Synthesis of Thermally Switchable Poly(N-isopropylacrylamide-block-dendronized methacrylate)s

A series of water-soluble linear diblock copolymers were synthesized, and their thermally switchable behavior under aqueous conditions was investigated. One block of these copolymers consists of poly( N -isopropylacrylamide) [poly( N iPAM)] and the other of positively charged first- and second-generation dendronized polymethacrylates [ PG1 and PG2 ]. The copolymers were prepared via reversible addition−fragmentation chain transfer (RAFT) polymerization and the block lengths varied. The thermally switchable aggregation behavior of the copolymers was investigated by 1 H NMR and fluorescence spectroscopy, and the lower critical aggregation temperatures (LCATs) were determined by turbidity measurements using UV/vis spectroscopy. Some of these block copolymers at elevated temperature formed supramolecular assemblies in the size range of 50−400 nm whose structures were investigated by transmission electron microscopy (TEM).