3D shape change of multi-responsive hydrogels based on a light-programmed gradient in volume phase transition

Abstract

We present a new multi-responsive hydrogel based on oligo(ethylene glycol) methacrylate (OEGMA) and incorporating the photosensitive monomer 4-acetoxystyrene (AOST). Light irradiation creates a gradient in the volume phase transition temperature (VPTT) across the hydrogel, resulting in stimuli-responsive 3D deformations, with a largest achievable bending angle of 354°. The gradient hydrogels exhibited controllable, reversible and repeatable 3D deformations driven by changes in temperature or ionic strength. Multiple complex shape changes were achieved through patterned illumination.