction coefficients were also synthesized for incorporation into ocular materials. Patent disclosures on UV absorbers and high refractive index polymers were prepared. A so called "glistening" phenomenon that occurs in all foldable intraocular lenses currently in clinical use is poorly understood and was studied. Research on this microvoid forming behavior included studies and development of methods to inhibit glistening in low Tg acrylic based copolymers. Glistenings were characterized using SEM and optical microscopy. A novel technique for inhibiting glistening was found and a patent disclosure was prepared.

  17. Hydrophilization of poly(caprolactone copolymers through introduction of oligo(ethylene glycol moieties.

    Directory of Open Access Journals (Sweden)

    Jonathan J Wurth

    Full Text Available In this study, a new family of poly(ε-caprolactone (PCL copolymers that bear oligo(ethylene glycol (OEG moieties is described. The synthesis of three different oligo(ethylene glycol functionalized epoxide monomers derived from 2-methyl-4-pentenoic acid, and their copolymerization with ε-caprolactone (CL to poly(CL-co-OEG-MPO copolymers is presented. The statistical copolymerization initiated with SnOct2/BnOH yielded the copolymers with varying OEG content and composition. The linear relationship between feed ratio and incorporation of the OEG co-monomer enables control over backbone functional group density. The introduction of OEG moieties influenced both the thermal and the hydrophilic characteristics of the copolymers. Both increasing OEG length and backbone content resulted in a decrease in static water contact angle. The introduction of OEG side chains in the PCL copolymers had no adverse influence on MC-3TE3-E1 cell interaction. However, changes to cell form factor (Φ were observed. While unmodified PCL promoted elongated (anisotropic morphologies (Φ = 0.094, PCL copolymer with tri-ethylene glycol side chains at or above seven percent backbone incorporation induced more isotropic cell morphologies (Φ = 0.184 similar to those observed on glass controls (Φ = 0.151.

  18. Electrochemical Study and Determination of Electroactive Species with Screen-Printed Electrodes

    Science.gov (United States)

    Martín-Yerga, Daniel; Costa Rama, Estefanía; Costa García, Agustín

    2016-01-01

    A lab appropriate to introduce voltammetric techniques and basic electrochemical parameters is described in this work. It is suitable to study theoretical concepts of electrochemistry in an applied way for analytical undergraduate courses. Two electroactive species, hexaammineruthenium and dopamine, are used as simple redox systems. Screen-printed…

  19. Thick electrodes including nanoparticles having electroactive materials and methods of making same

    Science.gov (United States)

    Xiao, Jie; Lu, Dongping; Liu, Jun; Zhang, Jiguang; Graff, Gordon L.

    2017-02-21

    Electrodes having nanostructure and/or utilizing nanoparticles of active materials and having high mass loadings of the active materials can be made to be physically robust and free of cracks and pinholes. The electrodes include nanoparticles having electroactive material, which nanoparticles are aggregated with carbon into larger secondary particles. The secondary particles can be bound with a binder to form the electrode.

  20. Self-Organization of Electroactive Suspensions in Discharging Slurry Batteries: A Mesoscale Modeling Investigation.

    Science.gov (United States)

    Shukla, Garima; Del Olmo Diaz, Diego; Thangavel, Vigneshwaran; Franco, Alejandro A

    2017-05-31

    We report a comprehensive modeling-based study of electroactive suspensions in slurry redox flow batteries undergoing discharge. A three-dimensional kinetic Monte Carlo model based on the variable step size method is used to describe the electrochemical discharge of a silicon/carbon slurry electrode in static mode (i.e., no fluid flow conditions). The model accounts for Brownian motion of particles, volume expansion of silicon upon lithium insertion, and formation and destruction of conducting carbon networks. Coupled to an electrochemical model, this study explores the impact of carbon fraction in the slurry and applied c-rate on the specific capacity. The trends obtained are analyzed by following the behavior of parameters such as number of contacts between electroactive particles and the percentage of electroactive silicon particles. Furthermore, instead of studying the bulk behavior of the slurry, here the focus is given to the slurry/current collector interface in order to illustrate its importance. Hereby, it is demonstrated how this modeling tool can lead to deeper understanding and optimization of electroactive particle suspensions in redox flow batteries.

  1. The impact of shearing flows on electroactive biofilm formation, structure, and current generation

    Science.gov (United States)

    Jones, A.-Andrew; Buie, Cullen

    2016-11-01

    A special class of bacteria exist that directly produce electricity. First explored in 1911, these electroactive bacteria catalyze hydrocarbons and transport electrons directly to a metallic electron acceptor forming thicker biofilms than other species. Electroactive bacteria biofilms are thicker because they are not limited by transport of oxygen or other terminal electron acceptors. Electroactive bacteria can produce power in fuel cells. Power production is limited in fuel cells by the bacteria's inability to eliminate protons near the insoluble electron acceptor not utilized in the wild. To date, they have not been successfully evolved or engineered to overcome this limit. This limitation may be overcome by enhancing convective mass transport while maintaining substantial biomass within the biofilm. Increasing convective mass transport increases shear stress. A biofilm may respond to increased shear by changing biomass, matrix, or current production. In this study, a rotating disk electrode is used to separate nutrient from physical stress. This phenomenon is investigated using the model electroactive bacterium Geobacter sulfurreducens at nutrient loads comparable to flow-through microbial fuel cells. We determine biofilm structure experimentally by measuring the porosity and calculating the tortuosity from confocal microscope images. Biofilm adaptation for electron transport is quantified using electrical impedance spectroscopy. Our ultimate objective is a framework relating biofilm thickness, porosity, shear stress and current generation for the optimization of bioelectrochemical systems The Alfred P Sloan Foundation MPHD Program.

  2. Thick electrodes including nanoparticles having electroactive materials and methods of making same

    Energy Technology Data Exchange (ETDEWEB)

    Xiao, Jie; Lu, Dongping; Liu, Jun; Zhang, Jiguang; Graff, Gordon L.

    2017-02-21

    Electrodes having nanostructure and/or utilizing nanoparticles of active materials and having high mass loadings of the active materials can be made to be physically robust and free of cracks and pinholes. The electrodes include nanoparticles having electroactive material, which nanoparticles are aggregated with carbon into larger secondary particles. The secondary particles can be bound with a binder to form the electrode.

  3. Inducing Order from Disordered Copolymers: On Demand Generation of Triblock Morphologies Including Networks

    Energy Technology Data Exchange (ETDEWEB)

    Tureau, Maëva S.; Kuan, Wei-Fan; Rong, Lixia; Hsiao, Benjamin S.; Epps, III, Thomas H. (Delaware); (Buffalo)

    2015-10-15

    Disordered block copolymers are generally impractical in nanopatterning applications due to their inability to self-assemble into well-defined nanostructures. However, inducing order in low molecular weight disordered systems permits the design of periodic structures with smaller characteristic sizes. Here, we have induced nanoscale phase separation from disordered triblock copolymer melts to form well-ordered lamellae, hexagonally packed cylinders, and a triply periodic gyroid network structure, using a copolymer/homopolymer blending approach, which incorporates constituent homopolymers into selective block domains. This versatile blending approach allows one to precisely target multiple nanostructures from a single disordered material and can be applied to a wide variety of triblock copolymer systems for nanotemplating and nanoscale separation applications requiring nanoscale feature sizes and/or high areal feature densities.

  4. BARRIER PROPERTIES OF VINYLIDENE CHLORIDE COPOLYMERS

    Institute of Scientific and Technical Information of China (English)

    LI Yuesheng; WENG Zhixue; HUANG Zhiming; PAN Zuren

    1996-01-01

    The permeability coefficients of a series of copolymers of vinylidene chloride (VDC)with methyl acrylate (MA), butyl acrylate (BA) or vinyl chloride (VC) (as comonomer)to oxygen and carbon dioxide have been measured at 1.0 MPa and 30℃, while those to water vapor have been measured at 30℃ and 100% relative humidity. All the copolymers are semicrystalline. VDC/MA copolymers have lower melting temperature compared with VDC/BA copolymers, while that melting temperature of VDC/VC copolymer is higher than that of VDC/acrylate copolymers with the same VDC content. The barrier property of the copolymers is predominantly controlled by crystallite, free volume fraction, and cohesive energy. The permeability coefficients of VDC/MA copolymers to oxygen, carbon dioxide, and water vapor were successfully correlated with the ratio of free volume to cohesive energy.

  5. Lignin poly(lactic acid) copolymers

    Energy Technology Data Exchange (ETDEWEB)

    Olsson, Johan Vilhelm; Chung, Yi-Lin; Li, Russell Jingxian; Waymouth, Robert; Sattely, Elizabeth; Billington, Sarah; Frank, Curtis W.

    2017-02-14

    Provided herein are graft co-polymers of lignin and poly(lactic acid) (lignin-g-PLA copolymer), thermoset and thermoplastic polymers including them, methods of preparing these polymers, and articles of manufacture including such polymers.

  6. Phase inversion in polylactide/soybean oil blends compatibilized by poly(isoprene-b-lactide) block copolymers.

    Science.gov (United States)

    Chang, Kwanho; Robertson, Megan L; Hillmyer, Marc A

    2009-10-01

    Renewable composites were prepared by melt blending of polylactide and soybean oil. The blend morphology was tuned by the addition of poly(isoprene-b-lactide) block copolymers. Due to the extreme difference in the viscosities of soybean oil and polylactide, a critical block copolymer composition was found to induce a phase inversion point at which the minor soybean oil phase became the matrix surrounding polylactide particles. This transition was due to the thermodynamic interactions between the block copolymer and the two phases and shear forces acting on the mixture during blending. The size of the soybean oil droplets in the polylactide matrix was also highly dependent on the block copolymer composition. In binary polylactide/soybean oil blends, there was a limiting concentration of soybean oil that could be incorporated into the polylactide matrix (6% of the total blend weight), which could be increased up to 20% by the addition of block copolymers.

  7. 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 leng...

  8. 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...

  9. Copolymers For Capillary Gel Electrophoresis

    Science.gov (United States)

    Liu, Changsheng; Li, Qingbo

    2005-08-09

    This invention relates to an electrophoresis separation medium having a gel matrix of at least one random, linear copolymer comprising a primary comonomer and at least one secondary comonomer, wherein the comonomers are randomly distributed along the copolymer chain. The primary comonomer is an acrylamide or an acrylamide derivative that provides the primary physical, chemical, and sieving properties of the gel matrix. The at least one secondary comonomer imparts an inherent physical, chemical, or sieving property to the copolymer chain. The primary and secondary comonomers are present in a ratio sufficient to induce desired properties that optimize electrophoresis performance. The invention also relates to a method of separating a mixture of biological molecules using this gel matrix, a method of preparing the novel electrophoresis separation medium, and a capillary tube filled with the electrophoresis separation medium.

  10. Polyethylene-Based Tadpole Copolymers

    KAUST Repository

    Alkayal, Nazeeha

    2017-02-15

    Novel well-defined polyethylene-based tadpole copolymers ((c-PE)-b-PS, PE: polyethylene, PS: polystyrene) with ring PE head and linear PS tail are synthesized by combining polyhomologation, atom transfer radical polymerization (ATRP), and Glaser coupling reaction. The -OH groups of the 3-miktoarm star copolymers (PE-OH)-b-PS, synthesized by polyhomologation and ATRP, are transformed to alkyne groups by esterification with propiolic acid, followed by Glaser cyclization and removal of the unreacted linear with Merrifield\\'s resin-azide. The characterization results of intermediates and final products by high-temperature size exclusion chromatography, H NMR spectroscopy, and differential scanning calorimetry confirm the tadpole topology.

  11. Towards a physics-based multiscale modelling of the electro-mechanical coupling in electro-active polymers.

    Science.gov (United States)

    Cohen, Noy; Menzel, Andreas; deBotton, Gal

    2016-02-01

    Owing to the increasing number of industrial applications of electro-active polymers (EAPs), there is a growing need for electromechanical models which accurately capture their behaviour. To this end, we compare the predicted behaviour of EAPs undergoing homogeneous deformations according to three electromechanical models. The first model is a phenomenological continuum-based model composed of the mechanical Gent model and a linear relationship between the electric field and the polarization. The electrical and the mechanical responses according to the second model are based on the physical structure of the polymer chain network. The third model incorporates a neo-Hookean mechanical response and a physically motivated microstructurally based long-chains model for the electrical behaviour. In the microstructural-motivated models, the integration from the microscopic to the macroscopic levels is accomplished by the micro-sphere technique. Four types of homogeneous boundary conditions are considered and the behaviours determined according to the three models are compared. For the microstructurally motivated models, these analyses are performed and compared with the widely used phenomenological model for the first time. Some of the aspects revealed in this investigation, such as the dependence of the intensity of the polarization field on the deformation, highlight the need for an in-depth investigation of the relationships between the structure and the behaviours of the EAPs at the microscopic level and their overall macroscopic response.

  12. Hybrid nanocomposites based on electroactive hydrogels and cellulose nanocrystals for high-sensitivity electro-mechanical underwater actuation

    Science.gov (United States)

    Santaniello, Tommaso; Migliorini, Lorenzo; Locatelli, Erica; Monaco, Ilaria; Yan, Yunsong; Lenardi, Cristina; Comes Franchini, Mauro; Milani, Paolo

    2017-08-01

    We report the synthesis, fabrication and characterization of a hybrid hydrogel/cellulose nanocomposite, which exhibits high-performance electro-mechanical underwater actuation and high sensitivity in response to electrical stimuli below the standard potential of water electrolysis. The macromolecular structure of the material is constituted by an electroactive hydrogel, obtained through a photo-polymerization reaction with the use of three vinylic co-monomers: Na-4-vinylbenzenesulfonate, 2-hydroxyethylmethacrylate, and acrylonitrile. Different amounts (from 0.1% to 1.4% w/w) of biodegradable cellulose nanocrystals (CNCs) with sulfonate surface groups, obtained through the acidic hydrolysis of sulphite pulp lapsheets, are physically incorporated into the gel matrix during the synthesis step. Freestanding thin films of the nanocomposites are molded, and their swelling, mechanical and responsive properties are fully characterized. We observed that the embedding of the CNCs enhanced both the material Young’s modulus and its sensitivity to the applied electric field in the sub-volt regime (down to 5 mV cm-1). A demonstrator integrating multiple actuators that cooperatively bend together, mimicking the motion of an electro-valve, is also prototyped and tested. The presented nanocomposite is suitable for the development of soft smart components for bio-robotic applications and cells-based and bio-hybrid fluidic devices fabrication.

  13. Synthesis and physicochemical characterization of copolymers of 3-octylthiophene and thiophene functionalized with azo chromophore

    Energy Technology Data Exchange (ETDEWEB)

    Nicho, M.E., E-mail: menicho@uaem.mx [Centro de Investigacion en Ingenieria y Ciencias Aplicadas, Universidad Autonoma del Estado de Morelos (UAEM), Av. Universidad 1001, Col. Chamilpa, C.P. 62209, Cuernavaca, Morelos (Mexico); Garcia-Carvajal, S.; Marquez-Aguilar, P.A.; Gueizado-Rodriguez, M. [Centro de Investigacion en Ingenieria y Ciencias Aplicadas, Universidad Autonoma del Estado de Morelos (UAEM), Av. Universidad 1001, Col. Chamilpa, C.P. 62209, Cuernavaca, Morelos (Mexico); Escalante-Garcia, J. [Centro de Investigaciones Quimicas, UAEM, C.P. 62210, Cuernavaca, Morelos (Mexico); Medrano-Baca, G. [Centro de Investigacion en Ingenieria y Ciencias Aplicadas, Universidad Autonoma del Estado de Morelos (UAEM), Av. Universidad 1001, Col. Chamilpa, C.P. 62209, Cuernavaca, Morelos (Mexico)

    2011-10-03

    Highlights: {yields} Azo chromophore in the copolymer showed an additional color to the P3OT. {yields} Non-linear optical properties by Z-scan technique in states: neutral and oxidized. {yields} The copolymers showed a change of non-linearity sign when the films were doped. {yields} We determined that the nonlinearity of the polymer films was a Kerr type. {yields} This study is the first report of NLO characterization of this material. - Abstract: Polythiophene derivatives with azo chromophore were synthesized via copolymerization of 3-octylthiophene (3OT) and 2-[N-ethyl-N-[4-[(4-nitrophenyl)azo]phenyl]amino]ethyl 3-thienylacetate (3-DRT). This copolymer has interesting optoelectronic properties and a variety of applications such as electrochromic and electronic devices. The polymerization process of 3OT and the functionalized thiophene was carried out via FeCl{sub 3} oxidative polymerization. Thin films of poly(3OT-co-3-DRT) copolymer were prepared by spin-coating technique from toluene. FTIR and {sup 1}H NMR spectroscopy revealed the presence of chromophore groups in the copolymer chain. Molecular weight and polydispersity of the polymers were measured by size exclusion chromatography. Changes in the surface topography of copolymers were analyzed by atomic force microscopy; the results showed that the copolymers presented some protuberances of variable size unlike the homogeneous granular morphology of P3OT. It is believed that these changes appeared by the incorporation of 3-DRT in the polymer. P3ATs are electrochromic materials that show color change upon oxidation-reduction process. We report that electrochemical characterization of poly(3OT-co-3-DRT) copolymer films synthesized chemically on indium-tin oxide (ITO) glass substrates showed an additional color to the P3OT homopolymer. Optical absorption properties of the polymer films were analyzed in the undoped and doped states and as a function of 3-DRT concentration in the copolymer. The nonlinear optical

  14. Synthesis and Properties of Poly(l-lactide-b-poly (l-phenylalanine Hybrid Copolymers

    Directory of Open Access Journals (Sweden)

    Marc Planellas

    2014-07-01

    Full Text Available Hybrid materials constituted by peptides and synthetic polymers have nowadays a great interest since they can combine the properties and functions of each constitutive block, being also possible to modify the final characteristics by using different topologies. Poly(l-lactide-b-l-phenylalanine copolymers with various block lengths were synthesized by sequential ring-opening polymerization of l-lactide and the N-carboxyanhydride of l-phenylalanine. The resulting block copolymers were characterized by NMR spectrometry, IR spectroscopy, gel permeation chromatography, MALDI-TOF and UV-vis, revealing the successful incorporation of the polyphenylalanine (PPhe peptide into the previously formed poly(l-lactide (PLLA polymer chain. X-ray diffraction and DSC data also suggested that the copolymers were phase-separated in domains containing either crystalline PLLA or PPhe phases. A peculiar thermal behavior was also found by thermogravimetric analysis when polyphenylalanine blocks were incorporated into polylactide.

  15. Polyether-polyester graft copolymer

    Science.gov (United States)

    Bell, Vernon L. (Inventor)

    1987-01-01

    Described is a polyether graft polymer having improved solvent resistance and crystalline thermally reversible crosslinks. The copolymer is prepared by a novel process of anionic copolymerization. These polymers exhibit good solvent resistance and are well suited for aircraft parts. Previous aromatic polyethers, also known as polyphenylene oxides, have certain deficiencies which detract from their usefulness. These commercial polymers are often soluble in common solvents including the halocarbon and aromatic hydrocarbon types of paint thinners and removers. This limitation prevents the use of these polyethers in structural articles requiring frequent painting. In addition, the most popular commercially available polyether is a very high melting plastic. This makes it considerably more difficult to fabricate finished parts from this material. These problems are solved by providing an aromatic polyether graft copolymer with improved solvent resistance and crystalline thermally reversible crosslinks. The graft copolymer is formed by converting the carboxyl groups of a carboxylated polyphenylene oxide polymer to ionic carbonyl groups in a suitable solvent, reacting pivalolactone with the dissolved polymer, and adding acid to the solution to produce the graft copolymer.

  16. Liquid ethylene-propylene copolymers

    Science.gov (United States)

    Rhein, R. A.; Ingham, J. D.; Humphrey, M. F.

    1975-01-01

    Oligomers are prepared by heating solid ethylene-propylene rubber in container that retains solid and permits liquid product to flow out as it is formed. Molecular weight and viscosity of liquids can be predetermined by process temperature. Copolymers have low viscosity for given molecular weight.

  17. Electroactivity of Polyaniline in High pH Solutions%聚苯胺在高pH值溶液中的电化学活性

    Institute of Scientific and Technical Information of China (English)

    宋晔; 吕惠玲; 胡颂伟; 杨春艳; 朱绪飞

    2013-01-01

    doping with macromolecular acids.The latter is to use a hybrid film fabricated by incorporating conductive nanomaterials into a PANI matrix,which can improve the charge transfer rate across the PANI matrix and facilitate its redox processes.The development of PANI nanocomposites prepared by doping with carbon nanotubes,graphenes and Au nanoparticles,etc.,falls into this category.This review article provides an overview of various approaches to preserve the electroactivity of PANI in high pH solutions on the basis of the two main strategies.Special emphasis is placed on the synthetic methods and electrochemical features for the self-doped,polymer acid-doped and CNT-doped PANIs,including their underlying mechanisms for achieving good electroactivity.The main challenges and future research directions in this field are also discussed.

  18. Syntheses and Surface Properties of Polyacrylonitrile-based Copolymer Membranes Containing Sugar Moieties

    Institute of Scientific and Technical Information of China (English)

    HUANG Xiao-jun; WAN Ling-shu; DAI Zheng-wei; KOU Rui-qiang; XU Zhi-kang

    2005-01-01

    To improve the hydrophilicity of polyacrylonitrile-based membranes, sugar moieties were incorporated into acrylonitrile-based copolymers via the radical copolymerization of α-allyl glucoside(AG) with acrylonitrile(AN) with 2,2'-azobis-iso-butyronitrile(AIBN) as the initiator in dimethyl sulphoxide(DMSO). It was found that the yield increased with the increase of the initiator concentration and reaction time, while it decreased with the increase of the monomer molar ratio of AG to AN. Raising the AG proportion in the monomer mixture resulted in the increase of the AG content in the copolymer. Mv of the copolymers decreased with increasing the AG monomer fraction in feed. The copolymers were fabricated into dense membranes and their surface properties were studied by means of the water contact angle measurement and platelet adhesion tests. It was found that the static water contact angle on the membrane decreased significantly from 70° to 33° with the increase of the AG content. The adhesive number of platelets on the membrane surface also decreased significantly with increasing AG content in the copolymers. These results demonstrate that the hydrophilicity and biocompatibility of the acrylonitrile-based copolymer membranes could be improved efficiently by the copolymerization of acrylonitrile with vinyl carbohydrates.

  19. A complete study of electroactive polymers for energy scavenging: modelling and experiments

    CERN Document Server

    Jean-Mistral, C; Chaillout, J J; Bonvilain, A

    2008-01-01

    Recent progresses in ultra low power microelectronics propelled the development of several microsensors and particularly the self powered microsystems (SPMS). One of their limitations is their size and their autonomy due to short lifetime of the batteries available on the market. To ensure their ecological energetic autonomy, a promising alternative is to scavenge the ambient energy such as the mechanical one. Nowadays, few microgenerators operate at low frequency. They are often rigid structures that can perturb the application or the environment; none of them are perfectly flexible. Thus, our objective is to create a flexible, non-intrusive scavenger using electroactive polymers. The goal of this work is to design a generator which can provide typically 100 ?W to supply a low consumption system. We report in this paper an analytical model which predicts the energy produced by a simple electroactive membrane, and some promising experimental results.

  20. Neutral, anionic, cationic, and zwitterionic diblock copolymers featuring poly(2-methoxyethyl acrylate) hydrophobic segments

    DEFF Research Database (Denmark)

    Javakhishvili, Irakli; Jankova Atanasova, Katja; Hvilsted, Søren

    2013-01-01

    Amphiphilic diblock copolymers incorporating hydrophobic poly(2-methoxyethyl acrylate) (PMEA) and hydrophilic neutral poly(ethylene glycol) monomethyl ether (mPEG), anionic poly(acrylic acid) (PAA) and poly(methacrylic acid) (PMAA), cationic poly(2-dimethylaminoethyl methacrylate) (PDMAEMA), and ...

  1. Impacts of Repeat Unit Structure and Copolymer Architecture on Thermal and Solution Properties in Homopolymers, Copolymers, and Copolymer Blends

    Science.gov (United States)

    Marrou, Stephen Raye

    Gradient copolymers are a relatively new type of copolymer architecture in which the distribution of comonomers gradually varies over the length of the copolymer chain, resulting in a number of unusual properties derived from the arrangement of repeat units. For example, nanophase-segregated gradient copolymers exhibit extremely broad glass transition temperatures (Tgs) resulting from the wide range of compositions present in the nanostructure. This dissertation presents a number of studies on how repeat unit structure and copolymer architecture dictate bulk and solution properties, specifically taking inspiration from the gradient copolymer architecture and comparing the response from this compositionally heterogeneous material to other more conventional materials. The glass transition behavior of a range of common homopolymers was studied to determine the effects of subunit structure on Tg breadth, observing a significant increase in T g breadth with increasing side chain length in methacrylate-based homopolymers and random copolymers. Additionally, increasing the composition distribution of copolymers, either by blending individual random copolymers of different overall composition or synthesizing random copolymers to high conversion, resulted in significant increases to Tg breadth. Plasticization of homopolymers and random copolymers with low molecular weight additives also served to increase the Tg breadth; the most dramatic effect was observed in the selective plasticization of a styrene/4-vinylpyridine gradient copolymer with increases in T g breadth to values above 100 °C. In addition, the effects of repeat unit structure and copolymer architecture on other polymer properties besides Tg were also investigated. The intrinsic fluorescence of styrene units in styrene-containing copolymers was studied, noting the impact of repeat unit structure and copolymer architecture on the resulting fluorescence spectra in solution. The impact of repeat unit structure on

  2. Waste Water Derived Electroactive Microbial Biofilms: Growth, Maintenance, and Basic Characterization

    OpenAIRE

    2013-01-01

    The growth of anodic electroactive microbial biofilms from waste water inocula in a fed-batch reactor is demonstrated using a three-electrode setup controlled by a potentiostat. Thereby the use of potentiostats allows an exact adjustment of the electrode potential and ensures reproducible microbial culturing conditions. During growth the current production is monitored using chronoamperometry (CA). Based on these data the maximum current density (j max) and the coulombic efficiency (CE) are d...

  3. Electroactive shape memory performance of polyurethane composite having homogeneously dispersed and covalently crosslinked carbon nanotubes

    OpenAIRE

    Jung, Yong Chae; Yoo, Hye Jin; Kim, Yoong Ahm; Cho, Jae Whan; Endo, Morinobu

    2010-01-01

    The electroactive shape memory of carbon nanotube-filled polyurethane composites, prepared by conventional blending, in situ and cross-linking polymerization, is studied in terms of the dispersion of the tubes The covalently bonded tubes are homogeneously dispersed within the polyurethane by introducing carboxyl groups on the sidewall of the tubes and selecting a cross-linking polymerization method The resultant composites, which have 92% shape retention and 95% shape recovery, are expected t...

  4. Three dimensional scaffolds based on electroactive polymers for tissue engineering applications

    OpenAIRE

    2016-01-01

    Tese de Doutoramento em Engenharia de Materiais Biomaterials play an increasingly prominent important role in the development and success of tissue engineering, particularly in the regeneration or reestablishment of tissue functions and organs. The improvement in the understanding of the role of biomaterials in the formation and regeneration of new tissue has promoted faster and more effective developments in this area. Biomaterials based on electroactive polymers have gaine...

  5. Synthetic process for preparation of high surface area electroactive compounds for battery applications

    Energy Technology Data Exchange (ETDEWEB)

    Evenson, Carl; Mackay, Richard

    2013-07-23

    A process is disclosed for the preparation of electroactive cathode compounds useful in lithium-ion batteries, comprising exothermic mixing of low-cost precursors and calcination under appropriate conditions. The exothermic step may be a spontaneous flameless combustion reaction. The disclosed process can be used to prepare any lithium metal phosphate or lithium mixed metal phosphate as a high surface area single phase compound.

  6. Electroactive nanocomposites made of poly (o-methoxyaniline) and natural polysaccharides

    OpenAIRE

    Carla Eiras; Ionara Nayana Gomes Passos; Ana Cristina Facundo de Brito; José Ribeiro dos Santos Júnior; Valtencir Zucolotto; Oliveira Jr., Osvaldo N.; Igor L. Kitagawa; Constantino, Carlos J. L.; Helder Nunes da Cunha

    2007-01-01

    In this work we take advantage of the polyelectrolyte character of some Brazilian native gums to fabricate electrically conductive, nanostructured films. The gums Sterculia urens, (caraia), Sterculia striata (chicha) or Anadenanthera macrocarpa Benth were assembled in conjunction with poly(o-methoxyaniline) (POMA) in the form of layered nanostructured films using the layer-by-layer (LbL) technique. All the LbL films displayed a well-defined electroactivity, as confirmed via cyclic voltammetry...

  7. A Self-Assembled Electro-Active M8L4 Cage Based on Tetrathiafulvalene Ligands

    Directory of Open Access Journals (Sweden)

    Sébastien Goeb

    2014-01-01

    Full Text Available Two self-assembled redox-active cages are presented. They are obtained by coordination-driven self-assembly of a tetra-pyridile tetrathiafulvalene ligand with cis-M(dppf(OTf2 (M = Pd or Pt; dppf = 1,1′-bis(diphenylphosphinoferrocene; OTf = trifluoromethane-sulfonate complexes. Both species are fully characterized and are constituted of 12 electro-active subunits that can be reversibly oxidized.

  8. Nanocasting technique to prepare lotus-leaf-like superhydrophobic electroactive polyimide as advanced anticorrosive coatings.

    Science.gov (United States)

    Chang, Kung-Chin; Lu, Hsin-I; Peng, Chih-Wei; Lai, Mei-Chun; Hsu, Sheng-Chieh; Hsu, Min-Hsiang; Tsai, Yuan-Kai; Chang, Chi-Hao; Hung, Wei-I; Wei, Yen; Yeh, Jui-Ming

    2013-02-01

    Nanocasting technique was used to obtain a biomimetic superhydrophobic electroactive polyimide (SEPI) surface structure from a natural Xanthosoma sagittifolium leaf. An electroactive polyimide (EPI) was first synthesized through thermal imidization. An impression of the superhydrophobic Xanthosoma sagittifolium leaf was then nanocasted onto the surface of the EPI so that the resulting EPI was superhydrophobic and would prevent corrosion. Polydimethylsiloxane (PDMS) was then used as a negative template to transfer the impression of the superhydrophobic surface of the biomimetic EPI onto a cold-rolled steel (CRS) electrode. The superhydrophobic electroactive material could be used as advanced coatings that protect metals against corrosion. The morphology of the surface of the as-synthesized SEPI coating was investigated using scanning electron microscopy (SEM). The surface showed numerous micromastoids, each decorated with many nanowrinkles. The water contact angle (CA) for the SEPI coating was 155°, which was significantly larger than that for the EPI coating (i.e., CA = 87°). The significant increase in the contact angle indicated that the biomimetic morphology effectively repelled water. Potentiodynamic and electrochemical impedance spectroscopic measurements indicated that the SEPI coating offered better protection against corrosion than the EPI coating did.

  9. Multicomponent Solvated Triblock Copolymer Network Systems: Fundamental Insights and Emerging Applications

    Science.gov (United States)

    Krishnan, Arjun Sitaraman

    Block copolymers have received significant research attention in recent times due to their ability to spontaneously self-assemble into a variety of nanostructures. Thermoplastic elastomers composed of styrenic triblock copolymers are of great importance in applications such as adhesives and vibration dampening due to their shape memory, resilience and facile processing. The swelling of these polymers by adding midblock selective solvents or oligomers provides an easy route by which to modify the morphology and mechanical behavior of these systems. We first consider a ternary blend of a poly[styrene- b-(ethylene-co-butylene)-b-styrene] triblock copolymer (SEBS) and mixtures of two midblock selective co-solvents, with significantly different physical states. We use dynamic rheology to study the viscoelastic response of a wide variety of systems under oscillatory shear. Frequency spectra acquired at ambient temperature display viscoelastic behavior that shifts in the frequency domain depending on the co-solvent composition. For each copolymer concentration, all the frequency data can be shifted by time-composition superpositioning (tCS) to yield a single master-curve. tCS fails at low frequencies due to presence of endblock pullout, which is a fundamentally different relaxation process from segmental relaxation of the midblock. As an emerging technology, we examine SEBS-oil gels as dielectric elastomers. Dielectric elastomers constitute one class of electroactive polymers (EAPs), polymeric materials that respond to an electric stimulus by changing their macroscopic dimensions, thereby converting electrical energy into mechanical work. We use standard configuration of EAP devices involving stretching, or "prestraining," the elastomer film biaxially. The effect of experimental parameters such as film thickness and amount of prestrain on the (electro)mechanical properties of the material become apparent by recasting as-obtained electroactuation data into compressive

  10. Bioinspired catecholic copolymers for antifouling surface coatings.

    Science.gov (United States)

    Cho, Joon Hee; Shanmuganathan, Kadhiravan; Ellison, Christopher J

    2013-05-01

    We report here a synthetic approach to prepare poly(methyl methacrylate)-polydopamine diblock (PMMA-PDA) and triblock (PDA-PMMA-PDA) copolymers combining mussel-inspired catecholic oxidative chemistry and atom transfer radical polymerization (ATRP). These copolymers display very good solubility in a range of organic solvents and also a broad band photo absorbance that increases with increasing PDA content in the copolymer. Spin-cast thin films of the copolymer were stable in water and showed a sharp reduction (by up to 50%) in protein adsorption compared to those of neat PMMA. Also the peak decomposition temperature of the copolymers was up to 43°C higher than neat PMMA. The enhanced solvent processability, thermal stability and low protein adsorption characteristics of this copolymer makes it attractive for variety of applications including antifouling coatings on large surfaces such as ship hulls, buoys, and wave energy converters.

  11. 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.

  12. The influence of chain stretching on the phase behavior of multiblock copolymer and comb copolymer melts

    NARCIS (Netherlands)

    Angerman, HJ; ten Brinke, G

    2003-01-01

    The subject of this paper is inspired by microphase-separated copolymer melts in which a small-scale structure is present inside one of the phases of a large-scale structure. Such a situation can arise in a diblock copolymer melt, if one of the blocks of the diblock is in itself a multiblock copolym

  13. Blends of Styrene-Butadiene-Styrene Triblock Copolymer with Random Styrene-Maleic Anhydride Copolymers

    NARCIS (Netherlands)

    Piccini, Maria Teresa; Ruggeri, Giacomo; Passaglia, Elisa; Picchioni, Francesco; Aglietto, Mauro

    2002-01-01

    Blends of styrene-butadiene-styrene triblock copolymer (SBS) with random styrene-maleic anhydride copolymers (PS-co-MA), having different MA content, were prepared in a Brabender Plastigraph mixer. The presence of polystyrene (PS) blocks in the SBS copolymer and the high styrene content (93 and 86 w

  14. 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

    2016-08-19

    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.

  15. 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.

    2016-08-01

    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.

  16. Multifunctional nanoassemblies of block copolymers for future cancer therapy

    Directory of Open Access Journals (Sweden)

    Horacio Cabral and Kazunori Kataoka

    2010-01-01

    Full Text Available Nanoassemblies from amphiphilic block copolymers are promising nanomedicine platforms for cancer diagnosis and therapy due to their relatively small size, high loading capacity of drugs, controlled drug release, in vivo stability and prolonged blood circulation. Recent clinical trials with self-assembled polymeric micelles incorporating anticancer drugs have shown improved antitumor activity and decreased side effects encouraging the further development of nanoassemblies for drug delivery. This review summarizes recent approaches considering stimuli-responsive, multifunctionality and more advanced architectures, such as vesicles or worm-like micelles, for tumor-specific drug and gene delivery.

  17. Silica reinforced triblock copolymer gels

    DEFF Research Database (Denmark)

    Theunissen, E.; Overbergh, N.; Reynaers, H.

    2004-01-01

    The effect of silica and polymer coated silica particles as reinforcing agents on the structural and mechanical properties of polystyrene-poly(ethylene/butylene)-polystyrene (PS-PEB-PS) triblock gel has been investigated. Different types of chemically modified silica have been compared in order...... a viscoclastic rubber to a plastic fluid and from a plastic fluid to a viscoelastic liquid are shifted to more elevated temperatures when silica is added to the triblock copolymer gel. (C) 2004 Elsevier Ltd. All rights reserved....

  18. Copolymers of fluorinated polydienes and sulfonated polystyrene

    Science.gov (United States)

    Mays, Jimmy W.; Gido, Samuel P.; Huang, Tianzi; Hong, Kunlun

    2009-11-17

    Copolymers of fluorinated polydienes and sulfonated polystyrene and their use in fuel cell membranes, batteries, breathable chemical-biological protective materials, and templates for sol-gel polymerization.

  19. Third-order nonlinear optical characterization of side-chain copolymers

    Science.gov (United States)

    Norwood, Robert A.; Sounik, James R.; Popolo, J.; Holcomb, Douglas P.

    1991-12-01

    Third order nonlinear optical properties of side-chain methacrylate copolymers incorporating 4-amino-4'-nitrostilbene, 4-oxy-4'nitrostilbene, and functionalized silicon phthalocyanine chromophores are measured by picosecond degenerate four wave mixing at 598 nm. The nonresonant stilbene system exhibits a pulse limited ultrafast response, while the resonant phthalocyanine system has a large excited state nonlinearity. Comparison of silicon phthalocyanine copolymers with solubilized guest/host systems dispersed in polymethylmethacrylate illustrate the importance of aggregation and phthalocyanine ring interaction in determining the linear optical properties and the magnitude and speed of the nonlinear optical response.

  20. Silk fibroin/copolymer composite hydrogels for the controlled and sustained release of hydrophobic/hydrophilic drugs.

    Science.gov (United States)

    Zhong, Tianyi; Jiang, Zhijuan; Wang, Peng; Bie, Shiyu; Zhang, Feng; Zuo, Baoqi

    2015-10-15

    In the present study, a composite system for the controlled and sustained release of hydrophobic/hydrophilic drugs is described. Composite hydrogels were prepared by blending silk fibroin (SF) with PLA-PEG-PLA copolymer under mild aqueous condition. Aspirin and indomethacin were incorporated into SF/Copolymer hydrogels as two model drugs with different water-solubility. The degradation of composite hydrogels during the drug release was mainly caused by the hydrolysis of copolymers. SF with stable β-sheet-rich structure was not easily degraded which maintained the mechanical integrity of composite hydrogel. The hydrophobic/hydrophilic interactions of copolymers with model drugs would significantly alter the morphological features of composite hydrogels. Various parameters such as drug load, concentration ratio, and composition of copolymer were considered in vitro drug release. Aspirin as a hydrophilic drug could be controlled release from composite hydrogel at a constant rate for 5 days. Its release was mainly driven by diffusion-based mechanism. Hydrophobic indomethacin could be encapsulated in copolymer nanoparticles distributing in the composite hydrogel. Its sustained release was mainly degradation controlled which could last up to two weeks. SF/Copolymer hydrogel has potential as a useful composite system widely applying for controlled and sustained release of various drugs.

  1. Fatigue Properties of Organic Ferroelectric Nano-Film with Electroactive Interlayer%含电活性界面层有机铁电纳米薄膜的疲劳性能

    Institute of Scientific and Technical Information of China (English)

    张修丽; 侯莹; 吕昭月; 徐国强; 徐海生

    2012-01-01

    采用3种类型的电活性界面层材料,如高介电常数材料酞菁铜(CuPc)、电子导体原位合成的聚(乙撑二氧噻吩)-聚(苯乙烯磺酸)(PEDOT-PSSH)以及离子导体聚乙烯基磷酸(PVPA)和商业的PEDOT-PSSH(BaytronP),研究了界面层对铁电共聚物薄膜的疲劳特性的影响。研究结果表明,三种类型的电活性界面层材料,包括电子、离子导体和含偶极子的高介电常数材料都能为铁电薄膜提供补偿电荷从而提高器件的铁电疲劳性能。%A series of ferroelectric polarization reversal measurements were conducted on spin-coating ultrathin poly(vinylidene fluoride-trifluoroethylene)(P(VDF-TrFE)) copolymer films sandwiched with different electroactive materials between P(VDF-TrFE) and metal electrode.Three types of electroactive interlayers,including highly polarized material copper-phthalocyanine(CuPc),electron conductor poly(ethylene dioxythiophene)-poly(styrene sulfonate acid)(PEDOT-PSSH) and ion proton conductor poly(vinyl phosphonic) acid(PVPA) were employed.Results showed that the compensated charges from electroative interlayers,such as electrons,protons,as well as dipoles,would improve the fatigue behaviors of electronic devices.

  2. Strong electroactive biodegradable shape memory polymer networks based on star-shaped polylactide and aniline trimer for bone tissue engineering.

    Science.gov (United States)

    Xie, Meihua; Wang, Ling; Ge, Juan; Guo, Baolin; Ma, Peter X

    2015-04-01

    Preparation of functional shape memory polymer (SMP) for tissue engineering remains a challenge. Here the synthesis of strong electroactive shape memory polymer (ESMP) networks based on star-shaped polylactide (PLA) and aniline trimer (AT) is reported. Six-armed PLAs with various chain lengths were chemically cross-linked to synthesize SMP. After addition of an electroactive AT segment into the SMP, ESMP was obtained. The polymers were characterized by (1)H NMR, GPC, FT-IR, CV, DSC, DMA, tensile test, and degradation test. The SMP and ESMP exhibited strong mechanical properties (modulus higher than GPa) and excellent shape memory performance: short recovery time (several seconds), high recovery ratio (over 94%), and high fixity ratio (almost 100%). Moreover, cyclic voltammetry test confirmed the electroactivity of the ESMP. The ESMP significantly enhanced the proliferation of C2C12 cells compared to SMP and linear PLA (control). In addition, the ESMP greatly improved the osteogenic differentiation of C2C12 myoblast cells compared to PH10 and PLA in terms of ALP enzyme activity, immunofluorescence staining, and relative gene expression by quantitative real-time polymerase chain reaction (qRT-PCR). These intelligent SMPs and electroactive SMP with strong mechanical properties, tunable degradability, good electroactivity, biocompatibility, and enhanced osteogenic differentiation of C2C12 cells show great potential for bone regeneration.

  3. Structural Color for Additive Manufacturing: 3D-Printed Photonic Crystals from Block Copolymers.

    Science.gov (United States)

    Boyle, Bret M; French, Tracy A; Pearson, Ryan M; McCarthy, Blaine G; Miyake, Garret M

    2017-03-28

    The incorporation of structural color into 3D printed parts is reported, presenting an alternative to the need for pigments or dyes for colored parts produced through additive manufacturing. Thermoplastic build materials composed of dendritic block copolymers were designed, synthesized, and used to additively manufacture plastic parts exhibiting structural color. The reflection properties of the photonic crystals arise from the periodic nanostructure formed through block copolymer self-assembly during polymer processing. The wavelength of reflected light could be tuned across the visible spectrum by synthetically controlling the block copolymer molecular weight and manufacture parts that reflected violet, green, or orange light with the capacity to serve as selective optical filters and light guides.

  4. PHASE STRUCTURE AND THERMAL BEHAVIOR OF LIQUID CRYSTALLINE MULTI-BLOCK COPOLYMERS,POLY[1,6-BIS(4-OXYBENZOYL-OXY)HEXANE TEREPHTHALATE]-b-BISPHENOL A POLYCARBONATE

    Institute of Scientific and Technical Information of China (English)

    Hui-qing Zhang; Xiong-yan Zhao; De-shan Liu; Qi-xiang Zhou

    1999-01-01

    Liquid crystalline multi-block copolymers poly[1,6-bis(4-oxybenzoyl-oxy)hexane terephthalate]-b-bisphenol A polycarbonate (PHTH-6-b-PC) with different segments of polycarbonate (PC) and thermotropic polyester PHTH-6 were synthesized in tetrachloroethane at 144~146℃. The influence of segment length on the resulting phase structure and thermal behavior of block copolymers was also discussed. It is demonstrated by TEM and DMA that the resulting block copolymers show a considerable microphase separation. The degree of phase separation and the thermal behavior of the block copolymers are strongly dependent on the molecular weight of the segments incorporated.

