Mechanically strengthened silicone-based origami structures via hierarchical interfacial shrink fitting

Abstract

Soft structured materials—e.g., silicone-based elastomer, capable of programmable morphologies and mechanical strength—are promising for high-performance structure construction in metamaterials and soft robots. However, once prototyped, polydimethylsiloxane (PDMS)–based silicone elastomer is limited in mechanical strength and programmable spatial construction due to the flexible polymer matrix and mismatched interface with other materials. We propose a mechanically strengthened PDMS-based origami structure (MSOS) via polymethyl methacrylate (PMMA)/acetone solution swelling. The planar elastomer precursor can be swollen-folded into programmable spatial construction based on mechanically strengthened creases during solvent diffusion and de-gelatinization. This strengthened crease is induced by a hierarchical shrink-fitting based on solute molecular chain insertion and a seamless coupling interface between elastomer microstructures and solidified PMMA. We present a programmable MSOS to support a load more than 58,100 times of its own weight and a pillbug-inspired ringbot to resist heavy impact. Our work provides a strategy toward customized mechanically strengthened soft material for developing functional structural architectures and soft origami robots.