王磊

Single-crystal to single-crystal photopolymerization reaction of a one-dimensional (1D) vinyl coordination polymer (CP) produces a two-dimensional CP accompanied by an unprecedented phenomenon of photoinduced nonlinear lattice expansion. This 1D CP can be uniformly mixed with polyvinyl alcohol to form a composite film that exhibits macroscopic photomechanical motions such as bending, rolling, unrolling, lifting, grasping and jacking.

Abstract

We report a unique vinyl coordination polymer (CP), [Zn(4-Fb)₂(tkpvb)] _n (1, 4-HFb=4-fluorobenzoic acid, tkpvb=1,2,4,5-tetrakis(4-pyridylvinyl)benzene) that undergoes a rare photopolymerization reaction to form a two-dimensional CP integrated with a one-dimensional linear organic polymer. Upon light irradiation at different wavelengths, 1 exhibits an unprecedented phenomenon of photoinduced nonlinear lattice expansion. 1 can be uniformly dispersed in polyvinyl alcohol (PVA) to form the composite film of 1-PVA. When this film is exposed to UV light, internal minute stresses within crystallites are released by lattice expansion, resulting in a variety of photopolymerization-driven macroscopic mechanical motions. The findings provide new insights into the conversion of small lattice expansions of CPs into macroscopic mechanical motions based on photopolymerization reactions, which can promote the development of CPs-based smart photoactuators in the burgeoning field of microrobotics.