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2. Electrochemically synthesized polypyrrole nanotubules: effects of different experimental conditions

Author

Roger Legras, Etienne Ferain, Sophie Demoustier-Champagne, Robert Jérôme, and Christine Jérôme

Subjects
Conductive polymer, Aqueous solution, Materials science, Polymers and Plastics, Nanoporous, Organic Chemistry, General Physics and Astronomy, Electrolyte, Electrosynthesis, Polypyrrole, Electrochemistry, chemistry.chemical_compound, chemistry, Polymerization, Chemical engineering, Polymer chemistry, Materials Chemistry
Abstract

Nanotubules of polypyrrole (PPy) were electrochemically synthesized using the pores of nanoporous polycarbonate (PC) particle track-etched membranes (PTM) as templates. The influence of some conditions of electrosynthesis (electrochemical method, monomer concentration, electrolyte concentration and nature) on the kinetics of pyrrole electropolymerization and on the morphology of the obtained nanomaterials has been investigated. In particular, the empirical kinetics of the electrochemical generation of polypyrrole-perchlorate (PPy-ClO4) from aqueous solution, at 0.8 V (vs SCE) was followed by electrical charges measurement. The orders with respect to pyrrole and LiClO4 are 0.34 and 0.70 respectively. The electrogeneration of polypyrrole-polystyrenesulfonate (PPy-PSS) was also followed and shows that an increase of the electrolyte concentration increases the polymerization rate at constant potential. Finally, the morphology of PPy nanotubules doped with LiClO4 and NaPSS has been studied by high resolution emission SEM and by TEM. (C) 1998 Elsevier Science Ltd. Ail rights reserved.

Published
1998

3. Synthesis and characterization of α,ω-dichloro-polymethylphenylsilane

Author

Jacques Devaux, Jacqueline Marchand-Brynaert, and Sophie Demoustier-Champagne

Subjects
chemistry.chemical_classification, Polymers and Plastics, Organic Chemistry, General Physics and Astronomy, Concentration effect, Polymer, Nuclear magnetic resonance spectroscopy, Ring-opening polymerization, Wurtz reaction, chemistry, Polymerization, Yield (chemistry), Polymer chemistry, Materials Chemistry, Physical chemistry, Molar mass distribution
Abstract

The synthesis of a functional polysilane, alpha,omega-dichloro-polymethylphenylsilane (alpha,omega-dichloro-PMPS), based on the Wurtz-type reductive coupling, has been considered. A study of some reaction parameters shows that both yield and molecular weight distribution of alpha,omega-dichloro-PMPS can be greatly influenced by the work-up conditions, reaction time, monomer concentration and temperature during the initiation of the polymerization. By varying the synthesis conditions, different ratios of high and low molecular weight fractions were obtained. Samples of different molecular weight were isolated by fractional precipitation of the crude polymers. The chlorine-end functionalization was confirmed by Si-29 NMR spectroscopy and the concentration of end-groups was quantitatively determined by elemental analysis of chlorine. Copyright (C) 1996 Elsevier Science Ltd

Published
1996

4. Factors impacting protein adsorption on layer-by-layer assembled stimuli-responsive thin films.

Author

Fustin, C.-A., Demoustier-Champagne, S., Osypova, A., Pradier, C.-M., and Landoulsi, J.

Subjects
*PROTEIN synthesis, *ADSORPTION (Chemistry), *STIMULUS & response (Biology), *POLYELECTROLYTES, *BLOCK copolymers
Abstract

Studying the stimuli-response of polyelectrolyte multilayers (PEMs) towards protein adsorption requires coping with the multiplicity of factors influencing interfacial processes. In this study, we report the design of a nanostructured stimuli-responsive coating based on the sequential layer-by-layer assembly of poly(N-isopropylacrylamide) block copolymers with poly (allylamine hydrochloride) and scrutinize its ability to modulate protein adsorption. The results reveal that the stimuli-response of the film towards protein adsorption under T, pH and I changes is strongly influenced by the type of buffer. This latter parameter has indeed a significant impact on the adsorbed amount of proteins, while it has only slight effect on the stimuli-response of free block copolymer, on the mechanism of PEM growth and the properties of the obtained film. In conditions favorable to protein adsorption, the use of anionic buffer leads to the adsorption of an apparent monolayer of proteins, while in zwitterionic buffer, proteins adsorb in a significantly higher amount. This trend may be explained by a more efficient charge screening of macromolecules by zwitterions which reduce the repulsion between proteins, leading to their accumulation at the interface. Finally, the length of the poly(N-isopropylacrylamide) block is shown to be another key factor impacting the amount of adsorbed proteins. The findings reported in this paper provide relevant information and allow the evaluation of stimuli-response of PEM to be carried out under optimized conditions. [ABSTRACT FROM AUTHOR]

Published
2017
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