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

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(2)MA-b-PDMAEMA-b-PEG-b-PDMAEMA-b-PMEO(2)MA) was synthesized by sequential atom transfer radical polymerization (ATRP). The copolymer is hydrophilic at low temperature and pH values (at temperatures lower than 26 degrees 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 degrees 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. (C) 2011 Elsevier B.V. All rights reserved.