Assembly behavior of double thermo-responsive block copolymers with controlled response temperature in aqueous solution

We reported the synthesis of double thermo-responsive block copolymers comprised of a poly(N-isopropylacrylamide (NIPAAm)) block and a poly(NIPAAm-co-N-(hydroxymethyl)acrylamide (HMAAm)) block, which was synthesized using an atom transfer radical polymerization (ATRP) technique. The cloud point of the poly(NIPAAm-co-HMAAm) (NH) block could be easily controlled by altering the HMAAm content. Below the cloud point of polyNIPAAm (N) block, the block copolymers were completely dissolved. Between the cloud points of each block, the block copolymer formed the aggregate structure that could be constructed with the hydrated NH shell and the dehydrated N core. Moreover with increases in temperature, the diameter decreased due to the dehydration of the NH block shell. The response was completely reversible by changes in temperature, as confirmed by 1H NMR, turbidity, and FE-SEM measurements.

Double thermo-responsive block copolymers were conveniently prepared in a single pot using the ATRP technique. These assembly-related behaviors were completely reversible via changes in temperature.Figure optionsDownload as PowerPoint slide