Dominique Teyssié

Robust solid polymer electrolyte for conducting IPN actuators

Interpenetrating polymer networks (IPNs) based on nitrile butadiene rubber (NBR) as first component and poly(ethylene oxide) (PEO) as second component were synthesized and used as a solid polymer electrolyte film in the design of a mechanically robust conducting IPN actuator. IPN mechanical properties and morphologies were mainly investigated by dynamic mechanical analysis and transmission electron microscopy. For 1-ethyl-3-methylimidazolium bis-(trifluoromethylsulfonyl)-imide (EMITFSI) swollen IPNs, conductivity values are close to 1 × 10−3 S cm−1 at 25 ° C. Conducting IPN actuators have been synthesized by chemical polymerization of 3,4-ethylenedioxythiophene (EDOT) within the PEO/NBR IPN. A pseudo-trilayer configuration has been obtained with PEO/NBR IPN sandwiched between two interpenetrated PEDOT electrodes. The robust conducting IPN actuators showed a free strain of 2.4% and a blocking force of 30 mN for a low applied potential of ±2 V.

Langmuir-Blodgett films of an alkoxy derivative of poly(3,4-ethylenedioxythiophene)

Abstract The amphiphilic character of a conducting polymer obtained by chemical polymerization of a C14 alkylated 3,4-ethylenedioxythiophene methanol monomer allowed the formation of a stable monolayer at the air-water interface. Several monolayers were transferred on a solid substrate and a lamellar well-organized structure was obtained. The doping was carried out in gas phase by NO2 and monitored by ultraviolet-visible spectroscopy and quartz crystal microbalance. The doped material showed a good conductivity as compared to other Langmuir-Blodgett films of conducting molecules.

Poly(azobenzene acrylate-co-fluorinated acrylate) spin-coated films: influence of the composition on the photo-controlled wettability.

The wetting properties of spin-coated films of copolymers based on azobenzene and fluorinated units have been investigated. The copolymers, denoted as poly(Azo-co-AcRf6), have been synthesized by free-radical polymerization of different proportions of acrylate monomers bearing either an azobenzene group or a semifluorinated side chain. The UV-visible spectroscopy analysis of the different spin-coating films through a cycle of UV and visible light irradiation indicates the reversible trans-cis isomerization of azobenzene groups. Simultaneously, atomic force microscopy shows that surface roughness does not exceed 1 nm. Advancing and receding contact angles of water and diiodomethane have been measured before and after UV photoirradiation of the different surfaces. In particular, a decrease in the advancing contact angles has been observed upon trans-cis isomerization of azobenzene groups. Switching variations up to 50° have been evidenced without any introduction of surface nanoroughness. Surface free-energy evaluations have been deduced from these measurements, including dispersive and polar components. The results show that, through surface composition and UV photoirradiation, a large range of surface free-energies can be obtained, from 7 to 46 mN·m(-1).

Interfacial polymerization of a 3,4-ethylenedioxythiophene derivative using Langmuir–Blodgett technique. Spectroscopic and electrochemical characterizations

Abstract In this study, we have used an EDT derivative with a tetradecyloxy chain (EDTMC14) that renders the monomer soluble in organic solvents as well as suitable for Langmuir–Blodgett (LB) experiments. EDTMC14 monomer was investigated regarding its spreading and polymerization behavior at the air–water interface. The polymerization at the interface depends on the CAN concentration and pH in the subphase. For comparison, we have studied the behavior of the corresponding polymer (PEDTMC14) obtained by chemical polymerization. The different LB films showed the same characteristics in FTIR spectroscopy and electrochemistry and conductivity measurements. These results may indicate that both polymers have essentially the same molecular structure in the p-doped state, and that the pre-organization of the monomers in the Langmuir films seems to have no dramatic influence on the polymer properties.

Liquid crystalline side-chain polymers. 1. Polysiloxanes with a carbonate group in the spacer

Abstract A series of new allyl and vinyl carbonates has been prepared by the reaction of allyl and vinyl chloroformates with 4-hydroxyphenyl esters of p -substituted benzoic acid, under phase-transfer catalysis conditions. These compounds, which exhibit nematic phases, have been bound onto a polysiloxane backbone by hydrosilylation. The side-chain polymers have been examined by 1 H and 13 C n.m.r. spectroscopy, g.p.c., differential scanning calorimetry and optical polarizing microscopy.

