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Chemical Polymerization (chemical + polymerization)

Distribution by Scientific Domains
Polymers and Materials Science80%

Terms modified by Chemical Polymerization

  • chemical polymerization method
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    Selected Abstracts

    Electrochemical polymerization and characterization of polyether-substituted aniline derivatives

    POLYMER INTERNATIONAL, Issue 8 2007
    Seha Tirke
    Abstract New compounds consisting of aniline units linked by polyether bridges have been synthesized and their electrochemical polymerization was performed via constant potential electrolysis and cyclic voltammetry in an aqueous solution containing 3.0 mol L,1 H2SO4. Chemical polymerization was carried out using (NH4)2S2O8 as oxidizing agent. It was found that both methods gave the same polymer product without any cleavage of the polyether bridge between aniline rings. The polymers were characterized using the Fourier transform infrared spectroscopic technique and the thermal behavior of electrochemically prepared polymers was investigated using thermogravimetric analysis. Spectroelectrochemical properties of the films were investigated using the in situ UV-visible spectroscopic technique. Copyright © 2007 Society of Chemical Industry [source]

    Polymerization at the gas/solution interface: Preparation of polymer microstructures with gas bubbles as templates

    JOURNAL OF APPLIED POLYMER SCIENCE, Issue 4 2007
    Maciej Mazur
    Abstract We report on the chemical polymerization of 2-methoxyaniline at the interface between an aqueous solution and air. The polymer is formed in the interfacial region, whereas the soluble trimer is yielded in the bulk of the polymerization solution. The preferential polymerization of 2-methoxyaniline is discussed in terms of monomer and oligomer accumulation at the interface, which influences the reactivity of these species and allows further polymerization. The phenomenon of polymer growth is employed to selectively deposit polymeric material onto glass slides decorated with gas microbubbles. Because of preferential polymerization at the bubble/solution interface, hemispherical features are produced on the surface of glass. When some polymeric material is mechanically removed, microrings or microholes are obtained. The anomalous polymerization of 2-methoxyaniline is compared to that of 2-methylaniline. This monomer polymerizes uniformly within the entire volume of the reaction mixture; thus, no preferential polymer formation at the gas/solution interface is observed. As a result, deposition on microbubble-decorated glass slides produces polymeric films containing a number of microholes. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007 [source]

    Polypyrrole Thin Films Formed by Admicellar Polymerization Support the Osteogenic Differentiation of Mesenchymal Stem Cells

    MACROMOLECULAR BIOSCIENCE, Issue 8 2004
    Harold Castano
    Abstract Summary: The objective of this study was to evaluate the attachment, proliferation, and differentiation of rat mesenchymal stem cells (MSC) toward the osteoblastic phenotype seeded on polypyrrole (PPy) thin films made by admicellar polymerization. Three different concentrations of pyrrole (Py) monomer (20, 35, and 50,×,10,3M) were used with the PPy films deposited on tissue culture polystyrene dishes (TCP). Regular TCP dishes and PPy polymerized on TCP by chemical polymerization without surfactant using 5,×,10,3M Py, were used as controls. Rat MSC were seeded on these surfaces and cultured for up to 20 d in osteogenic media. Surface topography was characterized by atomic force microscopy, X-ray photoelectron spectroscopy, and static contact angle. Cell attachment, proliferation, alkaline phosphatase (ALP) activity, and calcium content were measured to evaluate the ability of MSC to adhere and differentiate on PPy-coated TCP. Increased monomer concentrations resulted in PPy films of increased thickness and surface roughness. PPy films generated by different monomer concentrations induced drastically different cellular events. A wide spectrum of cell attachment characteristics (from excellent cell attachment to the complete inability to adhere) were obtained by varying the monomer concentration from 20 m to 50,×,10,3M. In particular the 20,×,10,3M PPy thin films demonstrated superior induction of MSC osteogenicity, which was comparable to standard TCP dishes, unlike PPy films of similar thickness prepared by chemical polymerization without surfactant. Adhesion of mesenchymal stem cells on tissue culture plates (TCP) coated with polypyrrole thin films made by admicellar polymerization. [source]

    Effects of alcoholic solvents on the conductivity of tosylate-doped poly(3,4-ethylenedioxythiophene) (PEDOT-OTs)

    POLYMER INTERNATIONAL, Issue 1 2006
    Tae Young Kim
    Abstract The effects of alcoholic solvents on the charge transport properties of tosylate-doped poly(3,4-ethylenedioxythiophene) (PEDOT-OTs) are investigated. The use of different alcoholic solvents in the oxidative chemical polymerization of 3,4-ethylenedioxythiophene (EDOT) with iron(III)- p -tosylate led to a change in the electrical conductivity of PEDOT-OTs. For example, PEDOT-OTs prepared from methanol shows a conductivity of 20.1 S cm,1 which is enhanced by a factor of 200 as compared to PEDOT-OTs prepared from hexanol. The variation of charge transport properties on the use of different alcoholic solvents is consistent with the data recorded by UV-visible and electrospin resonance (ESR) measurements. From XPS experiments, the PEDOT-OTs samples prepared from different alcoholic solvents were found to have almost the same doping level, suggesting that the number of charge carriers is not responsible for the change in conductivity. Supported by XRD results, it was found that the use of alcoholic solvents with shorter chain length induces more efficient packing of PEDOT chains. It is proposed that the alcoholic solvents associated with the counter ion of PEDOT via hydrogen bonding give rise to a change in the molecular ordering of PEDOT chains during the polymerization step, hence enhancing or depressing the inter-chain hopping rate of the resulting PEDOT-OTs. Copyright © 2005 Society of Chemical Industry [source]

    Synthesis and utilization of E. coli -encapsulated PEG-based microdroplet using a microfluidic chip for biological application

    BIOTECHNOLOGY & BIOENGINEERING, Issue 4 2010
    Kyoung G. Lee
    Abstract We report herein an effective strategy for encapsulating Escherichia coli in polyethylene glycol diacrylate (PEGDA) microdroplets using a microfluidic device and chemical polymerization. PEGDA was employed as a reactant due to the biocompatibility, high porosity, and hydrophilic property. The uniform size and shape of microdroplets are obtained in a single-step process using microfluidic device. The size of microdroplets can be controlled through the changing continuous flow rate. The combination of microdroplet generation and chemical polymerization techniques provide unique environment to produce non-toxic ways of fabricating microorganism-encapsulated hydrogel microbeads. Due to these unique properties of micro-sized hydrogel microbeads, the encapsulated E. coli can maintain viability inside of microbeads and green fluorescent protein (GFP) and red fluorescent protein (RFP) genes are efficiently expressed inside of microbeads after isopropyl- , - D -thiogalactopyranoside induction, suggesting that there is no low-molecular weight substrate transfer limitation inside of microbeads. Furthermore, non-toxic, gentle, and outstanding biocompatibility of microbeads, the encapsulated E. coli can be used in various applications including biotransformation, biosensing, bioremediation, and engineering of artificial cells. Biotechnol. Bioeng. 2010;107:747,751. © 2010 Wiley Periodicals, Inc. [source]