Photo-activated shape memory polymer with chiral twisting based on anisotropic bilayer thin sheets

The remotely controlled shape memory behaviors of a two-dimensional (2D) sheet to controlled helix structure upon external stimuli is of great significance in the field of smart materials. Herein, we devise a strategy to fabricate a series of shape memory polycaprolactone/[W.sub.18][O.sub.49] nanowire film via highly efficient UV-triggered thiol-acrylate click chemistry. The resultant polymer composites exhibited desirable photothermal transfer efficiency and can enable rapid temperature increase over the melting temperature of polymeric matrix, thus remotely actuating shape transformation within 8 s. Owing to the well- defined architecture of the polymer network, the fabricated elastic composite film exhibited a high degree of crystallinity and showed excellent shape memory properties with [R.sub.f] of 93.12% and [R.sub.r] of 95.32%. Remarkably, under a 160 mW/[cm.sup.2] simulated sunlight illumination, the transformation of flat 2D film into 3D chiral actuators is driven by designing anisotropic bilayer thin sheet, and it yields right- and left-handed helix. This work will pave the way for designing biomimetic flexible actuators toward multifunctional shape-shifting devices. Highlights * Shape memory polycaprolactone/[W.sub.18][O.sub.49] nanowires composite film is fabricated via UV-triggered thiol-ene click chemistry. * Polymer composites exhibit light-activated shape memory behaviors. * The composite films show excellent shape fixity and shape recovery ratio based on the well-defined network. * The shape morphing behaviors of a flexible 2D bilayer strip into 3D chiral actuators are achieved. KEYWORDS flexible actuators, polycaprolactone, shape memory polymers, stimuli- responsive polymers
1 | INTRODUCTION Stimuli-responsive morphing materials belong to one kind of molecules with 'intelligent' behavior, which can generate corresponding response signals upon the stimuli of heat, light, electric field, etc. [...]