Thermally resistant thermadapt shape memory crosslinked polymers based on silyl ether dynamic covalent linkages for self-folding and self-deployable smart 3D structures

Abstract

Thermadapt shape memory polymers with high glass transition temperature and high tensile strength are greatly important for developing high performance self-folding and self-deployable smart 3D structures. Herein, starting from an epoxy resin, ethanolamine, 4,4′-diaminodiphenylmethane and 3-isocyanatopropyltrimethoxysilane, new thermadapt shape memory polymers (EPSis) with highly tunable crosslinked networks and silyl ether dynamic covalent linkages were synthesized. The crosslinked structures and comprehensive performances of EPSis were investigated systematically. The results show that EPSis not only exhibit high glass transition temperatures, which can be adjusted from 118.1 to 156.4 °C, about 38.1–76.4 °C higher than those reported in the literature, but also have high tensile strengths. In addition, EPSis show good thermadapt shape memory behaviours (the shape retention ratio is 80.5–86.3%, the shape fixity ratio is 97.1–98.9%, and the shape recovery ratio is 95.6–99.8%), and they can convert from planar films into various shapes such as a “six-claw stool”, “wave-like rocking chair”, “windmill” and “paper airplane” under heating stimulation, proving that EPSis have great potential for developing high performance self-folding and self-deployable 3D structures. The mechanism study proves that these excellent properties originate from the crosslinked networks based on dynamic silyl ether bonds with both robust toughness and thermal stability, and the topological rearrangement of the network induced by dynamic exchange of silyl ether bonds is responsible for the outstanding thermadapt behaviour. This study provides a unique strategy for developing high performance smart 3D structures.