The Temperature-Responsive Nanoassemblies of Amphiphilic Random Copolymers Carrying Poly(siloxane) and Poly(oxyethylene) Pendant Chains

Novel amphiphilic random copolymers carrying poly(oxyethylene) and poly(siloxane) pendant chains are synthesized by atom transfer radical polymerization starting from either a fluorescent, julolidine-based initiator, or a nonfluorescent initiator. For both copolymer systems, dynamic light scattering measurements carried out on aqueous solutions as a function of temperature reveal the occurrence of a sharp and fully reversible transition between two different self-associative states of individual, single-chain self-folded nanoassemblies, so-called unimer micelles, (D-h = 8-10 nm) and collapsed multichain aggregates (D-h = 700-1400 nm) at a critical temperature T-c. Covalently linked julolidine terminal and added ethidium bromide are separately used as fluorescent probes and both prove the temperature-dependence of the different self-association of the copolymers in water.