Photo-induced Bending and Buckling of Polymer Sheets

Shape-shifting has widespread applications in soft robots and self-assembly structures. To achieve their functionalities, these architectures rely on the spatially bending and buckling to transform the polymer sheets into desired configurations. The goal of this work is to demonstrate that it is possible to tune the shape-shifting behavior through the photo-induced mismatch strain. For the mechanistic understanding, Finite element modeling of thin sheets with different geometry are performed to understand the fundamental mechanics behind the shape transformation behavior. Our experiments with cross-linked polymer samples that change shapes through variation in illumination dose and photo patterns confirm the proposed model predictions. Finally, self-folding structures include flowers, claws, pyramid and saddle are duplicated based on the computational models, indicating the guidelines reported here would be applicable to a diverse array of self-assembly devices. (paper)