  5. Micellization and Characterization of Block Copolymer Detergents

    DEFF Research Database (Denmark)

    Hvidt, Søren

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

  6. 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...

  7. Copolymers at the solid - liquid interface

    NARCIS (Netherlands)

    Wijmans, C.M.

    1994-01-01

    Copolymers consisting of both adsorbing and nonadsorbing segments can show an adsorption behaviour which is very different from that of homopolymers. We have mainly investigated the adsorption of AB diblock copolymers, which have one adsorbing block (anchor) and one nonadsorbing block

  8. Drug targeting to tumors using HPMA copolymers

    NARCIS (Netherlands)

    Lammers, T.G.G.M.

    2009-01-01

    Copolymers based on N-(2-hydroxypropyl)methacrylamide (HPMA) are prototypic and well-characterized polymeric drug carriers that have been broadly implemented in the delivery of anticancer agents. HPMA copolymers circulate for prolonged periods of time, and by means of the Enhance Permeability and Re

  9. Process-Accessible States of Block Copolymers

    Science.gov (United States)

    Sun, De-Wen; Müller, Marcus

    2017-02-01

    Process-directed self-assembly of block copolymers refers to thermodynamic processes that reproducibly direct the kinetics of structure formation from a starting, unstable state into a selected, metastable mesostructure. We investigate the kinetics of self-assembly of linear A C B triblock copolymers after a rapid transformation of the middle C block from B to A . This prototypical process (e.g., photochemical transformation) converts the initial, equilibrium mesophase of the A B B copolymer into a well-defined but unstable, starting state of the A A B copolymer. The spontaneous structure formation that ensues from this unstable state becomes trapped in a metastable mesostructure, and we systematically explore which metastable mesostructures can be fabricated by varying the block copolymer composition of the initial and final states. In addition to the equilibrium mesophases of linear A B diblock copolymers, this diagram of process-accessible states includes 7 metastable periodic mesostructures, inter alia, Schoen's F-RD periodic minimal surface. Generally, we observe that the final, metastable mesostructure of the A A B copolymer possesses the same symmetry as the initial, equilibrium mesophase of the A B B copolymer.

  10. Thermochemical characteristics of chitosan-polylactide copolymers

    Science.gov (United States)

    Goruynova, P. E.; Larina, V. N.; Smirnova, N. N.; Tsverova, N. E.; Smirnova, L. A.

    2016-05-01

    The energies of combustion of chitosan and its block-copolymers with different polylactide contents are determined in a static bomb calorimeter. Standard enthalpies of combustion and formation are calculated for these substances. The dependences of the thermochemical characteristics on block-copolymer composition are determined and discussed.

  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. PCL-PDMS-PCL copolymer-based microspheres mediate cardiovascular differentiation from embryonic stem cells

    Science.gov (United States)

    Song, Liqing

    Poly-epsilon-caprolactone (PCL) based copolymers have received much attention as drug or growth factor delivery carriers and tissue engineering scaffolds due to their biocompatibility, biodegradability, and tunable biophysical properties. Copolymers of PCL and polydimethylsiloxane (PDMS) also have shape memory behaviors and can be made into thermoresponsive shape memory polymers for various biomedical applications such as smart sutures and vascular stents. However, the influence of biophysical properties of PCL-PDMS-PCL copolymers on stem cell lineage commitment is not well understood. In this study, PDMS was used as soft segments of varying length to tailor the biophysical properties of PCL-based co-polymers. While low elastic modulus (embryonic stem cells, the range of 60-100 MPa PCL-PDMS-PCL showed little influence on the differentiation. Then different size (30-140 mum) of microspheres were fabricated from PCL-PDMS-PCL copolymers and incorporated within embryoid bodies (EBs). Mesoderm differentiation was induced using bone morphogenetic protein (BMP)-4 for cardiovascular differentiation. Differential expressions of mesoderm progenitor marker KDR and vascular markers CD31 and VE-cadherin were observed for the cells differentiated from EBs incorporated with microspheres of different size, while little difference was observed for cardiac marker alpha-actinin expression. Small size of microspheres (30 mum) resulted in higher expression of KDR while medium size of microspheres (94 mum) resulted in higher CD31 and VE-cadherin expression. This study indicated that the biophysical properties of PCL-based copolymers impacted stem cell lineage commitment, which should be considered for drug delivery and tissue engineering applications.

  13. ELECTROACTIVE AND NANOSTRUCTURED POLYMERS AS SCAFFOLD MATERIALS FOR NEURONAL AND CARDIAC TISSUE ENGINEERING

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Conducting polymer, polyaniline (PANI), has been studied as a novel electroactive and electrically conductive material for tissue engineering applications. The biocompatibility of the conductive polymer can be improved by (I) covalently grafting various adhesive peptides onto the surface of prefabricated conducting polymer flms or into the polymer structures during the synthesis, (ii) co-electrospinning or blending with natural proteins to form conducting nanofibers or films, and (iii) preparing conducting polymers using biopolymers, such as collagen, as templates. In this paper, we mainly describe and review the approaches of covalently attaching oligopeptides to PANI and electrospinning PANI-gelatin blend nanofibers. The employment of such modified conducting polymers as substrates for enhanced cell attachment, proliferation and differentiation has been investigated with neuronal PC-12 cells and H9c2 cardiac myoblasts. For the electrospun PANIgelatin fibers, depending on the concentrations of PANI, H9c2 cells initially displayed different morphologies on the fibrous substrates, but after one week all cultures reached confluence of similar densities and morphologies. Furthermore, we observed, that conductive PANI, when maintained in an aqueous physiologic environment, retained a significant level of electrical conductivity for at least 100 h, even though this conductivity was decreasing over time. Preliminary data show that the application of micro-current stimulates the differentiation of PC-12 cells. All the results demonstrate the potential for using PANI as an electroactive polymer in the culture of excitable cells and open the possibility of using this material as an electroactive scaffold for cardiac and/or neuronal tissue engineering applications that require biocompatibility of conductive polymers.

  14. Biomimetic electroactive polyimide with rose petal-like surface structure for anticorrosive coating application

    Directory of Open Access Journals (Sweden)

    W. F. Ji

    2017-08-01

    Full Text Available In this work, an electroactive polyimide (EPI coating with biomimetic surface structure of rose petal used in anticorrosion application was first presented. First of all, amino-capped aniline trimer (ACAT was synthesized by oxidative coupling reaction, followed by characterized through Fourier transform infrared spectroscooy (FTIR, liquid chromatography – mass spcerometry (LC-MS and proton nuclear magnetic resonance (1H-NMR spectroscopy. Subsequently, as-prepared ACAT was reacted with isopropylidenediphenoxy-bis(phthalic anhydride (BPADA to give electroactive poly(amic acid (EPAA. Moreover, poly(dimethylsiloxane (PDMS was used to be the soft negative template for pattern transfer from the surface of rose petal to the surface of polymer coating. The EPI coating with biomimetic structure was obtained by programmed heating the EPAA slurry casting onto the negative PDMS template. The anticorrosive performance of as-prepared biomimetic EPI coating was demonstrated by performing a series of electrochemical measurements (Tafel, Nyquist, and Bode plots upon cold-rolled steel (CRS electrode in a NaCl aqueous solution. It should be noted that the biomimetic EPI coating with rose petal-like structure was found to exhibit better anticorrosion than that of EPI without biomimetic structure. Moreover, the surface contact angle of water droplets for biomimetic EPI coating was found to be ~150°, which is significantly higher than that of EPI coating with smooth structure (~87°, indicating that the EPI coating with biomimetic structure reveals better hydrophobicity. The apparent mechanism for improved anticorrosive properties is twofold: (1 the biomimetic structure of EPI coating can repel water droplets. (2 electroactivity of EPI coating promotes the formation of densely passive layer of metal oxide on metallic surface.

  15. New inorganic/organic copolymers (ORMOCER{reg_sign}s) for dental applications

    Energy Technology Data Exchange (ETDEWEB)

    Wolter, H.; Storch, W. [Fraunhofer-Inst. fuer Silicatforschung, Wuerzburg (Germany); Ott, H. [Blendax GmbH, Mainz (Germany)

    1994-12-31

    Urethane and thioether (meth)acrylate alkoxysilanes have been used, as sol-gel precursors, for the preparation of a special family of inorganic/organic copolymers (ORMOCER{reg_sign}s). The basic silane type offers the following structural and synthetic possibilities for modifying the properties of the resulting copolymers: variation of the number of alkoxy groups, combination with other, different, sol-gel precursors, variation of the number of attached (meth)acrylate groups (1--5), and variation within the molecular segment (kind, structure and length) connecting the inorganic with the organic polymer structure. To achieve the additional organic polymer structure in the cured copolymer the use of different radically induced polymerization approaches (UV-, visible light-, thermal- and redox induced) is possible. Taking the incorporation of fillers into account, the Young`s modulus of these copolymers is adjustable in a range of 1--17,000 MPa, and the thermal expansion coefficient in a range of 17--250{center_dot}10{sup {minus}6}{center_dot}K{sup {minus}1} (5--50 C). Other advantages are the low shrinkage (1--2,8 vol.-%), the high flexural strength (up to 160 MPa), and the high abrasion resistance. This new copolymer type seems to have significant potential for medical applications, especially as dental filling material to replace the currently used controversial amalgam fillings.

  16. 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.

  17. Bistable electroactive polymer for refreshable Braille display with improved actuation stability

    Science.gov (United States)

    Niu, Xiaofan; Brochu, Paul; Stoyanov, Hristiyan; Yun, Sung Ryul; Pei, Qibing

    2012-04-01

    Poly(t-butyl acrylate) is a bistable electroactive polymer (BSEP) capable of rigid-to-rigid actuation. The BSEP combines the large-strain actuation of dielectric elastomers with shape memory property. We have introduced a material approach to overcome pull-in instability in poly(t-butyl acrylate) that significantly improves the actuation lifetime at strains greater than 100%. Refreshable Braille display devices with size of a smartphone screen have been fabricated to manifest a potential application of the BSEP. We will report the testing results of the devices by a Braille user.

  18. Magneto- to electroactive transmutation of spin waves in ErMnO3.

    Science.gov (United States)

    Chaix, L; de Brion, S; Petit, S; Ballou, R; Regnault, L-P; Ollivier, J; Brubach, J-B; Roy, P; Debray, J; Lejay, P; Cano, A; Ressouche, E; Simonet, V

    2014-04-04

    The low-energy dynamical properties of the multiferroic hexagonal perovskite ErMnO3 have been studied by inelastic neutron scattering as well as terahertz and far infrared spectroscopies on a synchrotron source. From these complementary techniques, we have determined the magnon and crystal field spectra and identified a zone center magnon excitable only by the electric field of an electromagnetic wave. Using a comparison with the isostructural YMnO3 compound and crystal field calculations, we propose that this dynamical magnetoelectric process is due to the hybridization of a magnon with an electroactive crystal field transition.

  19. Electroactive and biocompatible functionalization of graphene for the development of biosensing platforms

    DEFF Research Database (Denmark)

    Halder, Arnab; Zhang, Minwei; Chi, Qijin

    2017-01-01

    oxide (RGO) for the development of versatile biosensing platform. A highly branched polymer (PEI) is used for reduction and simultaneous derivation of graphene oxide (GO) to form a biocompatible polymeric matrix on RGO nanosheet. Ferrocene redox moieties are then wired onto RGO nanosheets through......Design and synthesis of low-cost, highly stable, electroactive and biocompatible material is one of the key steps for the advancement of electrochemical biosensing systems. To this end, we have explored a facile way for the successful synthesis of redox active and bioengineering of reduced graphene...

  20. Fabrication of an interpenetrated network of carbon nanotubes and electroactive polymers to be used in oligonucletide biosensing

    Energy Technology Data Exchange (ETDEWEB)

    Acevedo, D.F. [Departamento de Quimica, Universidad Nacional de Rio Cuarto - Ruta 8, km 601, 5800 Rio Cuarto (Argentina); Reisberg, S.; Piro, B. [ITODYS, University Paris VII-CNRS, 1, Rue Guy de la Brosse, 75005 Paris (France); Peralta, D.O.; Miras, M.C. [Departamento de Quimica, Universidad Nacional de Rio Cuarto - Ruta 8, km 601, 5800 Rio Cuarto (Argentina); Pham, M.C. [ITODYS, University Paris VII-CNRS, 1, Rue Guy de la Brosse, 75005 Paris (France); Barbero, C.A. [Departamento de Quimica, Universidad Nacional de Rio Cuarto - Ruta 8, km 601, 5800 Rio Cuarto (Argentina)], E-mail: cbarbero@exa.unrc.edu.ar

    2008-04-20

    Layers of multiwall carbon nanotubes (MWNT), with different thickness, are built by sequential drop coating of a MWNT-Nafion dispersion in ethanol onto glassy carbon substrates. The layers form a 3D conductive network towards the electrochemical reactions of soluble redox couples (Fe{sup 3+/2+}) in aqueous solutions. Digital simulation of the electrochemical response suggests that the electron transfer is controlled by finite diffusion of the redox species inside the network. It is possible to create an interpenetrated network of carbon nanotubes and electroactive polymers (poly(hydroxynaphtoquinones)) by electropolymerization in nonaqueous media, which are electroactive in aqueous and nonaqueous media. The electrochemical response, both in cyclic voltammetry (CV) and square wave voltammetry (SWV), is significantly increased. In that way, the sensitivity of sensors (e.g. DNA biosensors based on the change of electroactive polymer response upon hybridization) could be improved.

  1. Controlled self-assembly of conjugated rod-coil block copolymers for applications in organic optoelectronics

    Science.gov (United States)

    Tao, Yuefei

    Organic electronics are of great interest in manufacturing light weight, mechanical flexible, and inexpensive large area devices. While significant improvements have been made over the last several years and it is now clear that morphology on the lengthscale of exciton diffusion (10nm) is of crucial importance, a clear relationship between structure and device properties has not emerged. This lack of understanding largely emerges from an inability to control morphology on this lengthscale. This thesis will center around an approach, based on block copolymer self-assembly, to generate equilibrium nanostructures on the 10 nm lengthscale of exciton diffusion and study their effects on device performance. Self-assembly of semiconducting block copolymers is complicated by the non-classical chain shape of conjugated polymers. Unlike classical polymers, the chains do not assume a Gaussian coil shape which is stretched near block copolymer interfaces, instead the chains are elongated and liquid crystalline. Previous work has demonstrated how these new molecular interactions and shapes control the phase diagram of so-called rod-coil block copolymers. Here, we will focus on controlling domain size, orientation, and chemical structure. While domain size can be controlled directly through molecular weight, this requires significant additional synthesis of domain size is to be varied. Here, the domain size is controlled by blending homopolymers into a self-assembling rod-coil block copolymer. When coil-like blocks are incorporated, the domains swell, as expected. When rod-like blocks are incorporated, they interdigitate with the rods of the block copolymers. This results in an increase in interfacial area which forces the coils to rearrange and an overall decrease in domain size with increasing rod content. Control over lamellar orientation is crucial in order to design and control charge transport pathways and exciton recombination or separation interfaces. While numerous

  2. Voltage-stabilised elastomers with increased relative permittivity and high electrical breakdown strength by means of phase separating binary copolymer blends of silicone elastomers

    DEFF Research Database (Denmark)

    A Razak, Aliff Hisyam; Yu, Liyun; Skov, Anne Ladegaard

    2017-01-01

    Increased electrical breakdown strength and increased dielectric permittivity of silicone-based dielectric elastomers are achieved by means of the addition of so-called voltage-stabilisers prepared from PDMS–PPMS copolymers as well as PDMS–PEG copolymers in order to compensate for the negative...... effect of softness on electrical stability of silicone elastomers. The voltage-stabilised elastomer, incorporating a high-permittivity PDMS–PEG copolymer, possesses increased relative permittivity, high electrical breakdown strength, excellent network integrity and low dielectric loss and paves the way...... towards specialised silicone elastomers for dielectric elastomer transducer products with inherent softness and electrical stability, and thus increased actuation at a given voltage....

  3. 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.

  4. Waste water derived electroactive microbial biofilms: growth, maintenance, and basic characterization.

    Science.gov (United States)

    Gimkiewicz, Carla; Harnisch, Falk

    2013-12-29

    The growth of anodic electroactive microbial biofilms from waste water inocula in a fed-batch reactor is demonstrated using a three-electrode setup controlled by a potentiostat. Thereby the use of potentiostats allows an exact adjustment of the electrode potential and ensures reproducible microbial culturing conditions. During growth the current production is monitored using chronoamperometry (CA). Based on these data the maximum current density (jmax) and the coulombic efficiency (CE) are discussed as measures for characterization of the bioelectrocatalytic performance. Cyclic voltammetry (CV), a nondestructive, i.e. noninvasive, method, is used to study the extracellular electron transfer (EET) of electroactive bacteria. CV measurements are performed on anodic biofilm electrodes in the presence of the microbial substrate, i.e. turnover conditions, and in the absence of the substrate, i.e. nonturnover conditions, using different scan rates. Subsequently, data analysis is exemplified and fundamental thermodynamic parameters of the microbial EET are derived and explained: peak potential (Ep), peak current density (jp), formal potential (E(f)) and peak separation (ΔEp). Additionally the limits of the method and the state-of the art data analysis are addressed. Thereby this video-article shall provide a guide for the basic experimental steps and the fundamental data analysis.

  5. Creep-Fatigue Relationsihps in Electroactive Polymer Systems and Predicted Effects in an Actuator Design

    Science.gov (United States)

    Vinogradov, Aleksandra M.; Ihlefeld, Curtis M.; Henslee, Issac

    2009-01-01

    The paper concerns the time-dependent behavior of electroactive polymers (EAP) and their use in advanced intelligent structures for space exploration. Innovative actuator design for low weight and low power valves required in small plants planned for use on the moon for chemical analysis is discussed. It is shown that in-depth understanding of cyclic loading effects observed through accelerated creep rates due to creep-fatigue interaction in polymers is critical in terms of proper functioning of EAP based actuator devices. In the paper, an overview of experimental results concerning the creep properties and cyclic creep response of a thin film piezoelectric polymer polyvinylidene fluoride (PVDF) is presented. The development of a constitutive creep-fatigue interaction model to predict the durability and service life of electroactive polymers is discussed. A novel method is proposed to predict damage accumulation and fatigue life of polymers under oyclic loading conditions in the presence of creep. The study provides a basis for ongoing research initiatives at the NASA Kennedy Space Center in the pursuit of new technologies using EAP as active elements for lunar exploration systems.

  6. Development of Enterobacter aerogenes fuel cells: from in situ biohydrogen oxidization to direct electroactive biofilm.

    Science.gov (United States)

    Zhuang, Li; Zhou, Shungui; Yuan, Yong; Liu, Tinglin; Wu, Zhifeng; Cheng, Jiong

    2011-01-01

    This study described an Enterobacter aerogenes-catalyzed microbial fuel cell (MFC) with a carbon-based anode that exhibited a maximum power density of 2.51 W/m(3) in the absence of artificial electron mediators. The MFC was started up rapidly, within hours, and the current generation in the early stage was demonstrated to result from in situ oxidation of biohydrogen produced by E. aerogenes during glucose fermentation. Over periodic replacement of substrate, both planktonic biomass in the culture liquid and hydrogen productivity decreased, while increased power density and coulombic efficiency and decreased internal resistance were unexpectedly observed. Using scanning electron microscopy and cyclic voltammetry, it was found that the enhanced MFC performance was associated with the development of electroactive biofilm on the anodic surface, proposed to involve an acclimation and selection process of E. aerogenes cells under electrochemical tension. The significant advantage of rapid start-up and the ability to develop an electroactive biofilm identifies E. aerogenes as a suitable biocatalyst for MFC applications.

  7. A study of metalized electrode self-clearing in electroactive polymer (EAP) based actuators

    Science.gov (United States)

    Ahmed, Saad; Ounaies, Zoubeida

    2016-04-01

    Electroactive polymer (EAP) based technologies have shown promise in areas such as artificial muscles, actuator, aerospace, medical and soft robotics. Still challenges remain such as low induced forces and defects-driven electrical breakdown, which impede the practical implementation of this technology. Multilayered or stacked configuration can address the low induced force issue whereas self-clearing can be a technique to improve breakdown limit of EAP based actuators. Self-clearing refers to the partial local breakdown of dielectric medium due to the presence of impurities, which in turn results in the evaporation of some of the metalized electrode. After this evaporation, the impurity is cleared and any current path would be safely cut off, which means the actuator continues to perform. It is a widely studied concept in the capacitor community, while it has not been studied much for EAP technologies. In this paper we report a systematic approach to precondition a silver-metalized electroactive polymer (EAP), more specifically P(VDF-TrFE-CTFE) terpolymer, using self-clearing concept. First, we show improvement in the dielectric breakdown strength of EAP based unimorph actuators after pre-clearing the impurities using low electric field (lower than dielectric breakdown of the terpolymer). Inspired by this improvement, we used Weibull statistics to systematically estimate the self-clearing/ preconditioning field needed to clear the defects. Then electrical breakdown experiments are conducted with and without preconditioning the samples to investigate its effect on the breakdown strength of the sample.

  8. Electricity-driven metabolic shift through direct electron uptake by electroactive heterotroph Clostridium pasteurianum

    Science.gov (United States)

    Choi, Okkyoung; Kim, Taeyeon; Woo, Han Min; Um, Youngsoon

    2014-01-01

    Although microbes directly accepting electrons from a cathode have been applied for CO2 reduction to produce multicarbon-compounds, a high electron demand and low product concentration are critical limitations. Alternatively, the utilization of electrons as a co-reducing power during fermentation has been attempted, but there must be exogenous mediators due to the lack of an electroactive heterotroph. Here, we show that Clostridium pasteurianum DSM 525 simultaneously utilizes both cathode and substrate as electron donors through direct electron transfer. In a cathode compartment poised at +0.045 V vs. SHE, a metabolic shift in C. pasteurianum occurs toward NADH-consuming metabolite production such as butanol from glucose (20% shift in terms of NADH consumption) and 1,3-propandiol from glycerol (21% shift in terms of NADH consumption). Notably, a small amount of electron uptake significantly induces NADH-consuming pathways over the stoichiometric contribution of the electrons as reducing equivalents. Our results demonstrate a previously unknown electroactivity and metabolic shift in the biochemical-producing heterotroph, opening up the possibility of efficient and enhanced production of electron-dense metabolites using electricity. PMID:25376371

  9. Micro-pseudocapacitors with Electroactive Polymer Electrodes: Towards Ac-Line Filtering Applications

    KAUST Repository

    Kurra, Narendra

    2016-05-05

    In this study, we investigate the frequency response of microsupercapacitors based on pseudocapacitive conducting polymer electrodes such as poly(3,4-ethylenedioxythiophene) (PEDOT), polypyrrole (PPY) and polyaniline (PANI). It is shown that by proper choice of polymeric material and device structure, mainiturized microsupercapacitors based on electroactive polymers can match the frequency response of commercial bulky electrolytic capacitors. Specifically, we shsow that PEDOT-based microsupercapacitors exhibit phase angle of -80.5º at 120 Hz which is comparable to commercial bulky electrolytic capacitors, but with an order of magnitude higher capacitance density (3 FV/cm3). The trade-off between the areal capacitance (CA) and frequency response in the 2D architecture (CA = 0.3 mF/cm2, phase angle of -80.5º at 120 Hz) is improved by designing 3D thin film architecture (CA = 3 mF/cm2, phase angle of -60º at 120 Hz). Our work demonstrates that fast frequency response can be achieved using electroactive polymer electrodes.

  10. Coarse Grained Simulation of Lipid Membrane and Triblock Copolymers

    Science.gov (United States)

    Hatakeyama, Masaomi; Faller, Roland

    2008-02-01

    We investigated the interaction between DPPC (Dipalmitoyl phosphatidylcholine) bilayer and polyethylene oxide-polypropylene oxide-polyethylene oxide (PEO-PPO-PEO) triblock copolymers using coarse grained simulation. We simulated two systems of DPPC bilayer and PEO-PPO-PEO triblock copolymer containing different mole fractions, and simulated DPPC vesicle with the copolymers. We found different adsorption mechanisms of triblock copolymers depending on concentration. And we also observed docking process between a lipid vesicle and a micelle of the copolymers.

  11. 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.

  12. Injectible bodily prosthetics employing methacrylic copolymer gels

    Science.gov (United States)

    Mallapragada, Surya K.; Anderson, Brian C.

    2007-02-27

    The present invention provides novel block copolymers as structural supplements for injectible bodily prosthetics employed in medical or cosmetic procedures. The invention also includes the use of such block copolymers as nucleus pulposus replacement materials for the treatment of degenerative disc disorders and spinal injuries. The copolymers are constructed by polymerization of a tertiary amine methacrylate with either a (poly(ethylene oxide)-b-poly(propylene oxide)-b-poly(ethylene oxide) polymer, such as the commercially available Pluronic.RTM. polymers, or a poly(ethylene glycol) methyl ether polymer.

  13. Enzyme cleavable nanoparticles from peptide based triblock copolymers

    Science.gov (United States)

    Fuchs, Adrian V.; Kotman, Niklas; Andrieu, Julien; Mailänder, Volker; Weiss, Clemens K.; Landfester, Katharina

    2013-05-01

    A solid-phase synthesis based approach towards protease cleavable polystyrene-peptide-polystyrene triblock copolymers and their formulation to nanoparticulate systems is presented. These nanoparticles are suitable for the optical detection of an enzyme and have the potential for application as a drug delivery system. Two different peptide sequences, one cleaved by trypsin (GFF), the other by hepsin (RQLRVVGG), a protease overexpressed in early stages of prostate cancer, are used as the central part of the triblock. For optical detection a fluorophore-quencher pair is introduced around the cleavage sequence. The solid phase synthesis is conduced such that two identical sequences are synthesized from one branching point. Eventually, carboxy-terminated polystyrene is introduced into the peptide synthesizer and coupled to the amino-termini of the branched sequence. Upon cleavage, a fragment is released from the triblock copolymer, which has the potential for use in drug delivery applications. Conducting the whole synthesis on a solid phase in the peptide synthesizer avoids solubility issues and post-synthetic purification steps. Due to the hydrophobic PS-chains, the copolymer can easily be formulated to form nanoparticles using a nanoprecipitation process. Incubation of the nanoparticles with the respective enzymes leads to a significant increase of the fluorescence from the incorporated fluorophore, thereby indicating cleavage of the peptide sequence and decomposition of the particles.A solid-phase synthesis based approach towards protease cleavable polystyrene-peptide-polystyrene triblock copolymers and their formulation to nanoparticulate systems is presented. These nanoparticles are suitable for the optical detection of an enzyme and have the potential for application as a drug delivery system. Two different peptide sequences, one cleaved by trypsin (GFF), the other by hepsin (RQLRVVGG), a protease overexpressed in early stages of prostate cancer, are used as the

  14. Utilizing copper(I) catalyzed azide-alkyne Huisgen 1,3-dipolar cycloaddition for the surface modification of colloidal particles with electroactive and emissive moieties

    Science.gov (United States)

    Rungta, Parul

    The development of charge-transporting and fluorescing colloidal particles that can be directly printed into electroluminescent devices may result in a broad impact on the use of electrical energy for illumination. The objective of this work was to design and synthesize electroactive & fluorescing colloidal particles; establish their optical, electronic, and thermodynamic properties; and transition them into a device format for potential applications. The original intended application of this work was to build "better" colloidally-based organic light emitting devices (OLEDs) by creating functional particles with superior electrical and optical performance relative to commercially available technologies, but through the course of the research, the particles that were developed were found to be better suited for medical applications. Nonetheless, the global objective envisioned at the onset of this research was consistent with its final outcomes. The research tasks pursued to accomplish this global objective included: (1) The design and synthesis of electroactive moieties and their conversion into organic light emitting devices; An electron-transporting monomer was synthesized that was structurally & energetically similar to the small molecule 2-biphenyl-4-yl-5-(4-tert-butylphenyl)-1,3,4-oxadiazole (tBu-PBD). The monomer was copolymerized with 2-(9H-carbazol-9-yl)ethyl 2-methylacrylate (CE) and the resulting copolymer was utilized in OLEDs which employed fluorescent coumarin 6 (C6) or phosphorescent tris(2-phenylpyridine)iridium(III) [Ir(ppy)3] emitters. The copolymer devices exhibited a mean luminance of ca. 400 and 3,552 cd/m2 with the C6 and Ir(ppy)3 emitters, that were stable with thermal aging at temperatures ranging from 23°C to 130°C. Comparable poly(9-vinyl-9H-carbazole)/tBu-PBD blend devices exhibited more pronounced variations in performance with thermal aging. (2) The surface-modification of colloids with electroactive & fluorescing moieties via "click

  15. MISCIBILITY IN COPOLYMER/HOMOPOLYMER BLENDS

    Institute of Scientific and Technical Information of China (English)

    JIANG Ming

    1988-01-01

    In order to study the miscibility of a copolymer with its corresponding homopolymers, varieties of multicomponent polymers including simple graft, multibranch, diblock, triblock and four-arm block copolymers and so-called ABCPs were synthesized and characterized. The morphologies of the blends comprising the covolymers and the corresponding homopolymers were examined by electron microscopy. It is concluded that beeides molecular weight, architecture of a copolymers has apparent effect on the miscibility, i.e. the more complex is molecular architecture, the greater is conformation restriction in microdomain formation and the less is solubility of homopolymer in corresponding domains. In addition, a density gradient model is suggested for describing the segment distribution of the bound and free chains in block-homopolymer systems. Using this model, Helfand's theory is extended to the blends of copolymer and homopolymer predicting the miscibility which is in good agreement with the experimental results.

  16. Styrene-Isoprene-Styrene Triblock Copolymer (SIS)/Polydiphenylamine Blends for Actuator Application

    Science.gov (United States)

    Thongsak, Kraipop; Sirivat, Anuvat

    2008-03-01

    Styrene-Isoprene-Styrene triblock copolymer (SIS) is a dielectric material exhibiting many properties similar to polyisoprene elastomer, which has been widely studied for eletroactive applications. In our work, SIS films were prepared via film casting at various polystyrene (PS) contents (19 wt %, 29 wt %, and 44 wt %), yielding three different morphology films as characterized by an optical microscope, SEM, and TEM. Polydiphenylamine (PDPA), a conductive polymer, was synthesized by the oxidative polymerization and doped with HCl. For electroactive applications, electrorheological properties of pure SIS films and SIS/PDPA blends under stretching at a fixed temperature of 25^oC were measured to determine the effects of morphology (spherical, cylindrical, and lamella morphology), particle concentration, and doping level on the electrorheological properties measured: the storage and the loss modulii (G' and G''), the storage modulus responses (δG'2kV/mm), and the storage modulus sensitivities (δG'2kV/mm/G'0), under applied electric field strength varying from 0 to 2 kV/mm.

  17. Systematic study of the structure of alternate pyromellitimide-PEO copolymers: Influence of the chain flexibility

    Energy Technology Data Exchange (ETDEWEB)

    Djurado, David [Laboratoire d' Electronique Moleculaire Organique and Hybride, DRFMC/SPrAM/CEA Grenoble, UMR CEA-CNRS-UJF 5819, 17 Avenue des Martyrs, 38054 Grenoble Cedex 9 (France); Curtet, Jean Pierre; Bee, Marc [Laboratoire de Spectrometrie Physique (UMR CNRS-UJF-5588) Universite J. Fourier, Grenoble I, Domaine Universitaire, B.P. 87 38402 St Martin d' Heres Cedex (France); Michot, Christophe [Department of Chemistry, University of Montreal, C.P. 6128, Succursale Centre-Ville, Montreal, Quebec H3C JJ7 (Canada); Armand, Michel [Department of Chemistry, University of Montreal, C.P. 6128, Succursale Centre-Ville, Montreal, Quebec H3C JJ7 (Canada); Laboratoire de Reactivite et de Chimie des Solides, Universite de Picardie Jules Verne, UMR 6007 CNRS, 33 rue Saint-Leu, 80039 Amiens (France)

    2007-12-31

    The structure of a family of copolyimides in which are alternating stiff/redox pyromellitimide units and flexible/solvating polyethyleneoxide (PEO) strands were studied by using wide angle and small angle X-ray scattering techniques and is fully discussed. It is shown that the rich variety of structures exhibited by these compounds can be understood by considering the dramatic change of flexibility of the chain induced by the variation of the length of the PEO strand compared to that of the pyromellimide segment. In this respect, concerning the compounds which exhibit fully amorphous structures a better understanding of their structural behavior can be obtained in the framework of Flory's theory of semi-rigid polymers. In this approach, the degree of flexibility of the chain is mainly resulting from the relative amount of flexible units constituting the repetition unit of the polymer chain. The final structural mode adopted by each compound in the solid state is then directly a consequence of this intrinsic property of the chain. The introduction of a lithium salt in contact with the copolymer chains induces some structure changes which can also be explained by the modification of the degree of flexibility of the chain. It is found that the best performances in terms of electroactivity and mixed conduction are precisely obtained with the only compound which keeps full amorphicity in absence and in presence of the lithium salt. (author)

  18. Block Copolymers: Synthesis and Applications in Nanotechnology

    Science.gov (United States)

    Lou, Qin

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

  19. Optimizing PANi doped electroactive substrates as patches for the regeneration of cardiac muscle.

    Science.gov (United States)

    Borriello, A; Guarino, V; Schiavo, L; Alvarez-Perez, M A; Ambrosio, L

    2011-04-01

    In scaffold aided regeneration of muscular tissue, composite materials are currently utilized as a temporary substrate to stimulate tissue formation by controlled electrochemical signals as well as continuous mechanical stimulation until the regeneration processes are completed. Among them, composites from the blending of conductive (CPs) and biocompatible polymers are powerfully emerging as a successful strategy for the regeneration of myocardium due to their unique conductive and biological recognition properties able to assure a more efficient electroactive stimulation of cells. Here, different composite substrates made of synthesized polyaniline (sPANi) and polycaprolactone (PCL) were investigated as platforms for cardiac tissue regeneration. Preliminary, a comparative analysis of substrates conductivity performed on casted films endowed with synthesized polyaniline (sPANi) short fibres or blended with emeraldine base polyaniline (EBPANi) allows to study the attitude of charge transport, depending on the conducting filler amount, shape and spatial distribution. In particular, conducibility tests indicated that sPANi short fibres provide a more efficient transfer of electric signal due to the spatial organization of electroactive needle-like phases up to form a percolative network. On the basis of this characterization, sPANi/PCL electrospun membranes have been also optimized to mimic either the morphological and functional features of the cardiac muscle ECM. The presence of sPANi does not relevantly affect the fibre architecture as confirmed by SEM/image analysis investigation which shows a broader distribution of fibres with only a slight reduction of the average fibre diameter from 7.1 to 6.4 μm. Meanwhile, biological assays--evaluation of cell survival rate by MTT assay and immunostaining of sarcomeric α-actinin of cardiomyocites-like cells--clearly indicate that conductive signals offered by PANi needles, promote the cardiogenic differentiation of h

  20. Silicone containing copolymers: Synthesis, properties and applications

    OpenAIRE

    Yılgör, Emel; Yılgör, İskender

    2013-01-01

    Accepted Manuscript Title: Silicone containing copolymers: Synthesis, properties and applications Author: Emel Yilgor Iskender Yilgor PII: S0079-6700(13)00141-X DOI: http://dx.doi.org/doi:10.1016/j.progpolymsci.2013.11.003 Reference: JPPS 848 To appear in: Progress in Polymer Science Received date: 1-8-2013 Revised date: 4-11-2013 Accepted date: 8-11-2013 Please cite this article as: Yilgor E, Yilgor I, Silicone containing copolymers: Synthesis, properties ...

  1. Amphiphilic diblock copolymers for molecular recognition

    OpenAIRE

    Nehring, Rainer

    2009-01-01

    In this thesis, the synthesis and the characterization of poly(butadiene)-blockpoly( ethylene oxide) copolymers with terminal Me2+-NTA groups (copper or nickel) is described for the first time. A convenient “one-pot” procedure that allows control over the individual block lengths of the copolymer and the end-group functionalization was successfully established. The formation of the metal-polymer complex has been confirmed by EPR and UV/VIS spectroscopy. Mixing of the Ni2+-NT...

  2. Drug targeting to tumors using HPMA copolymers

    OpenAIRE

    Lammers, T.G.G.M.

    2009-01-01

    Copolymers based on N-(2-hydroxypropyl)methacrylamide (HPMA) are prototypic and well-characterized polymeric drug carriers that have been broadly implemented in the delivery of anticancer agents. HPMA copolymers circulate for prolonged periods of time, and by means of the Enhance Permeability and Retention (EPR) effect, they localize to tumors both effectively and selectively. As a consequence, the concentrations of attached active agents in tumors can be increased, and their accumulation in ...

  3. Responsive Copolymers for Enhanced Petroleum Recovery

    Energy Technology Data Exchange (ETDEWEB)

    McCormick, C.; Hester, R.

    2001-02-27

    The objectives of this work was to: synthesize responsive copolymer systems; characterize molecular structure and solution behavior; measure rheological properties of aqueous fluids in fixed geometry flow profiles; and to tailor final polymer compositions for in situ rheology control under simulated conditions. This report focuses on the synthesis and characterization of novel stimuli responsive copolymers, the investigation of dilute polymer solutions in extensional flow and the design of a rheometer capable of measuring very dilute aqueous polymer solutions at low torque.

  4. Synthesis and characterization of polyester copolymers based on poly(butylene succinate) and poly(ethylene glycol)

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, Xiao-Ming, E-mail: xiaomingzhou@tust.edu.cn

    2012-12-01

    A series of polyester copolymers was synthesized from 1,4-succinic acid with 1,4-butanediol and poly(ethylene glycol) through a two-step process of esterification and polycondensation in this article. The composition and physical properties of copolyesters were investigated via GPC, {sup 1}HNMR, DSC and PLM. The copolymer composition was in good agreement with that expected from the feed composition of the reactants. The melting temperature (T{sub m}), crystallization temperature (T{sub c}), and crystallinity (X{sub c}) of these copolyesters decreased gradually as the content of PEG unit increased. Otherwise, experimental results also showed that the contents of PEG in copolymers had an effect on the molecular weight, distribution, thermal properties, hydrolysis degradation properties, and crystalline morphology of polyester copolymers. - Graphical abstract: The composition of polyester copolymer was determined from the {sup 1}H NMR spectra using the relative intensities of the proton peaks. As a sample, the {sup 1}H NMR spectrum of polyester copolymer with 10 mol% of PEG is shown in Fig. 2: CO-(CH{sub 2}){sub 2}-CO; O-CH{sub 2}- and C-(CH{sub 2}){sub 2}-C from the SA and BD unit at {delta}2.59; {delta} 4.08 and {delta}1.67; O-(CH{sub 2}CH{sub 2}){sub n}-O from the PEG unit at {delta} 3.61. The molar composition of polyester copolymer was measured as the area ratio of {delta}3.61/({delta}4.08 + {delta}1.67) peak. The PEG unit is incorporated into the copolymers in an amount of about 9.12mol% less than that of the feed proportion. These results showed that the composition of the copolymers is in good agreement with that expected from the feed proportion. Highlights: Black-Right-Pointing-Pointer The introduction of PEG unit changed the flexibility of PBS main chain. Black-Right-Pointing-Pointer PEG unit did not alter the crystal form of PBS in copolymers. Black-Right-Pointing-Pointer PEG unit hindered the formation of ring-banded spherulite morphology in copolymers

  5. Platform Approach to Produce Polymer Nanoparticles with Modular Functionality from Amphiphilic Block Copolymer Stabilizers

    Science.gov (United States)

    2014-04-01

    functionality, an amphiphilic BCP scaffold was devised to serve as an emulsion polymerization stabilizer. The PS-b-P(EO-co-AGE) BCP contained a PS...synthesized via emulsion polymerization using an amphiphilic block copolymer (BCP) surfactant. The polystyrene-block-poly(ethylene oxide-co-allyl...glycidyl ether) BCPs with various lengths and functional monomer incorporation were synthesized using anionic polymerization . Modification of the allyl

  6. Electroactive Tissue Scaffolds with Aligned Pores as Instructive Platforms for Biomimetic Tissue Engineering

    Directory of Open Access Journals (Sweden)

    John G. Hardy

    2015-01-01

    Full Text Available Tissues in the body are hierarchically structured composite materials with tissue-specific chemical and topographical properties. Here we report the preparation of tissue scaffolds with macroscopic pores generated via the dissolution of a sacrificial supramolecular polymer-based crystal template (urea from a biodegradable polymer-based scaffold (polycaprolactone, PCL. Furthermore, we report a method of aligning the supramolecular polymer-based crystals within the PCL, and that the dissolution of the sacrificial urea yields scaffolds with macroscopic pores that are aligned over long, clinically-relevant distances (i.e., centimeter scale. The pores act as topographical cues to which rat Schwann cells respond by aligning with the long axis of the pores. Generation of an interpenetrating network of polypyrrole (PPy and poly(styrene sulfonate (PSS in the scaffolds yields electroactive tissue scaffolds that allow the electrical stimulation of Schwann cells cultured on the scaffolds which increases the production of nerve growth factor (NGF.

  7. Indentation of a compressible soft electroactive half-space: Some theoretical aspects

    Institute of Scientific and Technical Information of China (English)

    Wen-Liang Zhang; Jin Qian; Wei-Qiu Chen

    2012-01-01

    We theoretically study the indentation response of a compressible soft electroactive material by a rigid punch.The half-space material is assumed to be initially subjected to a finite deformation and an electric biasing field. By adopting the linearized theory for incremental fields,which is established on the basis of a general nonlinear theory for electroelasticity,the appropriate equations governing the perturbed infinitesimal elastic and electric fields are derived particularly when the material is subjected to a uniform equibiaxial stretch and a uniform electric displacement.A general solution to the governing equations is presented,which is concisely expressed in terms of four quasi-harmonic functions.By adopting the potential theory method,exact contact solutions for three common perfectly conducting rigid indenters of fiat-ended circular,conical and spherical geometries can be derived,and some explicit relations that are of practical importance are outlined.

  8. Mechanistic stratification in electroactive biofilms of Geobacter sulfurreducens mediated by pilus nanowires

    Science.gov (United States)

    Steidl, Rebecca J.; Lampa-Pastirk, Sanela; Reguera, Gemma

    2016-08-01

    Electricity generation by Geobacter sulfurreducens biofilms grown on electrodes involves matrix-associated electron carriers, such as c-type cytochromes. Yet, the contribution of the biofilm's conductive pili remains uncertain, largely because pili-defective mutants also have cytochrome defects. Here we report that a pili-deficient mutant carrying an inactivating mutation in the pilus assembly motor PilB has no measurable defects in cytochrome expression, yet forms anode biofilms with reduced electroactivity and is unable to grow beyond a threshold distance (~10 μm) from the underlying electrode. The defects are similar to those of a Tyr3 mutant, which produces poorly conductive pili. The results support a model in which the conductive pili permeate the biofilms to wire the cells to the conductive biofilm matrix and the underlying electrode, operating coordinately with cytochromes until the biofilm reaches a threshold thickness that limits the efficiency of the cytochrome pathway but not the functioning of the conductive pili network.

