Post-polymerization modification of reactive polymers derived from vinylcyclopropane: a poly(vinylcyclopropane) derivative with physical gelation and UCST behaviour in ethanol–water mixtures†
In this paper we describe a new polymer that combines an upper critical solution temperature (UCST) and reversible physical gelation in ethanol–water mixtures. The polymer, namely poly(1-cyano-N-propylcarboxyamidovinylcyclopropane) (poly(CNPCAVCP)), was synthesized by post-polymerization modification of poly(1-cyano-1-pentafluorophenoxycarbonyl-2-vinylcyclopropane) (poly(CPFPCVCP)) with n-propylamine. The stimuli responsiveness of the polymer was investigated in ethanol and ethanol–water mixtures by varying the water concentration in the mixture. It was found that, depending on the water concentration, the mixture features an upper critical solution temperature (UCST), physical gelation or both. In addition, it was observed that the hysteresis between the heating and the cooling phase was very large (about 45 °C).