Abstract:
Shape memory polymers (SMPs) are a class of smart polymers possessing reversible shape changing and recovery capabilities which have been widely implemented in both technological innovations and fundamental researches. Porous films with shape memory capability have significant advantages for applications in separation, tissue-engineering, microelectronics, photonic band gap materials and lithography. However, due to the difficulty for manipulating shape changing of pores by traditional methods, few shape memory porous films have been developed. Recently, Prof. Shaoliang Lin and co-workers at East China University of Science and Technology (ECUST) have presented a well-designed way to light-driven shape memory porous films. In their study, a new design of shape memory porous films by combining
in-situ crosslinking approach with directional light-manipulation technique was proposed. Diblock copolymer with potential for SMPs was synthesized and then employed to fabricate honeycomb films by a facile "breath figure" method. Through
in-situ crosslinking of solid porous films, a two-phase system with the stable network of crosslinked poly(4-vinylpyridine) blocks and reversible phase of photo-responsive azobenzene-containing blocks was readily fabricated. By subsequent directional light-manipulation, honeycomb round pores could be deterministically converted into rectangular shape, rhombus shape or diminished pores. Due to the cooperation of two phase structures, these reshaped pores could perfectly restore to their original structures upon thermal annealing or UV irradiation. This new design of SMPs could circumvent the predicament of traditional SMPs which were based on mechanical deformation and thermal activation, and thus possessed great advantages in the manufacture of novel shape memory microstructures.