  9. Application review of dielectric electroactive polymers (DEAPs) and piezoelectric materials for vibration energy harvesting

    Science.gov (United States)

    Yuan, Xuan; Changgeng, Shuai; Yan, Gao; Zhenghong, Zhao

    2016-09-01

    This paper reviews recent advances in vibration energy harvesting with particular emphasis on the solutions by using dielectric electroactive polymers (DEAPs) and piezoelectric materials. These smart materials are in essence capable of converting wasted vibration energy in the environment to usable electrical energy. Much previous researches have been devoted to studying the technology of harvesting mechanical energy using piezoelectric materials. The recent introduction of the DEAPs that exhibits large displacements under electric activation has led to their consideration as promising replacement for conventional piezoelectric materials. The properties of the two materials are described in this paper together with a comparison of their performance in relation with energy harvesting. Finally comparisons are made in the applications of vibration energy harvesting using these two materials. This paper has been written with reference to a large number of published papers listed in the reference section.

  10. An investigation of a thermally steerable electroactive polymer/shape memory polymer hybrid actuator

    Science.gov (United States)

    Ren, Kailiang; Bortolin, Robert S.; Zhang, Q. M.

    2016-02-01

    This paper investigates the thermal response of a hybrid actuator composed of an electroactive polymer (EAP) and a shape memory polymer (SMP). This study introduces the concept of using the large strain from a phase transition (ferroelectric to paraelectric phase) induced by temperature change in a poly(vinylidene fluoride-trifluoroethylene) film to tune the shape of an SMP film above its glass transition temperature (Tg). Based on the material characterization data, it is revealed that the thickness ratio of the EAP/SMP films plays a critical role in the displacement of the actuator. Further, it is also demonstrated that the displacement of the hybrid actuator can be tailored by varying the temperature, and finite element method simulation results fit well with the measurement data. This specially designed hybrid actuator shows great promise for future morphing aircraft applications.

  11. Bistable electroactive polymer with sharp rigid-to-rubbery phase transition

    Science.gov (United States)

    Qiu, Yu; Ren, Zhi; Hu, Wei; Liu, Chao; Pei, Qibing

    2016-04-01

    Bistable electroactive polymers (BSEP) usually exhibit glass transition that spans a rather broad temperature range and are normally actuated above 70 °C. High actuation temperature limits the BSEP for wearable and personal assistive applications. A phase-changing polymer is synthesized and employed as BSEP having a narrow rigid-to-rubbery transition temperature range. Shape memory effect with both fixation and recovery rate close to 100% was observed. Diaphragm actuators of the BSEP can be electrically actuated at 50 °C up to 70% strain, and the deformed shape was fixed after cooling the BSEP below the transition temperature. The rigid-to-rigid actuation can be repeated for at least 10,000 cycles.

  12. A novel quinoxaline bearing electroactive monomer: Pyrrole as the donor moiety

    Energy Technology Data Exchange (ETDEWEB)

    Taskin, Asli Tuba; Balan, Abidin; Epik, Bugra; Yildiz, Ersin [Middle East Technical University, Department of Chemistry, 06531, Ankara (Turkey); Udum, Yasemin Arslan [Gazi University, Institute of Science and Technology, Department of Advanced Technologies, 06570, Ankara (Turkey); Toppare, Levent [Middle East Technical University, Department of Chemistry, 06531, Ankara (Turkey)], E-mail: toppare@metu.edu.tr

    2009-09-30

    A novel electroactive monomer 5,8-di(1H-pyrrol-2-yl)-2,3-di(thiophen-2-yl)quinoxaline (PTQ) was successfully synthesized and its electrochromic properties were reported. Nuclear magnetic resonance ({sup 1}H NMR-{sup 13}C NMR) and mass spectroscopy were used to characterize the monomer. The monomer was electrochemically polymerized in the presence of tetrabutylammonium perchlorate (TBAP) as supporting electrolyte in dichloromethane. Monomer reveals relatively low oxidation potential at +0.70 V. Spectroelectrochemical behaviors and switching ability of homopolymer were investigated by UV-vis spectroscopy and cyclic voltammetry. Two {pi}-{pi}* transitions were observed at 400 and 815 nm with a low band gap, 1.0 eV. Polymer possesses 66% optical contrast in the Near IR region, which may be promising in NIR electrochromic device applications.

  13. Electrochemical energy storage device based on carbon dioxide as electroactive species

    Science.gov (United States)

    Nemeth, Karoly; van Veenendaal, Michel Antonius; Srajer, George

    2013-03-05

    An electrochemical energy storage device comprising a primary positive electrode, a negative electrode, and one or more ionic conductors. The ionic conductors ionically connect the primary positive electrode with the negative electrode. The primary positive electrode comprises carbon dioxide (CO.sub.2) and a means for electrochemically reducing the CO.sub.2. This means for electrochemically reducing the CO.sub.2 comprises a conductive primary current collector, contacting the CO.sub.2, whereby the CO.sub.2 is reduced upon the primary current collector during discharge. The primary current collector comprises a material to which CO.sub.2 and the ionic conductors are essentially non-corrosive. The electrochemical energy storage device uses CO.sub.2 as an electroactive species in that the CO.sub.2 is electrochemically reduced during discharge to enable the release of electrical energy from the device.

  14. Guest Editorial Introduction to the focused Section on electroactive Polymer Mechatronics

    DEFF Research Database (Denmark)

    Carpi, Federico; Kornbluh, Roy; Sommer-Larsen, Peter

    2011-01-01

    Mechatronic devices and systems based on so-called electroactive polymers (EAPs) represent a fast-growing and promising scientific field of research and development. EAPs consist of materials capable of changing dimensions and/or shape in response to suitable electrical stimuli. These polymers show...... unique properties, such as sizable electrically driven active strains or stresses, high mechanical flexibility, lowdensity, structural simplicity, ease of processing and scalability, no acoustic noise, and, in most cases, low costs. EAPs are today studied for applications that so far have been...... unachievable with conventional actuation technologies, with usage spanning from the micro- to the macro-scale, in several fields, including robotics, automation, prosthetics, orthotics, artificial organs, optics, energy harvesting, and even aerospace. In an effort to disseminate current advances in the field...

  15. Hybrid electrodes composed of electroactive polymer and metal hexacyanoferrates in aprotic electrolytes

    Energy Technology Data Exchange (ETDEWEB)

    Wilamowska, Monika; Lisowska-Oleksiak, Anna [Gdansk University of Technology, Chemical Faculty, Department of Chemical Technology, Narutowicza 11/12, 80-952 Gdansk (Poland)

    2009-10-20

    In this work hybrid materials composed of electroactive polymer poly(3,4-ethylenedioxythiophene) (pEDOT) and metal hexacyanoferrates (Mehcf) (Me = Fe, Co, Ni) were tested in ethylene carbonate (EC):propylene carbonate (PC) electrolytes containing 0.5 M KPF{sub 6} or 0.5 M LiPF{sub 6} salts. The hybrid materials pEDOT/Mehcf were examined by using: cyclic voltammetry (CVA), potentiometry and impedance spectroscopy (IS). The materials pEDOT/Mehcf exhibit electrode activity, good stability and high electrical capacity in tested nonaqueous electrolytes and they are considered to be suitable active materials for supercapacitors or for positive electrode of secondary cell with lithium and potassium salts. Contrary to the solid Prussian Blue ''PB'' analogues, hybrid pEDOT/Cohcf electrodes work with good efficiency in contact with nonaqueous electrolyte containing lithium salts. (author)

  16. Study on the possibility of cellulose-based electroactive paper sensor

    Science.gov (United States)

    Kim, Heung Soo; Kim, Jaehwan

    2012-04-01

    The possibility as a vibration sensor of Electro-Active paper (EAPap) based on piezoelectricity was investigated in the present paper. The EAPap was fabricated by regenerating and tape casting cellulose. The gold, silver and aluminum were deposited on both sides of the cut cellulose film using a thermal evaporator. The sample was coated by thin laminating film for packaging. The simple aluminum cantilevered beam was used for the vibration testing and EAPap was attached on the beam. The original EAPap sensor without grounding and shielding has greatly affected by the surrounding noise such as power noise especially. The power noise reduced dramatically with grounding and shielding of EAPap. The impulsive response of EAPap provided correct dynamic characteristics of the beam. Forced response of EAPap presented that gold and silver electrodes are suitable for EAPap sensor but aluminum electrode provides too many noise due to high resistance. PVDF provided similar characteristics of EAPap, which results EAPap has high potential as a vibration sensor.

  17. An electroactive polymer based concept for vibration reduction via adaptive supports

    Science.gov (United States)

    Wolf, Kai; Röglin, Tobias; Haase, Frerk; Finnberg, Torsten; Steinhoff, Bernd

    2008-03-01

    A concept for the suppression of resonant vibration of an elastic system undergoing forced vibration coupled to electroactive polymer (EAP) actuators based on dielectric elastomers is demonstrated. The actuators are utilized to vary the stiffness of the end support of a clamped beam, which is forced to harmonic vibration via a piezoelectric patch. Due to the nonlinear dependency of the elastic modulus of the EAP material, the modulus can be changed by inducing an electrostrictive deformation. The resulting change in stiffness of the EAP actuator leads to a shift of the resonance frequencies of the vibrating beam, enabling an effective reduction of the vibration amplitude by an external electric signal. Using a custom-built setup employing an aluminum vibrating beam coupled on both sides to electrodized strips of VHB tape, a significant reduction of the resonance amplitude was achieved. The effectiveness of this concept compared to other active and passive concepts of vibration reduction is discussed.

  18. The synthesis and characterization of a novel biodegradable and electroactive polyphosphazene for nerve regeneration

    Energy Technology Data Exchange (ETDEWEB)

    Zhang Qingsong, E-mail: zhangqingsong@whut.edu.cn [Biomedical Materials and Engineering Research Center, Wuhan University of Technology, Wuhan 430070 (China); Yan Yuhua; Li Shipu; Feng Tao [Biomedical Materials and Engineering Research Center, Wuhan University of Technology, Wuhan 430070 (China)

    2010-01-01

    Conductive polymers have been of great interest to the biopharmaceutical industry because of their cell adhesion and proliferation. In this paper, a novel electrically-conductive and biodegradable polyphosphazene polymer containing parent aniline pentamer (PAP) and glycine ethyl ester (GEE) as side chains was synthesized through a nucleophilic substitution reaction for its potential application in nerve regeneration. The electrical conductivity of the polymer was {approx} 2 x 10{sup -5} S/cm in the semiconducting region upon preliminarily protonic-doped experiment. Degradation studies carried out in phosphate-buffered saline at 37 deg. C showed a mass loss of {approx} 50% after 70 days. In vitro cytotoxicity to the RSC96 Schwann cells was evaluated using the cell viability assay. The polymer exhibited no cytotoxicity, indicating that such a polyphosphazene polymer has potential as scaffold material in tissue engineering for peripheral nerve regeneration or other biomedical devices that require electroactivity.

  19. Possibility of cellulose-based electro-active paper energy scavenging transducer.

    Science.gov (United States)

    Abas, Zafar; Kim, Heung Soo; Zhai, Lindong; Kim, Jaehwan; Kim, Joo Hyung

    2014-10-01

    In this paper, a cellulose-based Electro-Active Paper (EAPap) energy scavenging transducer is presented. Cellulose is proven as a smart material, and exhibits piezoelectric effect. Specimens were prepared by coating gold electrodes on both sides of cellulose film. The fabricated specimens were tested by a base excited aluminum cantilever beam at resonant frequency. Different tests were performed with single and multiple parallel connected electrodes coated on the cellulose film. A maximum of 131 mV output voltage was measured, when three electrodes were connected in parallel. It was observed that voltage output increases significantly with the area of electrodes. From these results, it can be concluded that the piezoelectricity of cellulose-based EAPap can be used in energy transduction application.

  20. Electro-Active Device Using Radial Electric Field Piezo-Diaphragm for Control of Fluid Movement

    Science.gov (United States)

    Bryant, Robert G. (Inventor); Working, Dennis C. (Inventor)

    2005-01-01

    A fluid-control electro-active device includes a piezo-diaphragm made from a ferroelectric material sandwiched by first and second electrode patterns configured to introduce an electric field into the ferroelectric material when voltage is applied thereto. The electric field originates at a region of the ferroelectric material between the first and second electrode patterns, and extends radially outward from this region of the ferroelectric material and substantially parallel to the plane of the ferroelectric material. The piezo-diaphragm deflects symmetrically about this region in a direction substantially perpendicular to the electric field. An annular region coupled to and extending radially outward from the piezo-diaphragm perimetrically borders the piezo-diaphragm, A housing is connected to the region and at least one fluid flow path with piezo-diaphragm disposed therein.

  1. The influence of chain stretching on the phase behavior of multiblock copolymer and comb copolymer melts

    NARCIS (Netherlands)

    Angerman, HJ; ten Brinke, G

    The subject of this paper is inspired by microphase-separated copolymer melts in which a small-scale structure is present inside one of the phases of a large-scale structure. Such a situation can arise in a diblock copolymer melt, if one of the blocks of the diblock is in itself a multiblock

  2. Facile Synthesis of Magnetic Copolymer Microspheres Based on Poly(glycidyl methacrylate-co-N-isopropylacrylamide/Fe3O4 by Suspension Photopolymerization

    Directory of Open Access Journals (Sweden)

    Siti Zulaikha Mazlan

    2014-01-01

    Full Text Available Magnetic copolymer based on poly(glycidyl methacrylate-co-N-isopropylacrylamide microspheres was prepared by 2,2-dimethoxy-2-phenylacetophenone- (DMPP- photo initiated and poly(vinyl alcohol- (PVA- stabilized single step suspension photopolymerization. The effect of chemical interaction, morphology, and thermal properties by adding 0.1% w/v Fe3O4 in the copolymer was investigated. Infrared analysis (FTIR showed that (C=C band disappeared after copolymerization, indicating that the magnetic copolymer microspheres were successfully synthesized and two important bands at 908 cm−1 and 1550 cm−1 appear. These are associated with the epoxy group stretching of GMA and secondary amide (N–H/C–H deformation vibration of NIPAAm in magnetic microspheres. The X-ray diffraction (XRD result proved the incorporation of Fe3O4 nanoparticles with copolymer microspheres as peak of Fe3O4 was observed. Morphology study revealed that magnetic copolymer exhibited uniform spheres and smoother appearance when entrapped with Fe3O4 nanoparticles. The lowest percentage of Fe3O4 nanoparticles leached from the copolymer microspheres was obtained at pH 7. Finally, thermal property of the copolymer microspheres was improved by adding a small amount of Fe3O4 nanoparticles that has been shown from the thermogram.

  3. Preparation and Characterization of Copolymer Micelles Formed by Poly(ethylene glycol)-Polylactide Block Copolymers as Novel Drug Carriers

    Institute of Scientific and Technical Information of China (English)

    姜维; 王运东; 甘泉; 张建铮; 赵秀文; 费维扬; 贝建中; 王身国

    2006-01-01

    Diblock copolymer poly(ethylene glycol) methyl ether-polylactide (MePEG-PLA) micelles were prepared by dialysis against water. Indomethacin (IMC) as a model drug was entrapped into the micelles by dialysis method. The critical micelle concentration (CMC) of the prepared micelles in distilled water investigated by fluorescence spectroscopy was 0.0051mg/mL which is lower than that of common low molecular weight surfactants. The diameters of MePEG-PLA micelles and IMC loaded MePEG-PLA micelles in a number-averaged scale measured by dynamic light scattering were 52.4 and 53.7 nm respectively. The observation with transmission electron microscope and scanning electron microscope showed that the appearance of MePEG-PLA micelles was in a spherical shape. The content of IMC incorporated in the core portion of the micelles was 18% (ω). The effects of the synthesis method of the copolymer on the polydispersity of the micelles and the yield of the micelles formation were discussed.

  4. 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."

  5. BODIPY-Based Donor-Acceptor Pi-Conjugated Alternating Copolymers

    Energy Technology Data Exchange (ETDEWEB)

    Popere, Bhooshan C.; Della Pelle, Andrea M.; Thayumanavan, S.

    2011-06-28

    Four novel π-conjugated copolymers incorporating 4,4-difluoro-4-borata-3a-azonia-4a-aza-s-indacene (BODIPY) core as the “donor” and quinoxaline (Qx), 2,1,3-benzothiadiazole (BzT), N,N'-di(2'-ethyl)hexyl-3,4,7,8-naphthalenetetracarboxylic diimide (NDI), and N,N'-di(2'-ethyl)hexyl-3,4,9,10-perylene tetracarboxylic diimide (PDI) as acceptors were designed and synthesized via Sonogashira polymerization. The polymers were characterized by ¹H NMR spectroscopy, gel permeation chromatography (GPC), UV–vis absorption spectroscopy, and cyclic voltammetry. Density functional theory (DFT) calculations were performed on polymer repeat units, and the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) energy levels were estimated from the optimized geometry using B3LYP functional and 6-311g(d,p) basis set. Copolymers with Qx and BzT possessed HOMO and LUMO energy levels comparable to those of BODIPY homopolymer, while PDI stabilized both HOMO and LUMO levels. Semiconductor behavior of these polymers was estimated in organic thin-film transistors (OTFT). While the homopolymer, Qx, and BzT-based copolymers showed only p-type semiconductor behavior, copolymers with PDI and NDI showed only n-type behavior.

  6. Synthesis and properties of random copolymers of functionalised polybenzimidazoles for high temperature fuel cells

    Energy Technology Data Exchange (ETDEWEB)

    Mader, J.A.; Benicewicz, B.C. [Department of Chemistry and Biochemistry and USC Nanocenter, University of South Carolina, 631 Sumter St., Columbia, SC 29208 (United States)

    2011-04-15

    A series of polybenzimidazoles (PBIs) incorporating main chain sulphonic acid groups were synthesised as random copolymers with p-PBI in varying ratios using polyphosphoric acid (PPA) as both the polymerisation solvent and polycondensation reagent. The PPA process was used to produce high molecular weight phosphoric acid (PA) doped PBI gel membranes in a one-step procedure. These membranes exhibit excellent mechanical properties (0.528-2.51 MPa tensile stress and 130-300% tensile strain) even at high acid doping levels [20-40 mol PA/PRU (polymer repeat unit)] and high conductivities (0.148-0.291 S cm{sup -1}) at elevated temperatures (>100 C) with no external humidification, depending on copolymer composition. Fuel cell testing was conducted with hydrogen fuel and air or oxygen oxidants for all membrane compositions at temperatures greater than 100 C without external feed gas humidification. Initial studies showed a maximum fuel performance of 0.675 V for the 25 mol% s-PBI/75 mol% p-PBI random copolymer at 180 C and 0.2 A cm{sup -2} with hydrogen and air, and 0.747 V for the same copolymer at 180 C and 0.2 A cm{sup -2} with hydrogen and oxygen. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  7. Ferrocene-Based Monomers, Oligomers and Polymers as Electro-Active Materials

    OpenAIRE

    Al Khalyfeh, Khaled

    2016-01-01

    The present PhD thesis deals with the synthesis and characterization of functionalized ferrocenes with up to four aldehyde and vinyl groups and their usage as monomers to produce novel ferrocene-based oligomers with conjugated backbones via ADMET (acyclic diene metathesis) and HWE (Horner-Wadsworth-Emmons) reaction protocols. In addition, ferrocene-containing polymers (linear, cross-linked and co-polymers) with aliphatic backbones generated by anionic bulk and solution polymerization routes, ...

  8. Electroactive Polymers as Environmentally Benign Coating Replacements for Cadmium Plating on High Strength Steels

    Science.gov (United States)

    2008-06-01

    materials is a random copolymer of thiophene acetic acid with hexylthiophene to produce a soluble polymer with good adhesion properties . While...R. and Walton, E., “Some Properties and Reactions of -chloroethyl, - cyanoethyl, and -carbethoxyethyl toluene-p- sulphonates Including an...87 ii List of Figures Figure 1. Synthesis of 3-(pyrrol-1-yl) propanoic acid (3PPA) p. 8 Figure 2

  9. Polyamide copolymers having 2,5-furan dicarboxamide units

    Energy Technology Data Exchange (ETDEWEB)

    Chisholm, Bret Ja; Samanta, Satyabrata

    2017-09-19

    Polyamide copolymers, and methods of making and using polyamide copolymers, having 2,5-furan dicarboxamide units are disclosed herein. Such polymers can be useful for engineering thermoplastics having advantageous physical and/or chemical properties.

  10. Oil recovery with vinyl sulfonic acid-acrylamide copolymers

    Energy Technology Data Exchange (ETDEWEB)

    Norton, C.J.; Falk, D.O.

    1973-12-18

    An aqueous polymer flood containing sulfomethylated alkali metal vinyl sulfonate-acrylamide copolymers was proposed for use in secondary or tertiary enhanced oil recovery. The sulfonate groups on the copolymers sustain the viscosity of the flood in the presence of brine and lime. Injection of the copolymer solution into a waterflooded Berea core, produced 30.5 percent of the residual oil. It is preferred that the copolymers are partially hydrolyzed.

  11. Calcium silicate nanowires - An effective alternative for improving mechanical properties of chitosan-hydroxyethyl methacrylate (HEMA) copolymer nanocomposites.

    Science.gov (United States)

    Bari, Sarang S; Mishra, Satyendra

    2017-08-01

    Nanowires of calcium silicate were successfully synthesized by ultrasonic irradiation process and incorporated into chitosan and hydroxyetheyl methacrylate (HEMA) copolymer matrix by solution blending for efficacious preparation of biodegradable nanocomposites. Remarkable improvement in mechanical properties of the nanocomposites was noticed after micro-tensile analysis. Enlarged surface area and higher aspect ratio of CaSiO3 nanowires were the key factors responsible for such improvement. This was supported by EDS and XRD analysis in terms of proper distribution of nanofiller through the copolymer matrix and corresponding rise in percentage crystallanity respectively. Contact angle and biodegradation studies further clarified that nano-CaSiO3 did not affect the hydrophilicity and general degradation route of chitosan copolymer respectively. This renders the nano-CaSiO3 as an ideal substitute for preparing high performance nanocomposites to be applicable for biomedical applications. Copyright © 2017 Elsevier Ltd. All rights reserved.

  12. Chain exchange in block copolymer micelles

    Science.gov (United States)

    Lu, Jie; Bates, Frank; Lodge, Timothy

    2014-03-01

    Block copolymer micelles are aggregates formed by self-assembly of amphiphilic copolymers dispersed in a selective solvent, driven by unfavorable interactions between the solvent and the core-forming block. Due to the relatively long chains being subject to additional thermodynamic and dynamic constraints (e.g., entanglements, crystallinity, vitrification), block copolymer micelles exhibit significantly slower equilibration kinetics than small molecule surfactants. As a result, details of the mechanism(s) of equilibration in block copolymer micelles remain unclear. This present works focuses on the chain exchange kinetics of poly(styrene-b-ethylenepropylene) block copolymers in squalane (C30H62) using time-resolved small angle neutron scattering (TR-SANS). A mixture of h-squalane and d-squalane is chosen so that it contrast matches a mixed 50/50 h/d polystyrene micelle core. When the temperature is appropriate and isotopically labeled chains undergo mixing, the mean core contrast with respect to the solvent decreases, and the scattering intensity is therefore reduced. This strategy allows direct probing of chain exchange rate from the time dependent scattering intensity I(q, t).

  13. Thermoreversible copolymer gels for extracellular matrix.

    Science.gov (United States)

    Vernon, B; Kim, S W; Bae, Y H

    2000-07-01

    To improve the properties of a reversible synthetic extracellular matrix based on a thermally reversible polymer, copolymers of N-isopropylacrylamide and acrylic acid were prepared in benzene with varying contents of acrylic acid (0 to 3%) and the thermal properties were evaluated. The poly(N-isopropylacrylamide) and copolymers made with acrylic acid had molecular weights from 0.8 to 1.7 x10(6) D. Differential scanning calorimetry (DSC) showed the high-molecular-weight acrylic acid copolymers had similar onset temperatures to the homopolymers, but the peak width was considerably increased with increasing acrylic acid content. DSC and cloud point measurements showed that polymers with 0 to 3% acrylic acid exhibit a lower critical solution temperature (LCST) transition between 30 degrees and 37 degrees C. In swelling studies, the homopolymer showed significant syneresis at temperatures above 31 degrees C. Copolymers with 1 and 1.5% showed syneresis beginning at 32 degrees and 37 degrees C, respectively. At 37 degrees C the copolymers with 1.5-3% acrylic acid showed little or no syneresis. Due to the high water content and a transition near physiologic conditions (below 37 degrees C), the polymers with 1.5-2.0% acrylic acid exhibited properties that would be useful in the development of a refillable synthetic extracellular matrix. Such a matrix could be applied to several cell types, including islets of Langerhans, for a biohybrid artificial pancreas.

  14. Charge Transport in Conjugated Block Copolymers

    Science.gov (United States)

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

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

  15. SCATTERING BY CYCLIC POLYMERS AND COPOLYMERS AT LARGE SCATTERING VECTORS

    NARCIS (Netherlands)

    KOSMAS, M; BENOIT, H; HADZIIOANNOU, G

    1994-01-01

    General formulae allowing the evaluation of the form factors of cyclic block copolymers are established and graphs for cyclic copolymers of the form (A-B)(N) are shown. When N is large, the linear and the cyclic copolymer have the same behaviour. It is possible to extend at large angle an analytical

  16. 21 CFR 175.210 - Acrylate ester copolymer coating.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Acrylate ester copolymer coating. 175.210 Section... COATINGS Substances for Use as Components of Coatings § 175.210 Acrylate ester copolymer coating. Acrylate ester copolymer coating may safely be used as a food-contact surface of articles intended for...

  17. 21 CFR 173.60 - Dimethylamine-epichlorohydrin copolymer.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Dimethylamine-epichlorohydrin copolymer. 173.60... HUMAN CONSUMPTION Polymer Substances and Polymer Adjuvants for Food Treatment § 173.60 Dimethylamine-epichlorohydrin copolymer. Dimethylamine-epichlorohydrin copolymer (CAS Reg. No. 25988-97-0) may be safely used in...

  18. SCATTERING BY CYCLIC POLYMERS AND COPOLYMERS AT LARGE SCATTERING VECTORS

    NARCIS (Netherlands)

    KOSMAS, M; BENOIT, H; HADZIIOANNOU, G

    1994-01-01

    General formulae allowing the evaluation of the form factors of cyclic block copolymers are established and graphs for cyclic copolymers of the form (A-B)(N) are shown. When N is large, the linear and the cyclic copolymer have the same behaviour. It is possible to extend at large angle an analytical

  19. Adsorption of graft copolymers onto silica and titania.

    NARCIS (Netherlands)

    Bijsterbosch, H.D.; Cohen Stuart, M.A.; Fleer, G.J.

    1998-01-01

    The adsorption of graft copolymers of poly(acrylamide) (PAAm, backbone) and poly(ethylene oxide) (PEO, side chains) from aqueous solution onto silica and titania was studied with reflectometry. Two high-molar-mass copolymers were used with different PEO graft densities (10 and 18% w/w PEO in copolym

  20. 21 CFR 177.1350 - Ethylene-vinyl acetate copolymers.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Ethylene-vinyl acetate copolymers. 177.1350 Section... Basic Components of Single and Repeated Use Food Contact Surfaces § 177.1350 Ethylene-vinyl acetate copolymers. Ethylene-vinyl acetate copolymers may be safely used as articles or components of...

  1. Nanotube Film Electrode and an Electroactive Device Fabricated with the Nanotube Film Electrode and Methods for Making Same

    Science.gov (United States)

    Kang, Jin Ho (Inventor); Park, Cheol (Inventor); Harrison, Joycelyn S. (Inventor)

    2017-01-01

    Disclosed is a single wall carbon nanotube (SWCNT) film electrode (FE), all-organic electroactive device systems fabricated with the SWNT-FE, and methods for making same. The SWCNT can be replaced by other types of nanotubes. The SWCNT film can be obtained by filtering SWCNT solution onto the surface of an anodized alumina membrane. A freestanding flexible SWCNT film can be collected by breaking up this brittle membrane. The conductivity of this SWCNT film can advantageously be higher than 280 S/cm. An electroactive polymer (EAP) actuator layered with the SWNT-FE shows a higher electric field-induced strain than an EAP layered with metal electrodes because the flexible SWNT-FE relieves the restraint of the displacement of the polymeric active layer as compared to the metal electrode. In addition, if thin enough, the SWNT-FE is transparent in the visible light range, thus making it suitable for use in actuators used in optical devices.

  2. Graphene-coated meshes for electroactive flow control devices utilizing two antagonistic functions of repellency and permeability

    Science.gov (United States)

    Tabassian, Rassoul; Oh, Jung-Hwan; Kim, Sooyeun; Kim, Donggyu; Ryu, Seunghwa; Cho, Seung-Min; Koratkar, Nikhil; Oh, Il-Kwon

    2016-10-01

    The wettability of graphene on various substrates has been intensively investigated for practical applications including surgical and medical tools, textiles, water harvesting, self-cleaning, oil spill removal and microfluidic devices. However, most previous studies have been limited to investigating the intrinsic and passive wettability of graphene and graphene hybrid composites. Here, we report the electrowetting of graphene-coated metal meshes for use as electroactive flow control devices, utilizing two antagonistic functions, hydrophobic repellency versus liquid permeability. Graphene coating was able to prevent the thermal oxidation and corrosion problems that plague unprotected metal meshes, while also maintaining its hydrophobicity. The shapes of liquid droplets and the degree of water penetration through the graphene-coated meshes were controlled by electrical stimuli based on the functional control of hydrophobic repellency and liquid permeability. Furthermore, using the graphene-coated metal meshes, we developed two active flow devices demonstrating the dynamic locomotion of water droplets and electroactive flow switching.

  3. Zinc Composite Layers, Incorporating Polymeric Nano-aggregates: Surface Analysis and Electrochemical Behavior

    NARCIS (Netherlands)

    Koleva, D.A.; Zhang, X.; Petrov, P.; Boshkov, N.; Van Breugel, K.; De Wit, J.H.W.; Mol, J.M.C.; Tsvetkova, N.

    2008-01-01

    This study reports on a comparative investigation of the corrosion behavior of zinc (Zn) and nano-composite zinc (ZnC) galvanic layers in 5% NaCl solution. The metallic matrix of the ZnC layers incorporates nano-sized, stabilized polymeric aggregates, formed from the amphiphilic tri-block co-polymer

  4. 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.

  5. Nanoscale Ionic Aggregate Morphology in Zwitterionic Copolymers

    Science.gov (United States)

    Choi, Jae-Hong; Huyck, Rebecca; Salas-de La Cruz, David; Long, Timothy E.; Winey, Karen I.

    2009-03-01

    The morphology of two different zwitterionic copolymers, poly(sulfobetaine methacrylate-ran-butyl acrylate), and poly(sulfobetaine methacrylamide-ran-butyl acrylate) are investigated as a function of the mol % content of SBMA (7 and 9 mol %) and SBMAm (6, 10 and 13 mol %), respectively. In both copolymers, X-ray scattering results show a new structure in the material arising from ionic aggregates. The sizes of the ionic aggregates are obtained through the scattering model. The sizes of the ionic aggregates increase as the ion content increases. The application of scanning transmission electron microscopy to the study of ionomer morphology has enabled direct, model-independent visualization of the ionic aggregates. The correlation between X-ray scattering results and the real space imaging for morphology of these zwitterionic copolymers will be presented.

  6. Optical properties of coumarins containing copolymers

    Science.gov (United States)

    Skowronski, L.; Krupka, O.; Smokal, V.; Grabowski, A.; Naparty, M.; Derkowska-Zielinska, B.

    2015-09-01

    We investigate the optical properties such as absorption coefficient, refractive index, real and imaginary parts of dielectric function and energy band gap of coumarin-containing copolymers thin films by means of spectroscopic ellipsometry (SE) combined with transmittance measurements (T) and atomic force microscopy (AFM). We found that the optical properties of coumarin-containing copolymers strongly depend from length of alkyl spacer as well as the type of substitution in coumarin moiety. In our case the refractive index as well as the energy band gap of coumarin-containing copolymer decrease with increase the length of alkyl spacer. Additionally, the lengthening of the alkyl spacer brings the bathochromic shifts of the absorption spectra towards longer wavelengths.

  7. Synthesis, characterization and antioxidant activity of a novel electroactive and biodegradable polyurethane for cardiac tissue engineering application

    Energy Technology Data Exchange (ETDEWEB)

    Baheiraei, Nafiseh [Department of Tissue Engineering, School of Advanced Medical Technologies, Tehran University of Medical Sciences, 1417755469 Tehran (Iran, Islamic Republic of); Yeganeh, Hamid, E-mail: h.yeganeh@ippi.ac.ir [Department of Polyurethane, Iran Polymer and Petrochemical Institute, P.O. Box: 14965/115, Tehran (Iran, Islamic Republic of); Ai, Jafar [Department of Tissue Engineering, School of Advanced Medical Technologies, Tehran University of Medical Sciences, 1417755469 Tehran (Iran, Islamic Republic of); Brain and Spinal Injury Research Center, Tehran University of Medical Sciences, Tehran (Iran, Islamic Republic of); Gharibi, Reza [Department of Polyurethane, Iran Polymer and Petrochemical Institute, P.O. Box: 14965/115, Tehran (Iran, Islamic Republic of); Azami, Mahmoud; Faghihi, Faezeh [Department of Tissue Engineering, School of Advanced Medical Technologies, Tehran University of Medical Sciences, 1417755469 Tehran (Iran, Islamic Republic of)

    2014-11-01

    There has been a growing trend towards applying conducting polymers for electrically excitable cells to increase electrical signal propagation within the cell-loaded substrates. A novel biodegradable electroactive polyurethane containing aniline pentamer (AP-PU) was synthesized and fully characterized by spectroscopic methods. To tune the physico-chemical properties and biocompatibility, the AP-PU was blended with polycaprolactone (PCL). The presence of electroactive moieties and the electroactivity behavior of the prepared films were confirmed by UV–visible spectroscopy and cyclic voltammetry. A conventional four probe analysis demonstrated the electrical conductivity of the films in the semiconductor range (∼ 10{sup −5} S/cm). MTT assays using L929 mouse fibroblast and human umbilical vein endothelial cells (HUVECs) showed that the prepared blend (PB) displayed more cytocompatibility compared with AP-PU due to the introduction of a biocompatible PCL moiety. The in vitro cell culture also confirmed that PB was as supportive as tissue culture plate. The antioxidant activity of the AP-PU was proved using 1,1-diphenyl-2-picrylhydrazyl (DPPH) scavenging assay by employing UV–vis spectroscopy. In vitro degradation tests conducted in phosphate-buffered saline, pH 7.4 and pH 5.5, proved that the films were also biodegradable. The results of this study have highlighted the potential application of this bioelectroactive polyurethane as a platform substrate to study the effect of electrical signals on cell activities and to direct desirable cell function for tissue engineering applications. - Highlights: • Straight forward methodology for synthesis of electroactive polyurethane • Biodegradability and non-toxicity through proper selection of starting materials • Supporting cell proliferation and attachment combined with antioxidant property.

  8. Electro-Active Polymers (EAPs): A Promising Route to Design Bio-Organic/Bioinspired Platforms with on Demand Functionalities

    OpenAIRE

    Vincenzo Guarino; Simona Zuppolini; Anna Borriello; Luigi Ambrosio

    2016-01-01

    Through recent discoveries and new knowledge among correlations between molecular biology and materials science, it is a growing interest to design new biomaterials able to interact—i.e., to influence, to guide or to detect—with cells and their surrounding microenvironments, in order to better control biological phenomena. In this context, electro-active polymers (EAPs) are showing great promise as biomaterials acting as an interface between electronics and biology. This is ascribable to the ...

  9. 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.

  10. Approach for discrimination and quantification of electroactive species: kinetics difference revealed by higher harmonics of Fourier transformed sinusoidal voltammetry.

    Science.gov (United States)

    Fang, Yishan; Huang, Xinjian; Wang, Lishi

    2015-01-06

    Discrimination and quantification of electroactive species are traditionally realized by a potential difference which is mainly determined by thermodynamics. However, the resolution of this approach is limited to tens of millivolts. In this paper, we described an application of Fourier transformed sinusoidal voltammetry (FT-SV) that provides a new approach for discrimination and quantitative evaluation of electroactive species, especially thermodynamic similar ones. Numerical simulation indicates that electron transfer kinetics difference between electroactive species can be revealed by the phase angle of higher order harmonics of FT-SV, and the difference can be amplified order by order. Thus, even a very subtle kinetics difference can be amplified to be distinguishable at a certain order of harmonics. This method was verified with structurally similar ferrocene derivatives which were chosen as the model systems. Although these molecules have very close redox potential (<10 mV), discrimination and selective detection were achieved by as high as the thirteenth harmonics. The results demonstrated the feasibility and reliability of the method. It was also implied that the combination of the traditional thermodynamic method and this kinetics method can form a two-dimension resolved detection method, and it has the potential to extend the resolution of voltammetric techniques to a new level.

  11. Synthesis, characterization and antioxidant activity of a novel electroactive and biodegradable polyurethane for cardiac tissue engineering application.

    Science.gov (United States)

    Baheiraei, Nafiseh; Yeganeh, Hamid; Ai, Jafar; Gharibi, Reza; Azami, Mahmoud; Faghihi, Faezeh

    2014-11-01

    There has been a growing trend towards applying conducting polymers for electrically excitable cells to increase electrical signal propagation within the cell-loaded substrates. A novel biodegradable electroactive polyurethane containing aniline pentamer (AP-PU) was synthesized and fully characterized by spectroscopic methods. To tune the physico-chemical properties and biocompatibility, the AP-PU was blended with polycaprolactone (PCL). The presence of electroactive moieties and the electroactivity behavior of the prepared films were confirmed by UV-visible spectroscopy and cyclic voltammetry. A conventional four probe analysis demonstrated the electrical conductivity of the films in the semiconductor range (~10(-5)S/cm). MTT assays using L929 mouse fibroblast and human umbilical vein endothelial cells (HUVECs) showed that the prepared blend (PB) displayed more cytocompatibility compared with AP-PU due to the introduction of a biocompatible PCL moiety. The in vitro cell culture also confirmed that PB was as supportive as tissue culture plate. The antioxidant activity of the AP-PU was proved using 1,1-diphenyl-2-picrylhydrazyl (DPPH) scavenging assay by employing UV-vis spectroscopy. In vitro degradation tests conducted in phosphate-buffered saline, pH7.4 and pH5.5, proved that the films were also biodegradable. The results of this study have highlighted the potential application of this bioelectroactive polyurethane as a platform substrate to study the effect of electrical signals on cell activities and to direct desirable cell function for tissue engineering applications.

  12. Electrical conductivity, dielectric response and space charge dynamics of an electroactive polymer with and without nanofiller reinforcement

    Science.gov (United States)

    Kochetov, R.; Tsekmes, I. A.; Morshuis, P. H. F.

    2015-07-01

    Electroactive polymers have gained considerable attention over the last 20 years for exhibiting a large displacement in response to electrical stimulation. The promising fields of application include wave energy converters, muscle-like actuators, sensors, robotics, and biomimetics. For an electrical engineer, electroactive polymers can be seen as a dielectric elastomer film or a compliant capacitor with a highly deformable elastomeric medium. If the elastomer is pre-stretched and pre-charged, a reduction of the tensile force lets the elastomer revert to its original form and increases the electrical potential. The light weight of electroactive polymers, low cost, high intrinsic breakdown strength, cyclical way of operation, reliable performance, and high efficiency can be exploited to utilize the elastomeric material as a transducer. The energy storage for a linear dielectric polymer is determined by its relative permittivity and the applied electric field. The latter is limited by the dielectric breakdown strength of the material. Therefore, to generate a high energy density of a flexible capacitor, the film must be used at the voltage level close to the material’s breakdown or inorganic particles with high dielectric permittivity which can be introduced into the polymer matrix. In the present study, silicone-titania elastomer nanocomposites were produced and the influence of nanoparticles on the macroscopic dielectric properties of the neat elastomer including space charge dynamics, complex permittivity, and electrical conductivity, were investigated.

  13. Substrate tolerant direct block copolymer nanolithography

    DEFF Research Database (Denmark)

    Li, Tao; Wang, Zhongli; Schulte, Lars

    2016-01-01

    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...... 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...

  14. Polaronic Tunnelling in Organic Triblock Copolymers

    Institute of Scientific and Technical Information of China (English)

    LIU De-Sheng; ZHANG Da-Cheng; XIE Shi-Jie; MEI Liang-Mo

    2005-01-01

    @@ Polaron tunnelling is studied in xPA/nPPP/xPA (PA for polyacetylene and PPP poly (p-phenylene)) triblock copolymer, which has a well-barrier-well structure. An extended tight-binding Hamiltonian including external electric field is adopted. Without electric field, the injected electrons would not extend over the whole copolymer chain but instead be confined in the segments of PA. This is different from the behaviour of the traditional semiconductors. It is found that the polaron can transfer to the potential barrier-PPP segment when the applied electric field reaches a certain value. The critical polaron tunnelling electric fields depend upon the lengths of PPP segments.

  15. Co-polymer Films for Sensors

    Science.gov (United States)

    Ryan, Margaret A. (Inventor); Homer, Margie L. (Inventor); Yen, Shiao-Pin S. (Inventor); Kisor, Adam (Inventor); Jewell, April D. (Inventor); Shevade, Abhijit V. (Inventor); Manatt, Kenneth S. (Inventor); Taylor, Charles (Inventor); Blanco, Mario (Inventor); Goddard, William A. (Inventor)

    2012-01-01

    Embodiments include a sensor comprising a co-polymer, the co-polymer comprising a first monomer and a second monomer. For some embodiments, the first monomer is poly-4-vinyl pyridine, and the second monomer is poly-4-vinyl pyridinium propylamine chloride. For some embodiments, the first monomer is polystyrene and the second monomer is poly-2-vinyl pyridinium propylamine chloride. For some embodiments, the first monomer is poly-4-vinyl pyridine, and the second monomer is poly-4-vinyl pyridinium benzylamine chloride. Other embodiments are described and claimed.

  16. Ordering phenomena in ABA triblock copolymer gels

    DEFF Research Database (Denmark)

    Reynders, K.; Mischenko, N.; Kleppinger, R.

    1997-01-01

    Temperature and concentration dependencies of the degree of order in ABA triblock copolymer gels are discussed. Two factors can influence the ordering phenomena: the conformation of the midblocks (links of the network) and the polydispersity of the endblock domains (nodes of the network). The lat......Temperature and concentration dependencies of the degree of order in ABA triblock copolymer gels are discussed. Two factors can influence the ordering phenomena: the conformation of the midblocks (links of the network) and the polydispersity of the endblock domains (nodes of the network...

  17. Electrochemical and spectroscopic characterization of poly (bithiophene + 2-methylfuran) copolymer

    Science.gov (United States)

    Lamiri, Leila; Nessark, Belkacem; Habelhames, Farid; Sibous, Lakhdar

    2017-09-01

    In this work, Poly(bithiophene + 2-methylfuran) copolymer was successfully synthetized by an electrochemical polymerization of two monomers, bithiophene and 2-methylfuran in acetonitrile containing lithium perchlorate. The obtained copolymer was characterized via cyclic voltammetry, impedance spectroscopy, UV-visible, scanning electron microscope, conductivity and photocurrent measurements. The cyclic voltammetry study showed two redox couples characteristic of Poly (bithiophene + 2-methylfuran) copolymer. The impedance spectroscopy study revealed that the resistance of the copolymer film increases with the addition of 2-methylfuran. The photocurrent measurement showed good photoelectrochemical properties, making this copolymer an ideal candidate for photovoltaic cell applications.