Synthesis, thermal and surface characterization of fluorinated polystyrenes

Three styrene derivatives bearing fluoroalkyl substituents in para or (meta/para) positions have been synthesized under phase-transfer-catalysis conditions. Homopolymers and copolymers with styrene have been prepared by free-radical polymerization. The monomer reactivity ratios of each monomer with styrene are determined by the Kelen–Tudo″s method. The results show that the fluoroalkyl substituent does not significantly affect the reactivity of the styrene double bond. Thermal and surface properties of the copolymers have been examined. Copolymers from the para-substituted styrene derivative show higher glass transition temperatures (Tg) than those obtained with the mixture of isomers. Low dispersive surface energies (11 < γ < 17 mNm-1) are determined from contact angle data measured with the Wilhelmy plate method. © 1999 Society of Chemical Industry

Anionic polymerization and copolymerization of cyclosiloxanes initiated by trimethylsilylmethyllithium

SummaryA novel initiator, i.e. trimethylsilylmethyllithium has been successfully used for the ring opening polymerization of cyclosiloxanes, in toluene or in the bulk, in the presence of the cryptand [211] or DMSO. Suitable conditions have been found in which monomodal distributions of molecular weights are observed for homopolymers of 1,3,5,7-tetramethyl-1,3,5,7-tetravinylcyclotetrasiloxane (V4) as well as for copolymers of V4 with D3 or D4.

A convenient approach to perfluorinated organosilicons. Preparation of a fluorinated polysiloxane precursor

Abstract Addition of perfluorooctyl iodide to the double bonds of vinyltrimethylsilane and 1,3-divinyltetramethyldisiloxane, followed by a reduction of the carbon-iodide bond, gives the corresponding C 8 F 17 CH 2 CH 2 Si moicty. Following this approach, |C 8 F 17 CH 2 CH 2 Si(Me)O| 4 . a precursor of highly fluorinated silicones. was conveniently prepared. without using hydrosilylation or Grignard reaction.

Synthesis and characterization of photosensitive cinnamate-modified cellulose acetate butyrate spin-coated or network derivatives

The photochemical behavior of photosensitive materials obtained by spin-coating or network synthesis of a cellulosic polymer bearing photo-cross-linkable cinnamate groups was investigated. First, cinnamate groups were grafted on a cellulose acetate butyrate polymer, with different grafting densities. The photochemical properties of the polymers were studied in solution by UV–visible and 1H NMR spectroscopy. Then spin-coated films and networks were prepared and characterized as a function of the number of cinnamate groups per cellulosic unit. The water-wetting properties of both surfaces were studied by dynamic contact angle measurements, before and after photoirradiation, and subsequent heating. The surfaces obtained by the two methods have significantly different behaviors that can be assigned to the distinct photochemical pathways of the cinnamate groups upon irradiation depending on the sample preparation. Indeed, dimerization reaction is evidenced as the main process in the spin-coated films while the expected isomerization is predominant at the surface of the polymer networks.

Synthesis and properties of liquid crystalline polysiloxanes

Most studies on the structure-property relationship of liquid crystalline polysiloxanes are focused on the side-chain-type polymers bearing calamitic or discotic side groups decoupled from the backbone via a flexible spacer. However, main-chain liquid crystalline polymers have been obtained by combining flexible siloxane segments with rigid rod-type mesogens. The synthesis and properties of these two types of liquid crystalline polysiloxanes are examined. One of the most widely used methods of preparation is the hydrosilylation of unsaturated mesogens. However, this reaction is not always as clean and clear-cut as would be necessary for the obtention of polymers with reproducible characteristics. This point is discussed and specific examples of side reactions are given. Some data concerning liquid crystalline polysiloxanes with no mesogenic groups as well as liquid crystalline elastomers are presented. Potential applications of these polymers and future developments are discussed.