The fabrication of desired structures is one of the most urgent topics in current research on porous polymer films. Herein, directional photomanipulation in conjunction with breath figure processing has been demonstrated for the preparation of porous polymeric films with finely tunable pore shape and size. Because of the photoinduced directional mass migration of azobenzene units upon vertical incident linearly polarized light (LPL) irradiation, round pores on honeycomb films can be reshaped into multifarious shapes including rectangle, rhombus, dumbbell, line, and so forth. In addition, slantwise LPL irradiation produces unique asymmetrical structure inside the pores oriented along the polarized direction. On the other hand, circularly polarized light (CPL) irradiation affords manipulation of the wall thickness without changing the pore shape. This versatile directional photomanipulation method can be implemented to large-area and high-throughput reshaping processes, which paves the way to a number of promising applications such as a flexible etching mask for patterning.
Keywords: azobenzene; block copolymers; photomanipulation; porous films; self-assembly.