  18. Sulfonation and characterization of styrene-indene copolymers for the development of proton conducting polymer membranes

    Directory of Open Access Journals (Sweden)

    Cristiane M. Becker

    2012-01-01

    Full Text Available The aim of this work is to obtain polymer precursors based on styrene copolymers with distinct degrees of sulfonation, as an alternative material for fuel cell membranes. Acetyl sulfate was used to carry out the sulfonation and the performance of the polyelectrolyte was evaluated based on the content of acid polar groups incorporated into the macromolecular chain. Polymeric films were produced by blending the sulfonated styrene-indene copolymer with poly(vinylidene fluoride. The degree of sulfonation of the polymer was strongly affected by the sulfonation reaction parameters, with a direct impact on the ionic exchange capacity and the ionic conductivity of the sulfonated polymers and the membranes obtained from them. The films produced with the blends showed more suitable mechanical properties, although the conductivity of the membranes was still lower than that of commercially available membranes used in fuel cells.

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

    KAUST Repository

    Patil, Yogesh

    2017-05-31

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

  20. 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.

  1. Molecular Interaction Control in Diblock Copolymer Blends and Multiblock Copolymers with Opposite Phase Behaviors

    Science.gov (United States)

    Cho, Junhan

    2014-03-01

    Here we show how to control molecular interactions via mixing AB and AC diblock copolymers, where one copolymer exhibits upper order-disorder transition and the other does lower disorder-order transition. Linear ABC triblock copolymers possessing both barotropic and baroplastic pairs are also taken into account. A recently developed random-phase approximation (RPA) theory and the self-consistent field theory (SCFT) for general compressible mixtures are used to analyze stability criteria and morphologies for the given systems. It is demonstrated that the copolymer systems can yield a variety of phase behaviors in their temperature and pressure dependence upon proper mixing conditions and compositions, which is caused by the delicate force fields generated in the systems. We acknowledge the financial support from National Research Foundation of Korea and Center for Photofunctional Energy Materials.

  2. Synthesis and properties of poly(aryl sulfone benzimidazole) and its copolymers for high temperature membrane electrolytes for fuel cells

    DEFF Research Database (Denmark)

    Yang, Jingshuai; Li, Qingfeng; Cleemann, Lars Nilausen

    2012-01-01

    Poly(aryl sulfone benzimidazole) (SO2PBI) and its copolymers with poly[2,2′-p-(phenylene)-5,5′-bibenzimidazole] (pPBI), termed as Co-SO2PBI, were synthesized with varied feeding ratios of 4,4′-sulfonyldibenzoic acid (SDBA) to terephthalic acid (TPA). Incorporation of the stiff para-phenylene and ......Poly(aryl sulfone benzimidazole) (SO2PBI) and its copolymers with poly[2,2′-p-(phenylene)-5,5′-bibenzimidazole] (pPBI), termed as Co-SO2PBI, were synthesized with varied feeding ratios of 4,4′-sulfonyldibenzoic acid (SDBA) to terephthalic acid (TPA). Incorporation of the stiff para......-phenylene and flexible aryl sulfone linkages in the macromolecular structures resulted in high molecular weight copolymers with good solubility. The chemical stability towards radical oxidation was improved for SO2PBI and its copolymer membranes due to the electron-withdrawing sulfone functional groups. Upon acid doping...

  3. Demonstration of an integrated electroactive polymer actuator on a microfluidic electrophoresis device.

    Science.gov (United States)

    Price, Alexander K; Anderson, Kristen M; Culbertson, Christopher T

    2009-07-21

    The construction of microfluidic devices from siloxane-based polymers is widely reported in the current literature. While the use of these materials is primarily due to their rapid and facile fabrication, low cost and robustness, they also have the ability to function as smart materials. This feature, however, has not been commonly exploited in conjunction with their fluid-handling capabilities. Siloxanes are considered smart materials because their shapes can be modified in the presence of an electric field. The energy in the electric field can be transduced into mechanical energy and directly coupled with a microfabricated channel network in order to affect or initiate the movement of fluids. Here, we present a novel microfluidic device into which an electroactive polymer (EAP) actuation unit is integrated. The EAP actuation unit features a microfluidic channel placed above a patterned electrode. The patterned electrode is insulated from the channel by an EAP layer that is composed of PDMS. When a potential is applied across the EAP layer, it changes shape, which also changes the volume of the microfluidic channel above it. With this proof-of-concept device we demonstrated the ability to inject plugs of sample on a standard electrophoresis cross chip solely by changing the magnitude of the electric field between the channel and the electrode. Using an EAP actuation unit, the size of the injection plugs can be varied as a function of the electric field, the active area of the EAP actuation unit and the softness of the EAP.

  4. Biophysical and electrochemical properties of Self-assembled noncovalent SWNT/DNA hybrid and electroactive nanostructure

    Science.gov (United States)

    Mirzapoor, Aboulfazl; Ranjbar, Bijan

    2017-09-01

    DNA self-assembled hybrid nanostructures are widely used in recent research in nanobiotechnology. Combination of DNA with carbon based nanoparticles such as single-walled carbon nanotube (SWNT), multi-walled carbon nanotube (MWNT) and carbon quantum dot were applied in important biological applications. Many examples of biosensors, nanowires and nanoelectronic devices, nanomachine and drug delivery systems are fabricated by these hybrid nanostructures. In this study, a new hybrid nanostructure has been fabricated by noncovalent interactions between single or double stranded DNA and SWNT nanoparticles and biophysical properties of these structures were studied comparatively. Biophysical properties of hybrid nanostructures studied by circular dichroism, UV-vis and fluorescence spectroscopy techniques. Also, electrochemical properties studied by cyclic voltammetry, linear sweep voltammetry, square wave voltammetry, choronoamperometry and impedance spectroscopy (EIS). Results revealed that the biophysical and electrochemical properties of SWNT/DNA hybrid nanostructures were different compare to ss-DNA, ds-DNA and SWNT singly. Circular dichroism results showed that ss-DNA wrapped around the nanotubes through π-π stacking interactions. The results indicated that after adding SWNT to ss-DNA and ds-DNA intensity of CD and UV-vis spectrum peaks were decreased. Electrochemical experiments indicated that the modification of single-walled carbon nanotubes by ss-DNA improves the electron transfer rate of hybrid nanostructures. It was demonstrated SWNT/DNA hybrid nanostructures should be a good electroactive nanostructure that can be used for electrochemical detection or sensing.

  5. A new bistable electroactive polymer for prolonged cycle lifetime of refreshable Braille displays

    Science.gov (United States)

    Ren, Zhi; Niu, Xiaofan; Chen, Dustin; Hu, Wei; Pei, Qibing

    2014-03-01

    ABSTRACT: Bistable electroactive polymers (BSEP) amalgamating electrically induced large-strain actuation and shape memory effect present a unique opportunity for refreshable Braille displays. A new BSEP material with long-chain crosslinkers to achieve prolonged cycle lifetime of refreshable Braille displays is reported here. The modulus of the BSEP material decreases by more than three orders of magnitude from a rigid, plastic state to a rubbery state when heated above the polymer's glass transition temperature. In its rubbery state, the polymer film can be electrically actuated to buckle convexly when a high voltage is applied across a circular active area. Modifying the concentration of long-chain crosslinkers in the polymer allows not only for fine-tuning of the polymer's glass transition temperature and elasticity in the rubbery state, but also enhancement of the actuation stability. For a raised height of 0.4 mm by a Braille dot with a 1.3 mm diameter, actuation can be repeated over 2000 cycles at 70°C in the rubbery state. The actuated dome shape can be fixed by cooling the polymer below the glass transition temperature. This refreshable rigid-to-rigid actuation simultaneously provides large-strain actuation and large force support. Devices capable of displaying Braille characters over a page-size area consisting of 324 Braille cells have been fabricated.

  6. Micro- and nanostructured electro-active polymer actuators as smart muscles for incontinence treatment

    Science.gov (United States)

    Osmani, Bekim; Töpper, Tino; Deschenaux, Christian; Nohava, Jiri; Weiss, Florian M.; Leung, Vanessa; Müller, Bert

    2015-02-01

    Treatments of severe incontinence are currently based on purely mechanical systems that generally result in revision after three to five years. Our goal is to develop a prototype acting in a natural-analogue manner as artificial muscle, which is based on electro-active polymers. Dielectric actuators have outstanding performances including millisecond response times, mechanical strains of more than 10 % and power to mass densities similar to natural muscles. They basically consist of polymer films sandwiched between two compliant electrodes. The incompressible but elastic polymer film transduces the electrical energy into mechanical work according to the Maxwell pressure. Available polymer films are micrometers thick and voltages as large as kV are necessary to obtain 10 % strain. For medical implants, polymer films should be nanometer thin to realize actuation below 48 V. The metallic electrodes have to be stretchable to follow the strain of 10 % and remain conductive. Recent results on the stress/strain behavior of anisotropic EAP-cantilevers have shown dependencies on metal electrode preparation. We have investigated tunable anisotropic micro- and nanostructures for metallic electrodes. They show a preferred actuation direction with improved stress-strain behavior. The bending of the cantilever has been characterized by the laser beam deflection method. The impact of the electrode on the effective Young's Modulus is measured using an Ultra Nanoindentation Tester with an integrated reference system for soft polymer surfaces. Once ten thousand layers of nanometer-thin EAP actuators are available, devices beyond the envisioned application will flood the market.

  7. Application of stochastic system identification to the study of the compliance of electroactive polymers.

    Science.gov (United States)

    Pillai, Priam V; Hunter, Ian W; Hernandez, Emanuel

    2011-02-01

    Electroactive polymers have shown promising applications as transducers that can mimic biological muscle. The modulus or the compliance of many of these devices can change significantly as they are actuated making these materials attractive for applications that require tunable stiffness. We have developed a dynamic mechanical analyzer that is capable of making in situ measurements of the dynamic compliance transfer function of conducting polymers as a function of an electrochemical stimulus. We do this by simultaneously applying a stochastic stress waveform over a potential waveform and calculating the compliance as it changes over the course of electrochemical excitation. Using these signals we can calculate the compliance transfer function between 0.1 and 100 Hz and the impulse response function with up to 3% variation in its parameters. These functions are then computed as charge is injected into the polymer and it is shown that the low frequency gain of the transfer function can change by 30%-40% in the electrochemical system tested.

  8. Energy harvesting using ionic electro-active polymer thin films with Ag-based electrodes

    Science.gov (United States)

    Anand, S. V.; Arvind, K.; Bharath, P.; Mahapatra, D. Roy

    2010-04-01

    In this paper we employ the phenomenon of bending deformation induced transport of cations via the polymer chains in the thickness direction of an electro-active polymer (EAP)-metal composite thin film for mechanical energy harvesting. While EAPs have been applied in the past in actuators and artificial muscles, promising applications of such materials in hydrodynamic and vibratory energy harvesting are reported in this paper. For this, functionalization of EAPs with metal electrodes is the key factor in improving the energy harvesting efficiency. Unlike Pt-based electrodes, Ag-based electrodes have been deposited on an EAP membrane made of Nafion. The developed ionic metal polymer composite (IPMC) membrane is subjected to a dynamic bending load, hydrodynamically, and evaluated for the voltage generated against an external electrical load. An increase of a few orders of magnitude has been observed in the harvested energy density and power density in air, deionized water and in electrolyte solutions with varying concentrations of sodium chloride (NaCl) as compared to Pt-based IPMC performances reported in the published literature. This will have potential applications in hydrodynamic and residual environmental energy harvesting to power sensors and actuators based on micro-and nano-electro-mechanical systems (MEMS and NEMS) for biomedical, aerospace and oceanic applications.

  9. Development of Electroactive and Anaerobic Ammonium-Oxidizing (Anammox Biofilms from Digestate in Microbial Fuel Cells

    Directory of Open Access Journals (Sweden)

    Enea Gino Di Domenico

    2015-01-01

    Full Text Available Microbial Fuel cells (MFCs have been proposed for nutrient removal and energy recovery from different wastes. In this study the anaerobic digestate was used to feed H-type MFC reactors, one with a graphite anode preconditioned with Geobacter sulfurreducens and the other with an unconditioned graphite anode. The data demonstrate that the digestate acts as a carbon source, and even in the absence of anode preconditioning, electroactive bacteria colonise the anodic chamber, producing a maximum power density of 172.2 mW/m2. The carbon content was also reduced by up to 60%, while anaerobic ammonium oxidation (anammox bacteria, which were found in the anodic compartment of the reactors, contributed to nitrogen removal from the digestate. Overall, these results demonstrate that MFCs can be used to recover anammox bacteria from natural sources, and it may represent a promising bioremediation unit in anaerobic digestor plants for the simultaneous nitrogen removal and electricity generation using digestate as substrate.

  10. Study on electroactive and electrocatalytic surfaces of single walled carbon nanotube-modified electrodes

    Energy Technology Data Exchange (ETDEWEB)

    Salinas-Torres, David [Departamento de Quimica Fisica and Instituto Universitario de Materiales de Alicante, Universidad de Alicante, Apdo. de Correos 99, E-03080 Alicante (Spain); Huerta, Francisco [Departamento de Ingenieria Textil y Papelera, Universidad Politecnica de Valencia, Plaza Ferrandiz y Carbonell, 1. E-03801 Alcoy (Spain); Montilla, Francisco, E-mail: francisco.montilla@ua.e [Departamento de Quimica Fisica and Instituto Universitario de Materiales de Alicante, Universidad de Alicante, Apdo. de Correos 99, E-03080 Alicante (Spain); Morallon, Emilia [Departamento de Quimica Fisica and Instituto Universitario de Materiales de Alicante, Universidad de Alicante, Apdo. de Correos 99, E-03080 Alicante (Spain)

    2011-02-01

    An investigation of the electrocatalysis of single-walled carbon nanotubes modified electrodes has been performed in this work. Nanotube-modified electrodes present a surface area much higher than the bare glassy carbon surfaces as determined by capacitance measurements. Several redox probes were selected for checking the reactivity of specific sites at the carbon nanotube surface. The presence of carbon nanotubes on the electrode improves the kinetics for all the reactions studied compared with the bare glassy carbon electrode with variations of the heterogeneous electron transfer rate constant up to 5 orders of magnitude. The most important effects are observed for the benzoquinone/hydroquinone and ferrocene/ferricinium redox couples, which show a remarkable improvement of their electron transfer kinetics on SWCNT-modified electrodes, probably due to strong {pi}-{pi} interaction between the organic molecules and the walls of the carbon nanotubes. For many of the reactions studied, less than 1% of the nanotube-modified electrode surface is transferring charge to species in solution. This result suggests that only nanotube tips are active sites for the electron transfer in such cases. On the contrary, the electroactive surface for the reactions of ferrocene and quinone is higher indicating that the electron transfer is produced also from the nanotube walls.

  11. Impact of a surfactant on the electroactivity of proteins at an aqueous-organogel microinterface array.

    Science.gov (United States)

    O'Sullivan, Shane; Arrigan, Damien W M

    2013-02-05

    The impact of surfactant addition to the organic phase on the electroactivity of proteins at the aqueous-organogel interface was examined by voltammetry. The presence of bis(2-ethylhexyl)sulfosuccinate (AOT) in the organogel phase, as the sodium salt, caused marked changes in the peak currents for myoglobin detection. The protein desorption voltammetric peak exhibited a 6-fold increase in the current compared to the corresponding experiment without surfactant. Interfacial coverage showed a 17-fold increase in the adsorbed protein at the interface, from 50 pmol cm(-2), in the absence of surfactant, to 850 pmol cm(-2), in the presence of 10 mM surfactant. Additionally, the presence of the surfactant resulted in a second pair of adsorption/desorption peaks at lower potentials and in a change in the capacitance of the system. The formation of surfactant-protein and surfactant-protein-organic anion deposits is proposed on the basis of these features, leading to increased voltammetric signals for myoglobin, hemoglobin, and cytochrome c. The mechanism of protein-surfactant interaction was probed by using the surfactant as the anion in the organic phase electrolyte salt. Repetitive cyclic voltammetry of cytochrome c showed that in the presence of surfactant there was an enhancement of the signal, caused by a buildup of the protein-surfactant-electrolyte anion assembly at the interface. These findings provide the basis for surfactant-modified interfaces to enhance the electroanalytical performance for protein detection.

  12. Artificial Muscles Based on Electroactive Polymers as an Enabling Tool in Biomimetics

    Science.gov (United States)

    Bar-Cohen, Y.

    2007-01-01

    Evolution has resolved many of nature's challenges leading to working and lasting solutions that employ principles of physics, chemistry, mechanical engineering, materials science, and many other fields of science and engineering. Nature's inventions have always inspired human achievements leading to effective materials, structures, tools, mechanisms, processes, algorithms, methods, systems, and many other benefits. Some of the technologies that have emerged include artificial intelligence, artificial vision, and artificial muscles, where the latter is the moniker for electroactive polymers (EAPs). To take advantage of these materials and make them practical actuators, efforts are made worldwide to develop capabilities that are critical to the field infrastructure. Researchers are developing analytical model and comprehensive understanding of EAP materials response mechanism as well as effective processing and characterization techniques. The field is still in its emerging state and robust materials are still not readily available; however, in recent years, significant progress has been made and commercial products have already started to appear. In the current paper, the state-of-the-art and challenges to artificial muscles as well as their potential application to biomimetic mechanisms and devices are described and discussed.

  13. Flexible Low-Mass Devices and Mechanisms Actuated by Electroactive Polymers

    Science.gov (United States)

    Bar-Cohen, Y; Leary, S.; Shahinpoor, M.; Harrison, J. O.; Smith, J.

    1999-01-01

    Miniature, lightweight, miser actuators that operate similar to biological muscles can be used to develop robotic devices with unmatched capabilities to impact many technology areas. Electroactive polymers (EAP) offer the potential to producing such actuators and their main attractive feature is their ability to induce relatively large bending or longitudinal strain. Generally, these materials produce a relatively low force and the applications that can be considered at the current state of the art are relatively limited. This reported study is concentrating on the development of effective EAPs and the resultant enabling mechanisms employing their unique characteristics. Several EAP driven mechanisms, which emulate human hand, were developed including a gripper, manipulator arm and surface wiper. The manipulator arm was made of a composite rod with an EAP actuator consisting of a scrolled rope that is activated longitudinally by an electrostatic field. A gripper was made to serve as an end effector and it consisted of multiple bending EAP fingers for grabbing and holding such objects as rocks. An EAP surface wiper was developed to operate like a human finger and to demonstrate the potential to remove dust from optical and IR windows as well as solar cells. These EAP driven devices are taking advantage of the large actuation displacement of these materials but there is need for a significantly greater actuation force capability.

  14. Electroactive SWNT/PEGDA hybrid hydrogel coating for bio-electrode interface.

    Science.gov (United States)

    He, Lei; Lin, Demeng; Wang, Yanping; Xiao, Yinghong; Che, Jianfei

    2011-10-15

    Electric interface between neural tissue and electrode plays a significant role in the development of implanted devices for continuous monitoring and functional stimulation of central nervous system in terms of electroactivity, biocompatibility and long-term stability. To engineer an interface that possesses these merits, a polymeric hydrogel based on poly(ethylene glycol) diacrylate (PEGDA) and single-walled carbon nanotubes (SWNTs) were employed to fabricate a hybrid hydrogel via covalent anchoring strategy, i.e., self-assembly of cysteamine (Cys) followed by Michael addition between Cys and PEGDA. XPS characterization proves that the Cys molecules are linked to gold surface via the strong S-Au bond and that the PEGDA macromers are covalently bonded to Cys. FTIR spectra indicate the formation of hybrid hydrogel coating during photopolymerization. Electrochemical measurements using cyclic voltammetry (CV) and impedance spectrum clearly show the enhancement of electric properties to the hydrogel by the SWNTs. The charge transfer of the hybrid hydrogel-based electrode is quasi-reversible and charge transfer resistance decreases to the tenth of that of the pure hydrogel due to electron hopping along the SWNTs. Additionally, this hybrid hydrogel provides a favorable biomimetic microenvironment for cell attachment and growth due to its inherent biocompatibility. Combination of these merits yields hybrid hydrogels that can be good candidates for application to biosensors and biomedical devices. More importantly, the hybrid hydrogel coatings fabricated via the current strategy have good adhesion to the electrode substrate which is highly desired for chronically implantable devices.

  15. Ferrocene-coated CdSe/ZnS quantum dots as electroactive nanoparticles hybrids

    Energy Technology Data Exchange (ETDEWEB)

    Dorokhin, Denis; Vancso, G Julius [Materials Science and Technology of Polymers, Faculty of Science and Technology and MESA Institute for Nanotechnology, University of Twente, PO Box 217, 7500 AE Enschede (Netherlands); Tomczak, Nikodem [Institute of Materials Research and Engineering, A-STAR (Agency for Science, Technology and Research), 3 Research Link, 117602 (Singapore); Reinhoudt, David N; Velders, Aldrik H, E-mail: g.j.vancso@utwente.nl [Supramolecular Chemistry and Technology, Faculty of Science and Technology and MESA Institute for Nanotechnology, University of Twente, PO Box 217, 7500 AE Enschede (Netherlands)

    2010-07-16

    Electrochemical properties of core-shell CdSe/ZnS quantum dots (QDs) in a non-aqueous solution are presented. Cathodic reduction and anodic oxidation processes involving the QD HOMO and LUMO levels as well as defect states were identified by cyclic voltammetry. The electrochemical bandgap was estimated from the anodic and cathodic redox peaks and found to match well with the optical bandgap estimated from the absorption spectrum. The trioctylphosphine oxide ligands on the surface of the QDs were exchanged to electroactive ferrocenyl thiols and the resulting material was characterized by NMR and optical spectroscopy. Cyclic voltammetry showed that the redox potentials of the QDs are modified due to the presence of ferrocene on the surface of the QD. The QD oxidation peak decreased and the reduction peak shifted to more negative potentials. The concurrent shift of the ferrocene redox peaks indicates that the system displays features of a 'molecular hybrid', where both the QD and the ligand influence each other.

  16. Finite element modeling of electromechanical behavior of a dielectric electroactive polymer actuator

    Science.gov (United States)

    Deodhar, Aseem; York, Alexander; Hodgins, Micah; Seelecke, Stefan

    2011-04-01

    Dielectric Electroactive Polymers (DEAP) will undergo large deformations when subject to an electric field making them an attractive material for use in novel actuator systems. There are many challenges with successful application and design of DEAP actuators resulting from their inherent electromechanical coupling and non-linear material behavior. FE modeling of the material behavior is a useful tool to better understand such systems and aid in the optimal design of prototypes. These modeling efforts must account for the electromechanical coupling in order to accurately predict their response to multiple loading conditions expected during real operating conditions. This paper presents a Finite Element model of a dielectric elastomer undergoing out-of-plane, axisymmetric deformation. The response of the elastomer was investigated while it was subjected to mechanical and electric fields and combined electro-mechanical actuation. The compliant electrodes have a large effect on the mechanical behavior of the EAP which needs to be taken into consideration while modeling the EAP as a system. The model is adapted to include the effect of electrode stiffness on the mechanical response of the actuator. The model was developed using the commercial Finite Element Modeling software, COMSOL. The results from the mechanical simulations are presented in the form of forcedisplacement curves and are validated with comparisons to experimental results. Electromechanical simulations are carried out and the stroke of the actuator for different electrode stiffness values is compared with experimental values when the EAP is biased with a constant force.

  17. Shell-encoded Au nanoparticles with tunable electroactivity for specific dual disease biomarkers detection.

    Science.gov (United States)

    Zhao, Yuan; Yang, Yaxin; Sun, Yali; Cui, Linyan; Zheng, Fangjie; Zhang, Jiru; Song, Qijun; Xu, Chuanlai

    2018-01-15

    The exploration of electroactive labelling with tailorable and strong differential pulse voltammetry (DPV) responses is of great importance in accurate and sensitive screening of a panel of biomarkers related to cancer. Herein, shell-encoded gold nanoparticles (Au NPs) are fabricated and give rise to shell species-dominated DPV peak potentials. Two independent DPV peaks appear at -0.08V for Au@Cu2O core-shell NPs and 0.26V for Au@Ag core-shell NPs. Shell-encoded Au NPs drastically exhibit shell thickness-tunable amplified peak currents. The non-interfering and amplified DPV responses enable shell-encoded Au NPs to be an alternative electrochemical signal amplifier for dual screening of carcinoembryonic antigen (CEA) and alpha-fetoprotein (AFP). The limits of detection (LODs) are calculated to be 1.8pg/mL for CEA and 0.3pg/mL for AFP. In comparison to the parallel single-analyte assays, shell-encoded Au NPs engineered electrochemical aptasensors offer multiplexing capability and show significant prospects in biomedical research and early diagnosis of diseases. Copyright © 2017. Published by Elsevier B.V.

  18. On the impact of self-clearing on electroactive polymer (EAP) actuators

    Science.gov (United States)

    Ahmed, Saad; Ounaies, Zoubeida; Lanagan, Michael T.

    2017-10-01

    Electroactive polymer (EAP)-based actuators have large potential for a wide array of applications; however, their practical implementation is still a challenge because of the requirement of high driving voltage, which most often leads to premature defect-driven electrical breakdown. Polymer-based capacitors have the ability to clear defects with partial electrical breakdown and subsequent removal of a localized electrode section near the defect. In this study, this process, which is known as self-clearing, is adopted for EAP technologies. We report a methodical approach to self-clear an EAP, more specifically P(VDF-TrFE-CTFE) terpolymer, to delay premature defect-driven electrical breakdown of the terpolymer actuators at high operating electric fields. Breakdown results show that electrical breakdown strength is improved up to 18% in comparison to a control sample after self-clearing. Furthermore, the electromechanical performance in terms of blocked force and free displacement of P(VDF-TrFE-CTFE) terpolymer-based bending actuators are examined after self-clearing and precleared samples show improved blocked force, free displacement and maximum sustainable electric field compared to control samples. The study demonstrates that controlled self-clearing of EAPs improves the breakdown limit and reliability of the EAP actuators for practical applications without impeding their electromechanical performance.

  19. A review of integrating electroactive polymers as responsive systems for specialized drug delivery applications.

    Science.gov (United States)

    Pillay, Viness; Tsai, Tong-Sheng; Choonara, Yahya E; du Toit, Lisa C; Kumar, Pradeep; Modi, Girish; Naidoo, Dinesh; Tomar, Lomas K; Tyagi, Charu; Ndesendo, Valence M K

    2014-06-01

    Electroactive polymers (EAPs) are promising candidate materials for the design of drug delivery technologies, especially in conditions where an "on-off" drug release mechanism is required. To achieve this, EAPs such as polyaniline, polypyrrole, polythiophene, ethylene vinyl acetate, and polyethylene may be blended into responsive hydrogels in conjunction with the desired drug to obtain a patient-controlled drug release system. The "on-off" drug release mechanism can be achieved through the environmental-responsive nature of the interpenetrating hydrogel-EAP complex via (i) charged ions initiated diffusion of drug molecules; (ii) conformational changes that occur during redox switching of EAPs; or (iii) electroerosion. These release mechanisms are not exhaustive and new release mechanisms are still under investigation. Therefore, this review seeks to provide a concise incursion and critical overview of EAPs and responsive hydrogels as a strategy for advanced drug delivery, for example, controlled release of neurotransmitters, sulfosalicyclic acid from cross-linked hydrogel, and vaccine delivery. The review further discusses techniques such as linear sweep voltammetry, cyclic voltammetry, impedance spectroscopy, and chronoamperometry for the determination of the redox capability of EAPs. The future implications of the hydrogel-EAP composites include, but not limited to, application toward biosensors, DNA hybridizations, microsurgical tools, and miniature bioreactors and may be utilized to their full potential in the form of injectable devices as nanorobots or nanobiosensors.

  20. High-efficiency generation-collection microelectrochemical platform for interrogating electroactive thin films.

    Science.gov (United States)

    Anderson, Morgan J; Crooks, Richard M

    2014-10-07

    Here we report on the development of a high-efficiency, dual channel-electrode (DCE) generation-collection system and its application for interrogating redox-active surface-adsorbed thin films. DCE systems consist of two electrodes configured on the base of a microfluidic channel. Under laminar flow conditions, a redox reaction can be driven on the upstream generator electrode, and the products carried by convection to the downstream collector electrode where the reverse redox reaction occurs. One significant outcome of this report is that simple fabrication techniques can be used to prepare DCE systems that have collection efficiencies of up to 97%. This level of efficiency makes it possible to quantitatively measure the charge associated with redox-active thin films interposed between the generator and collector electrodes. This is important, because it provides a means for interrogating species that are not in sufficiently close proximity to an electrode to enable direct electron transfer or electroactive films adsorbed to insulating surfaces. Here, the method is demonstrated by comparing results from this indirect surface interrogation method, using Fe(CN)6(3-) as the redox probe, and direct electroreduction of Au oxide thin films. These experimental results are further compared to finite-element simulations.

  1. Electro-active device using radial electric field piezo-diaphragm for sonic applications

    Science.gov (United States)

    Bryant, Robert G. (Inventor); Fox, Robert L. (Inventor)

    2005-01-01

    An electro-active transducer for sonic applications includes a ferroelectric material sandwiched by first and second electrode patterns to form a piezo-diaphragm coupled to a mounting frame. When the device is used as a sonic actuator, the first and second electrode patterns are configured to introduce an electric field into the ferroelectric material when voltage is applied to the electrode patterns. When the device is used as a sonic sensor, the first and second electrode patterns are configured to introduce an electric field into the ferroelectric material when the ferroelectric material experiences deflection in a direction substantially perpendicular thereto. In each case, the electrode patterns are designed to cause the electric field to: i) originate at a region of the ferroelectric material between the first and second electrode patterns, and ii) extend radially outward from the region of the ferroelectric material (at which the electric field originates) and substantially parallel to the plane of the ferroelectric material. The mounting frame perimetrically surrounds the peizo-diaphragm and enables attachment of the piezo-diaphragm to a housing.

  2. Nylon 46-polytetramethylene oxide segmented block copolymers

    NARCIS (Netherlands)

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

    1989-01-01

    Block copolymers were synthesized from amine-terminated polytetramethylene oxide (PMTO) (Mw 800 and 1130) and polyamide 4,6 salt. First prepolymers were prepared at 200–210°C in the presence of a solvent (pyrrolidone). The prepolymers were postcondensed at 255°C (where possible in the solid state) t

  3. Shear instability of a gyroid diblock copolymer

    DEFF Research Database (Denmark)

    Eskimergen, Rüya; Mortensen, Kell; Vigild, Martin Etchells

    2005-01-01

    -induced destabilization is discussed in relation to analogous observations on shear-induced order-to-order and disorder-to-order transitions observed in related block copolymer systems and in microemulsions. It is discussed whether these phenomena originate in shear-reduced fluctuations or shear-induced dislocations....

  4. CONJUGATED BLOCK-COPOLYMERS FOR ELECTROLUMINESCENT DIODES

    NARCIS (Netherlands)

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

    1995-01-01

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

  5. Gyroid Membranes made from Nanoporous Blck Copolymers

    DEFF Research Database (Denmark)

    Szewczykowski, Piotr Plzemystaw; Vigild, Martin Etchells; Ndoni, Sokol;

    2007-01-01

    of the membrane and its nanoporosity is e.g. obtained by cross-linking the majority blocks and selectively etching the minority blocks. Here we report on ultrafiltration membranes prepared from a 1,2-polybutadiene-b-polydimethylsiloxane diblock copolymer with gyroid structure. Different experimental methods...

  6. Glycine/Glycolic acid based copolymers

    NARCIS (Netherlands)

    in 't Veld, P.J.A.; in 't Veld, Peter J.A.; Shen, Zheng-Rong; Shen, Z.; Takens, Gijsbert A.J.; Takens, G.A.J.; Dijkstra, Pieter J.; Feijen, Jan

    1994-01-01

    Glycine/glycolic acid based biodegradable copolymers have been prepared by ring-opening homopolymerization of morpholine-2,5-dione, and ring-opening copolymerization of morpholine-2,5-dione and glycolide. The homopolymerization of morpholine-2,5-dione was carried out in the melt at 200°C for 3 min

  7. Helical Ordering in Chiral Block Copolymers

    Science.gov (United States)

    Zhao, Wei; Hong, Sung Woo; Chen, Dian; Grason, Gregory; Russell, Thomas

    2012-02-01

    Introducing molecular chirality into the segments of block copolymers can influence the nature of the resultant morphology. Such an effect was found for poly(styrene-b-L-lactide) (PS-b-PLLA) diblock copolymers where hexagonally packed PLLA helical microdomains (H* phase) form in a PS matrix. However, molecular ordering of PLLA within the helical microdomains and the transfer of chirality from the segmental level to the mesoscale is still not well understood. We developed a field theoretic model to describe the interactions between segments of chiral blocks, which have the tendency to form a ``cholesteric'' texture. Based on the model, we calculated the bulk morphologies of chiral AB diblock copolymers using self-consistent field theory (SCFT). Experiments show that the H* phase only forms when microphase separation between PS and PLLA block happens first and crystallization of PLLA block is suppressed or happens within confined microdomain. Hence, crystalline ordering is not necessary for H* phase formation. The SCFT offers the chance to explore the range of thermodynamic stability of helical structures in the phase diagram of chiral block copolymer melts, by tuning parameters not only like the block segregation strength and composition, but also new parameters such as the ratio between preferred helical pitch to the radius of gyration and the Frank elastic constant for inter-segment distortions.

  8. CONJUGATED BLOCK-COPOLYMERS FOR ELECTROLUMINESCENT DIODES

    NARCIS (Netherlands)

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

    1995-01-01

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

  9. Chiral Block Copolymer Structures for Metamaterial Applications

    Science.gov (United States)

    2015-01-27

    MONITOR’S REPORT NUMBER(S) AOARD-114078 12. DISTRIBUTION/AVAILABILITY STATEMENT Distribution A: Approved for public release. Distribtion is...researchers focused o synthesis and processing, morphology and physical characterization of chiral block copolymer (BCP) materials. Such materials a...developed a platform process technology that can fabricate novel netwo morphologies from initial bicontinuous cubic phases through supergroup/subgroup

  10. LEDs based on conjugated PPV block copolymers

    NARCIS (Netherlands)

    Brouwer, H.J.; Hilberer, A.; Krasnikov, V.V.; Werts, M.; Wildeman, J.; Hadziioannou, G.

    1997-01-01

    A way to control the bandgap in semi-conducting polymers is by preparing polymers with a partially conjugated backbone. In our laboratory, three conjugated copolymers containing PPV trimers as light emitting chromophores have been synthesized, which emit in the blue, green and orange wavelength regi

  11. Glycine/Glycolic acid based copolymers

    NARCIS (Netherlands)

    Veld, in 't Peter J.A.; Shen, Zheng-Rong; Takens, Gijsbert A.J.; Dijkstra, Pieter J.; Feijen, Jan

    1994-01-01

    Glycine/glycolic acid based biodegradable copolymers have been prepared by ring-opening homopolymerization of morpholine-2,5-dione, and ring-opening copolymerization of morpholine-2,5-dione and glycolide. The homopolymerization of morpholine-2,5-dione was carried out in the melt at 200°C for 3 min u

  12. Stable material modication with polymers incorporation for broad application in microfabrication

    DEFF Research Database (Denmark)

    Mednova, Olga

    , is successfully applied. The novelty of the study consists in design and synthesis of the most optimal copolymer composition, which can self-assemble in SU-8 resin. In the first part of the thesis, solubility prediction with the Hansen Solubility Parameters method is described in details and poly(ethyl ethylene......The aim of this thesis is to improve SU-8 fracture resistance in order to eliminate micro crack formation during fabrication of microelectromechanical system (MEMS). An amphiphilic block copolymer incorporation, as an efficient method of material toughening without changing its original properties...

  13. Block copolymer/ferroelectric nanoparticle nanocomposites

    Science.gov (United States)

    Pang, Xinchang; He, Yanjie; Jiang, Beibei; Iocozzia, James; Zhao, Lei; Guo, Hanzheng; Liu, Jin; Akinc, Mufit; Bowler, Nicola; Tan, Xiaoli; Lin, Zhiqun

    2013-08-01

    Nanocomposites composed of diblock copolymer/ferroelectric nanoparticles were formed by selectively constraining ferroelectric nanoparticles (NPs) within diblock copolymer nanodomains via judicious surface modification of ferroelectric NPs. Ferroelectric barium titanate (BaTiO3) NPs with different sizes that are permanently capped with polystyrene chains (i.e., PS-functionalized BaTiO3NPs) were first synthesized by exploiting amphiphilic unimolecular star-like poly(acrylic acid)-block-polystyrene (PAA-b-PS) diblock copolymers as nanoreactors. Subsequently, PS-functionalized BaTiO3 NPs were preferentially sequestered within PS nanocylinders in the linear cylinder-forming polystyrene-block-poly(methyl methacrylate) (PS-b-PMMA) diblock copolymer upon mixing the BaTiO3 NPs with PS-b-PMMA. The use of PS-b-PMMA diblock copolymers, rather than traditional homopolymers, offers the opportunity for controlling the spatial organization of PS-functionalized BaTiO3 NPs in the PS-b-PMMA/BaTiO3 NP nanocomposites. Selective solvent vapor annealing was utilized to control the nanodomain orientation in the nanocomposites. Vertically oriented PS nanocylinders containing PS-functionalized BaTiO3 NPs were yielded after exposing the PS-b-PMMA/BaTiO3 NP nanocomposite thin film to acetone vapor, which is a selective solvent for PMMA block. The dielectric properties of nanocomposites in the microwave frequency range were investigated. The molecular weight of PS-b-PMMA and the size of BaTiO3 NPs were found to exert an apparent influence on the dielectric properties of the resulting nanocomposites.Nanocomposites composed of diblock copolymer/ferroelectric nanoparticles were formed by selectively constraining ferroelectric nanoparticles (NPs) within diblock copolymer nanodomains via judicious surface modification of ferroelectric NPs. Ferroelectric barium titanate (BaTiO3) NPs with different sizes that are permanently capped with polystyrene chains (i.e., PS-functionalized BaTiO3NPs) were

  14. Nanopatterned block copolymers for use as vascular biomaterials

    Science.gov (United States)

    Silverstein, Joshua S.

    Manipulation of surface topography or chemistry has been a growing trend in efforts to enhance the properties of medical devices. Understanding the interactions of biomolecules with nanoengineered surfaces is vital to assess the safety and efficacy of devices that incorporate these structures. In this dissertation, a model block copolymer (BCP) system based on poly(styrene)-block-poly(1,2-butadiene) was systematically modified using photochemical thiol-ene chemistry. Poly(1,2-butadiene) molecular weight and thiol-ene ratios were systematically varied based on a model monomer, boc-cysteamine, to determine the efficiency of the reaction. The results demonstrate the polydispersity index of modified BCPs significantly increased when low thiol-ene ratios were employed and sometimes induced gelation of the reacted polymers. Using a tenfold excess of thiol, functionalizations between 60-90% were obtained for an acid, amine, amide, and a pharmaceutical with a pendant thiol. Calorimetry showed a 30-60 °C increase in the glass transition temperature of the daughter polymers. Subsequently, films were cast from solvents found suitable to forming self-assembled BCP thin films. The synthetic and processing approach allows for the formation of nanopatterned block copolymer films with controlled chemistries from a single source material. The BCPs were further characterized using water contact angle measurements and atomic force microscopy in liquid. Significantly decreased contact angles were caused by selective swelling of charged BCP domains. Protein (fibrinogen, albumin, cytochrome C, immunoglobulin G) adsorption experiments were conducted under static and dynamic conditions with a quartz crystal microbalance with dissipation. The results indicate that nanopatterned chemistry and experimental conditions strongly impact adsorption dynamics. Adsorption behavior was dependent both on protein structure and the characteristics of the surface. Depending on the structural stability

  15. Analysis of the mechanical properties and characterization by solid state 13C NMR of recycled EVA copolymer/silica composites

    Directory of Open Access Journals (Sweden)

    Giovanni Chaves Stael

    2005-09-01

    Full Text Available The incorporation of micrometer sized silica particles on poly (ethylene-co-vinyl acetate - EVA - residues from the footwear industry was evaluated. The effects of the processing parameters - temperature and mixing ratio - on the mechanical behavior of molded plates of neat recycled EVA and EVA/silica composites were also investigated. The mechanical properties measured by the tensile test, the fractographic analysis by scanning electron microscopy (SEM, and the 13C Nuclear Magnetic Resonance (NMR showed a reduced EVA to silica compatibility. Therefore, incorporation of untreated silica to recycled EVA copolymer produced a slight decrease on the mechanical performance of EVA/silica composites in respect to neat EVA copolymer. The NMR analysis also shows that the crosslinking process on recycled EVA may be occurring at the carbonyl group.

  16. Imparting electroactivity to polycaprolactone fibers with heparin-doped polypyrrole: Modulation of hemocompatibility and inflammatory responses.

    Science.gov (United States)

    Xiong, Gordon M; Yuan, Shaojun; Wang, Jun Kit; Do, Anh Tuan; Tan, Nguan Soon; Yeo, Kiat Seng; Choong, Cleo

    2015-09-01

    Hemocompatibility, anti-inflammation and anti-thrombogenicity of acellular synthetic vascular grafts remains a challenge in biomaterials design. Using electrospun polycaprolactone (PCL) fibers as a template, a coating of polypyrrole (PPy) was successfully polymerized onto the fiber surface. The fibers coated with heparin-doped PPy (PPy-HEP) demonstrated better electroactivity, lower surface resistivity (9-10-fold) and better anti-coagulation response (non-observable plasma recalcification after 30min vs. recalcification at 8-9min) as compared to fibers coated with pristine PPy. Red blood cell compatibility, measured by% hemolysis, was greatly improved on PPy-HEP-coated PCL in comparison to uncoated PCL (3.9±2.1% vs. 22.1±4.1%). PPy-HEP-coated PCL fibers also exhibited higher stiffness values (6.8±0.9MPa vs. 4.2±0.8MPa) as compared to PCL fibers, but similar tensile strengths. It was also observed that the application of a low alternating current led to a 4-fold reduction of platelet activation (as quantitated by CD62p expression) for the PPy-HEP-coated fibers as compared to non-stimulated conditions. In parallel, a reduction in the leukocyte adhesion to both pristine PPy-coated and PPy-HEP-coated fibers was observable with AC stimulation. Overall, a new strategy involving the use of hemocompatible conducting polymers and electrical stimulation to control thrombogenicity and inflammatory responses for synthetic vascular graft designs was demonstrated. Copyright © 2015 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

  17. Micro- and nanostructured electro-active polymer actuators as smart muscles for incontinence treatment

    Energy Technology Data Exchange (ETDEWEB)

    Osmani, Bekim, E-mail: bekim.osmani@unibas.ch, E-mail: tino.toepper@unibas.ch; Töpper, Tino, E-mail: bekim.osmani@unibas.ch, E-mail: tino.toepper@unibas.ch; Weiss, Florian M., E-mail: vanessa.leung@unibas.ch, E-mail: bert.mueller@unibas.ch; Leung, Vanessa, E-mail: vanessa.leung@unibas.ch, E-mail: bert.mueller@unibas.ch; Müller, Bert, E-mail: vanessa.leung@unibas.ch, E-mail: bert.mueller@unibas.ch [Biomaterials Science Center, University of Basel, c/o University Hospital, 4031 Basel (Switzerland); Deschenaux, Christian, E-mail: jiri.nohava@anton-paar.com; Nohava, Jiri, E-mail: jiri.nohava@anton-paar.com [Anton Paar TriTec SA, Rue de la Gare 4, Galileo Center, 2034 Peseux (Switzerland)

    2015-02-17

    Treatments of severe incontinence are currently based on purely mechanical systems that generally result in revision after three to five years. Our goal is to develop a prototype acting in a natural-analogue manner as artificial muscle, which is based on electro-active polymers. Dielectric actuators have outstanding performances including millisecond response times, mechanical strains of more than 10 % and power to mass densities similar to natural muscles. They basically consist of polymer films sandwiched between two compliant electrodes. The incompressible but elastic polymer film transduces the electrical energy into mechanical work according to the Maxwell pressure. Available polymer films are micrometers thick and voltages as large as kV are necessary to obtain 10 % strain. For medical implants, polymer films should be nanometer thin to realize actuation below 48 V. The metallic electrodes have to be stretchable to follow the strain of 10 % and remain conductive. Recent results on the stress/strain behavior of anisotropic EAP-cantilevers have shown dependencies on metal electrode preparation. We have investigated tunable anisotropic micro- and nanostructures for metallic electrodes. They show a preferred actuation direction with improved stress-strain behavior. The bending of the cantilever has been characterized by the laser beam deflection method. The impact of the electrode on the effective Young's Modulus is measured using an Ultra Nanoindentation Tester with an integrated reference system for soft polymer surfaces. Once ten thousand layers of nanometer-thin EAP actuators are available, devices beyond the envisioned application will flood the market.

