Characterization of Thermo-Responsive Poly [N-(2-hydoxypropyl) Methacrylamide-Dimethylsiloxane] Block Copolymers
Nobuyuki TANIGAWA, Kohei SHIRAISHI and Kazuo SUGIYAMA
Abstract:Block copolymers, Poly（HPMA-b-DMS）-1〜7, were obtained from polymerization of N-（2-hydroxypropyl） methacrylamide （HPMA） initiated with polydimethylsiloxane （PDMS） type of azo-initiator [4,4'-azobis（polydimethylsiloxane）-4-cyanopentanoate （azo-PDMS）]. From XPS measurements of freeze dried samples, the hydrophilic PHPMA segment was found to migrate to the surface of Poly（HPMA-b-DMS） films in water. Poly（HPMA-b-DMS） showed lower contact angle （θ= 54°〜100°） than PDMS itself （θ= 103°）. It was also found that the contact angle of block copolymers was changed in response to change in temperature, I.e., θ= 64°〜 79° at 40℃ andθ= 54°〜69° at 20℃ for Poly（HPMA-b-DMS）. The amount of adsorption of albumin on the Poly（HPMA-b-DMS） film was depressed at 20℃ compared to the case at 40℃. For the purpose of an application to a thermo-responsive drug delivery system, copolymer hydrogel Gel（HPMA-b-DMS） was also prepared by radical copolymerization of HPMA and N,N'-ethylenebisacrylamide initiated with azo-PDMS. Key Words:Block copolymers, Polydimethylsiloxane, N-（2-hydroxypropyl) methacrylamide, Thermo-responsive, Copolymer hydrogel, Swelling-shrinking change