SYNTHESIS, HOMOPOLYMERIZATION, AND BLOCK COPOLYMERIZATION OF N-ETHYL-2-ETHYNYL-PYRIDINIUM TRIFLUOROMETHANESULFONATE WITH STYRENE AND BUTADIENE

A novel acetylenic monomer 2-N-ethyl pyridinium trifluoromethane sulfo nate (2EPyEtTf) was synthesized and polymerized. Diblock copolymers of 2EPyEtTf with styrene and with butadiene were prepared. Initiation of the polymerization by living anionic polystyryl(-)-Li+ and polybutadi enyl(-)-Li+ (Scheme 1) resulted in polystyrene-block-poly(N-ethyl-2-et hynylpyridinium trifluoromethanesulfonate) (PS(57)PA(8)), and lybutadi ene-block-poly(N-ethyl-2-ethynylpyridinium trifluoromethanesulfonate) (PB(30)PA(8)). These amphiphilic block. molecules contain rigid, conju gated, and strongly hydrophilic polyacetylene chain fragments attached to hydrophobic polystyrene or flexible polybutadiene chain fragments. The structure of these copolymers was studied by FTIR, UV-visible, an d NMR spectroscopy. GPC and viscometry were also used to obtain inform ation on the molecular mass and the molecular mass distribution. Therm al behavior was investigated by means of TGA and DSC. Both block copol ymers were shown to form stable monolayers at the air-water interface. The positively charged rigid polyacetylene portion of the copolymer i s believed to be partially submerged, while the more flexible hydropho bic chains are forced out of the water. Multilayers of PB(30)PA(8) dep osited using the Langmuir-Blodgett technique were found to be less uni form than in the case of the previously reported polystyrene-bloch-pol y (2EPyMeTf)(PS(12)PA(4)) copolymer (Balogh et al., Macromolecules, 29 , 1996). Polycation-polyanion self-assembly deposition was also invest igated, using polystyrenesulfonate (PSS) as polyanion. While PS(57)PA( 8)/PSS layer-by-layer deposition was not uniform, it was found that PB (30)PA(8)/PSS gave homogenous and stable films on hydrophilic glass su bstrates. (C) 1998 John Wiley & Sons, Inc.