  18. Determination of the specific interaction between sulfonylurea-incorporated polymer and rat islets.

    Science.gov (United States)

    Park, Keun-Hong; Song, Soo Chang; Akaike, Toshihiro

    2002-03-01

    A SU derivative, mimicking glibenclamide in chemical structure, was synthesized to incorporate it into a water-soluble polymeric backbone as a biospecific and stimulating polymer for insulin secretion. The ability of insulin secretion was examined with different glucose concentrations (3.3 and 11.6 mM). Although the vinylated SU did not exhibit significant activity compared to the control, the SU-incorporated copolymer could enhance insulin secretion as much as or more than glibenclamide did. In this study, a polymer fluorescence-labeled with rodamine-B isothiocyanate was used to visualize the interactions and we found that the labeled polymer was strongly absorbed to rat islets, probably due to its specific interaction mediated by SU receptors on the cell membrane. To verify the specific interaction between the SU (K+ channel closer)-incorporated copolymer and rat islets, cells were pretreated with diazoxide, an agonist of ATP-sensitive K+ channels (K+ channel opener), before adding the incorporated polymer to the cell culture medium. This treatment suppressed the action of SUs on rat islets. A confocal laser microscopic study further confirmed this interaction. The results of this study provided evidence that the SU-incorporated copolymer stimulates insulin secretion through specific interactions of SU moieties in the polymer with rat islets.

  19. Responsive copolymers for enhanced petroleum recovery. Quarterly technical progress report, December 22, 1993--March 21, 1994

    Energy Technology Data Exchange (ETDEWEB)

    McCormick, C.; Hester, R.

    1994-06-01

    The overall goal of this research is the development of advanced water-soluble copolymers for use in enhanced oil recovery. This report summarizes technical progress for the following tasks: advanced copolymer synthesis; and characterization of molecular structure of copolymers.

  20. COMPOSITIONAL HETEROGENEITY OF ETHYLENE OXIDE-BUTYLENE TEREPHTHALATE SEGMENTED COPOLYMER

    Institute of Scientific and Technical Information of China (English)

    De-zhu Ma; Dong-sheng Li; Ming-chuan Zhao; Mo-zhen Wang; Ran Ye; Xiao-lie Luo

    1999-01-01

    A series of ethylene oxide-butylene terephthalate (EOBT) segmented copolymers with different soft segment length and hard segment content were synthesized. The compositional heterogeneity was studied by solvent extraction. The results show that the compositional heterogeneity increases when soft segment length and hard segment content increase. The compositional heterogeneity is also reflected in the crystallization behavior and morphology of soft and hard segment in EOBT segmented copolymer. The more compositional heterogeneous the EOBT segmented copolymer is, the more different the morphology and the crystallization behavior between separated fractions. Compared with ethylene oxide-ethylene terephthalate (EOET) segmented copolymer, compositional heterogeneity in EOBT segmented copolymer is weaker. But the compositional heterogeneity in EOBT segmented copolymer with long soft segment and high hard segment content is still obvious.

  1. Surface modification of polyacrylonitrile co-polymer membranes using pulsed direct current nitrogen plasma

    Energy Technology Data Exchange (ETDEWEB)

    Pal, Dipankar; Neogi, Sudarsan; De, Sirshendu, E-mail: sde@che.iitkgp.ernet.in

    2015-12-31

    Low temperature plasma treatment using pulsed direct current discharge of nitrogen gas was employed to enhance hydrophilicity of the polyacrylonitrile co-polymer membranes. The membranes were characterized in terms of morphology, structure, hydrophilicity, and membrane performance. Properties and functional groups on the surface of polyacrylonitrile co-polymer membranes were investigated by contact angle, scanning electron microscopy, Fourier transform infrared and X-ray photoelectron spectroscopy. Effects of plasma conditions, namely, pulsed voltage, duty cycle and treatment time on increase in membrane hydrophilicity were studied. Permeability of treated membrane was increased by 47% and it was retained up to 70 days. Surface etching due to plasma treatment was confirmed by weight loss of the treated membranes. Due to surface etching, average pore size increased and rejection of 200 kDa polyethylene glycol decreased to about 70% for the treated membrane. Oxygen and nitrogen functional groups were responsible for surface hydrophilicity. - Highlights: • Surface modification of polyacrylonitrile co-polymer membranes by pulsed direct current nitrogen plasma • Hydrophilic functional groups incorporated on the membrane surface • Significant enhancement of the permeability and wettability of the membranes • Water contact angle increased with storage time and finally stabilized.

  2. Poly(butylene cyclohexanedicarboxylate/diglycolate random copolymers reinforced with SWCNTs for multifunctional conductive biopolymer composites

    Directory of Open Access Journals (Sweden)

    E. Fortunati

    2016-02-01

    Full Text Available The objective of this work was to develop a versatile strategy for preparing multifunctional composite films with tunable properties. Novel conductive composites based on the combination of single walled carbon nanotubes (SWCNTs and biodegradable poly(butylene cyclohexanedicarboxylate/diglycolate random copolymers (P(BCEmBDGn are here presented. In particular, synthesized PBCE homopolymer and two copolymers containing different amounts of ether–oxygen containing co-units, P(BCE90BDG10 and P(BCE70BDG30, have been considered as matrices of SWCNTs based composites. The effect of incorporation of different amounts of SWCNTs (0.1–0.5–0.75–1 wt% on morphological, thermal, mechanical and electrical properties was deeply investigated. The morphology of the fracture surfaces is affected by the SWCNT presence, while the increase in the SWCNT content does not provide significant microstructure modifications. The thermal properties underlined that nanotubes can act as nucleating agents, favouring the polymer crystallization process. The mechanical behavior demonstrated that the introduction of carbon nanotubes both in the case of PBCE homopolymer and in random copolymers based formulations exerted a reinforcing effect. All composites exhibit high electrical conductivity in comparison to the neat polymers. This work demonstrates that this combinatorial approach can be used to develop materials with tunable and advanced functional properties.

  3. Optoelectronic properties of a perylene substituted (cholesteryl)benzoateethynylene co-polymer

    Energy Technology Data Exchange (ETDEWEB)

    Zappia, Stefania [Dipartimento di Chimica e Chimica Industriale, Università di Genova, Via Dodecaneso 31, 16146 Genoa (Italy); Centro de Investigación en Química Aplicada, Boulevard Enrique Reyna 140, 25294 Saltillo, Coahuila (Mexico); León, Arxel de [Centro de Investigación en Química Aplicada, Boulevard Enrique Reyna 140, 25294 Saltillo, Coahuila (Mexico); Alloisio, Marina [Dipartimento di Chimica e Chimica Industriale, Università di Genova, Via Dodecaneso 31, 16146 Genoa (Italy); Arias, Eduardo [Centro de Investigación en Química Aplicada, Boulevard Enrique Reyna 140, 25294 Saltillo, Coahuila (Mexico); Dellepiane, Giovanna; Petrillo, Giovanni [Dipartimento di Chimica e Chimica Industriale, Università di Genova, Via Dodecaneso 31, 16146 Genoa (Italy); Moggio, Ivana, E-mail: ivana.moggio@ciqa.edu.mx [Centro de Investigación en Química Aplicada, Boulevard Enrique Reyna 140, 25294 Saltillo, Coahuila (Mexico); Thea, Sergio [Dipartimento di Chimica e Chimica Industriale, Università di Genova, Via Dodecaneso 31, 16146 Genoa (Italy); Gallardo-Vega, Carlos; Rodríguez, Marlene [Centro de Investigación en Química Aplicada, Boulevard Enrique Reyna 140, 25294 Saltillo, Coahuila (Mexico)

    2014-10-15

    A perylene cholesteryl-benzoateethynylene co-polymer was synthesized by Sonogashira reaction and characterized by NMR, UV–Vis, static and dynamic fluorescence spectroscopy and cyclic voltammetry. The optical and electrochemical properties in solution are consistent with photoinduced energy transfer from the electron donor conjugated backbone to the electron acceptor perylene substituent. Photovoltaic properties are indeed found, even if the performance of the solar cells is quite low due to the formation of aggregates. The incorporation of (6,6)-phenyl C61–butyric acid methyl ester (PCBM), however, increases by an order of magnitude the efficiency of the prototype (from 10{sup −4} to 10{sup −3}%) due to both better phase mixing and improved electrical continuity as supported by Atomic Force Microscopy (AFM) and Electrical Force Microscopy (EFM) studies. - Highlights: • Synthesis of a benzoateethynylene backbone co-polymer with perylene substituent. • Optical and electrochemical properties consistent with photoinduced energy transfer. • Enhancement of photovoltaic efficiency when PCBM is added to the co-polymer. • EFM studies of active layers.

  4. Synthesis of comb-like copolymers from renewable resources: Itaconic anhydride, stearyl methacrylate and lactic acid

    Science.gov (United States)

    Shang, Shurui

    The synthesis and properties of comb-like copolymers and ionomers derived from renewable resources: itaconic anhydride (ITA), stearyl methacrylate (SM) and lactic acid (LA) are described. The copolymers based on ITA and SM (ITA-SM) were nearly random with a slight alternating tendency. The copolymers exhibited a nanophase-separated morphology, with the stearate side-chains forming a bilayer, semi-crystalline structure. The crystalline side-chains suppressed molecular motion of the main-chain, so that a glass transition temperature (Tg) was not resolved unless the ITA concentration was sufficiently high so that Tg > the melting point (Tm). The softening point and modulus of the copolymers increased with the increasing ITA concentration, but the thermal stability decreased. The ITA moiety along the main chain of the copolymers was neutralized with metal acetates to produce Na-, Ca- and Zn- random ionomers with comb-like architectures. In general, the incorporation of the ionic groups increased the Tg and suppressed the crystallinity of the side-chain packing. Ionomers with high SM side-chain density had two competing driving forces for self-assembled nano-phase separation: ionic aggregation and side-chain crystalline packing. Upon neutralization, a morphological transition from semi-crystalline lamella to spherical ionic aggregation was observed by small angle X-ray scattering (SAXS) analysis and transmission electron microscopy (TEM). Thermomechanical analysis revealed an increasing resistance to penetration deformation with an increasing degree of neutralization and an apparent rubbery plateau was observed above Tg. A controlled transesterification of PLA in glassware was an effective way to prepare a methacrylate functionalized PLA macromonomer with controlled molecular weight, which was used to synthesize a variety of copolymers. The copolymerization of this functionalized PLA macromonomer with ITA totally suppressed the side-chain crystallinity for the PLA chain

  5. Silica nanoparticles for the layer-by-layer assembly of fully electro-active cytochrome c multilayers

    Directory of Open Access Journals (Sweden)

    Feifel Sven C

    2011-12-01

    Full Text Available Abstract Background For bioanalytical systems sensitivity and biomolecule activity are critical issues. The immobilization of proteins into multilayer systems by the layer-by-layer deposition has become one of the favorite methods with this respect. Moreover, the combination of nanoparticles with biomolecules on electrodes is a matter of particular interest since several examples with high activities and direct electron transfer have been found. Our study describes the investigation on silica nanoparticles and the redox protein cytochrome c for the construction of electro-active multilayer architectures, and the electron transfer within such systems. The novelty of this work is the construction of such artificial architectures with a non-conducting building block. Furthermore a detailed study of the size influence of silica nanoparticles is performed with regard to formation and electrochemical behavior of these systems. Results We report on interprotein electron transfer (IET reaction cascades of cytochrome c (cyt c immobilized by the use of modified silica nanoparticles (SiNPs to act as an artificial matrix. The layer-by-layer deposition technique has been used for the formation of silica particles/cytochrome c multilayer assemblies on electrodes. The silica particles are characterized by dynamic light scattering (DLS, Fourier transformed infrared spectroscopy (FT-IR, Zeta-potential and transmission electron microscopy (TEM. The modified particles have been studied with respect to act as an artificial network for cytochrome c and to allow efficient interprotein electron transfer reactions. We demonstrate that it is possible to form electro-active assemblies with these non-conducting particles. The electrochemical response is increasing linearly with the number of layers deposited, reaching a cyt c surface concentration of about 80 pmol/cm2 with a 5 layer architecture. The interprotein electron transfer through the layer system and the

  6. Nanocoating of ionic liquid and polypyrrole for durable electro-active paper actuators working under ambient conditions

    Energy Technology Data Exchange (ETDEWEB)

    Mahadeva, Suresha K; Kim, Jaehwan, E-mail: jaehwan@inha.ac.k [Centre for EAPap Actuator, Department of Mechanical Engineering INHA University, 253 Young-Hyun Dong, Nam Gu, Incheon 402-751 (Korea, Republic of)

    2010-05-26

    This paper reports that nanocoating of polypyrrole (PPy) and ionic liquid (IL) on cellulose film improves the electromechanical performance and durability of a cellulose electro-active paper actuator. Cellulose-PPy-IL nanocomposites were fabricated by the polymerization-induced adsorption process of PPy followed by subsequent activation in IL solutions. X-ray photoelectron spectroscopy, transmission electron microscopy and secondary ion mass spectroscopy analyses validated the successful nanocoating of the PPy and IL layers on the cellulose. The results revealed that the cellulose-PPy-IL nanocomposites are suitable for durable bending actuators working under ambient conditions. Preparation, characterization and performance test of the nanocomposites are explained.

  7. Imide/Arylene Ether Copolymers Containing Phosphine Oxide

    Science.gov (United States)

    Jensen, Brian J.; Partos, Richard D.

    1993-01-01

    Phosphine oxide groups react with oxygen to form protective phosphate surface layers. Series of imide/arylene ether block copolymers containing phosphine oxide units in backbone synthesized and characterized. In comparison with commercial polyimide, these copolymers display better resistance to etching by oxygen plasma. Tensile strengths and tensile moduli greater than those of polyarylene ether homopolymer. Combination of properties makes copolymers attractive for films, coatings, adhesives, and composite matrices where resistance to atomic oxygen needed.

  8. Development of a High-Frequency Multilayer Copolymer Acoustic Projector

    Science.gov (United States)

    1994-03-31

    Vinylidene Fluoride/Trifluoroethylene Copolymers in Relation to Their Structures," Japanese Journal of Applied Physics , vol. 103, 1987, p. 554. 4. R. AI... Journal of Applied Physics , vol. 21, 1982, p. L455. 17. K. Rittenmyer, *Report on the Electromechanical Evaluation of PVDF Copolymer Materials," U. S...Ohigashi and K. Koga, "Ferroelectric Copolymers of Vinylidene Fluoride and Trifluoroethylene with a Large Electromechanical Coupling Factor,* Japanese

  9. Electrochemical characterisation of a lithium-ion battery electrolyte based on mixtures of carbonates with a ferrocene-functionalised imidazolium electroactive ionic liquid.

    Science.gov (United States)

    Forgie, John C; El Khakani, Soumia; MacNeil, Dean D; Rochefort, Dominic

    2013-05-28

    Electrolytic solutions of lithium-ion batteries can be modified with additives to improve their stability and safety. Electroactive molecules can be used as such additives to act as an electron (redox) shuttle between the two electrodes to prevent overcharging. The electroactive ionic liquid, 1-ferrocenylmethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)amide (TFSI), was synthesised and its electrochemical properties were investigated when diluted with ethylene carbonate-diethyl carbonate solvent at various concentrations. Cyclic voltammetry data were gathered to determine the redox potential, diffusion coefficient and heterogeneous rate constants of the electroactive imidazolium TFSI ionic liquid in the carbonate solution. The properties of this molecule as an additive in lithium battery electrolytes were studied in standard coin cells with a metallic Li anode and a Li4Ti5O12 cathode.

  10. Mechanism of Molecular Exchange in Copolymer Micelles

    Science.gov (United States)

    Choi, Soo-Hyung; Lodge, Timothy; Bates, Frank

    2010-03-01

    Compared to thermodynamic structure, much less has been known about the kinetics of block copolymer micelles which should underlay the attainment of thermodynamic equilibrium. In this presentation, molecular exchange between spherical micelles formed by isotopically labeled diblock copolymers was investigated using time-resolved small-angle neutron scattering. Two pairs of structurally matched poly(styrene-b-ethylene-alt-propylene) (PS-PEP) were synthesized and dispersed in isotopic mixture of squalane, highly selective to PEP block. Each pair includes polymers with fully deuterated (dPS-PEP) and a normal (hPS-PEP) PS blocks. Temperature dependence of the micelle exchange rate R(t) is consistent with melt dynamics for the core polymer. Furthermore, R(t) is significantly sensitive to the core block length N due to the thermodynamic penalty associated with ejecting a core block into the solvent. This hypersensitivity, combined with modest polydispersity in N, leads to an approximately logarithmic decay in R(t).

  11. 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

  12. Rapid ordering of block copolymer thin films

    Science.gov (United States)

    Majewski, Pawel W.; Yager, Kevin G.

    2016-10-01

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

  13. Formation of Anisotropic Block Copolymer Gels

    Science.gov (United States)

    Liaw, Chya Yan; Shull, Kenneth; Henderson, Kevin; Joester, Derk

    2011-03-01

    Anisotropic, fibrillar gels are important in a variety of processes. Biomineralization is one example, where the mineralization process often occurs within a matrix of collagen or chitin fibers that trap the mineral precursors and direct the mineralization process. We wish to replicate this type of behavior within block copolymer gels. Particularly, we are interested in employing gels composed of cylindrical micelles, which are anisotropic and closely mimic biological fibers. Micelle geometry is controlled in our system by manipulating the ratio of molecular weights of the two blocks and by controlling the detailed thermal processing history of the copolymer solutions. Small-Angle X-ray Scattering and Dynamic Light Scattering are used to determine the temperature dependence of the gel formation process. Initial experiments are based on a thermally-reversible alcohol-soluble system, that can be subsequently converted to a water soluble system by hydrolysis of a poly(t-butyl methacrylate) block to a poly (methacrylic acid) block. MRSEC.

  14. TOPICAL REVIEW: Multifunctional nanoassemblies of block copolymers for future cancer therapy

    Science.gov (United States)

    Cabral, Horacio; Kataoka, Kazunori

    2010-02-01

    Nanoassemblies from amphiphilic block copolymers are promising nanomedicine platforms for cancer diagnosis and therapy due to their relatively small size, high loading capacity of drugs, controlled drug release, in vivo stability and prolonged blood circulation. Recent clinical trials with self-assembled polymeric micelles incorporating anticancer drugs have shown improved antitumor activity and decreased side effects encouraging the further development of nanoassemblies for drug delivery. This review summarizes recent approaches considering stimuli-responsive, multifunctionality and more advanced architectures, such as vesicles or worm-like micelles, for tumor-specific drug and gene delivery.

  15. Metal nanodot arrays fabricated via seed-mediated electroless plating with block copolymer thin film scaffolding.

    Science.gov (United States)

    Komiyama, Hideaki; Iyoda, Tomokazu; Sanji, Takanobu

    2015-10-02

    We present an alternative approach to fabricating hexagonally arranged nanodot arrays of various metals by seed-mediated electroless plating with a cylinder-forming block copolymer thin film, PEO-b-PMA(Az), as a scaffold. Metal ions were selectively incorporated into PEO cylinders, followed by their reduction to metal and the etching of the scaffold to obtain highly ordered seed arrays of Au, Pd, and Pt. Nanodot arrays of the target metals (Au, Ag, and Ni) were selectively grown on the seed with their highly ordered arrangement by electroless plating. We studied the fabrication processes' suitability for control of the nanodot array size, as well as the plasmonic properties thereof.

  16. Parallel Computing Properties of Tail Copolymer Chain

    Directory of Open Access Journals (Sweden)

    Hong Li

    2013-08-01

    Full Text Available The properties of a AB diblock copolymer chain are calculated by Monte Carlo methods. Monomer A contacting to the surface has an adsorption energy E=-1 and monomer B E= 0. The polymer chain is simulated by self-avoiding walk in simple cubic lattice. The adsorption properties and the conformation properties of the polymer chain are computed by using message passing interface (MPI. The speedup is close to linear speedup by parallel computing independent samples.    

  17. Nanostructured Block Copolymer Coatings for Biofouling Inhibition

    Science.gov (United States)

    2015-06-30

    biofouling program contractors. 15. SUBJECT TERMS antifouling; coatings; block copolymers; IR nanoscale imaging ; biocides 16. SECURITY CLASSIFICATION OF...diagnostics and drug delivery. In our scanned probe microscopy studies on collaborator coatings and marine organisms, we have provided teamwork . We have...Studies of Organisms on model fouiants: • H. elegans studies 3. Testing of other contractor materials 4. Imaging technology. We applied our organic

  18. Comparing the morphology and phase diagram of H-shaped ABC block copolymers and linear ABC block copolymers.

    Science.gov (United States)

    Ye, Xianggui; Yu, Xifei; Sun, Zhaoyan; An, Lijia

    2006-06-22

    By using a combinatorial screening method based on the self-consistent field theory (SCFT) for polymers, we have investigated the morphology of H-shaped ABC block copolymers (A2BC2) and compared them with those of the linear ABC block copolymers. By changing the ratios of the volume fractions of two A arms and two C arms, one can obtain block copolymers with different architectures ranging from linear block copolymer to H-shaped block copolymer. By systematically varying the volume fractions of block A, B, and C, the triangle phase diagrams of the H-shaped ABC block copolymer with equal interactions among the three species are constructed. In this study, we find four different morphologies (lamellar phase (LAM), hexagonal lattice phase (HEX), core-shell hexagonal lattice phase (CSH), and two interpenetrating tetragonal lattice (TET2)). Furthermore, the order-order transitions driven by architectural change are discussed.

  19. 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.

  20. Effect of Small Molecule Osmolytes on the Self-Assembly and Functionality of Globular Protein-Polymer Diblock Copolymers

    Energy Technology Data Exchange (ETDEWEB)

    Thomas, Carla S.; Xu, Liza; Olsen, Bradley D. [MIT

    2013-12-05

    Blending the small molecule osmolytes glycerol and trehalose with the model globular protein–polymer block copolymer mCherry-b-poly(N-isopropyl acrylamide) (mCherry-b-PNIPAM) is demonstrated to improve protein functionality in self-assembled nanostructures. The incorporation of either additive into block copolymers results in functionality retention in the solid state of 80 and 100% for PNIPAM volume fractions of 40 and 55%, respectively. This represents a large improvement over the 50–60% functionality observed in the absence of any additive. Furthermore, glycerol decreases the thermal stability of block copolymer films by 15–20 °C, while trehalose results in an improvement in the thermal stability by 15–20 °C. These results suggest that hydrogen bond replacement is responsible for the retention of protein function but suppression or enhancement of thermal motion based on the glass transition of the osmolyte primarily determines thermal stability. While both osmolytes are observed to have a disordering effect on the nanostructure morphology with increasing concentration, this effect is less pronounced in materials with a larger polymer volume fraction. Glycerol preferentially localizes in the protein domains and swells the nanostructures, inducing disordering or a change in morphology depending on the PNIPAM coil fraction. In contrast, trehalose is observed to macrophase separate from the block copolymer, which results in nanodomains becoming more disordered without changing significantly in size.

  1. Influence of Methacrylic-Acrylic Copolymer Composition on Plasticiser-free Optode Films for pH Sensors

    Directory of Open Access Journals (Sweden)

    Musa Ahmad

    2003-03-01

    Full Text Available In this work we have examined the use of plasticiser-free polymeric films incorporating a proton selective chromoionophore for optical pH sensor. Four types of methacrylic-acrylic copolymers containing different compositions of n-butyl acrylate (nBA and methyl methacrylate (MMA were synthesised for use as optical sensor films. The copolymers were mixed with appropriate amounts of chromoionophore (ETH5294 and a lipophilic salt before spin coated on glass slides to form films for the evaluation of pH response using spectrophotometry. Co-polymer films with high nBA content gave good response and the response time depended on the film thickness. A preliminary evaluation of the optical films of high nBA content with pHs from 2 - 14 showed distinguishable responses from pH 5 - 9. However, the adhesion of the pH sensitive film was good for copolymers with higher content of MMA but not for films with high nBA.

  2. New Anti-Corrosive Coatings with Resin-Bonded Polyaniline and Related Electroactive Groups

    Science.gov (United States)

    Weil, Edward D.

    1997-01-01

    It is already known that polyaniline (an electroactive polymer) functions as a corrosion inhibitor for steel and in view of the fact that it is known to perform in the presence of hydrochloric acid, it has been considered likely that it may be useful to NASA for protecting launch structures at KSC which are exposed to not only continual ocean-side salt spray but also to hydrochloric acid at the times that solid-fuel boosters are fired. The currently used zinc-rich silicate-bonded coating is not wholly protective against the hydrochloric acid. Water pollution from zinc salts is another concern. Other earlier and concurrent NASA sponsored projects have been focussed on polyaniline specifically. Our project, administered for NASA by Dr. K. Thompson of KSC and these more-specifically polyaniline-related projects are included in a CRADA coordinated by Dr. F. Via of Akzo Nobel. A parallel project at Polytechnic under Prof K. Levon concentrated more specifically on polyaniline with various dopants. Our exploratory project reported herein was aimed at broadening the range of such corrosion inhibitors, to give protective paint compounders a wider latitude for adding corrosion inhibitors having polyaniline-like performance, and thus we diverged in several probing directions from polyaniline. Our working hypothesis was that physical variants of polyaniline, such as supported formulations on pigments or carriers, and chemical variants of polyaniline, including those having no electroconductive character, may have enhanced anticorrosion activity. We also hypothesized that small (non-polymeric) molecules having structures related to those occurring in polyaniline, may be active as corrosion inhibitors. We did preliminary testing, using an ASTM salt spray method at a nearby commercial paint testing laboratory. Our most interesting findings were that a non-electroconductive meta-isomer of polyaniline showed some corrosion activity, suggesting that the features of the polyaniline

  3. On guided circumferential waves in soft electroactive tubes under radially inhomogeneous biasing fields

    Science.gov (United States)

    Wu, Bin; Su, Yipin; Chen, Weiqiu; Zhang, Chuanzeng

    2017-02-01

    Soft electroactive (EA) tube actuators and many other cylindrical devices have been proposed recently in literature, which show great advantages over those made from conventional hard solid materials. However, their practical applications may be limited because these soft EA devices are prone to various failure modes. In this paper, we present an analysis of the guided circumferential elastic waves in soft EA tube actuators, which has potential applications in the in-situ nondestructive evaluation (NDE) or online structural health monitoring (SHM) to detect structural defects or fatigue cracks in soft EA tube actuators and in the self-sensing of soft EA tube actuators based on the concept of guided circumferential elastic waves. Both circumferential SH and Lamb-type waves in an incompressible soft EA cylindrical tube under inhomogeneous biasing fields are considered. The biasing fields, induced by the application of an electric voltage difference to the electrodes on the inner and outer cylindrical surfaces of the EA tube in addition to an axial pre-stretch, are inhomogeneous in the radial direction. Dorfmann and Ogden's theory of nonlinear electroelasticity and the associated linear theory for small incremental motion constitute the basis of our analysis. By means of the state-space formalism for the incremental wave motion along with the approximate laminate technique, dispersion relations are derived in a particularly efficient way. For a neo-Hookean ideal dielectric model, the proposed approach is first validated numerically. Numerical examples are then given to show that the guided circumferential wave propagation characteristics are significantly affected by the inhomogeneous biasing fields and the geometrical parameters. Some particular phenomena such as the frequency veering and the nonlinear dependence of the phase velocity on the radial electric voltage are discussed. Our numerical findings demonstrate that it is feasible to use guided circumferential

  4. Effect of non-electroactive additives on the early stage pyrrole electropolymerization on indium tin oxide electrodes

    Energy Technology Data Exchange (ETDEWEB)

    Castro-Beltran, A. [Facultad de Ingeniería Mecánica y Eléctrica, Universidad Autónoma de Nuevo León, Ave. Pedro de Alba s/n, Ciudad Universitaria, C.P. 66451 San Nicolás de los Garza, N.L. (Mexico); Centro de Innovación Investigación y Desarrollo en Ingeniería y Tecnología (CIIDIT), Universidad Autónoma de Nuevo León, PIIT-Monterrey C.P. 66600 Apodaca, N.L. (Mexico); Dominguez, C.; Bahena-Uribe, D. [Centro Investigación en Ingeniería y Ciencias Aplicadas (CIICAp), Universidad Autónoma del Estado de Morelos, Av. Universidad 1001, Col. Chamilpa, C.P. 62209 Cuernavaca, Mor. (Mexico); Sepulveda-Guzman, S., E-mail: selene.sepulvedagz@uanl.edu.mx [Facultad de Ingeniería Mecánica y Eléctrica, Universidad Autónoma de Nuevo León, Ave. Pedro de Alba s/n, Ciudad Universitaria, C.P. 66451 San Nicolás de los Garza, N.L. (Mexico); Centro de Innovación Investigación y Desarrollo en Ingeniería y Tecnología (CIIDIT), Universidad Autónoma de Nuevo León, PIIT-Monterrey C.P. 66600 Apodaca, N.L. (Mexico); Cruz-Silva, R. [Research Center for Exotic NanoCarbon, Shinshu University, 4-17-1 Wakasato, Nagano 380-8553 (Japan)

    2014-09-01

    The use of non-electroactive additives during electrodeposition of conducting polymers has long been used to modify the properties of deposited films. These additives can improve the adhesion, and not only change the morphology and deposition rate but also modify the chemical composition of the electrodeposited polymer. Several compounds have been used to modify deposition of polypyrrole; however, there is no systematic study of these compounds. In this work, we comparatively studied several water soluble chemical compounds, a cationic polymer, an anionic polymer, a cationic surfactant, and an anionic surfactant during potentiostatic electrodeposition of polypyrrole. In order to study the effect of these compounds on the interface, where the electrochemical polymerization takes place, we used electrochemical impedance spectroscopy. The morphology during the initial stage of growth was studied by atomic force microscopy, whereas the resulting polypyrrole films were observed by scanning electron microscopy. - Highlights: • Early-stage polymerization polypyrrole particles on indium tin oxide (ITO). • Anionic additives promote pyrrole oxidation and polypyrrole film growth on ITO. • Cationic polyelectrolyte promotes adhesion between ITO and polypyrrole film. • Non-electroactive additives strongly influence polypyrrole nucleation on ITO.

  5. Fabrication of a self-sensing electroactive polymer bimorph actuator based on polyvinylidene fluoride and its electrostrictive terpolymer

    Science.gov (United States)

    Engel, Leeya; Van Volkinburg, Kyle R.; Ben-David, Moti; Washington, Gregory N.; Krylov, Slava; Shacham-Diamand, Yosi

    2016-04-01

    In this paper, we report on the fabrication of a self-sensing electroactive polymer cantilevered bimorph beam actuator and its frequency response. Tip deflections of the beam, induced by applying an AC signal across ferroelectric relaxor polyvinylidene fluoride-trifluoroethylene chlorotrifluoroethylene (P(VDF-TrFE-CTFE)), reached a magnitude of 350μm under a field of ~55MV/m and were recorded externally using a laser Doppler vibrometer (LDV). Deflections were determined simultaneously by applying a sensing model to the voltage measured across the bimorph's integrated layer of piezoelectric polymer polyvinylidene fluoride (PVDF). The sensing model treats the structure as a simple Euler- Bernoulli cantilevered beam with two distributed active elements represented through the use of generalized functions and offers a method through which real time tip deflection can be measured without the need for external visualization. When not being used as a sensing element, the PVDF layer can provide an additional means for actuation of the beam via the converse piezoelectric effect, resulting in bidirectional control of the beam's deflections. Integration of flexible sensing elements together with modeling of the electroactive polymer beam can benefit the developing field of polymer microactuators which have applications in soft robotics as "smart" prosthetics/implants, haptic displays, tools for less invasive surgery, and sensing.

  6. Nitrogen, sulfur-codoped graphene sponge as electroactive carbon interlayer for high-energy and -power lithium-sulfur batteries

    Science.gov (United States)

    Xing, Ling-Bao; Xi, Kai; Li, Qiuyan; Su, Zhong; Lai, Chao; Zhao, Xinsheng; Kumar, R. Vasant

    2016-01-01

    Sulfur is an attractive cathode material in energy storage devices since its high theoretical capacity of 1672 mAh g-1. However, practical application of lithium sulfur (Li-S) batteries can be achieved only when the major barriers, including the insulating nature of element sulfur and shuttling effect of polysulfides (Li2Sx, x = 3-8), are tackled. Here, nitrogen, sulfur-codoped (N,S-codoped) sponge-like graphene, which presents a high reversible capacity, is used as electroactive interlayer for Li-S batteries to address these issues. An impressive high capacity of 2193.2 mAh g-1 can be obtained for the sulfur cathodes with such an interlayer at the rate of 0.2C, and it can be stably maintained at 829.4 mAh g-1 at the rate of 6C, for which the contribution from the electroactive interlayer is ca. 30.0%. High energy density of 418.5 Wh Kg-1 still can be released at the power density of 4.55 kW kg-1 (6C) based on the total mass of the sulfur cathode and interlayer for the assembled Li-S batteries.

  7. Native and structurally modified gum arabic: exploring the effect of the gum's microstructure in obtaining electroactive nanoparticles.

    Science.gov (United States)

    Cornelsen, Patricia A; Quintanilha, Ronaldo C; Vidotti, Marcio; Gorin, Philip A J; Simas-Tosin, Fernanda F; Riegel-Vidotti, Izabel C

    2015-03-30

    Electroactive nanoparticles combining gum arabic (GA) and polyaniline (PANI) were prepared by chemical synthesis. The gum consists of highly branched anionic polysaccharides with some protein content. GA was structurally modified by Smith controlled degradation, in order to reduce its degree of branching (GAD), aiming the elucidation of the relationship between the structure and the properties of complex polysaccharides. The modification was studied by SEC, GC-MS, (13)C NMR and colorimetric methods. GAD has lower molecular mass, lower degree of branching and lower uronic acid content. Besides it is enriched in galactose and protein when compared with GA. The obtained composites (GA-PANI and GAD-PANI) were thoroughly characterized. Although the use of both polysaccharides (GA and GAD) produced highly stable electroactive nanoparticles, the best combination of properties was achieved for GA-PANI. The sample GAD was not able to prevent the occurrence of crosslinking between PANI chains, possibly due to its lower microstructural complexity which diminishes the occurrence of hydrogen bonds between the polymers.

  8. A Photochromic Copolymer Hydrogel Contact Lens: From Synthesis to Application

    Directory of Open Access Journals (Sweden)

    Xiaoli Yang

    2016-01-01

    Full Text Available A photochromic poly(2-hydroxyl-ethyl methacrylate-N-vinylpyrrolidone-spironaphthoxazine hydrogel (p(HEMA-NVP-SPO has been designed and synthesized by free radical polymerization in this work. The chemical and structural information of hydrogels was investigated by IR spectra, equilibrium water content (EWC, and SEM. The IR spectra confirmed successful synthesis of copolymer. The domain of NVP contributed to not only EWC but also inner structure of hydrogel, while SPO had little influence on these properties of hydrogel. The photochromic behaviors of hydrogel including photochromic properties and thermal fading kinetics were systematically studied and compared with hydrogel made by immersing method. Results showed that when SPO was incorporated in hydrogel by polymerization, maximum absorbance wavelength got shorter, and the relaxation half-life became longer. In addition, salicylic acid as a drug model could be loaded into hydrogel by immersing method, and its sustained drug release in a given period was dependent on the characteristics of solution and loading time.

  9. Crystallization Behavior of Copolymer Poly (ethylene terephthalate/isophthalate) (IPET)

    Institute of Scientific and Technical Information of China (English)

    顾书英; 肖茹; 顾利霞

    2001-01-01

    The non-isothermal crystallization kinetics, isothermal crystallization and the morphology of crystals of the copolymer poly (ethylene terephthalate/ isophthalate )(IPET) were studied by DSC and polarized-light microscopy in this paper. DSC results indicate that the glass transition temperature Tg of IPET is slightly lower than that of poly(ethylene terephthalate) (PET), but the melting temperature Tm and the crystallization temperature Tc of PET and IPET have much difference.The difference of Tc between PET and IPET2 is about 7℃, and the difference of Tm between PET and IPET2 is about 16℃. From the kinetics analysis of the crystallization, the crystallization mechanism of all samples is of three-dimension spherulitic growth from instantaneous nuclei and the incorporation of isophthalate (IPA) decreases the crystallization rate of IPET greatly. The isothermal results indicate that the morphologies of PET and IPET crystals are all spherulite, which is in conformity to the results of nonisothermal dynamic crystallization. At the same time,the spherulite of IPET grows slower and has longer incubation time than the spherulite of PET under the same crystallization condition.

  10. Morphological studies on block copolymer modified PA 6 blends

    Science.gov (United States)

    Poindl, M.; Bonten, C.

    2014-05-01

    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.

  11. 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.

  12. 21 CFR 177.1310 - Ethylene-acrylic acid copolymers.

    Science.gov (United States)

    2010-04-01

    ... (CONTINUED) FOOD FOR HUMAN CONSUMPTION (CONTINUED) INDIRECT FOOD ADDITIVES: POLYMERS Substances for Use as... this section are not applicable to ethylene-acrylic acid copolymers used in food-packaging adhesives... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Ethylene-acrylic acid copolymers. 177.1310...

  13. Surface morphology of PS-PDMS diblock copolymer films

    DEFF Research Database (Denmark)

    Andersen, T.H.; Tougaard, S.; Larsen, N.B.

    2001-01-01

    Spin coated thin films (∼400 Å) of poly(styrene)–poly(dimethylsiloxane) (PS–PDMS) diblock copolymers have been investigated using X-ray Photoelectron Spectroscopy and Atomic Force Microscopy. Surface segregation of the poly(dimethylsiloxane) blocks was studied for five diblock copolymers which...

  14. 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...

  15. Alternation and tunable composition in hydrogen bonded supramolecular copolymers.

    Science.gov (United States)

    Felder, Thorsten; de Greef, Tom F A; Nieuwenhuizen, Marko M L; Sijbesma, Rint P

    2014-03-07

    Sequence control in supramolecular copolymers is limited by the selectivity of the associating monomer end groups. Here we introduce the use of monomers with aminopyrimidinone and aminohydroxynaphthyridine quadruple hydrogen bonding end groups, which both homodimerize, but form even stronger heterodimers. These features allow the formation of supramolecular copolymers with a tunable composition and a preference for alternating sequences.

  16. Hierarchical structure formation in supramolecular comb-shaped block copolymers

    NARCIS (Netherlands)

    Hofman, Anton; ten Brinke, Gerrit; Loos, Katja

    2016-01-01

    Block copolymers are known to spontaneously form ordered structures at the nano-to mesoscale. Although the number of different morphologies is rather limited in diblock copolymer systems, their phase behavior becomes increasingly more complex with each additional building block. Synthesis of such al

  17. Functional silicone elastomers via novel siloxane copolymers and chain extenders

    DEFF Research Database (Denmark)

    Madsen, Frederikke Bahrt; Daugaard, Anders Egede; Hvilsted, Søren

    of siloxane copolymers[1] (via the tris(pentafluorophenyl)borane catalysed Piers-Rubinsztajn reaction[2]), which allows for the attachment of functional molecules through copper-catalysed azide-alkyne 1,3-dipolar cycloaddition (CuAAC)[3]. The synthesised copolymers allow for a high degree of chemical freedom...

  18. Functional silicone copolymers and elastomers with high dielectric permittivity

    DEFF Research Database (Denmark)

    Madsen, Frederikke Bahrt; Daugaard, Anders Egede; Hvilsted, Søren

    . This was done trough the synthesis of new functionalizable siloxane copolymers [2] that allow for the attachment of high dielectric permittivity molecules through copper-catalyzed azide-alkyne 1,3-dipolar cycloaddition (CuAAC) reactions. The synthesised siloxane copolymers were prepared via the tris...

  19. 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

  20. 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

  1. 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.

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

    KAUST Repository

    Menk, Florian

    2016-02-29

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

  3. Structure and Mechanical Properties of Ethylene-butene Copolymers

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    The crystallinity of ethylene-butene copolymers prepared by copolymerization of ethylene and butene in the presence of a new highly active catalyst was studied by means of DSC, WAXD and DMA. The results show that the melting temperature, the crystallinity and the crystallite size decreased with increasing the content of butene in the copolymers. The copolymers have a high degree of branching, the butene segments are mainly in the amorphous regions of the copolymers, while the polyethylene sequence forms crystal phase acting as crosslinking bondage between the molecules at room temperature. The ethylene-butene copolymers have a low modulus, a low stress and a high strain analogous to the stress-strain behavior of non-cross thermoplastic elastomer.

  4. 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.

  5. Sulfomethylated graft copolymers of xanthan gum and polyacrylamide

    Energy Technology Data Exchange (ETDEWEB)

    Cottrell, I.W.; Empey, R.A.; Racciato, J.S.

    1978-08-08

    A water-soluble anionic graft copolymer of xanthan gum and polyacrylamide is described in which at least part of the amide function of the acrylamide portion of the copolymer is sulfomethylated and the xanthan gum portion of the copolymer is unreacted with formaldehyde. The copolymer is sulfomethylated by reaction with formaldehyde and sodium metabisulfite. The formaldehyde does not cause any appreciable cross-linking between hydroxyl groups of the xanthan moieties. The sulfomethylation of the acrylamido group takes place at temperatures from 35 to 70 C. The pH is 10 or higher, typically from 12 to 13. The degree of anionic character may be varied by adjusting the molar ratio of formaldehyde and sodium metabisulfite with respect to the copolymer. 10 claims.

  6. PREPARATION AND SURFACE PROPERTIES OF ACRYLIC COPOLYMERS CONTAINING FLUORINATED MONOMERS

    Institute of Scientific and Technical Information of China (English)

    Tai-jiang Gui; Hao Wei; Ying Zhao; Xiu-lin Wang; Du-jin Wang; Duan-fu Xu

    2006-01-01

    A series of copolymers comprising butylmethacrylate, styrene, butylacrylate, hydroxypropyl acrylate and perfluoroalkyl methacrylate were synthesized by the free radical polymerization using BPO as an initiator. The surface property of the copolymer films was subsequently characterized. The contact angle measurements and energy dispersive analysis of X-ray (EDAX) show that the length and content ofperfluoroalkyl side chains in the copolymers are crucial for the preparation of the film with low surface energy. At a given content of fluorinated monomers in the copolymers, the longer the perfluoroalkyl side chain, the larger the water contact angle of the copolymer films will be. On the other hand, the higher the content of fluorinated monomers, the lower the surface energy is. The water contact angle increases with the increase of the fluorinated monomer content and reaches a plateau at 3 wt% of fluorinated monomer content.

