Temperature- and Light-Responsive Polyacrylamides Prepared by a Double Polymer Analogous Reaction of Activated Ester Polymers

Two different series of polyacrylamides containing different amounts of salicylideneaniline moieties have been synthesized via a double polymer analogous reaction of poly(pentafluorophenyl acrylate) (PPFPA). All copolymers were designed to exhibit a lower critical solution temperature (LCST) in aqueous solution, which was dependent on (i) the amount of incorporated chromophoric salicylideneaniline groups and (ii) the isomerization state of the respective salicylideneaniline group. Higher LCST values were measured for UV-irradiated solutions of the copolymers in comparison to the nonirradiated copolymer solutions. A maximum difference in the LCST of up to 13 degrees C was found for poly(N-cyclopropylacrylamide) copolymer containing 15.0 mol % of salicylideneaniline groups. Within this temperature range, a reversible solubility change of the copolymer could be induced by irradiation with light.