Gel formation in organic solvents: synthesis and association of copolymers of N,N-dimethylacrylamide and methacrylates having perfluorocarbon pendent groups connected through polyethyleneoxide spacers

摘要

Over the past few years the study of hydrophobically associating polymers has continued to be of interest. It was demonstrated that hydrophilic polymers such as polyacrylamide (PAM) or N,N-dimethylacrylamide (PDMA) wit perfluorocarbon acrylate methacrylate and similar comonomers show an associative tendency that exceeds that of the corresponding polymers with hydrocarbon groups with the same carbon number. Increasing the length of spacers between the hydrophilic groups and the main chain was demonstrated to increase polyacrylamide association by Schulz et al. for hydrocarbon- and by Hwang and Hogen-Esch for perfluorocarbon (R_F) pendent groups. In the latter case the spacers were limited to between one and three oxymethylene units. Here we report the synthesis and characterization of poly (N,N-dimethylacrylamide) (PDMA) copolymers synthesized by copolymerization of DMA and methacrylate comonomers having pendent 2,2'-dihydroperfluorodecanoyl groups connected via PEG chains with number average MW's of between 1000 and 14,800 (23-336 EO units) (Scheme 1). The choice of PDMA as the carrier chain was based on its excellent solubility in organic solvents such as benzene, methanol, THF, dioxane etc. as well as in aqueous media. This allows copolymerizations in non-aqueous solvents thus avoiding in need for surfactants that may greatly affect viscosities for instance through micellar bridging.