Self-Assembly and Photoresponsive Behavior of Amphiphilic Diblock Copolymers Containing Azobenzene Moieties

Abstract

An amphiphilic diblock copolymer, poly(ethylene oxide)-block-poly {6-[4-(4-ethoxyphenylazo)phenoxy] hexyl methacrylate}, was synthesized using atom transfer radical polymerization. In the solution of tetrahydrofuran and water, the diblock copolymer formed micrometer scale vesicles by self-assembly. Under the irradiation of UV light at 365 nm, these microvesicles generated such photoresponsive behavior as photoinduced expansion, swelling and fusion due to trans-cis photoisomerization of azobenzene units. The self-assembled vesicles even enlarged to be about five times their original size because of photoinduced fusion.

Keywords:

• amphiphilic block copolymer
• azobenzene
• microvesicle
• photodeformation
• self-assembly

Acknowledgments

Financial supports from National Natural Science Foundation of China (No. 50873028), Shuguang Plan of Shanghai Education Development Foundation (05SG07), Shanghai Rising-Star Program (06QA14009) and Shanghai Leading Academic Discipline Project (B113) are gratefully acknowledged.

Notes

^a G, glass; N, nematic; I, isotropic.

^b Calculated from ¹H-NMR data.