  7. Electroactive polyurethane/siloxane derived from castor oil as a versatile cardiac patch, part I: Synthesis, characterization, and myoblast proliferation and differentiation.

    Science.gov (United States)

    Baheiraei, Nafiseh; Gharibi, Reza; Yeganeh, Hamid; Miragoli, Michele; Salvarani, Nicolò; Di Pasquale, Elisa; Condorelli, Gianluigi

    2015-11-05

    Tissue-engineered cardiac patch aims at regenerating an infarcted heart by improving cardiac function and providing mechanical support to the diseased myocardium. In order to take advantages of electroactivity, a new synthetic method was developed for the introduction of an electroactive oligoaniline into the backbone of prepared patches. For this purpose, a series of electroactive polyurethane/siloxane films containing aniline tetramer (AT) was prepared through sol-gel reaction of trimethoxysilane functional intermediate polyurethane prepolymers made from castor oil and poly(ethylene glycol). Physicochemical, mechanical, and electrical conductivity of samples were evaluated and the recorded results were correlated to their structural characteristics. The optimized films were proved to be biodegradable and have tensile properties suitable for cardiac patch application. The embedded AT moieties in the backbone of the prepared samples preserved their electroactivity with the electrical conductivity in the range of 10(-4) S/cm. The prepared films were compatible with proliferation of C2C12 and had potential for enhancing myotube formation even without external electrical stimulation. © 2015 Wiley Periodicals, Inc. J Biomed Mater Res Part A, 2015.

  8. A comprehensive overview on electro-active biofilms, role of exo-electrogens and their microbial niches in microbial fuel cells (MFCs).

    Science.gov (United States)

    Saratale, Ganesh Dattatraya; Saratale, Rijuta Ganesh; Shahid, Muhammad Kashif; Zhen, Guangyin; Kumar, Gopalakrishnan; Shin, Han-Seung; Choi, Young-Gyun; Kim, Sang-Hyoun

    2017-07-01

    Microbial fuel cells (MFCs) are biocatalyzed systems which can drive electrical energy by directly converting chemical energy using microbial biocatalyst and are considered as one of the important propitious technologies for sustainable energy production. Much research on MFCs experiments is under way with great potential to become an alternative to produce clean energy from renewable waste. MFCs have been one of the most promising technologies for generating clean energy industry in the future. This article summarizes the important findings in electro-active biofilm formation and the role of exo-electrogens in electron transfer in MFCs. This study provides and brings special attention on the effects of various operating and biological parameters on the biofilm formation in MFCs. In addition, it also highlights the significance of different molecular techniques used in the microbial community analysis of electro-active biofilm. It reviews the challenges as well as the emerging opportunities required to develop MFCs at commercial level, electro-active biofilms and to understand potential application of microbiological niches are also depicted. Thus, this review is believed to widen the efforts towards the development of electro-active biofilm and will provide the research directions to overcome energy and environmental challenges. Copyright © 2017 Elsevier Ltd. All rights reserved.

  9. Enhancing relative permittivity by incorporating PDMS-PEG multiblock copolymers in binary polymer blends

    DEFF Research Database (Denmark)

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

    Polydimethylsiloxane (PDMS) elastomers are well-known to be soft and highly stretchable, yet they never achieve maximum elongation when utilised as dielectric elastomers, simply because their dielectric permittivity remains rather low. Conversely, polyethyleneglycols (PEG) are not stretchable...

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

    DEFF Research Database (Denmark)

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

    Polydimethylsiloxane (PDMS) is well-known to cause hydrophobic surfaces due to their low surface energy as well as they possess low conductivity and extremely low glass transition temperature 1. On the other hand, polyethyleneglycol (PEG) behaves hydrophilic and is a highly conductive polymer...

  11. Ionization of amphiphilic acidic block copolymers.

    Science.gov (United States)

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

    2012-06-28

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

  12. Absorption ability and kinetics of a liquid electrolyte in PVDF-HFP copolymer containing or not SiO 2

    Science.gov (United States)

    Caillon-Caravanier, M.; Claude-Montigny, B.; Lemordant, D.; Bosser, G.

    Gel polymer electrolytes have been prepared from PVDF-HFP copolymer with various silica contents incorporating Gamma valerolactone (VL) or VL/EC (80/20 in mole) (EC: ethylene carbonate) solutions of lithium bis(trifluoromethane sulfone) imide (LiTFSI). The influence of temperature, salt content and silica addition on the kinetics of absorption and wettability of the copolymer has been investigated. An empirical model, taking into account gel swelling during the absorption allows us to relate, at constant temperature, the wetting time and the volumetric fraction of trapped electrolyte, which is a critical factor for ionic conductivity of the gel. Increasing the silica content in the dry copolymer increases the porosity and consequently the rate of absorption and thus the amount of incorporated liquid phase at saturation. To a lower extent, an increase in the temperature of absorption has the same effects. The prepared gels have good mechanicals properties and conductivities. As an example, a gel of composition: PVDF- HFP/ SiO2/ VL/ EC/ LiTFSI of molar percentages 36/6.7/42/10.5/4.8 exhibits a conductivity of 2.9 mS cm - 1 at 293 K.

  13. Preparation of Impact and Weather Resistant Copolymer

    Institute of Scientific and Technical Information of China (English)

    LIANG Tao

    2001-01-01

    @@ Synthesis method of the resin is that crosslinked polybutyl acrylate latex is used as base latex. Styrene (St) and acrylonitrile (AN) are grafted onto polybutyl acrylate latex particle and turn into core-shell copolymer. The resin is a good resin's impact modifier. There are study of influence regularity about additive emulsifier, initiator, monomer concentration, the ratio of St to AN, chain transfer to graft polymerization. A kind of core-shell resin used as impact modifier is obtained. (A) Preparation of Crosslinked Butyl Acrylate Rubber Latex

  14. Preparation of Impact and Weather Resistant Copolymer

    Institute of Scientific and Technical Information of China (English)

    LIANG; Tao

    2001-01-01

    Synthesis method of the resin is that crosslinked polybutyl acrylate latex is used as base latex. Styrene (St) and acrylonitrile (AN) are grafted onto polybutyl acrylate latex particle and turn into core-shell copolymer. The resin is a good resin's impact modifier. There are study of influence regularity about additive emulsifier, initiator, monomer concentration, the ratio of St to AN, chain transfer to graft polymerization. A kind of core-shell resin used as impact modifier is obtained. (A) Preparation of Crosslinked Butyl Acrylate Rubber Latex  ……

  15. Small domain-size multiblock copolymer electrolytes

    Science.gov (United States)

    Pistorino, Jonathan; Eitouni, Hany Basam

    2016-09-20

    New block polymer electrolytes have been developed which have higher conductivities than previously reported for other block copolymer electrolytes. The new materials are constructed of multiple blocks (>5) of relatively low domain size. The small domain size provides greater protection against formation of dendrites during cycling against lithium in an electrochemical cell, while the large total molecular weight insures poor long range alignment, which leads to higher conductivity. In addition to higher conductivity, these materials can be more easily synthesized because of reduced requirements on the purity level of the reagents.

  16. Small domain-size multiblock copolymer electrolytes

    Energy Technology Data Exchange (ETDEWEB)

    Pistorino, Jonathan; Eitouni, Hany Basam

    2016-09-20

    New block polymer electrolytes have been developed which have higher conductivities than previously reported for other block copolymer electrolytes. The new materials are constructed of multiple blocks (>5) of relatively low domain size. The small domain size provides greater protection against formation of dendrites during cycling against lithium in an electrochemical cell, while the large total molecular weight insures poor long range alignment, which leads to higher conductivity. In addition to higher conductivity, these materials can be more easily synthesized because of reduced requirements on the purity level of the reagents.

  17. 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

  18. 21 CFR 177.1360 - Ethylene-vinyl acetate-vinyl alcohol copolymers.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Ethylene-vinyl acetate-vinyl alcohol copolymers... acetate-vinyl alcohol copolymers. Ethylene-vinyl acetate-vinyl alcohol copolymers (CAS Reg. No. 26221-27-2... accordance with the following prescribed conditions: (a) Ethylene-vinyl acetate-vinyl alcohol copolymers...

  19. Novel docetaxel-loaded nanoparticles based on PCL-Tween 80 copolymer for cancer treatment

    Directory of Open Access Journals (Sweden)

    Mei L

    2011-11-01

    Full Text Available Yuandong Ma1,2*, Yi Zheng1,2*, Xiaowei Zeng1-3*, Liqin Jiang4, Hongbo Chen1,2, Ranyi Liu5, Laiqiang Huang1,2, Lin Mei1,21School of Life Sciences, Tsinghua University, Beijing, 2Division of Life and Health Sciences, Graduate School at Shenzhen, Tsinghua University, Shenzhen, Guangdong, 3Materials and Environment Experimental Center, Department of Materials Science and Engineering, Qinhuangdao Branch, Northeastern University, Qinhuangdao, 4Insitute of Biomedical Engineering, Peking Union Medical College, Chinese Academy of Medical Sciences, Tianjin, 5State Key Laboratory of Oncology in South China, Sun Yat-sen University Cancer Center, Guangzhou, People’s Republic of China *These authors contributed equally to this workBackground: The formulation of docetaxel available for clinical use (Taxotere® contains a high concentration of polysorbate 80 (Tween 80. After incorporation of Tween 80 into poly-ε-caprolactone (PCL-Tween 80 copolymer, the relative amount of Tween 80 should be decreased and the advantages of PCL and Tween 80 should be combined.Methods: A novel PCL-Tween 80 copolymer was synthesized from ε-caprolactone and Tween 80 in the presence of stannous octoate as a catalyst via ring opening polymerization. Two types of nanoparticle formulation were made from commercial PCL and a self-synthesized PCL-Tween 80 copolymer using a modified solvent extraction/evaporation method.Results: The nanoparticles were found by field emission scanning electron microscopy to have a spherical shape and be 200 nm in diameter. The copolymers could encapsulate 10% of the drug in the nanoparticles and release 34.9% of the encapsulated drug over 28 days. PCL-Tween 80 nanoparticles could be internalized into the cells and had higher cellular uptake than the PCL nanoparticles. The drug-loaded PCL-Tween 80 nanoparticles showed better in vitro cytotoxicity towards C6 cancer cells than commercial Taxotere at the same drug concentration.Conclusion: Nanoparticles

  20. Stable material modication with polymers incorporation for broad application in microfabrication

    DEFF Research Database (Denmark)

    Mednova, Olga

    The aim of this thesis is to improve SU-8 fracture resistance in order to eliminate micro crack formation during fabrication of microelectromechanical system (MEMS). An amphiphilic block copolymer incorporation, as an efficient method of material toughening without changing its original properties...... analytical techniques. The second part of the thesis describes modified SU-8 blends. Thermal stability, structural organization, components interaction, hardness and brittleness of the composites are described. Finally, lithographic properties of modified SU-8 blends have been tested. Commercial SU-8...

  1. Synthesizing A Phase Changing Bistable Electroactive Polymer And Silver Nanoparticles Coated Fabric As A Resistive Heating Element

    Science.gov (United States)

    Ren, Zhi

    Transducer technologies that convert energy from one form to another (e.g. electrical energy to mechanical energy or thermal energy and vise versa) are considered as the basic building blocks of robots and wearable electronics, two of the rapidly emerging technologies that impact our daily life. With an emphasis on developing the essential smart materials, this dissertation focuses on two specific transducer technologies, bistable large-strain electro-mechanical actuation and resistive Joule heating, in pursuit of refreshable Braille electronic displays and wearable thermal management element, respectively. Dielectric elastomers (DEs) have been intensively studied for their promising ability to mimic human muscles in providing efficient electro-mechanical actuation. They exhibit a unique combination of properties, including large strain, fast response, high energy density, mechanical compliancy, lightweight, and low cost. However, the softness of the DE materials, which is a prerequisite for electrically induced large actuation strain, has been hindering their application in adaptive structures. In these applications such as braille displays, a certain amount of mechanical support is necessary in addition to large strains for the device or system to function. Bistable electroactive polymers (BSEP) that leverage the electrically induced large-strain actuation of DE actuators and the bi-stable rigid-to-rigid deformation of shape memory polymers are innovated to provide large electrical actuation strain in their rubbery state and fix the deformation by cooling down to room temperature to incorporate mechanical rigidity. BSEP materials that can suppress electromechanical instability and exhibit stable mechanical properties in the rubbery state are desired. A bimodal BSEP material with a glass transition temperature right above room temperature has been synthesized employing simple UV curing process. The BSEP has a large storage modulus over 1GPa at room temperature

  2. Conjugated Polymer Chains Confined in Vertical Nanocylinders of a Block-Copolymer Film: Preparation, Characterization, and Optoelectronic Function

    KAUST Repository

    Dong, Ban Xuan

    2013-01-15

    Hybrid materials composed of phase-separated block copolymer films and conjugated polymers of the phenylenevinylene family (PPV) are prepared. The PPV chains are embedded in vertical cylinders of nanometer diameter in the block-copolymer films. The cylinders span continuously the whole film thickness of 70 nm. Incorporation of the PPV chains into the one-dimensional cylinders leads to modified photoluminescence spectra and to large absorption anisotropy. The hybrid films show electroluminescence from the PPV chains in a simple light-emitting device at minute doping concentrations, and also exhibit a factor of 19 increase in electron transport efficiency along the single PPV chains. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  3. Effect of Comonomer Ethylene on Plateau Modulus of Crystalline Ethylene-propylene Random Copolymer with Broad Molecular Weight Distribution

    Institute of Scientific and Technical Information of China (English)

    丁健; 徐日炜; 丁雪佳; 余鼎声

    2005-01-01

    Ethylene-propylene random copolymer with ultra-high molecular weight (UHPPR) and broad molecular weight distribution (MWD) was prepared with Ziegler-Natta catalyst. The viscoelastic behavior of UHPPR has been investigated by means of oscillatory rheometer at 180, 200 and 220℃. The loss modulus (G"""") curves of 180 and 200℃ present a pronounced maximum at 38.10 and 84.70r/s, respectively, For the first time, this makes it possible to directly determine the plateau modulus ( GN0 ) of crystalline ethylene-propylene random copolymer with broad MWD in a certain experimental temperature G""""(w) curve. The plateau modulus of UHPPR is 4.51×105 and 3.67×105 Paat 180 and 200℃ respectively, increasing with random incorporation of comonomer ethylene into the molecular chains and being independent of molecular weight.

  4. 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.

  5. Facilitated Transport of Ethylene in Poly (Amide 12-Block Tetramethylenoxide) Copolymer/AgBF4 Membranes Containing Silver (I) and Copper (I) Ions as Carriers

    Science.gov (United States)

    Ben Hamouda, Sofiane; Trong Nguyen, Quang; Langevin, Dominique; Roudesli, Sadok

    Metal-incorporated poly(amide 12-block-tetramethylenoxide) (PA12-co-PTMO) copolymer was used for studying facilitated transport of olefines through new composite membranes. The metals incorporated were silver {Ag(I)} and copper {Cu(I)}. Tests were carried out at room temperature (25±2°C) to determine the selectivity and permeability of these membranes to ethylene and ethane gas. The membranes prepared by mixing in solution the copolymer with silver (AgBF4) or copper (CuBF4) salt show a ethylene/ethane selectivity much higher than that of pure PA12-co-PTMO. The membranes were also characterized by Fourier Transform Infra Red (FTIR) spectroscopy and Scanning Electron Microscopy (SEM) in order to understand the structural feature responsible for the observed behaviour. The IRFT spectrum indicate that Ag+ and Cu+ ions are developing interactions with the copolymer. The permeation results obtained with copper containing membranes show that CuBF4 salt introduction in the copolymer tends to reduce ethane permeability. This phenomenon is explained by a diminution of the free volume caused by a decrease of the interchain distance due to the formation of metal ions-polymer matrix complexes. At the same time, for ethylene, the decrease in permeability observed at low salt content is recouped rapidly, when the salt content increases, by a dramatic increase of the permeability which attains 10 times that of the pure PA12-co-PTMO. This behaviour is attributed to the facilitated transport mechanism of the ethylene molecules able to develop specific interactions with the incorporated metal ions. It results from these two antagonistic phenomena a multiplication by 18 of the ethylene/ethane selectivity of the pure copolymer when the CuBF4 content of the composite attains 60%.

  6. 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.

  7. Chain exchange in triblock copolymer micelles

    Science.gov (United States)

    Lu, Jie; Lodge, Timothy; Bates, Frank

    2015-03-01

    Block polymer micelles offer a host of technological applications including drug delivery, viscosity modification, toughening of plastics, and colloidal stabilization. Molecular exchange between micelles directly influences the stability, structure and access to an equilibrium state in such systems and this property recently has been shown to be extraordinarily sensitive to the core block molecular weight in diblock copolymers. The dependence of micelle chain exchange dynamics on molecular architecture has not been reported. The present work conclusively addresses this issue using time-resolved small-angle neutron scattering (TR-SANS) applied to complimentary S-EP-S and EP-S-EP triblock copolymers dissolved in squalane, a selective solvent for the EP blocks, where S and EP refer to poly(styrene) and poly(ethylenepropylene), respectively. Following the overall SANS intensity as a function of time from judiciously deuterium labelled polymer and solvent mixtures directly probes the rate of molecular exchange. Remarkably, the two triblocks display exchange rates that differ by approximately ten orders of magnitude, even though the solvophobic S blocks are of comparable size. This discovery is considered in the context of a model that successfully explains S-EP diblock exchange dynamics.

  8. Preparation and Osteogenesis Activities of Electroactive Biodegradable Nanocomposites PAP/op-HA/PLGA%电活性可生物降解纳米复合材料PAP/op-HA/PLGA的制备及成骨活性

    Institute of Scientific and Technical Information of China (English)

    邬海涛; 于婷; 朱庆三; 焦自学; 危岩; 章培标; 陈学思

    2011-01-01

    以苯胺五聚体(AP)与聚乳酸(PLA)的三嵌段共聚物(PAP)与表面接枝低聚乳酸的纳米羟基磷灰石(op-HA)和聚丙交酯-乙交酯(PLGA)的复合物共混,制备了电活性可降解纳米复合材料PAP/op-HA/PLGA,采用紫外-可见光谱、循环伏安扫描和标准四探针法分析其电化学特性及电导率.采用ESEM观察其膜表面形貌,用接触角评价其亲水性.通过在材料膜表面接种兔成骨细胞进行体外培养,采用荧光染色、NIH ImageJ图像分析和Real-time PCR综合评价细胞在材料表面的黏附、扩展(细胞面积比)和成骨相关基因的表达水平,以此评价新犁电活性纳米复合骨修复材料PAP/op-HA/PLGA的表面性质和生物活性.结果表明,PAP/op-HA/PLGA的电导牢较低(5×10S/cm),但具有良好的电化学氧化还原性能,PAP质量分数为0.1%时,材料的亲水性明显改善,成骨细胞的黏附和扩展明显增强.培养7 d时骨形态蛋白-2(BMP-2)和骨连接蛋白(Osteonectin)的基因表达水平明显提高,而对Ⅰ型胶原蛋白的基因表达无明显影响.表明PAP/op-HA/PLGA具有良好的细胞相容性和成骨活性.%The electroactive biodegradable nanocomposites PAP/op-HA/PLGA were prepared by blending a triblock copolymer PLA-b-AP-b-PLA (PAP) of polylactide(PLA)and aniline pentamer(AP)with oligomeric lactic acid-surface grafted hydroxyapatite ( op-HA )/poly(lactide-co-glycolide)(PLGA).The electrochemical properties and conductivity were characterized using UV-Vis spectroscopy, cyclic voltammetry and standard four-probe method.The film's surface morphology was displayed by ESEM and the contact angle was measured to evaluate the film' s hydrophilicity.Rabbit's osteoblasts were cultured in vitro on the film surface.For comprehensively evaluating surface properties and biological activity of the new electroactive nanocomposites PAP/op-HA/PLGA for bone repair,cell adhesion and cell spreading(cell area fraction)were determined using fiuorescein

  9. Highly durable, biomimetic electro-active paper actuator based on cellulose polypyrrole-ionic liquid (CPIL) nanocomposite.

    Science.gov (United States)

    Mahadeva, Suresha K; Yun, Kiju; Kim, Jaehwan; Kim, Joo-Hyung

    2011-01-01

    Cellulose has received much attention as a emerging smart material, named as electro-active paper (EAPap), which can produce a large bending displacement with applied external electrical field. In spite of many advantages over other reported electro active polymers, there are some issues to be addressed: its actuator performance: (i) sensitive to environmental humidity, (ii) humidity dependent displacement output of the actuator and (iii) degradation of performance with time. In present paper, we have successfully developed the highly durable EAPap actuator working at ambient condition with large displacement output. To improve the performance and durability of EAPap, nanoscaled PPy layer into cellulose EAPap was formed by in-situ polymerization technique. Cellulose-PPy-IL nanocomposite based EAPap actuator showed nearly 100% improvement of the actuator performance compared that of pure cellulose based EAPap actuator systems.

  10. MOLECULAR DESIGN SYNTHESIS AND PROPERTIES OF SIX KINDS OF MULTIPHASE (STYRENE-ETHYLENE OXIDE) COPOLYMERS

    Institute of Scientific and Technical Information of China (English)

    XIE Hongquan; ZHOU Peiguang; SUN Wenbo; XIA Jun; LIU Jin; XIE Dong

    1991-01-01

    @@ Multiphase copolymers of styrene (S) and ethylene oxide (EO) are amphiphilic,because of the hydrophobic and amorphous polystyrene (PS) segments and the hydrophilic and crystalline polyoxyethylene (PEO). They have many uses including polymeric surfactants, electrostatic charge reducers, compatibilizer in polymer blending, phase transfer catalysts or solid polymer electrolytes. These copolymers include different types of block copolymers, graft copolymers and star-shaped block copolymers.

  11. Incorporating Feminist Standpoint Theory

    DEFF Research Database (Denmark)

    Ahlström, Kristoffer

    2005-01-01

    As has been noted by Alvin Goldman, there are some very interesting similarities between his Veritistic Social Epistemology (VSE) and Sandra Harding’s Feminist Standpoint Theory (FST). In the present paper, it is argued that these similarities are so significant as to motivate an incorporation...

  12. Differentiating leucine incorporation of

    NARCIS (Netherlands)

    Yokokawa, T.; Sintes, E.; de Corte, D.; Olbrich, K.; Herndl, G.J.

    2012-01-01

    The abundance (based on catalyzed reporter deposition-fluorescence in situ hybrid ization, CARD-FISH) and leucine incorporation rates of Archaea and Bacteria were determined throughout the water column in the eastern Atlantic. Bacteria dominated throughout the water column, although their contributi

  13. Self-assembled antimicrobial and biocompatible copolymer films on titanium.

    Science.gov (United States)

    Pfaffenroth, Cornelia; Winkel, Andreas; Dempwolf, Wibke; Gamble, Lara J; Castner, David G; Stiesch, Meike; Menzel, Henning

    2011-11-10

    Copolymers of 4-vinyl-N-hexylpyridinium bromide and dimethyl(2-methacryloyloxyethyl) phosphonate self-assemble to form ultrathin layers on titanium surfaces that show antimicrobial activity, and biocompatibility. The copolymer layers are characterized by contact angle measurements, ellipsometry and XPS. Antibacterial activity is assessed by investigation of adherence of S. mutans. Biocompatibility is rated based on human gingival fibroblast adhesion and proliferation. By balancing the opposing effects of the chemical composition on biocompatibility and antimicrobial activity, copolymer coatings are fabricated that are able to inhibit the growth of S. mutans on the surface but still show attachment of gingival fibroblasts, and therefore might prevent biofilm formation on implants.

  14. Synthesis and properties of polystyrene/polydimethylsiloxane graft copolymers

    Institute of Scientific and Technical Information of China (English)

    Wu Ningjing; Huang Likan; Zheng Anna

    2006-01-01

    Polystyrene-graft-polydimethylsiloxane (PS-g-PDMS) copolymers with different PDMS content were synthesized by the radical bulk copolymerization of PDMS macromonomer and styrene.The copolymers were characterized by Fourier transform infrared (FT-IR),1H-nuclear magnetic resonance (NMR),thermogravimetric analysis (TGA),dynamic mechanical analysis (DMA),transmission electron microscopy (TEM) and the mechanical properties of the copolymers were also carried out.It was indicated that the notched impact strength and elongation at break of the polymers increased with the increase of PDMS content.The thermal stability of PS-g-PDMS is better than that of PS.

  15. Phase Transition Induced by Small Molecules in Confined Copolymer Films

    Institute of Scientific and Technical Information of China (English)

    ZHOU Ling

    2007-01-01

    We investigate the phase transition induced by small molecules in confined copolymer films by using density functional theory.It is found that the addition of small molecules can effectively promote the phase separation of copolymers.In a symmetric diblock copolymer film,the affinity and concentration of small molecules play an important role in the structure transjtions.The disordered-lamellar transitions lamellar-lamellar transitions and the re-entrant transitions of the same structures are observed.Our results have potential applications in the fabrication of new functional materials.

  16. Verapamil hydrochloride release characteristics from new copolymer zwitterionic matrix tablets.

    Science.gov (United States)

    Kostova, Bistra; Kamenska, Elena; Ivanov, Ivo; Momekov, George; Rachev, Dimitar; Georgiev, George

    2008-01-01

    The aim of this study was to synthesize stable copolymer (vinyl acetate-co-3-dimethyl[methacryloyloxyethyl] ammonium propane sulfinate) zwitterionic latex with different compositions for the first time by emulsifier-free emulsion copolymerization. Throughout the course of the study, a proposal was made for the explanation of the relationship between the "overshooting" phenomenon (a swelling kinetics with a maximum) and the specific self-association of the zwitterionic copolymers. The zwitterionic monomer unit mole fraction, pH, and ionic strength effects on this relationship, on the swelling kinetics of the zwitterionic copolymers, and on the sustained verapamil hydrochloride release from the model tablets were established by the study's authors.

  17. STUDY ON SOLID STATE POLYCONDENSATION OF POLYETHYLENE TEREPHTHALATE COPOLYMERS

    Institute of Scientific and Technical Information of China (English)

    WU Rongrui; DENG Yuan; HUANG Guanbao; DENG Jianyuan; LI Huiping

    1994-01-01

    The kinetic data of solid state polycondensation of PET and its copolymers are determined.It is shown that the reaction rate of copolycondensation is higher than that of PET polycondensation, and increases with the comonomers content. But the reaction rate of copolycondensation in melt state of this kind of copolymers is lower than that of PET. It is considered that the chemical reactivity of comonomer is the main factor which affect the polycondensation in melt state,whereas the aggregative structure of the polymer is the main factor in solid state. The crystallinity and crystallite size of the copolymers have been measured by X-ray method.

  18. Directed self assembly of block copolymers using chemical patterns with sidewall guiding lines, backfilled with random copolymer brushes.

    Science.gov (United States)

    Pandav, Gunja; Durand, William J; Ellison, Christopher J; Willson, C Grant; Ganesan, Venkat

    2015-12-21

    Recently, alignment of block copolymer domains has been achieved using a topographically patterned substrate with a sidewall preferential to one of the blocks. This strategy has been suggested as an option to overcome the patterning resolution challenges facing chemoepitaxy strategies, which utilize chemical stripes with a width of about half the period of block copolymer to orient the equilibrium morphologies. In this work, single chain in mean field simulation methodology was used to study the self assembly of symmetric block copolymers on topographically patterned substrates with sidewall interactions. Random copolymer brushes grafted to the background region (space between patterns) were modeled explicitly. The effects of changes in pattern width, film thicknesses and strength of sidewall interaction on the resulting morphologies were examined and the conditions which led to perpendicular morphologies required for lithographic applications were identified. A number of density multiplication schemes were studied in order to gauge the efficiency with which the sidewall pattern can guide the self assembly of block copolymers. The results indicate that such a patterning technique can potentially utilize pattern widths of the order of one-two times the period of block copolymer and still be able to guide ordering of the block copolymer domains up to 8X density multiplication.

  19. Morphology and phase diagram of complex block copolymers: ABC linear triblock copolymers.

    Science.gov (United States)

    Tang, Ping; Qiu, Feng; Zhang, Hongdong; Yang, Yuliang

    2004-03-01

    Using a real space implementation of the self-consistent field theory for the polymeric system, we explore microphases of ABC linear triblock copolymers. For the sake of numerical tractability, the calculation is carried out in a two-dimensional (2D) space. Seven microphases are found to be stable for the ABC triblock copolymer in 2D, which include lamellae, hexagonal lattice, core-shell hexagonal lattice, tetragonal lattice, lamellae with beads inside, lamellae with beads at the interface, and hexagonal phase with beads at the interface. By systematically varying the composition, triangle phase diagrams are constructed for four classes of typical triblock polymers in terms of the relative strengths of the interaction energies between different species. In general, when both volume fractions and interaction energies of the three species are comparable, lamellar phases are found to be the most stable. While one of the volume fractions is large, core-shell hexagonal or tetragonal phases can be formed, depending on which of the blocks dominates. Furthermore, more complex morphologies, such as lamellae with beads inside, lamellae with beads at the interface, and hexagonal phases with beads at the interface compete for stability with lamellae structures, as the interaction energies between distinct blocks become asymmetric. Our study provides guidance for the design of microstructures in complex block copolymers.

  20. Influence Of Zwitterions on Properties and Morphology of Ionomers: Implications for Electro-Active Applications

    Science.gov (United States)

    2010-08-01

    acrylate and n-butyl acrylate ( nBA ) based sulfobetaine-containing polymers.13,14 They demonstrated that the incorporation of zwitterionic functionalities...propanesulfonate (SBMA). Through copolymerizing the two charge-containing monomers with nBA , a series of zwitterionomers and their corresponding...graciously provided by Raschig GmbH. n-Butyl acrylate ( nBA ), dimethyl sulfoxide (DMSO, 99.9+%) and hydroquinone (99%) were purchased from Alfa Aesar. 2

  1. Photophysical characterization of pyrromethene 597 laser dye in cross-linked silicon-containing organic copolymers

    Energy Technology Data Exchange (ETDEWEB)

    Tyagi, A.; Agua, D. del [Institut II - Experimentelle und Angewandte Physik, Universitaet Regensburg, Universitaetsstrasse 31, 93053 Regensburg (Germany); Penzkofer, A. [Institut II - Experimentelle und Angewandte Physik, Universitaet Regensburg, Universitaetsstrasse 31, 93053 Regensburg (Germany)], E-mail: alfons.penzkofer@physik.uni-regensburg.de; Garcia, O.; Sastre, R. [Instituto de Ciencia y Tecnologia de Polimeros, CSIC, Juan de la Cierva 3, 28006 Madrid (Spain); Costela, A.; Garcia-Moreno, I. [Instituto de Quimica Fisica ' Rocasolano' , CSIC, Serrano 119, 28006 Madrid (Spain)

    2007-12-06

    Samples of the dipyrromethene-BF{sub 2} dye PM597 incorporated in copolymers of 3-trimethoxysilylpropyl 2-methylprop-2-enoate (TMSPMA, number of polymerizable CC double bonds: {kappa} = 1) with 2-(2-methylprop-2-enoyloxy)ethyl 2-methylprop-2-enoate (EGDMA, {kappa} = 2), [2-(hydroxymethyl)-3-prop-2-(prop-2-enoyloxymethyl)propyl] prop-2-enoate (PETA, {kappa} = 3), and [3-prop-2-enoyloxy-2,2-bis(prop-2-2-enoyloxymethyl)propyl]prop-2-enoate (PETRA, {kappa} = 4) are characterized. The fluorescence quantum distributions, fluorescence quantum yields, degrees of fluorescence polarization, and fluorescence lifetimes are measured. The radiative lifetimes are calculated from fluorescence lifetime and quantum yield. Absorption coefficient spectra are determined from transmission measurements. Absolute absorption cross-section spectra and dye concentrations are obtained by calibration to the radiative lifetimes and to saturable absorptions. Excited-state absorption cross-sections at 527 nm are determined by saturable absorption measurements. The photo-degradation is studied under cw laser excitation conditions and quantum yields of photo-degradation are extracted. The excited-state absorption cross-sections were found to be rather small, and the photo-stability turned out to be high (up to 3 million excitation cycles before degradation) making this class of dipyrromethene dye-doped polymers attractive active laser media. Structural and thermo-mechanical properties of the materials have been determined by Fourier transform infrared spectroscopy, differential scanning calorimetry, thermogravimetry, densitometry, and refractometry. They improve with increasing inter-crossing (copolymerization of TMSPMA with PETA and PETRA). The laser properties of the PM597 doped copolymers were evaluated by transverse pumping with 6 ns laser pulses at 532 nm. The best laser materials resulted to be the 7:3 and 9:1 TMSPMA-monomer copolymers.

  2. Study of rheological properties in modified random propylene-ethylene copolymer

    Energy Technology Data Exchange (ETDEWEB)

    Santos, Sivelton G.; Otaguro, Harumi; Lima, Luis F.C.P.; Lugao, Ademar B. [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil). Centro de Quimica e Meio Ambiente], E-mail: sgsantos@ipen.br; Artel, Beatriz W.H. [Empresa Brasileira de Radiacao Ltda (EMBRARAD), Cotia, SP (Brazil)

    2007-07-01

    The random copolymer of propylene and ethylene (RP) presents exceptional transparency and brightness; possess low transference of odor and flavor showing better relation of rigidity/impact than homopolymer of polypropylene (PP). Due to the existence of units of ethylene this copolymer has distinct characteristics than PP of the same melt flow rate, improving its processability and allowing the use in processes such as: injection and blow molding and thermoforming of the plates. In the case of the thermoforming, the melt conventional polypropylene has the tendency to collapse during the process. It is well known, that the incorporation of a second monomer diminishes drastically the melting point of the sample up to 5 deg C changing its rheological characteristic and processing conditions. Therefore, the aim of the present work is to modify the random copolymer of propylene-ethylene with melt flow of 10 g/10 min and check its properties. In this process gamma irradiation technique was used to induce chemical changes in RP in the presence of Tri-allyl-cyanurate (TAC), with concentration ranging from 0 to 5.0 mmol/100 g of the pure resin. All samples had been characterized adequately with respect to rheological properties as: viscosity at low shear rate, storage and loss modulus, as well as, the evaluation of molecular mass distribution from zero shear viscosity value ({eta}0). The improvements in the rheological properties and processability had been evaluated in term of its performance during the thermoforming vacuum process. The modified samples showed a good performance during the thermoforming process. This behavior was observed exactly when the monomer concentration increase, except in the case of 5.0 mmol, where the sample tores during thermoforming, probably due to the high degree of ramification and branching in polymer chain. (author)

  3. Confined assembly of asymmetric block-copolymer nanofibers via multiaxial jet electrospinning.

    Science.gov (United States)

    Kalra, Vibha; Lee, Jung Hun; Park, Jay Hoon; Marquez, Manuel; Joo, Yong Lak

    2009-10-01

    Multiaxial (triaxial/coaxial) electrospinning is utilized to fabricate block copolymer (poly(styrene-b-isoprene), PS-b-PI) nanofibers covered with a silica shell. The thermally stable silica shell allows post-fabrication annealing of the fibers to obtain equilibrium self-assembly. For the case of coaxial nanofibers, block copolymers with different isoprene volume fractions are studied to understand the effect of physical confinement and interfacial interaction on self-assembled structures. Various confined assemblies such as co-existing cylinders and concentric lamellar rings are obtained with the styrene domain next to the silica shell. This confined assembly is then utilized as a template to guide the placement of functional nanoparticles such as magnetite selectively into the PI domain in self-assembled nanofibers. To further investigate the effect of interfacial interaction and frustration due to the physically confined environment, triaxial configuration is used where the middle layer of the self-assembling material is sandwiched between the innermost and outermost silica layers. The results reveal that confined block-copolymer assembly is significantly altered by the presence and interaction with both inner and outer silica layers. When nanoparticles are incorporated into PS-b-PI and placed as the middle layer, the PI phase with magnetite nanoparticles migrates next to the silica layers. The migration of the PI phase to the silica layers is also observed for the blend of PS and PS-b-PI as the middle layer. These materials not only provide a platform to further study the effect of confinement and wall interactions on self-assembly but can also help develop an approach to fabricate multilayered, multistructured nanofibers for high-end applications such as drug delivery.

  4. Small angle neutron scattering study on the aggregation behaviour of PEO–PPO–PEO copolymers in the presence of a hydrophobic diol

    Indian Academy of Sciences (India)

    B Bharatiya; V K Aswal; P Bahadur

    2008-11-01

    Small angle neutron scattering (SANS) measurements on aqueous solutions of four polyethylene oxide–polypropylene oxide–polyethylene oxide block copolymers (commercially known as Pluronic®)F88, P85, F127 and P123 in the presence of hydrophobic C14Diol (also known as Surfynol® 104) reveal information on micellization, micellar size and micellar transitions. While most hydrophilic F88 (with least PPO/PEO ratio) remained unimers in water at 30◦ C, other copolymers formed micellar solutions. Surfynol® 104 is sparingly soluble in water to only about ∼ 0.1 wt%, but on addition to pluronic solution, it gets incorporated in the micellar region of block copolymer which leads to increase in aggregation number and transformation of spherical to ellipsoidal micelles. The added diol-induced micellization in F88, though hydrophilic copolymers F88 and F127 did not show any appreciable micellar growth or shape changes as observed for P85 and P123 (which are comparatively more hydrophobic). The SANS results on copolymer pairs with same molecular weight PPO but different % PEO (viz. F88 and P85, F127 and P123) and with same molecular weight PEO but different PPO (F88 and F127) reveal that the copolymer with large PPO/PEO ratio facilitate micellar transition in the presence of diol. An increase in temperature and presence of added electrolyte (sodium chloride) in the solution further enhances these effects. The micellar parameters for these systems were found out using available software and are reported.

  5. Amphiphilic copolymers for fouling-release coatings

    DEFF Research Database (Denmark)

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

    Polydimethylsiloxane (PDMS) resins are extensively used as binder in fouling-release coatings due to the low critical surface energy and low elastic modulus of PDMS. These properties result in poor adhesion of the fouling organisms, which are therefore detached by hydrodynamic forces during...... navigation [1,2,3]. Other compounds are usually mixed together with the binder (e.g. silica and pigments) in order to improve the mechanical, thixotropic and visual properties of the coatings. It has ben shown, however, that these ingredients have a negative effect on the fouling-release properties...... of the coatings [1,2,4]. Together with the PDMS-system, non-reactive polymers have been used to improve the fouling-release properties of the coatings. Initially, hydrophobic siloxane-based polymers were used, which aimed to increase the hydrophobicity of the PDMS surface [5,6]. However, copolymers comprising...

  6. Concentration Dependent Structure of Block Copolymer Solutions

    Science.gov (United States)

    Choi, Soohyung; Bates, Frank S.; Lodge, Timothy P.

    2015-03-01

    Addition of solvent molecules into block copolymer can induce additional interactions between the solvent and both blocks, and therefore expands the range of accessible self-assembled morphologies. In particular, the distribution of solvent molecules plays a key role in determining the microstructure and its characteristic domain spacing. In this study, concentration dependent structures formed by poly(styrene-b-ethylene-alt-propylene) (PS-PEP) solution in squalane are investigated using small-angle X-ray scattering. This reveals that squalane is essentially completely segregated into the PEP domains. In addition, the conformation of the PS block changes from stretched to nearly fully relaxed (i.e., Gaussian conformation) as amounts of squalane increases. NRF

  7. Block copolymer templated etching on silicon.

    Science.gov (United States)

    Qiao, Yinghong; Wang, Dong; Buriak, Jillian M

    2007-02-01

    The use of self-assembled polymer structures to direct the formation of mesoscopic (1-100 nm) features on silicon could provide a fabrication-compatible means to produce nanoscale patterns, supplementing conventional lithographic techniques. Here we demonstrate nanoscale etching of silicon, applying standard aqueous-based fluoride etchants, to produce three-dimensional nanoscale features with controllable shapes, sizes, average spacing, and chemical functionalization. The block copolymers serve to direct the silicon surface chemistry by controlling the spatial location of the reaction as well as concentration of reagents. The interiors of the resulting etched nanoscale features may be selectively functionalized with organic monolayers, metal nanoparticles, and other materials, leading to a range of ordered arrays on silicon.

  8. 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.

  9. Preparation and modification of itaconic anhydride–methyl methacrylate copolymers

    Directory of Open Access Journals (Sweden)

    MILOS B. MILOVANOVIC

    2007-12-01

    Full Text Available The free radical copolymerisation of itaconic anhydride and methyl methacrylate in solution was studied at 60 °C. The copolymer composition was determined by 1H-NMR spectroscopy and the obtained monomer reactivity ratios were calculated, rITA = 1.35±0.11; rMMA = 0.22±0.22 (by the Fineman–Ross method and rITA = 1.27±0.38; rMMA = 0.10±0.05 (by the Mayo–Lewis method. The synthesised copolymers were modified by reaction with di-n-butyl amine. The copolymer composition after amidation was determined by elemental analysis via the nitrogen content. Amidation of the anhydride units in the copolymers with di-n-butyl amine resulted in complete conversion to itaconamic acid.

  10. Synthesis of CO2 Copolymer Based Polyurethane Foams

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    CO2-copolymer based polyurethane foams were synthesized and characterized in this paper. The foams were found to have higher strength and lower heat of combustion than the conventional polyether polyurethane foams. They may find wide applications in many fields.

  11. Composition fluctuations in homopolymer blends and diblock copolymers

    DEFF Research Database (Denmark)

    Frielinghaus, H.; Mortensen, K.; Almdal, K.

    2000-01-01

    The thermal composition fluctuations of a deuterogenous polystyrene/polyethyleneoxide (dPS/PEO) homopolymer blend and corresponding diblock copolymer have been investigated by small angle neutron scattering (SANS). The measured susceptibilities could be described by theories, which take strong...

  12. Controlled Synthesis of Fluorinated Copolymers with Pendant Sulfonates

    DEFF Research Database (Denmark)

    Dimitrov, Ivaylo; Jankova Atanasova, Katja; Hvilsted, Søren

    2008-01-01

    Novel fluorinated copolymers of different architectures and bearing sulfopropyl groups were synthesized by atom transfer radical polymerization (ATRP) of aromatic fluorinated monomers and two modification reactions performed on the polymer chain - demethylation followed by sulfopropylation. As a ...

  13. HPMA and HEMA copolymer bead interactions with eukaryotic cells

    Directory of Open Access Journals (Sweden)

    Cristina D. Vianna-Soares

    2004-09-01

    Full Text Available Two different hydrophilic acrylate beads were prepared via aqueous suspension polymerization. Beads produced of a hydroxypropyl methacrylate (HPMA and ethyleneglycol methacrylate (EDMA copolymer were obtained using a polyvinyl alcohol suspending medium. Copolymers of 2hydroxyethyl methacrylate (HEMA, methyl methacrylate (MMA and ethyleneglycol methacrylate (EDMA beads were obtained using magnesium hydroxide as the suspending agent. Following characterization by scanning electron microscopy (SEM, nitrogen sorption analysis (NSA and mercury intrusion porosimetry (MIP, the beads were cultured with monkey fibroblasts (COS7 to evaluate their ability to support cell growth, attachment and adhesion. Cell growth behavior onto small HPMA/EDMA copolymer beads and large HEMA/MMA/EDMA copolymer beads is evaluated regarding their hidrophilicity/hidrophobicity and surface roughness.

