Multiple morphologies of self-assembled star aggregates of amphiphilic PEO-b-PNPMA diblock copolymers in solution,synthesis and micellization

摘要

Novel amphiphilic block copolymers,poly(ethylene oxide)-b-poly(p-nitrophenyl methacrylate) (PEO-b-PNPMA) with controlled molecular weights and narrow molecular weight distribution were successively synthesized by ATRP of NPMA using PEO-Br as initiator.Self-assembling of the diblock copolymer PEO113-b-PNPMA28 in the different solvent mixtures yielded various morphologies of star micelle-like aggregates,such as spheres,vesicles,cauliflower-like aggregates and rod-like aggregates,which are determined by the nature of the common solvents and the selective solvents.Thus the critical selective solvent contents and the solvent contents in PNPMA-rich phase were measured,and they have the following order:ethanol > methanol > water,and THF > CH3NO2 > DMSO.The probable self-assembling mechanism is discussed.This method is convenient for preparation of multiple morphological star micelle-like aggregates in solution,especially from the amphiphilic block copolymers with relatively longer block shell.