Self-reinforced triple-shape memory silicone rubber composites with precise designable second temporary shapes by one step fixation

Silicone rubber (SR) plays an irreplaceable role in biomedicine and aerospace applications due to its biocompatibility, flexibility and excellent stability in extreme harsh conditions. However, only a few studies focus on SR based shape memory materials, and the increasing intelligent applications of SR materials are limited by the insufficient strength and poor designable recovery behavior. Herein, we report a simple method via monomers/prepolymers blend and in-situ polymerization/cross-linking to prepare thermal responsive shape memory silicone rubber composites (SRCs) with three transition temperatures. In the SRCs, poly (methyl methacrylate) (PMMA) and poly (ethyl methacrylate) (PEMA) are used as switching segments and reinforced phase, polydimethylsiloxane (PDMS) networks provide a third transition and dominate the permanent shape. In a thermal stimulus recovery of SRCs with PMMA and PEMA switching segments are used, second temporary shapes can be precisely designed by just tuning the proportions of PMMA and PEMA, and a practical linear relationship between recovered scale and PEMA content is built. The shape memory and mechanical properties of SRCs are both enhanced by micro-nano particles (800 nm) of PMMA and PEMA. The SRCs present excellent thermal stability, hydrophobicity and hygroscopicity. The triple-shape memory SRC materials have potential applications in smart materials and actuators.