  14. Synthesis of Polyacrylate/Polysiloxane Copolymer and Its Damping Performance

    Institute of Scientific and Technical Information of China (English)

    夏宇正; 石淑先; 焦书科; 李素青

    2003-01-01

    The copolymer of polyacrylate/polysiloxane for vibration damping materials was synthesized through emulsion polymerization. The effects of the amount of methyl methacrylate (MMA),polysiloxane containing vinyl, initiator and emulsifier on the conversion, stability of polyacrylate/polysiloxane emulsion were discussed when the emulsion was prepared by pre-emulsifying half continuous method. The graft copolymer has good vibration damping performance. The widest glass transition region of the copolymer spans 100℃, and the highest value of tanδ reached 2.0. The glass transition of the samples was examined by dynamic mechanical analysis (DMA). The vibration damping performance of the graft copolymer was affected by the amount of poly-vinyl dimethylsiloxane (PVMS).

  15. Thermal analytical study of polyamide copolymer/Surlyn Ionomers Blends

    Energy Technology Data Exchange (ETDEWEB)

    Qin, C.; Ding, Y.P. [Baxter Healthcare Corp., Round Lake, IL (United States)

    1993-12-31

    Thermal analytical technique was used as a screening method to study polyamide(Nylon)/ethylene-co-methacrylic acid copolymer-based ionomer(Surlyn)blends. The retardation of crystallization process from molten state of Nylon-12 by the existence of the ionomer was observed, but the crystallization of Nylon-12 can not be thwarted even at high concentration of ionomers. Zinc ionomers shows stronger effect than sodium ionomers. A Nylon copolymer, polyamide-6,6-co-polyamide-6,10, was used to blend with different ionomers and the crystallization process from molten state of Nylon copolymer could be thwarted at high concentration of zinc ionomer even at very cooling rate. Interesting cold crystallization behavior of polyamide copolymer was observed during second DSC heating cycle in the temperature range of the melting process of ionomer.

  16. BARRIER PROPERTY AND STRUCTURE OF ACRYLONITRILE/ACRYLIC COPOLYMERS

    Institute of Scientific and Technical Information of China (English)

    YANG Zhenghua; LI Yuesheng

    1997-01-01

    A series of acrylonitrile (AN) copolymers with methyl acrylate (MA) or ethyl acrylate (EA) as comonomer (5-23 wt%) was prepared by free-radical copolymerization. The permeability coefficients of the copolymers to oxygen and carbon dioxide were measured at 1.0 MPa and at 30 ℃, and those to water vapor also measured at 100% relative humidity and at 30 ℃. All the AN/acrylic copolymers are semicrystalline. As the acrylate content increase, the permeability coefficients of the copolymers to oxygen and carbon dioxide are increased progressively, but those to water vapor are decreased progressively. The gas permeability coefficients of the polymers were correlated with free-volume fractions or the ratio of free volume to cohesive energy.

  17. Nanopatterned articles produced using reconstructed block copolymer films

    Energy Technology Data Exchange (ETDEWEB)

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

    2017-05-02

    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.

  18. Opto-electronic devices from block copolymers and their oligomers.

    NARCIS (Netherlands)

    Hadziioannou, G

    1997-01-01

    This paper presents research activities towards the development of polymer materials and devices for optoelectronics, An approach to controlling the conjugation length and transferring the luminescence properties of organic molecules to polymers through black copolymers containing well-defined conju

  19. Thermal Stability of Poly (acrylonitrile-methyl acrylate) Copolymers

    Institute of Scientific and Technical Information of China (English)

    HAN Na; ZHANG Xing-xiang; WANG Xue-chen

    2008-01-01

    Poly (acrylonitrile-methyl acrylate) copolymer was synthesized by water depositing polymerization and has a typical feed ratio of 85/15. And then 1 - 3 wt% lauryl alcohol maleic anhydride (LAM) was adopted as stabilizer to mix with the acrylonitrile based copolymer. The mixtures were characterized by using Fourier Transform Infrared Spectroscopy (FTIR), Nuclear Magnetic Resonance (1H NMR ), Gel Permeation Chromatography ( GPC ), Differential Scanning Calorimetry (DSC), optic microscope and Ubbelohde viscosimetryr etc. The melting point (Tm) and glass transition temperature (Tg) of the 85/15 AN/MA copolymer mixed with LAM all decrease with the increase of stabilizer content. The lowest Tg and Tm were 116.1 ℃ and 209. 1℃ respectively at the heating rate of 100℃/min when the content of LAM is 2 wt%. The 85°/15 AN/MA copolymer mixed with 1 - 3 w t% LAM possess good thermal stability up to 30 min at 220 ℃.

  20. Fluctuations, conformational asymmetry and block copolymer phase behaviour

    DEFF Research Database (Denmark)

    Bates, F.S.; Schulz, M.F.; Khandpur, A.K.;

    1994-01-01

    Phase behaviour near the order-disorder transition (ODT) of 58 model hydrocarbon diblock copolymers, representing four different systems, is summarized. Six distinct ordered-state microstructures are reported, including hexagonally modulated lamellae (HML), hexagonally perforated layers (HPL) and...

  1. A complicated biocomputing system based on multi-responsive P(NIPAM-co-APBA) copolymer film electrodes and electrocatalysis of NADH.

    Science.gov (United States)

    Liang, Jiying; Yu, Xue; Yang, Tiangang; Li, Menglu; Shen, Li; Jin, Yue; Liu, Hongyun

    2017-08-23

    In this paper, poly(N-isopropylacrylamide-co-3-aminophenylboronic acid) (P(NIPAM-co-APBA)) copolymer films were successfully electropolymerized on the Au electrode surface. The electroactive probe ferrocene carboxylic acid (FCA) in solution showed reversible thermal-, glucose- and pH-responsive on-off cyclic voltammetric (CV) behaviors at the film electrodes. The comparative experiments demonstrated that the thermo-responsive property of the film electrode was ascribed to the PNIPAM component of the films, whereas the glucose- and pH-sensitive behaviors came from the PAPBA constituent. The reduced form of nicotinamide adenine dinucleotide (NADH) could be electrocatalytically oxidized by FCA at the film electrodes, which would greatly amplify the multi-responsive CV signal difference between the on and off states. On the basis of these results, a binary 4-input/4-output logic circuit was fabricated with temperature, glucose, pH and NADH as inputs and the CV responses at 4 different levels as outputs. Moreover, a ternary CONSENSUS logic circuit was established on the same platform, which was the first report on the combination of ternary logic gate and bioelectrocatalysis without using enzymes. This work provided a novel idea for constructing complicated biocomputing systems by increasing the number of inputs/outputs with multi-sensitive interfaces and by designing new types of multi-valued logic gates on the basis of bioelectrocatalysis.

  2. Supramolecular Multiblock Copolymers Featuring Complex Secondary Structures.

    Science.gov (United States)

    Elacqua, Elizabeth; Manning, Kylie B; Lye, Diane S; Pomarico, Scott K; Morgia, Federica; Weck, Marcus

    2017-09-06

    This contribution introduces main-chain supramolecular ABC and ABB'A block copolymers sustained by orthogonal metal coordination and hydrogen bonding between telechelic polymers that feature distinct secondary structure motifs. Controlled polymerization techniques in combination with supramolecular assembly are used to engineer heterotelechelic π-sheets that undergo high-fidelity association with both helical and coil-forming synthetic polymers. Our design features multiple advances to achieve our targeted structures, in particular, those emulating sheet-like structural aspects using poly(p-phenylenevinylene)s (PPVs). To engineer heterotelechelic PPVs in a sheet-like design, we engineer an iterative one-pot cross metathesis-ring-opening metathesis polymerization (CM-ROMP) strategy that affords functionalized Grubbs-II initiators that subsequently polymerize a paracyclophanediene. Supramolecular assembly of two heterotelechelic PPVs is used to realize a parallel π-sheet, wherein further orthogonal assembly with helical motifs is possible. We also construct an antiparallel π-sheet, wherein terminal PPV blocks are adjacent to a flexible coil-like poly(norbornene) (PNB). The PNB is designed, through supramolecular chain collapse, to expose benzene and perfluorobenzene motifs that promote a hairpin turn via charge-transfer-aided folding. We demonstrate that targeted helix-(π-sheet)-helix and helix-(π-sheet)-coil assemblies occur without compromising intrinsic helicity, while both parallel and antiparallel β-sheet-like structures are realized. Our main-chain orthogonal assembly approach allows the engineering of multiblock copolymer scaffolds featuring diverse secondary structures via the directional assembly of telechelic building blocks. The targeted assemblies, a mix of sequence-defined helix-sheet-coil and helix-sheet-helix architectures, are Nature-inspired synthetic mimics that expose α/β and α+β protein classes via de novo design and cooperative assembly

  3. Multicompartmental Microcapsules from Star Copolymer Micelles

    Energy Technology Data Exchange (ETDEWEB)

    Choi, Ikjun; Malak, Sidney T.; Xu, Weinan; Heller, William T.; Tsitsilianis, Constantinos; Tsukruk, Vladimir V.

    2013-02-26

    We present the layer-by-layer (LbL) assembly of amphiphilic heteroarm pH-sensitive star-shaped polystyrene-poly(2-pyridine) (PSnP2VPn) block copolymers to fabricate porous and multicompartmental microcapsules. Pyridine-containing star molecules forming a hydrophobic core/hydrophilic corona unimolecular micelle in acidic solution (pH 3) were alternately deposited with oppositely charged linear sulfonated polystyrene (PSS), yielding microcapsules with LbL shells containing hydrophobic micelles. The surface morphology and internal nanopore structure of the hollow microcapsules were comparatively investigated for shells formed from star polymers with a different numbers of arms (9 versus 22) and varied shell thickness (5, 8, and 11 bilayers). The successful integration of star unimers into the LbL shells was demonstrated by probing their buildup, surface segregation behavior, and porosity. The larger arm star copolymer (22 arms) with stretched conformation showed a higher increment in shell thickness due to the effective ionic complexation whereas a compact, uniform grainy morphology was observed regardless of the number of deposition cycles and arm numbers. Small-angle neutron scattering (SANS) revealed that microcapsules with hydrophobic domains showed different fractal properties depending upon the number of bilayers with a surface fractal morphology observed for the thinnest shells and a mass fractal morphology for the completed shells formed with the larger number of bilayers. Moreover, SANS provides support for the presence of relatively large pores (about 25 nm across) for the thinnest shells as suggested from permeability experiments. The formation of robust microcapsules with nanoporous shells composed of a hydrophilic polyelectrolyte with a densely packed hydrophobic core based on star amphiphiles represents an intriguing and novel case of compartmentalized microcapsules with an ability to simultaneously store different hydrophilic, charged, and hydrophobic

  4. Self-Assembled Antimicrobial and biocompatible copolymer films on Titanium

    OpenAIRE

    2011-01-01

    Biofilm formation on biomedical devices such as dental implants can result in serious infections and finally in device failure. Polymer coatings which provide antimicrobial action to surfaces without compromising the compatibility with human tissue are of great interest. Copolymers of 4-vinyl-N-hexylpyridinium bromide and dimethyl(2-methacryloyloxyethyl) phosphonate are interesting candidates in this respect. These copolymers form ultrathin polycationic layers on titanium surfaces. As the cop...

  5. SYNTHESIS OF A NEW SILICONE-CONTAINING BISMALEIMIDE COPOLYMER RESIN

    Institute of Scientific and Technical Information of China (English)

    KUANG Wenfeng; CAI Xingxian; JIANG Luxia

    1997-01-01

    A copolymer of bismaleimide-diallylbisphenol A-diphenylsilandiol was synthesized and the copolymerization was studied by using N-phenylmaleimide, bisphenol A and diphenylsilandiol as model compounds. The copolymer could be well cured around 200 ℃, and the cured resins had good thermal stability. In the range of 170-210 ℃, a higher curing temperature was favorable to obtain more thermal stable resin by reducing the content of diphenylsilandiol cyclo-homopolymer in resin which would spoil its thermal stability.

  6. Thin Film Assembly of Spider Silk-like Block Copolymers

    Science.gov (United States)

    2011-01-01

    Film Assembly of Spider Silk -like Block Copolymers Sreevidhya T. Krishnaji,†,‡ Wenwen Huang,§ Olena Rabotyagova,†,‡ Eugenia Kharlampieva, ) Ikjun Choi...Received November 26, 2010 We report the self-assembly of monolayers of spider silk -like block copolymers. Langmuir isotherms were obtained for a series of...bioengineered variants of the spider silks , and stable monolayers were generated. Langmuir-Blodgett films were prepared by transferring the monolayers

  7. Synthesis and characterization of HPMA copolymer-5-FU conjugates

    Institute of Scientific and Technical Information of China (English)

    Fang Yuan; Fu Chen; Qing Yu Xiang; Xuan Qin; Zhi Rong Zhang; Yuan Huang

    2008-01-01

    N-(2-Hydroxypropyl)methacrylamide copolymer-5-fluorouracil (PHPMA-FU)conjugates were synthesized by a novel and simplified synthetic mute,and characterized by UV,FTIR and HPLC analyses.The conjugated content of 5-fluorouracil (5-FU)was 3.41 ± 0.07 wt%.The stabilities of PHPMA-FU conjugates under different conditions were studied.The results showed that HPMA copolymer was a potential carrier for tumor-targeting delivery of 5-FU.

  8. Single-layer electroluminescent devices based on fluorene-1H-pyrazolo[3,4-b]quinoxaline co-polymers

    Science.gov (United States)

    Pokladko-Kowar, Monika; Danel, Andrzej; Chacaga, Łukasz

    2013-11-01

    A fluorene based copolymer was synthesized for electroluminescent application. To the main chain of polymer the nitrogen heterocyclic, 1H-pyrazolo[3,4-b]quinoxaline, unit was introduced. The incorporation of this derivative tuned the emission from the blue to yellow-green one. A simple, single layered device was fabricated with the configuration ITO/PEDOT/co-poly-FLU-PQX/Ca/Mg.

  9. DNA Island Formation on Binary Block Copolymer Vesicles.

    Science.gov (United States)

    Luo, Qingjie; Shi, Zheng; Zhang, Yitao; Chen, Xi-Jun; Han, Seo-Yeon; Baumgart, Tobias; Chenoweth, David M; Park, So-Jung

    2016-08-17

    Here, we report DNA-induced polymer segregation and DNA island formation in binary block copolymer assemblies. A DNA diblock copolymer of polymethyl acrylate-block-DNA (PMA-b-DNA) and a triblock copolymer of poly(butadiene)-block-poly(ethylene oxide)-block-DNA (PBD-b-PEO-b-DNA) were synthesized, and each was coassembled with a prototypical amphiphilic polymer of poly(butadiene)-block-poly(ethylene oxide) (PBD-b-PEO). The binary self-assembly of PMA-b-DNA and PBD-b-PEO resulted in giant polymersomes with DNA uniformly distributed in the hydrophilic PEO shell. When giant polymersomes were connected through specific DNA interactions, DNA block copolymers migrated to the junction area, forming DNA islands within polymersomes. These results indicate that DNA hybridization can induce effective lateral polymer segregation in mixed polymer assemblies. The polymer segregation and local DNA enrichment have important implications in DNA melting properties, as mixed block copolymer assemblies with low DNA block copolymer contents can still exhibit useful DNA melting properties that are characteristic of DNA nanostructures with high DNA density.

  10. MALDI-ToF Analysis of Model Copolymer Blends

    Science.gov (United States)

    Pan, David; Arnould, Mark

    2008-03-01

    MALDI-ToF mass spectrometry was used to determine the composition of a low MW styrene (S) / n-butyl acrylate (nBA) copolymer. Bernoullian chain statistics were used to predict the copolymer distribution and confirm that MALDI-ToF detects the correct composition. The copolymer was blended with a low MW polystyrene homopolymer having the same end group as the copolymer at several levels to determine if MALDI-ToF could be used to calculate the amount of homopolymer by subtracting homopolymer peak areas. It is found that, while MALDI-ToF can be used to monitor the amount of homopolymer blended into the copolymer, the observed increase is always greater than the actual amount added, e.g. up to 13% error. This could be due to the fact that the homopolymer ionizes more efficiently than the low MW copolymer. A model to improve the accuracy of the calculated amount of homopolymer in the blend is discussed.

  11. Influence of copolymer composition on the transport properties of conducting copolymers: poly(aniline-co-o-anisidine)

    Indian Academy of Sciences (India)

    S S Umare; A D Borkar; M C Gupta

    2002-06-01

    The effect of different compositions of monomers on the transport properties of copolymers by various techniques such as optical, electrical and magnetic has been investigated and compared with the homopolymers. The UV-visible absorption spectra show a hypsochromic shift with an increase in the o-anisidine content in copolymers indicating a decrease in the extent for conjugation (i.e. an increase in the bandgap). From temperature dependence of electrical conductivity the transport parameters such as charge localization length and average hopping distance are calculated and also the effect of the monomeric composition on the coherence length has been discussed. The magnetic studies show the paramagnetic and diamagnetic nature of homopolymers and copolymers. The X-ray diffraction pattern indicates that the copolymers are of amorphous nature.

  12. Directed self-assembly of high-chi block copolymer for nano fabrication of bit patterned media via solvent annealing

    Science.gov (United States)

    Xiong, Shisheng; Chapuis, Yves-Andre; Wan, Lei; Gao, He; Li, Xiao; Ruiz, Ricardo; Nealey, Paul F.

    2016-10-01

    We report the formation of nanoimprint master templates that can be used for the fabrication of bit patterned media (BPM). The template was formed by directed self-assembly, with solvent annealing, of a symmetric ABA triblock copolymer to form perpendicularly oriented lamellae on chemical patterns. We used a high-χ block copolymer, poly(2-vinyl pyridine)-block-polystyrene-block-poly(2-vinyl pyridine) to achieve smaller feature sizes than are possible with polystyrene-block-poly(methyl methacrylate). The work shows that triblock copolymers can provide a large processing window in terms of pitch commensurability. Using block-selective infiltration (atomic layer deposition with sequential long soaking/purge cycles), an alumina composite with high etch resistance was specifically incorporated into the polar and hydrophilic P2VP domains. Subsequently, the surface pattern was successfully transferred into underlying Si substrates by etching with a fluorine-containing plasma to create a nanoimprint master. The line/space pattern of the nanoimprint master met the BPM fabrication requirement of defectivity <10-3. For demonstration purposes, the nanoimprint master was used to imprint a replica pattern of photoresist on a quartz wafer.

  13. Approaching two-dimensional copolymers: photoirradiation of anthracene- and diaza-anthracene-bearing monomers in Langmuir monolayers.

    Science.gov (United States)

    Payamyar, Payam; Servalli, Marco; Hungerland, Tim; Schütz, Andri P; Zheng, Zhikun; Borgschulte, Andreas; Schlüter, A Dieter

    2015-01-01

    By using structurally similar amphiphilic monomers, it is shown that compressed monolayers of varying amounts of such monomers at the air/water interface can be converted by photo-irradiation into the corresponding covalently connected monolayer sheets. Since one of the monomers carries three anthracene units and the other three 1,8-diaza-anthracene units, the growth reaction is proposed to take place through photochemically achieved [4+4]-cycloaddition between pairs of these units that are co-facially (face-to-face) arranged, to furnish the corresponding covalent dimers. While evidence for both homodimers is amply available, the existence of the heterodimer needs to be established with the help of a model reaction to support the conceptual aspect of this work, copolymerization in two dimensions. The sheet copolymers exhibit substantial robustness in that they can be spanned over 20 × 20 μm(2)-sized holes without rupturing under their own weight. X-ray photoelectron spectroscopy (XPS) studies reveal that the monomers are incorporated into the sheet copolymers according to feed. These results establish existence of the first covalent sheet copolymer, which is considered a step ahead towards novel 2D materials.

  14. LOW DENSITY POLYETHYLENE/CLAY NANOCOMPOSITES MODIFIED BY ETHYLENE COPOLYMERS: EFFECTS OF FUNCTIONALIZED SEGMENTS ON MORPHOLOGY

    Institute of Scientific and Technical Information of China (English)

    Bo Xu; Yi-hu Song; Yong-gang ShangGuan; Qiang Zheng

    2006-01-01

    Melt extrusion was used to prepare binary nanocomposites of ethylene copolymers and organoclay and trinary nanocomposites of low-density polyethylene (LDPE), ethylene copolymer and organoclay. X-ray diffraction (XRD) and transmission electron microscopy (TEM) were used to analyze the structure of the clay phase and the morphology of the nanocomposites. Influences of the comonomer in the copolymer and the content of the copolymer on the morphology of the resulting nanocomposites were discussed. The binary and the trinary composites may form intercalated or exfoliated structures depending on the interaction between the copolymer and the clay layers and the content of the copolymer.

  15. Weathering and Biodegradation Study on Graft Copolymer Compatibilized Hybrid Bionanocomposites of Poly(Lactic Acid)

    Science.gov (United States)

    Sajna, VP; Nayak, Sanjay K.; Mohanty, Smita

    2016-07-01

    This work reports on the influence of moisture absorption and accelerated weathering on the properties of graft copolymer compatibilized bionanocomposites of poly(lactic acid) (PLA). Moisture absorption tests were conducted for 30 days by immersing the samples in a distilled water bath at room temperature, and the amount of moisture absorbed in each time interval was measured. The rate of moisture uptake decreased by incorporation of C30B nanoclay and graft copolymer into fiber-reinforced PLA composites. Changes in the mechanical properties of composites in each time interval of moisture absorption were investigated using tensile and impact tests. Exposure to moisture caused significant drops in the mechanical properties. The morphological characterization of biocomposites during the aforementioned tests has been made using SEM, while bionanocomposites were analyzed by TEM. Further, this paper also reported the effect of accelerated weathering on the mechanical properties and the results are confirmed through SEM analysis. Biodegradation behaviors of PLA biocomposites and bionanocomposites have also been studied.

  16. Oligomeric Dithienopyrrole-Thienopyrrolodione (DTP-TPD) Donor-Acceptor Copolymer for Organic Photovoltaics: Preprint

    Energy Technology Data Exchange (ETDEWEB)

    Hammond, S. R.; Braunecker, W.; Garcia, A.; Larsen, R.; Owczarczyk, Z.; Olson, D.; Ginley, D.

    2011-07-01

    A new donor-acceptor copolymer system based upon a dithienopyrrole (DTP) donor moiety and a thienopyrrolodione (TPD) accepting moiety has been designed and synthesized for organic photovoltaic (OPV) applications. The TPD accepting moiety has recently gained significant attention in the OPV community and is being incorporated into a number of different polymer systems. In contrast, the DTP donor moiety has received only limited attention, likely due in part to synthetic difficulties relating to the monomer. In our hands, the bis(trimethyltin)-DTP monomer was indelibly contaminated with ~5% of the mono-destannylated DTP, which limited the Stille polymerization with the dibromo-TPD monomer (>99% pure) to produce material with Mn ~ 4130 g/mol (PDI = 1.10), corresponding to around eight repeat units. Despite this limitation, UV-visible absorption spectroscopy demonstrates strong absorption for this material with a band gap of ~1.6 eV. Cyclic voltammetry indicates a highest occupied molecular orbital (HOMO) energy level of -5.3 eV, which is much lower than calculations predicted. Initial bulk heterojunction OPV devices fabricated with the fullerene acceptor phenyl C61 butyric acid methyl ester (PCBM) exhibit Voc ~ 700 mV, which supports the deep HOMO value obtained from CV. These results suggest the promise of this copolymer system.

  17. Tartaric Acid-Assisted Self-Assembly of Hybrid Block Copolymer Composites

    Science.gov (United States)

    Yao, Li; Lin, Ying; Watkins, James

    2014-03-01

    Enantiopure tartaric acid was used as an additive to increase the segregation strength of poly(ethylene oxide-block-tert-butyl acrylate) (PEO-b-PtBA) copolymers through strong, selective interactions with one of the polymer chain segments. Addition of tartaric acid to PEO-b-PtBA exhibiting cylindrical morphologies resulted in the formation of helical superstructures as observed by transmission electron microscopy. It was also found that this small acid additive can also enable phase-selective ultra-high loading of nanoparticles (NPs) into target domains of the block copolymer composites. The loading of tartaric acid can increase enthalpically favorable interactions between the nanoparticle ligands and the host domain and mitigate entropic penalties associated with NP incorporation into the target domain. A metal content of over 40 weight percent by mass of the resulting well ordered composites was achieved as measured by thermal gravimetric analysis in PEO-b-PtBA/tartaric acid/4-hydroxythiophenol functionalized Au NP hybrid system. Funding from Center for Hierarchical Manufacturing (CHM); Facility support from Materials Research Science and Engineering Center at UMass Amherst.

  18. Novel Injectable Pentablock Copolymer Based Thermoresponsive Hydrogels for Sustained Release Vaccines.

    Science.gov (United States)

    Bobbala, Sharan; Tamboli, Viral; McDowell, Arlene; Mitra, Ashim K; Hook, Sarah

    2016-01-01

    The need for multiple vaccinations to enhance the immunogenicity of subunit vaccines may be reduced by delivering the vaccine over an extended period of time. Here, we report two novel injectable pentablock copolymer based thermoresponsive hydrogels made of polyethyleneglycol-polycaprolactone-polylactide-polycaprolactone-polyethyleneglycol (PEG-PCL-PLA-PCL-PEG) with varying ratios of polycaprolactone (PCL) and polylactide (PLA), as single shot sustained release vaccines. Pentablock copolymer hydrogels were loaded with vaccine-encapsulated poly lactic-co-glycolic acid nanoparticles (PLGA-NP) or with the soluble vaccine components. Incorporation of PLGA-NP into the thermoresponsive hydrogels increased the complex viscosity of the gels, lowered the gelation temperature, and minimized the burst release of antigen and adjuvants. The two pentablock hydrogels stimulated both cellular and humoral responses. The addition of PLGA-NP to the hydrogels sustained immune responses for up to 49 days. The polymer with a higher ratio of PCL to PLA formed a more rigid gel, induced stronger immune responses, and stimulated effective anti-tumor responses in a prophylactic melanoma tumor model.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2017-08-01

    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.

  20. 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

  1. Real-time monitoring of the penetration of amphiphilic acrylate copolymer in leather using a fluorescent copolymer as tracer.

    Science.gov (United States)

    Du, Jin-Xia; Shi, Lu; Peng, Bi-Yu

    2015-12-01

    A fluorescent tracer, poly (acrylic-co-stearyl acrylate-co-3-acryloyl fluorescein) [poly (AA-co-SA-co-Ac-Flu)], used for real-time monitoring the penetration of amphiphilic acrylate copolymer, poly (acrylic-co-stearyl acrylate) [poly (AA-co-SA)], in leather was synthesized by radical polymerization of acrylic, stearyl acrylate and fluorescent monomer, 3-acryloyl fluorescein (Ac-Flu). The structure, molecular weight, introduced fluorescent group content and fluorescent characteristics of the fluorescent tracer and target copolymer, amphiphilic acrylate copolymer, were also characterized. The results show that the tracer presents the similar structural characteristics to the target and enough fluorescence intensity with 1.68 wt % of the fluorescent monomer introduced amount. The vertical section of the leather treated with the target copolymer mixing with 7% of the tracer exhibits evident fluorescence, and the change of fluorescence intensity along with the vertical section with treating time increasing can reflect the penetration depth of the target copolymer. The introduction of the fluorescent group in polymer structure through copolymerization with a limited amount of fluorescent monomer, Ac-Flu, is an effective way to make a tracer to monitor the penetration of the target in leather, which provides a new thought for the penetration research of syntans such as vinyl copolymer materials in leather manufacture.

  2. “Stable-on-the-Table” Biosensors: Hemoglobin-Poly (Acrylic Acid) Nanogel BioElectrodes with High Thermal Stability and Enhanced Electroactivity

    Science.gov (United States)

    Ghimire, Ananta; Zore, Omkar V.; Thilakarathne, Vindya K.; Briand, Victoria A.; Lenehan, Patrick J.; Lei, Yu; Kasi, Rajeswari M.; Kumar, Challa V.

    2015-01-01

    In our efforts toward producing environmentally responsible but highly stable bioelectrodes with high electroactivities, we report here a simple, inexpensive, autoclavable high sensitivity biosensor based on enzyme-polymer nanogels. Met-hemoglobin (Hb) is stabilized by wrapping it in high molecular weight poly(acrylic acid) (PAA, MW 450k), and the resulting nanogels abbreviated as Hb-PAA-450k, withstood exposure to high temperatures for extended periods under steam sterilization conditions (122 °C, 10 min, 17–20 psi) without loss of Hb structure or its peroxidase-like activities. The bioelectrodes prepared by coating Hb-PAA-450k nanogels on glassy carbon showed well-defined quasi-reversible redox peaks at −0.279 and −0.334 V in cyclic voltammetry (CV) and retained >95% electroactivity after storing for 14 days at room temperature. Similarly, the bioelectrode showed ~90% retention in electrochemical properties after autoclaving under steam sterilization conditions. The ultra stable bioelectrode was used to detect hydrogen peroxide and demonstrated an excellent detection limit of 0.5 μM, the best among the Hb-based electrochemical biosensors. This is the first electrochemical demonstration of steam-sterilizable, storable, modular bioelectrode that undergoes reversible-thermal denaturation and retains electroactivity for protein based electrochemical applications. PMID:26393601

  3. “Stable-on-the-Table” Biosensors: Hemoglobin-Poly (Acrylic Acid Nanogel BioElectrodes with High Thermal Stability and Enhanced Electroactivity

    Directory of Open Access Journals (Sweden)

    Ananta Ghimire

    2015-09-01

    Full Text Available In our efforts toward producing environmentally responsible but highly stable bioelectrodes with high electroactivities, we report here a simple, inexpensive, autoclavable high sensitivity biosensor based on enzyme-polymer nanogels. Met-hemoglobin (Hb is stabilized by wrapping it in high molecular weight poly(acrylic acid (PAA, MW 450k, and the resulting nanogels abbreviated as Hb-PAA-450k, withstood exposure to high temperatures for extended periods under steam sterilization conditions (122 °C, 10 min, 17–20 psi without loss of Hb structure or its peroxidase-like activities. The bioelectrodes prepared by coating Hb-PAA-450k nanogels on glassy carbon showed well-defined quasi-reversible redox peaks at −0.279 and −0.334 V in cyclic voltammetry (CV and retained >95% electroactivity after storing for 14 days at room temperature. Similarly, the bioelectrode showed ~90% retention in electrochemical properties after autoclaving under steam sterilization conditions. The ultra stable bioelectrode was used to detect hydrogen peroxide and demonstrated an excellent detection limit of 0.5 μM, the best among the Hb-based electrochemical biosensors. This is the first electrochemical demonstration of steam-sterilizable, storable, modular bioelectrode that undergoes reversible-thermal denaturation and retains electroactivity for protein based electrochemical applications.

  4. "Stable-on-the-Table" Biosensors: Hemoglobin-Poly (Acrylic Acid) Nanogel BioElectrodes with High Thermal Stability and Enhanced Electroactivity.

    Science.gov (United States)

    Ghimire, Ananta; Zore, Omkar V; Thilakarathne, Vindya K; Briand, Victoria A; Lenehan, Patrick J; Lei, Yu; Kasi, Rajeswari M; Kumar, Challa V

    2015-09-18

    In our efforts toward producing environmentally responsible but highly stable bioelectrodes with high electroactivities, we report here a simple, inexpensive, autoclavable high sensitivity biosensor based on enzyme-polymer nanogels. Met-hemoglobin (Hb) is stabilized by wrapping it in high molecular weight poly(acrylic acid) (PAA, M(W) 450k), and the resulting nanogels abbreviated as Hb-PAA-450k, withstood exposure to high temperatures for extended periods under steam sterilization conditions (122 °C, 10 min, 17-20 psi) without loss of Hb structure or its peroxidase-like activities. The bioelectrodes prepared by coating Hb-PAA-450k nanogels on glassy carbon showed well-defined quasi-reversible redox peaks at -0.279 and -0.334 V in cyclic voltammetry (CV) and retained >95% electroactivity after storing for 14 days at room temperature. Similarly, the bioelectrode showed ~90% retention in electrochemical properties after autoclaving under steam sterilization conditions. The ultra stable bioelectrode was used to detect hydrogen peroxide and demonstrated an excellent detection limit of 0.5 μM, the best among the Hb-based electrochemical biosensors. This is the first electrochemical demonstration of steam-sterilizable, storable, modular bioelectrode that undergoes reversible-thermal denaturation and retains electroactivity for protein based electrochemical applications.

  5. Preparation of epoxy resin copolymers with low luminous decay%低光衰环氧树脂共聚物的制备

    Institute of Scientific and Technical Information of China (English)

    冯钠; 张小扉; 张桂霞; 陈涛; 王旭

    2011-01-01

    Copolymers of epoxy resin grafted by hydroxy-terminated silicone(EP-g-HTPDMS) with low luminous decay were prepared by graft condensation polymerization from EP and HTPDMS. The structure of the EP-g-HTPDMS copolymers was characterized by Fourier transform infrared spectroscopy(FTIR) and therm ogravimetric(TG) analysis. The EP-g-HTPDMS copolymers were applied to package of light-emitting diode, and its optical properties were studied by luminous decay and refractive index test. The mechanical properties and micro-morphology of the copolymers were analyzed by hardness tester and scanning electron microscope(SEM). The results indicate that HTPDMS is successfully incorporated into EP molecular chain.Adding HTPDMS has unobvious effect on the refractive index of the copolymers. When HTPDMS mass content is less than 9%, the relative light output of the EP-g-HTPDMS copolymers is higher than that of unmodified EP and luminous decay reduces significantly. The hardness of the copolymers decreases with increasing HTPDMS mass content. The introduction of HTPDMS makes the copolymer exhibit the features of tough fracture, lowers the internal stress in the system and improves the resistance to cracking.%采用接枝缩聚的方法,将端羟基硅酮(HTPDMS)与环氧树脂(EP)反应,制备低光衰HTPDMS接枝EP(EP-g-HTPDMS)共聚物.利用傅里叶变换红外光谱和热重分析表征其结构,并将制备的EP-g-HTPDMS共聚物应用于发光二级管封装,通过测试光衰和折射率分析其光学性能,同时利用硬度测试仪和扫描电子显微镜研究其力学性能和微观结构.结果表明:HTPDMS成功接枝在EP分子链中;引入HTPDMS对共聚物折射率的影响并不明显,当w(HTPDMS)小于9%时,共聚物的相对输出功率均高于EP,光衰明显降低;随着w(HTPDMS)增加,共聚物的硬度减小;引入HTPDMS使共聚物断面呈韧性断裂,体系的内应力降低,抗开裂性能得到改善.

  6. Targeted delivery of Bcl-2 conversion gene by MPEG-PCL-PEI-FA cationic copolymer to combat therapeutic resistant cancer.

    Science.gov (United States)

    Li, Zibiao; Liu, Xuan; Chen, Xiaohong; Chua, Ming Xuan; Wu, Yun-Long

    2017-07-01

    Deregulation of anti-apoptosis Bcl-2 protein expression was a key feature in human cancers with therapeutic resistance. Nuclear receptor Nur77 could induce the conformation change of Bcl-2 protein and converted it into an apoptosis inducer by "enemy to friend" strategy. However, the safe and effective delivery of this gene to combat therapeutic resistant cancer remained largely unexplored. In this report, we designed an amphiphilic cationic MPEG-PCL-PEI-FA copolymer, comprising biocompatible and hydrophilic methoxy-poly(ethylene glycol) (MPEG), biodegradable and hydrophobic poly(ε-caprolactone) (PCL), cationic poly(ethylene imine) (PEI) segments, and folic acid (FA) as targeting group, as a high efficient Nur77 gene carrier to folate receptor (FR) highly expressed and therapeutic resistant HeLa/Bcl-2 cancer cells. Interestingly, due to the incorporation of PCL and PEG segments, this MPEG-PCL-PEI-FA copolymer showed less toxicity but better gene transfection efficiency than non-viral gene carrier gold standard PEI (25kDa). This might be due to the formation of micelles to stabilize polyplex for enhanced gene transfection ability. More importantly, MPEG-PCL-PEI-FA copolymer exhibited excellent growth inhibition ability on therapeutic resistant HeLa/Bcl-2 cancer cells, which was FR overexpressed HeLa cervical cancer cells with high expression of Bcl-2 protein, thanks to its FA induced targeting ability, high gene transfection efficiency, and low cytotoxicity. This work signifies the first time that cationic amphiphilic MPEG-PCL-PEI-FA copolymers could be utilized for the gene delivery to therapeutic resistant cancer cells with high expression of anti-apoptosis Bcl-2 protein and the positive results are encouraging for the further design of polymeric platforms for combating drug resistant tumors. Copyright © 2017 Elsevier B.V. All rights reserved.

  7. Shape memory rubber bands & supramolecular ionic copolymers

    Science.gov (United States)

    Brostowitz, Nicole

    subject covered in this dissertation is supra-molecular ionic copolymers. Supramolecular interactions are non-covalent; e.g. hydrogen bonding, ionic interactions, van der Waals forces. Supramolecular interactions in polymers can be used to tailor the thermo-mechanical properties by controlling bond association and dissociation. Recent research has focused on hydrogen bonded systems due to established synthesis mechanisms. Reversibility of the supramolecular interactions can be triggered by environmental changes. Ionic interactions would provide greater bond strength and more control over operating conditions. Research has been limited on ionic copolymers due to complicated synthesis methods needed to include functionalization. Low molecular weight polymers were synthesized by atom transfer radical polymerization with post polymerization conversion to phosphonium end-groups. Both polystyrene and poly(methyl acrylate) were investigated with similar reaction conditions. Chromatography measured the molecular weight and indicated a low polydispersity consistent with controlled reactions. Copolymers were formed by interfacial mixing of the cationic polymers with multifunctional, anionic oligomers. Oligomers containing sulfonate groups were used to create linear or three-dimensional polymer networks. NMR and rheology was used to characterize the presence and effect of ionic groups when compared to the neat polymer.

  8. Nanoparticle carriers based on copolymers of poly(l-aspartic acid co-l-lactide)-1,2-dipalmitoyl-sn-glycero-3-phosphoethanolamine for drug delivery

    Energy Technology Data Exchange (ETDEWEB)

    Han Siyuan; Wang Huan; Liang Xingjie [National Center for Nanoscience and Technology, Laboratory of Nanobiomedicine and Nanosafety, Division of Nanomedicine and Nanobiology (China); Hu Liming, E-mail: huliming@bjut.edu.cn [Beijing University of Technology, College of Life Science and Bioengineering (China); Li Min; Wu Yan, E-mail: wuy@nanoctr.cn [National Center for Nanoscience and Technology, Laboratory of Nanobiomedicine and Nanosafety, Division of Nanomedicine and Nanobiology (China)

    2011-09-15

    A novel poly(l-aspartic) derivative (PAL-DPPE) containing polylactide and 1,2-dipalmitoyl-sn-glycero-3-phosphoethanolamine (DPPE) segments has been successfully synthesized. The chemical structures of the copolymers were confirmed by Fourier-transform infrared spectroscopy (FTIR), NMR ({sup 1}H NMR, {sup 13}C NMR, {sup 31}P NMR), and thermogravimetric analysis (TGA). Fluorescence spectroscopy, dynamic light scattering (DLS), and transmission electron microscopy (TEM) confirmed the formation of micelles of the PAL-DPPE copolymers. In order to estimate the feasibility as novel drug carriers, an anti-tumor model drug doxorubicin (DOX) was incorporated into polymeric micelles by double emulsion and nanoprecipitation method. The DOX-loaded micelle size, size distribution, and encapsulation efficiency (EE) were influenced by the feed weight ratio of the copolymer to DOX. In addition, in vitro release experiments of the DOX-loaded PAL-DPPE micelles exhibited that faster release in pH 5.0 than their release in pH 7.4 buffer. The poly(l-aspartic) derivative copolymer was proved to be an available carrier for the preparation of micelles for anti-tumor drug delivery.

  9. Stress-strain behavior of block-copolymers and their nanocomposites filled with uniform or Janus nanoparticles under shear: a molecular dynamics simulation.

    Science.gov (United States)

    Wang, Lu; Liu, Hongji; Li, Fanzhu; Shen, Jianxiang; Zheng, Zijian; Gao, Yangyang; Liu, Jun; Wu, Youping; Zhang, Liqun

    2016-10-05

    Although numerous research studies have been focused on studying the self-assembled morphologies of block-copolymers (BCPs) and their nanocomposites, little attention has been directed to explore the relation between their ordered structures and the resulting mechanical properties. We adopt coarse-grained molecular dynamics simulation to study the influence of the morphologies on the stress-strain behavior of pure block copolymers and block copolymers filled with uniform or Janus nanoparticles (NPs). At first, we examine the effect of the arrangement (di-block, tri-block, alternating-block) and the components of the pure block copolymers, and by varying the component ratio between A and B blocks, spherical, cylindrical and lamellar phases are all formed, showing that spherical domains bring the largest reinforcing effect. Then by studying BCPs filled with NPs, the Janus NPs induce stronger bond orientation of polymer chains and greater mechanical properties than the uniform NPs, when these two kinds of NPs are both located in the interface region. Meanwhile, some other anisotropic Janus NPs, such as Janus rods and Janus sheets, are incorporated to examine the effect on the morphology and the stress-strain behavior. These findings deepen our understanding of the morphology-mechanics relation of BCPs and their nanocomposites, opening up a vast number of approaches such as designing the arrangement and components of BCPs, positioning uniform or Janus NPs with different shapes and shear flow to tailor their stress-strain performance.

  10. Nanoparticle carriers based on copolymers of poly( l-aspartic acid co- l-lactide)-1,2-dipalmitoyl-sn-glycero-3-phosphoethanolamine for drug delivery

    Science.gov (United States)

    Han, Siyuan; Wang, Huan; Liang, Xingjie; Hu, Liming; Li, Min; Wu, Yan

    2011-09-01

    A novel poly( l-aspartic) derivative (PAL-DPPE) containing polylactide and 1,2-dipalmitoyl-sn-glycero-3-phosphoethanolamine (DPPE) segments has been successfully synthesized. The chemical structures of the copolymers were confirmed by Fourier-transform infrared spectroscopy (FTIR), NMR (1H NMR, 13C NMR, 31P NMR), and thermogravimetric analysis (TGA). Fluorescence spectroscopy, dynamic light scattering (DLS), and transmission electron microscopy (TEM) confirmed the formation of micelles of the PAL-DPPE copolymers. In order to estimate the feasibility as novel drug carriers, an anti-tumor model drug doxorubicin (DOX) was incorporated into polymeric micelles by double emulsion and nanoprecipitation method. The DOX-loaded micelle size, size distribution, and encapsulation efficiency (EE) were influenced by the feed weight ratio of the copolymer to DOX. In addition, in vitro release experiments of the DOX-loaded PAL-DPPE micelles exhibited that faster release in pH 5.0 than their release in pH 7.4 buffer. The poly( l-aspartic) derivative copolymer was proved to be an available carrier for the preparation of micelles for anti-tumor drug delivery.

