Synthesis and self-assembly of double-hydrophilic pentablock copolymer with pH and temperature responses via sequential atom transfer radical polymerization

Abstract

ABCBA pentablock double-hydrophilic copolymer of poly(diethylene glycol monomethyl ether methacrylate)- block-poly(2-( N,N-dimethylamino)ethyl methacrylate)- block-poly(ethylene glycol)- block-poly(2-( N,N-dimethylamino)ethyl methacrylate)- block-poly(diethylene glycol monomethyl ether methacrylate) (PMEO 2MA- b-PDMAEMA- b-PEG- b-PDMAEMA- b-PMEO 2MA) was synthesized by sequential atom transfer radical polymerization (ATRP). The copolymer is hydrophilic at low temperature and pH values (at temperatures lower than 26 °C and acidic pH values), and became amphiphilic when pH and (or) temperature changed. Investigation shows that the copolymer can self-assembly into micelles with various structures under the conditions of temperature higher than 26 °C or basic solutions. The self-assembly behavior and multi-responsive properties of the copolymer in water were investigated by DLS and TEM. The self-assembly behavior of the copolymer can be adjusted by the alteration of pH values or temperature. Therefore, the copolymer will have the potential applications in biomedical field.