  11. Hydrogen Bonding-Mediated Microphase Separation during the Formation of Mesoporous Novolac-Type Phenolic Resin Templated by the Triblock Copolymer, PEO-b-PPO-b-PEO

    Directory of Open Access Journals (Sweden)

    Wei-Cheng Chu

    2013-11-01

    Full Text Available After blending the triblock copolymer, poly(ethylene oxide-b-propylene oxide-b-ethylene oxide (PEO-b-PPO-b-PEO with novolac-type phenolic resin, Fourier transform infrared spectroscopy revealed that the ether groups of the PEO block were stronger hydrogen bond acceptors for the OH groups of phenolic resin than were the ether groups of the PPO block. Thermal curing with hexamethylenetetramine as the curing agent resulted in the triblock copolymer being incorporated into the phenolic resin, forming a nanostructure through a mechanism involving reaction-induced microphase separation. Mild pyrolysis conditions led to the removal of the PEO-b-PPO-b-PEO triblock copolymer and formation of mesoporous phenolic resin. This approach provided a variety of composition-dependent nanostructures, including disordered wormlike, body-centered-cubic spherical and disorder micelles. The regular mesoporous novolac-type phenolic resin was formed only at a phenolic content of 40–60 wt %, the result of an intriguing balance of hydrogen bonding interactions among the phenolic resin and the PEO and PPO segments of the triblock copolymer.

  12. Block copolymer hollow fiber membranes with catalytic activity and pH-response.

    Science.gov (United States)

    Hilke, Roland; Pradeep, Neelakanda; Madhavan, Poornima; Vainio, Ulla; Behzad, Ali Reza; Sougrat, Rachid; Nunes, Suzana P; Peinemann, Klaus-Viktor

    2013-08-14

    We fabricated block copolymer hollow fiber membranes with self-assembled, shell-side, uniform pore structures. The fibers in these membranes combined pores able to respond to pH and acting as chemical gates that opened above pH 4, and catalytic activity, achieved by the incorporation of gold nanoparticles. We used a dry/wet spinning process to produce the asymmetric hollow fibers and determined the conditions under which the hollow fibers were optimized to create the desired pore morphology and the necessary mechanical stability. To induce ordered micelle assembly in the doped solution, we identified an ideal solvent mixture as confirmed by small-angle X-ray scattering. We then reduced p-nitrophenol with a gold-loaded fiber to confirm the catalytic performance of the membranes.

  13. Fouling release nanostructured coatings based on PDMS-polyurea segmented copolymers

    KAUST Repository

    Fang, Jason

    2010-05-01

    The bulk and surface characteristics of a series of coatings based on PDMS-polyurea segmented copolymers were correlated to their fouling release performance. Incorporation of polyurea segments to PDMS backbone gives rise to phase separation with the extensively hydrogen bonded hard domains creating an interconnected network that imparts mechanical rigidity. Increasing the compositional complexity of the system by including fluorinated or POSS-functionalized chain extenders or through nanoclay intercalation, confers further thermomechanical improvements. In analogy to the bulk morphology, the surface topography also reflects the compositional complexity of the materials, displaying a wide range of motifs. Investigations on settlement and subsequent removal of Ulva sporelings on those nanostructured surfaces indicate that the work required to remove the microorganisms is significantly lower compared to coatings based on standard PDMS homopolymer. All in all, the series of materials considered in this study demonstrate advanced fouling release properties, while exhibiting superior mechanical properties and, thus, long term durability. © 2010 Elsevier Ltd.

  14. Flexible one diode-one phase change memory array enabled by block copolymer self-assembly.

    Science.gov (United States)

    Mun, Beom Ho; You, Byoung Kuk; Yang, Se Ryeun; Yoo, Hyeon Gyun; Kim, Jong Min; Park, Woon Ik; Yin, You; Byun, Myunghwan; Jung, Yeon Sik; Lee, Keon Jae

    2015-04-28

    Flexible memory is the fundamental component for data processing, storage, and radio frequency communication in flexible electronic systems. Among several emerging memory technologies, phase-change random-access memory (PRAM) is one of the strongest candidate for next-generation nonvolatile memories due to its remarkable merits of large cycling endurance, high speed, and excellent scalability. Although there are a few approaches for flexible phase-change memory (PCM), high reset current is the biggest obstacle for the practical operation of flexible PCM devices. In this paper, we report a flexible PCM realized by incorporating nanoinsulators derived from a Si-containing block copolymer (BCP) to significantly lower the operating current of the flexible memory formed on plastic substrate. The reduction of thermal stress by BCP nanostructures enables the reliable operation of flexible PCM devices integrated with ultrathin flexible diodes during more than 100 switching cycles and 1000 bending cycles.

  15. Precise Control over the Rheological Behavior of Associating Stimuli-Responsive Block Copolymer Gels

    Directory of Open Access Journals (Sweden)

    Jérémy Brassinne

    2015-12-01

    Full Text Available “Smart” materials have considerably evolved over the last few years for specific applications. They rely on intelligent macromolecules or (supra-molecular motifs to adapt their structure and properties in response to external triggers. Here, a supramolecular stimuli-responsive polymer gel is constructed from heterotelechelic double hydrophilic block copolymers that incorporate thermo-responsive sequences. These macromolecular building units are synthesized via a three-step controlled radical copolymerization and then hierarchically assembled to yield coordination micellar hydrogels. The dynamic mechanical properties of this particular class of materials are studied in shear flow and finely tuned via temperature changes. Notably, rheological experiments show that structurally reinforcing the micellar network nodes leads to precise tuning of the viscoelastic response and yield behavior of the material. Hence, they constitute promising candidates for specific applications, such as mechano-sensors.

  16. Phase diagram of rod-coil diblock copolymer melts by self-consistent field theory

    Science.gov (United States)

    Yan, Dadong; Tang, Jiuzhou; Jiang, Ying; Zhang, Xinghua; Chen, Jeff

    A unified phase diagram is presented for rod-coil diblock copolymer melts in the isotropic phase regime as a function of the asymmetric parameter. The study is based on free-energy calculation, which incorporates three-dimensional spatial variations of the volume fraction with angular dependence. The wormlike-chain model is used in a self-consistent field treatment. Body-centered cubic, A15, hexagonal, gyroid, and lamellar structures where the rod segments are packed inside the convex rod-coil interface are found stable. As the conformational asymmetric parameter increases, the A15 phase region expands and the gyroid phase region reduces. The stability of the structures is analyzed by concepts such as packing frustration, spinodal limit, and interfacial curvature.

  17. Block copolymer hollow fiber membranes with catalytic activity and pH-response

    KAUST Repository

    Hilke, Roland

    2013-08-14

    We fabricated block copolymer hollow fiber membranes with self-assembled, shell-side, uniform pore structures. The fibers in these membranes combined pores able to respond to pH and acting as chemical gates that opened above pH 4, and catalytic activity, achieved by the incorporation of gold nanoparticles. We used a dry/wet spinning process to produce the asymmetric hollow fibers and determined the conditions under which the hollow fibers were optimized to create the desired pore morphology and the necessary mechanical stability. To induce ordered micelle assembly in the doped solution, we identified an ideal solvent mixture as confirmed by small-angle X-ray scattering. We then reduced p-nitrophenol with a gold-loaded fiber to confirm the catalytic performance of the membranes. © 2013 American Chemical Society.

  18. Zirconia doped barium titanate induced electroactive β polymorph in PVDF-HFP: high energy density and dielectric properties

    Science.gov (United States)

    Sharma, Maya; Ranganatha, S.; Kalyani, Ajay Kumar; Ranjan, Rajeev; Madras, Giridhar; Bose, Suryasarathi

    2014-12-01

    Zirconium-doped barium titanate (BZT-08, Ba(Ti0.92 Zr0.08)O3) particles were synthesized and PVDF-HFP-based composites were prepared by melt mixing to design materials with tunable dielectric and ferroelectric properties. Composites of PVDF-HFP and barium titanate (BT) particles were also prepared to realize the exceptional properties associated with the BZT-08-like stabilization of two ferroelectric phases, i.e. tetragonal and orthorhombic at room temperature. To facilitate the uniform dispersion and interfacial adhesion with the matrix, the particles were modified with (3-aminopropyl) triethoxysilane. The dependence of the dielectric and ferroelectric properties of the as-prepared composites were systematically investigated in this study with respect to a wide range of frequencies. The composites with BZT-08 exhibited the significantly high dielectric permittivity of ca. 26 (at 100 Hz) and a high energy density (2.7 J cm-3 measured on 100 μm thick film) at room temperature with respect to the control PVDF-HFP and PVDF-HFP/BT composites. Interestingly, the BZT-08 particles facilitated the electroactive β polymorph in the PVDF-HFP and enhanced polarization in the composites, leading to improved ferroelectric properties in the composites.

  19. Graphene oxide directed in-situ deposition of electroactive silver nanoparticles and its electrochemical sensing application for DNA analysis.

    Science.gov (United States)

    Gao, Ningning; Gao, Feng; He, Suyu; Zhu, Qionghua; Huang, Jiafu; Tanaka, Hidekazu; Wang, Qingxiang

    2017-01-25

    The development of high-performance biosensing platform is heavily dependent on the recognition property of the sensing layer and the output intensity of the signal probe. Herein, we present a simple and highly sensitive biosensing interface for DNA detection on the basis of graphene oxide nanosheets (GONs) directed in-situ deposition of silver nanoparticles (AgNPs). The fabrication process and electrochemical properties of the biosensing interface were probed by electrochemical techniques and scanning electron microscopy. The results indicate that GONs can specifically adsorb at the single-stranded DNA probe surface, and induces the deposition of highly electroactive AgNPs. Upon hybridization with complementary oligonucleotides to generate the duplex DNA on the electrode surface, the GONs with the deposited AgNPs will be liberated from the sensing interface due to the inferior affinity of GONs and duplex DNA, resulting in the reduction of the electrochemical signal. Such a strategy combines the superior recognition of GONs toward single-stranded DNA and double-stranded DNA, and the strong electrochemical response of in-situ deposited AgNPs. Under optimal conditions, the biosensor can detect target DNA over a wide range from 10 fM to 10 nM with a detection limit of 7.6 fM. Also, the developed biosensor shows outstanding discriminating ability toward oligonucleotides with different mismatching degrees.

  20. Electro-Active Polymers (EAPs: A Promising Route to Design Bio-Organic/Bioinspired Platforms with on Demand Functionalities

    Directory of Open Access Journals (Sweden)

    Vincenzo Guarino

    2016-05-01

    Full Text Available Through recent discoveries and new knowledge among correlations between molecular biology and materials science, it is a growing interest to design new biomaterials able to interact—i.e., to influence, to guide or to detect—with cells and their surrounding microenvironments, in order to better control biological phenomena. In this context, electro-active polymers (EAPs are showing great promise as biomaterials acting as an interface between electronics and biology. This is ascribable to the highly tunability of chemical/physical properties which confer them different conductive properties for various applicative uses (i.e., molecular targeting, biosensors, biocompatible scaffolds. This review article is divided into three parts: the first one is an overview on EAPs to introduce basic conductivity mechanisms and their classification. The second one is focused on the description of most common processes used to manipulate EAPs in the form of two-dimensional (2D and three-dimensional (3D materials. The last part addresses their use in current applications in different biomedical research areas including tissue engineering, biosensors and molecular delivery.

  1. Simultaneous selection of soil electroactive bacterial communities associated to anode and cathode in a two-chamber Microbial Fuel Cell

    Science.gov (United States)

    Chiellini, Carolina; Bacci, Giovanni; Fani, Renato; Mocali, Stefano

    2016-04-01

    Different bacteria have evolved strategies to transfer electrons over their cell surface to (or from) their extracellular environment. This electron transfer enables the use of these bacteria in bioelectrochemical systems (BES) such as Microbial Fuel Cells (MFCs). In MFC research the biological reactions at the cathode have long been a secondary point of interest. However, bacterial biocathodes in MFCs represent a potential advantage compared to traditional cathodes, for both their low costs and their low impact on the environment. The main challenge in biocathode set-up is represented by the selection of a bacterial community able to efficiently accept electrons from the electrode, starting from an environmental matrix. In this work, a constant voltage was supplied on a two-chamber MFC filled up with soil over three weeks in order to simultaneously select an electron donor bacterial biomass on the anode and an electron acceptor biomass on the cathode, starting from the same soil. Next Generation Sequencing (NGS) analysis was performed to characterize the bacterial community of the initial soil, in the anode, in the cathode and in the control chamber not supplied with any voltage. Results highlighted that both the MFC conditions and the voltage supply affected the soil bacterial communities, providing a selection of different bacterial groups preferentially associated to the anode (Betaproteobacteria, Bacilli and Clostridia) and to the cathode (Actinobacteria and Alphaproteobacteria). These results confirmed that several electroactive bacteria are naturally present within a top soil and, moreover, different soil bacterial genera could provide different electrical properties.

  2. Potentiometric determination of Nickel (II ion using 2-hydroxy-1-naphthylidene-N-cyanoacetohydrazone as electroactive material

    Directory of Open Access Journals (Sweden)

    Harish Kumar Sharma

    2014-01-01

    Full Text Available A potentiometric Nickel sensor was prepared using 2-hydroxy-1-naphthylidene-N-cyanoacetohydrazone as electro-active material and epoxy resin as a binding material. A membrane composed of 40% Schiff's base and 60% epoxy resin exhibited the best performance. The membrane showed excellent response in the concentration range of 0.15 ppm to 0.1 mol L- 1 Ni+2 ions with non-Nernstian slope of 22.0 mV/decade, had a rapid response time (less than 10 s, and can be used for three months without any considerable loss of potential. The sensor was useful within the pH range of 1.3 to 9.6, and was able to discriminate between Ni2+ and a large number of alkaline earth and transition metal ions. The practical utility of the sensor has been demonstrated by using it successfully as an indicator electrode in the potentiometric titration of Ni2+ with EDTA and oxalic acid.

  3. Monte Carlo simulations of the phase separation of a copolymer blend in a thin film

    KAUST Repository

    Wang, Zhexiao

    2014-12-11

    Monte Carlo simulations were carried out to study the phase separation of a copolymer blend comprising an alternating copolymer and/or block copolymer in a thin film, and a phase diagram was constructed with a series of composed recipes. The effects of composition and segregation strength on phase separation were discussed in detail. The chain conformation of the block copolymer and alternating copolymer were investigated with changes of the segregation strength. Our simulations revealed that the segment distribution along the copolymer chain and the segregation strength between coarse-grained beads are two important parameters controlling phase separation and chain conformation in thin films of a copolymer blend. A well-controlled phase separation in the copolymer blend can be used to fabricate novel nanostructures.

  4. Block Copolymer-Tuned Fullerene Electron Transport Layer Enhances the Efficiency of Perovskite Photovoltaics.

    Science.gov (United States)

    Lin, Hsi-Kuei; Su, Yu-Wei; Chen, Hsiu-Cheng; Huang, Yi-Jiun; Wei, Kung-Hwa

    2016-09-21

    In this study, we enhanced the power conversion efficiency (PCE) of perovskite solar cells by employing an electron transfer layer (ETL) comprising [6,6]phenyl-C61-butyric acid methyl ester (PC61BM) and, to optimize its morphology, a small amount of the block copolymer polystyrene-b-poly(ethylene oxide) (PS-b-PEO), positioned on the perovskite active layer. When incorporating 0.375 wt % PS-b-PEO into PC61BM, the PCE of the perovskite photovoltaic device increased from 9.4% to 13.4%, a relative increase of 43%, because of a large enhancement in the fill factor of the device. To decipher the intricate morphology of the ETL, we used synchrotron grazing-incidence small-angle X-ray scattering for determining the PC61BM cluster size, atomic force microscopy and scanning electron microscopy for probing the surface, and transmission electron microscopy for observing the aggregation of PC61BM in the ETL. We found that the interaction between PS-b-PEO and PC61BM resulted in smaller PC61BM clusters that further aggregated into dendritic structures in some domains, a result of the similar polarities of the PS block and PC61BM; this behavior could be used to tune the morphology of the ETL. The optimal PS-b-PEO-mediated PC61BM cluster size in the ETL was 17 nm, a large reduction from 59 nm for the pristine PC61BM layer. This approach of incorporating a small amount of nanostructured block copolymer into a fullerene allowed us to effectively tune the morphology of the ETL on the perovskite active layer and resulted in enhanced fill factors of the devices and thus their device efficiency.

  5. Molecular Exchange in Ordered Diblock Copolymer Micelles

    Science.gov (United States)

    Choi, Soo-Hyung; Lodge, Timothy; Bates, Frank

    2011-03-01

    Previously, molecular exchange between spherical micelles in dilute solution (1 vol% polymer) was investigated using time-resolved small-angle neutron scattering (TR-SANS). As the concentration of spherical micelles formed by the diblock copolymers increases, the micelles begin to overlap and eventually pack onto body-centered cubic (BCC) lattice. In this study, concentrated, ordered micelles (15 vol% polymers) prepared by dispersing isotopically labeled poly(styrene- b -ethylene-alt-propylene) in an isotopic squalane mixture was investigated to understand the micellar concentration dependence of the molecular exchange. Perfectly random mixing of isotopically labeled micelles on the BCC lattice was confirmed by SANS patterns where the interparticle contribution vanishes, resulting in an intensity that directly relates to the exchange kinetics. The measured molecular exchange process for the concentrated, ordered system is qualitatively consistent with the previous observations, but the rate is more than an order of magnitude slower than that for the dilute, disordered system. Infineum(IPrime), MRSEC(NSF), NIST.

  6. Molecular Exchange Dynamics in Block Copolymer Micelles

    Science.gov (United States)

    Bates, Frank; Lu, Jie; Choi, Soohyung; Lodge, Timothy

    2012-02-01

    Poly(styrene-b-ethylene propylene) (PS-PEP) diblock copolymers were mixed with squalane (C30H62) at 1% by weight resulting in the formation of spherical micelles. The structure and dynamics of molecular exchange were characterized by synchrotron small-angle x-ray scattering (SAXS) and time resolved small-angle neutron scattering (TR-SANS), respectively, between 100 C and 160 C. TR-SANS measurements were performed with solutions initially containing deuterium labeled micelle cores and normal cores dispersed in a contrast matched squalane. Monitoring the reduction in scattering intensity as a function of time at various temperatures revealed molecular exchange dynamics highly sensitive to the core molecular weight and molecular weight distribution. Time-temperature superposition of data acquired at different temperatures produced a single master curve for all the mixtures. Experiments conducted with isotopically labeled micelle cores, each formed from two different but relatively mondisperse PS blocks, confirmed a simple dynamical model based on first order kinetics and core Rouse single chain relaxation. These findings demonstrate a dramatic transition to nonergodicity with increasing micelle core molecular weight and confirm the origins of the logarithmic exchange kinetics in such systems.

  7. Morphologies of A_2B Simple Graft Copolymer Blends: Copolymer/Copolymer and Copolymer/Homopolymer Systems to Further Elucidate the Stability of Simple Graft Phase Behavior

    Science.gov (United States)

    Lee, Chin; Pochan, Darrin; Gido, Samuel P.; Pispas, Stergios; Mays, Jimmy; Tan, Nora Beck; Trevino, Samuel

    1997-03-01

    The morphological behavior of two series of binary blends of A_2B simple graft block copolymers (A is polyisoprene and B is polystyrene) was characterized via transmission electron microscopy (TEM) and small-angle neutron scattering (SANS). Binary blends of A_2B samples with other A_2B samples of similar relative volume fractions were composed to map out the volume fraction window of stability of the randomly oriented worm phase, or ROW. This novel equilibrium phase behavior was found to occur in a neat A_2B sample with a B volume fraction of 0.81. At this unique composition the single B graft chain first becomes large enough to force the two A chains to the concave side of the AB interface in the microphase separated state. Another set of binary blends of A_2B samples was composed with the respective homopolymers in order to more rigorously determine the phase boundaries relative to volume fraction of the respective microphase separated morphologies in the A_2B systems.

  8. Tunable Morphologies from Charged Block Copolymers

    Energy Technology Data Exchange (ETDEWEB)

    Goswami, Monojoy [ORNL; Sumpter, Bobby G [ORNL; Mays, Jimmy [ORNL; Messman, Jamie M [ORNL

    2010-01-01

    The bulk morphologies formed by a new class of charged block copolymers, 75 vol % fluorinated polyisoprene (FPI) 25 vol% sulfonated polystyrene (PSS) with 50% sulfonation, are characterized, and the fundamental underlying forces that promote the self-assembly processes are elucidated. The results show how the bulk morphologies are substantially different from their uncharged diblock counterparts (PS-PI) and also how morphology can be tuned with volume fraction of the charged block and the casting solvent. A physical understanding based on the underlying strong electrostatic interactions between the charged block and counterions is obtained using Monte Carlo (MC) and Molecular Dynamics (MD) simulations. The 75/25 FPI-PSS shows hexagonal morphologies with the minority blocks (PSS) forming the continuous phase due to charge percolation and the FPI blocks arranged in hexagonal cylinders. Some long-range order can be sustained even if lipophobicity is increased (addition of water), albeit with lower dimensional structures. However, thermal annealing provides sufficient energy to disrupt the percolated charges and promotes aggregation of ionic sites which leads to a disordered system. Diverse and atypical morphologies are readily accessible by simply changing the number distribution of the charges on PSS block.

  9. Contrast variation SANS experiments to the study of detergent-induced micellization of block copolymers

    Indian Academy of Sciences (India)

    V K Aswal; J Kohlbrecher

    2004-08-01

    PEO-PPO-PEO triblock copolymer P85 [(EO)26 (PO)39 (EO)26] dissolves as unimers and detergent sodium dodecyl sulfate (SDS) forms micelles in aqueous solution at 20°C. The mixing of detergent with triblock copolymer induces the micellization of triblock copolymers. Contrast variation small-angle neutron scattering measurements show that triblock copolymer forms mixed micelles with detergent and the mixing of two components in the mixed micelles is uniform.

  10. Heat Capacity of Spider Silk-like Block Copolymers.

    Science.gov (United States)

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

    2011-07-12

    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 state, we then calculated the heat capacities of our novel block copolymers based on the vibrational motions of the constituent poly(amino acid)s, whose heat capacities are known or can be estimated from the ATHAS Data Bank. For the liquid state, the heat capacity was estimated by using the rotational and translational motions in the polymer chain. Excellent agreement was found between the measured and calculated values of the heat capacity, showing that this method can serve as a standard by which to assess the Cp for other biologically inspired block copolymers. The fraction of beta sheet crystallinity of spider silk block copolymers was also determined by using the predicted Cp, and was verified by wide angle X-ray diffraction and Fourier transform infrared spectroscopy. The glass transition temperatures of spider silk block copolymer were fitted by Kwei's equation and the results indicate that attractive interaction exists between the A-block and B-block.

  11. 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.

  12. 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.

  13. 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.

  14. Relaxation processes in a lower disorder order transition diblock copolymer

    Energy Technology Data Exchange (ETDEWEB)

    Sanz, Alejandro; Ezquerra, Tiberio A.; Nogales, Aurora, E-mail: aurora.nogales@csic.es [Instituto de Estructura de la Materia, IEM-CSIC. C/ Serrano 121, Madrid 28006 (Spain); Hernández, Rebeca [Instituto de Ciencia y Tecnología de Polímeros, ICTP-CSIC. C/ Juan de la Cierva 3, Madrid 28006 (Spain); Sprung, Michael [Petra III at DESY, Notkestr. 85, 22607 Hamburg (Germany)

    2015-02-14

    The dynamics of lower disorder-order temperature diblock copolymer leading to phase separation has been observed by X ray photon correlation spectroscopy. Two different modes have been characterized. A non-diffusive mode appears at temperatures below the disorder to order transition, which can be associated to compositional fluctuations, that becomes slower as the interaction parameter increases, in a similar way to the one observed for diblock copolymers exhibiting phase separation upon cooling. At temperatures above the disorder to order transition T{sub ODT}, the dynamics becomes diffusive, indicating that after phase separation in Lower Disorder-Order Transition (LDOT) diblock copolymers, the diffusion of chain segments across the interface is the governing dynamics. As the segregation is stronger, the diffusive process becomes slower. Both observed modes have been predicted by the theory describing upper order-disorder transition systems, assuming incompressibility. However, the present results indicate that the existence of these two modes is more universal as they are present also in compressible diblock copolymers exhibiting a lower disorder-order transition. No such a theory describing the dynamics in LDOT block copolymers is available, and these experimental results may offer some hints to understanding the dynamics in these systems. The dynamics has also been studied in the ordered state, and for the present system, the non-diffusive mode disappears and only a diffusive mode is observed. This mode is related to the transport of segment in the interphase, due to the weak segregation on this system.

  15. Preparation and icephobic properties of polymethyltrifluoropropylsiloxane-polyacrylate block copolymers

    Science.gov (United States)

    Li, Xiaohui; Zhao, Yunhui; Li, Hui; Yuan, Xiaoyan

    2014-10-01

    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.

  16. Synthesis, characterization and antimicrobial activity of important heterocyclic acrylic copolymers

    Directory of Open Access Journals (Sweden)

    2008-10-01

    Full Text Available The acrylate monomer, 7-acryloyloxy-4-methyl coumarin (AMC has been synthesized by reacting 7-hydroxy-4-methyl coumarin, with acryloyl chloride in the presence of NaOH at 0–5°C. Copolymers of 7-acryloyloxy-4-methyl coumarin (AMC with vinyl acetate (VAc were synthesized in DMF (dimethyl formamide solution at 70±1°C using 2,2′-azobisisobutyronitrile (AIBN as an initiator with different monomer-to-monomer ratios in the feed. The copolymers were characterized by Fourier transform infra red (FTIR spectroscopy. The copolymer composition was evaluated by 1H-NMR (proton nuclear magnetic resonance and was further used to determine reactivity ratios. The monomer reactivity ratios for AMC (M1-VAc (M2 pair were determined by the application of conventional linearization methods such as Fineman-Ross (r1 = 0.6924; r2 = 0.6431, Kelen-Tüdõs (r1 = 0.6776; r2 = 0.6374 and extended Kelen-Tüdõs (r1 = 0.6657; r2 = 0.6256. Thermo gravimetric analysis showed that thermal decomposition of the copolymers occurred in single stage in the temperature range of 263–458°C. The molecular weights of the polymers were determined using gel permeation chromatography. The homo and copolymers were tested for their antimicrobial properties against selected microorganisms.

  17. Plastic Deformation and Morphological Evolution of Precise Acid Copolymers

    Science.gov (United States)

    Middleton, L. Robert; Azoulay, Jason; Murtagh, Dustin; Cordaro, Joseph; Winey, Karen

    2014-03-01

    Acid- and ion-containing polymers have specific interactions that produce complex and hierarchical morphologies that provide remarkable mechanical properties. Historically, correlating the hierarchical structure and the mechanical properties of these polymers has been challenging due to the random arrangements of the polar groups along the backbone, ex situ characterization and the difficulty in deconvolution the effects of crystalline and amorphous regions along with secondary interactions between polymer chains. We address these challenges through in situ deformation of precise acid copolymers and relate the structural evolution to bulk properties by considering a series of copolymers with 9, 15 or 21 carbons between acid groups. Simultaneous synchrotron X-ray scattering and room temperature uniaxial tensile experiments of these precise acid copolymers were conducted. The different deformation mechanisms are compared and the microstructural evolution during deformation is discussed. For example, the liquid-like distribution of acid aggregates within the bulk copolymer transitions into a layered structure concurrent to a dramatic increase in tensile strength. Overall, we evaluate the effect and control of introducing acid groups on mechanical deformation of the bulk copolymers.

  18. Dextran-b-poly(L-histidine copolymer nanoparticles for pH-responsive drug delivery to tumor cells

    Directory of Open Access Journals (Sweden)

    Hwang JH

    2013-08-01

    Full Text Available Jong-Ho Hwang,1,2 Cheol Woong Choi,1 Hyung-Wook Kim,1 Do Hyung Kim,3 Tae Won Kwak,3 Hye Myeong Lee,3 Cy Hyun Kim,3 Chung Wook Chung,3 Young-Il Jeong,3 Dae Hwan Kang1,3 1Department of Internal Medicine, Medical Research Institute, Pusan National University School of Medicine, Yangsan, Republic of Korea; 2Department of Internal Medicine, Busan Medical Center, Yeonje-gu, Busan, Republic of Korea; 3National Research and Development Center for Hepatobiliary Disease, Pusan National University Yangsan Hospital, Yangsan, Republic of Korea Purpose: Nanoparticles based on stimuli-sensitive drug delivery have been extensively investigated for tumor targeting. Among them, pH-responsive drug targeting using pH-sensitive polymers has attracted attention because solid tumors have an acidic environment. A dextran-b-poly(L-histidine (DexPHS copolymer was synthesized and pH-responsive nanoparticles were fabricated for drug targeting. Methods and results: A DexPHS block copolymer was synthesized by attaching the reductive end of dextran to the amine groups of poly(L-histidine. pH-responsive nanoparticles incorporating doxorubicin were fabricated and studied in HuCC-T1 cholangiocarcinoma cells. Synthesis of DexPHS was confirmed by 1H nuclear magnetic resonance spectroscopy, with specific peaks of dextran and PHS observed at 2–5 ppm and 7.4–9.0 ppm, respectively. DexPHS nanoparticles showed changes in particle size with pH sensitivity, ie, the size of the nanoparticles increased at an acidic pH and decreased at a basic pH. DexPHS block copolymer nanoparticles incorporating doxorubicin were prepared using the nanoprecipitation dialysis method. The doxorubicin release rate was increased at acidic pH compared with basic pH, indicating that DexPHS nanoparticles have pH-sensitive properties and that drug release can be controlled by variations in pH. The antitumor activity of DexPHS nanoparticles incorporating doxorubicin were studied using HuCC-T1

  19. A 3D Electroactive Polypyrrole-Collagen Fibrous Scaffold for Tissue Engineering

    Directory of Open Access Journals (Sweden)

    Kam W. Leong

    2011-02-01

    Full Text Available Fibers that can provide topographical, biochemical and electrical cues would be attractive for directing the differentiation of stem cells into electro-responsive cells such as neuronal or muscular cells. Here we report on the fabrication of polypyrrole-incorporated collagen-based fibers via interfacial polyelectrolyte complexation (IPC. The mean ultimate tensile strength of the fibers is 304.0 ± 61.0 MPa and the Young’s Modulus is 10.4 ± 4.3 GPa. Human bone marrow-derived mesenchymal stem cells (hMSCs are cultured on the fibers in a proliferating medium and stimulated with an external electrical pulse generator for 5 and 10 days. The effects of polypyrrole in the fiber system can be observed, with hMSCs adopting a neuronal-like morphology at day 10, and through the upregulation of neural markers, such as noggin, MAP2, neurofilament, β tubulin III and nestin. This study demonstrates the potential of this fiber system as an attractive 3D scaffold for tissue engineering, where collagen is present on the fiber surface for cellular adhesion, and polypyrrole is encapsulated within the fiber for enhanced electrical communication in cell-substrate and cell-cell interactions.

  20. 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.

  1. Realization of an integrated VDF/TrFE copolymer-on-silicon pyroelectric sensor

    NARCIS (Netherlands)

    Setiadi, D.; Regtien, P.P.L.; Sarro, P.M.

    1995-01-01

    An integrated pyroelectric sensor based on a vinylidene fluoride trifluoroethylene (VDF/TrFE) copolymer is presented. A silicon substrate that contains FET readout electronics is coated with the VDF/TrFE copolymer film using a spin-coating technique. On-chip poling of the copolymer has been applied

  2. A 3 x 1 Integrated Pyroelectric Sensor Based on VDF/TrFE Copolymer

    NARCIS (Netherlands)

    Setiadi, D.; Sarro, P.M.; Regtien, P.P.L.

    1995-01-01

    This paper presents an integrated pyroelectric sensor based on a Vinylidene Fluoride TriFluoroEthylene (VDF/TrFE) copolymer. A silicon substrate that contains FET readout electronics is coated with the VDF/TrFE copolymer film using a spin-coating technique. On-chip poling of the copolymer has been a

  3. 40 CFR 721.10179 - Copolymers of phenol and aromatic hydocarbon (generic).

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Copolymers of phenol and aromatic... Specific Chemical Substances § 721.10179 Copolymers of phenol and aromatic hydocarbon (generic). (a... generically as copolymers of phenol and aromatic hydocarbon (PMNs P-04-346 and P-04-347) are subject...

  4. Bandgap determination of P(VDF–TrFE) copolymer film by electron energy loss spectroscopy

    Indian Academy of Sciences (India)

    Dipankar Mandal; K Henkel; K Müller; D Schmeißer

    2010-08-01

    The ferroelectric of poly(vinylidene fluoride trifluoroethylene), P(VDF–TrFE) is confirmed for 100 nm thickness spin coated copolymer film. The homogeneous coverage of the copolymer film is investigated by the help of X-ray photoelectron spectroscopy (XPS). Most importantly, the existing bandgap in the crystalline phase of the copolymer is determined directly from the electron energy loss spectroscopy (EELS).

  5. 40 CFR 180.1162 - Acrylate polymers and copolymers; exemption from the requirement of a tolerance.

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 23 2010-07-01 2010-07-01 false Acrylate polymers and copolymers... RESIDUES IN FOOD Exemptions From Tolerances § 180.1162 Acrylate polymers and copolymers; exemption from the requirement of a tolerance. (a) Acrylate polymers and copolymers are exempt from the requirement of...

  6. 21 CFR 177.1960 - Vinyl chloride-hexene-1 copolymers.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Vinyl chloride-hexene-1 copolymers. 177.1960... Basic Components of Single and Repeated Use Food Contact Surfaces § 177.1960 Vinyl chloride-hexene-1 copolymers. The vinyl chloride-hexene-1 copolymers identified in paragraph (a) of this section or...

  7. 21 CFR 177.1970 - Vinyl chloride-lauryl vinyl ether copolymers.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Vinyl chloride-lauryl vinyl ether copolymers. 177... for Use as Basic Components of Single and Repeated Use Food Contact Surfaces § 177.1970 Vinyl chloride-lauryl vinyl ether copolymers. The vinyl chloride-lauryl vinyl ether copolymers identified in...

  8. STUDY ON THE SYNTHESIS OF COPOLYMER CONTAINING N-SUBSTITUTED ACRYLAMIDE COMPONENT

    Institute of Scientific and Technical Information of China (English)

    LI Xuefen; WANG Shenguo; LI Zhifen

    1984-01-01

    In this paper the synthesis of linear and crosslinked N-substituted acrylamide copolymer is reported. In order to obtain the terpolymer with appropriate hydrophilicity, the conditions of aminolysis of St-MMA copolymer have been selected.It is shown that the copolymer with predictable hydrophilicity possesses good blood compatibility.

  9. 21 CFR 177.1020 - Acrylonitrile/butadiene/sty-rene co-polymer.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Acrylonitrile/butadiene/sty-rene co-polymer. 177... SERVICES (CONTINUED) FOOD FOR HUMAN CONSUMPTION (CONTINUED) INDIRECT FOOD ADDITIVES: POLYMERS Substances.../butadiene/sty-rene co-polymer. Acrylonitrile/butadiene/styrene copolymer identified in this section may be...

  10. Synthesis of imide/arylene ether copolymers for adhesives and composite matrices

    Science.gov (United States)

    Jensen, B. J.; Hergenrother, P. M.; Bass, R. G.

    1991-01-01

    A series of imide/arylene ether copolymers were prepared from the reaction of an amorphous arylene ether oligomer and a semi-crystalline imide oligomer. These copolymers were thermally characterized and mechanical properties were measured. One block copolymer was endcapped and the molecular weight was controlled to provide a material that displayed good compression moldability and attractive adhesion and composite properties.

  11. 21 CFR 175.350 - Vinyl acetate/crotonic acid copolymer.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Vinyl acetate/crotonic acid copolymer. 175.350... COATINGS Substances for Use as Components of Coatings § 175.350 Vinyl acetate/crotonic acid copolymer. A copolymer of vinyl acetate and crotonic acid may be safely used as a coating or as a component of a...

  12. Compatibilizing Effect of Random or Block Copolymer Added to Binary Mixture of Homopolymers.

    Science.gov (United States)

    2014-09-26

    copolymer R50/50 (Mw 25000); filled squares: random copolymer RF50/50 (M 16300); filled diamonds : random copolymer SPP45 (Mw > 2.3 x 105); open squares...Pennsylvania 18015 Dr. R. S. Porter Professor Brian Newman Department of Polymer Science Department of Mechanics and and Engineering Materials Science

  13. 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.

  14. Efficient White Light Emission Using a Single Copolymer with Red and Green Chromophores on a Conjugated Polyfluorene Backbone Hybridized with InGaN-Based Light-Emitting Diodes

    Institute of Scientific and Technical Information of China (English)

    ZHANG Yong; HOU Qiong; NIU Qiao-Li; ZHENG Shu-Wen; LI Shu-Ti; HE Miao; FAN Guang-Han

    2009-01-01

    We report an efficient white-light emission based on a single copolymer/InGaN hybrid light-emitting diode.The single copolymer consists of a conjugated polyfluorene backbone by incorporating 2,1,3-benzothiadiazole (BT) and 4, 7-bis(2-thienyl)-2,1,3-benzothiadiazole (DBT) as green and red light-emitting units, respectively. For the single eopolymer/lnGaN hybrid device, the Commission Internationale de l'Eclairage (CIE) coordinates,color temperature Tc and color rendering index Ra at 20mA are (0.323,0.329), 5960K and 86, respectively.In comparison with the performance of red copolymer PFO-DBT15 (DOF:DBT=85:15 with DOF being 9'9-dioctylfluorene) and green copolymer PFO-BT35 (DOF:BT=65:35) blend/InGaN hybrid white devices, it is concluded that the chemically doped copolymer hybridized device shows a higher emission intensity and spectral stability at a high driving current than the polymer blend.

  15. A Photosensitive Copolymer for UV-curable Eleetrodeposition Coatings

    Institute of Scientific and Technical Information of China (English)

    LIU Ren; LI Xiaojie; AN Fenglci; ZHANG Shengwen; LIU Xiaoya

    2011-01-01

    A series of photosensitive random copolymers (UPDHES) were prepared by introducing acrylate groups onto the side chain of the copolymer backbone of N,N-domethyl amimethyl methacrylate (DMAEMA),2-hydroxypropyl acrylate (HEA),2-ethylhexyl acrylate (EHA),and styrene (St) (PDHES).The molecular structure of UPDHES was characterized by FTIR,1HNMR and GPC.The photopolymerization kinetics of UPDHES with different C=C content was investigated using real time FTIR in which it was found that the UPDHES system had notable photosensitivity.The effect of C=C content on the properties of cured films were studied by evaluating various film properties such as thermal stability,glass transition temperature and tensile properties.The thermal degradation of cured films was investigated via thermogravimetric analysis/infrared spectrometry (TGA-IR).Thus a series of UV-curable electrodeposition coatings with good photosensitivity and mechanical properties were prepared from a low-cost photosensitive random copolymer.

  16. Acrylate Copolymers as Impact Modiifer for Epoxy Resin

    Institute of Scientific and Technical Information of China (English)

    WANG Tao; WANG Jun; CHEN Wei; DUAN Huajun; YANG Shuang; CHEN Xi; ZHANG Bin

    2015-01-01

    P(BA-GMA) (PBG), having various molecular weights, was synthesized by in situ polymerization of butyl acrylate (BA) and glycidyl methacrylate (GMA), and further used as a modifier to improve the comprehensive properties of the epoxy curing system. The copolymers were characterized by gel permeation chromatography (GPC). The effects of various molecular weights of copolymers on the mechanical properties, thermal performance, and phase behavior of the curing system were carefully evaluated. The experimental results of differential scanning calorimetry (DSC) and dynamic mechanical analysis (DMA) showed that glass transition temperature decreased and the tan δ peak shifted to a lower temperature with decreasing molecular weight of copolymer. Mechanical properties analysis of curing films showed that the impact strength and fracture toughness increased significantly upon the addition of PBG, indicating good toughness of the modified epoxy resins. From scanning electron microscopy (SEM) studies of the fracture surfaces of ER/PBG systems, the fracture behavior of epoxy matrix was changed from brittleness to toughness.

  17. Performance behavior of modified cellulosic fabrics using polyurethane acrylate copolymer.

    Science.gov (United States)

    Zuber, Mohammad; Shah, Sayyed Asim Ali; Jamil, Tahir; Asghar, Muhammad Irfan

    2014-06-01

    The surface of the cellulosic fabrics was modified using self-prepared emulsions of polyurethane acrylate copolymers (PUACs). PUACs were prepared by varying the molecular weight of polycaprolactone diol (PCL). The PCL was reacted with isophorone diisocyanate (IPDI) and chain was extended with 2-hydroxy ethyl acrylate (HEA) to form vinyl terminated polyurethane (VTPU) preploymer. The VTPU was further co-polymerized through free radical polymerization with butyl acrylate in different proportions. The FT-IR spectra of monomers, prepolymers and copolymers assured the formation of proposed PUACs structure. The various concentrations of prepared PUACs were applied onto the different fabric samples using dip-padding techniques. The results revealed that the application of polyurethane butyl acrylate copolymer showed a pronounced effect on the tear strength and pilling resistance of the treated fabrics.

  18. STRUCTURE OF CRYSTALLINE DOMAINS IN SEMICRYSTALLINE BLOCK COPOLYMER THIN FILMS

    Institute of Scientific and Technical Information of China (English)

    Guo-dong Liang; Jun-ting Xu; Zhi-qiang Fan

    2006-01-01

    Thin film morphology of a symmetric semicrystalline oxyethylene/oxybutylene diblock copolymer (E76B38) on silicon was investigated by tapping mode atomic force microscopy (AFM). It is found that the nascent thin film is composed of multiple polymer layers having mixed thicknesses of L ≈ L0 and L ≈ L0/2 (L0 is the long period of the block copolymer in bulk) besides the first layer near the substrate. This shows that the crystalline domain in the block copolymer consists of double poly(oxyethylene) layers. Annealing leads to disappearance of the polymer layers with thickness L ≈ L0/2, indicating that such polymer layers are metastable.

  19. Structure of Block Copolymer Hydrogel Formed by Complex Coacervate Process

    Science.gov (United States)

    Choi, Soohyung; Ortony, Julia; Krogstad, Daniel; Spruell, Jason; Lynd, Nathaniel; Han, Songi; Kramer, Edward

    2012-02-01

    Complex coacervation occurs when oppositely charged polyelectrolytes associate in solution, forming dense micron-sized droplets. Hydrogels with coacervate block domains were formed by mixing two ABA and A'BA' triblock copolymer solutions in water where the A and A' blocks are oppositely charged. Small-angle neutron scattering (SANS) was used to investigate the structure of hydrogels formed by ABA triblock copolymers (A block: poly(allyl glycidyl ether) functionalized with guanidinium (A) or sulfonate (A'), B block: poly(ethylene oxide)). By using an appropriate fitting model, structural information such as coacervate core block radius and water volume fraction w can be extracted from SANS data. The results reveal that w in the coacervate core block was significantly higher than in conventional triblock copolymer hydrogels where microphase separation is driven by the hydrophobicity of the core-forming blocks.

  20. Solubility of dense CO2 in two biocompatible acrylate copolymers

    Directory of Open Access Journals (Sweden)

    A. R. C. Duarte

    2006-06-01

    Full Text Available Biocompatible polymers and copolymers are frequently being used as part of controlled delivery systems. These systems can be prepared using a "clean and environment friendly" technology like supercritical fluids. One great advantage of this process is that compressed carbon dioxide has excellent plasticizing properties and can swell most biocompatible polymeric matrixes, thus promoting drug impregnation processes. Mass sorption of two acrylate biocompatible copolymers contact with supercritical carbon dioxide is reported. Equilibrium solubility of dense carbon dioxide in poly(methylmethacrylate-co-ethylhexylacrylate and poly(methylmethacrylate-co-ethylhexylacrylate-co-ethyleneglycoldimethacrylate was studied by a static method at 10.0 MPa and 313 K. The reticulated copolymer had Fickean behavior and its diffusion coefficient was calculated, under operating conditions.