Reconfigurable Shape Memory Polythiourethane with Covalent Adaptable Networks

Introducing dynamic covalent bonds into polymer networks to construct thermoadaptive networks enables materials to exhibit plasticity and facilitates the reconstruction of permanent shapes. This study implements dynamic thiol-based carbamate bonds as cross-linking points within shape memory polyurethane networks, connecting segments of crystalline polycaprolactone (PCL) and amorphous hydroxyl-terminated polybutadiene (HTPB) to form a cross-linked structure. The one-pot synthesis method facilitates the facile adjustment of the ratio between PCL and HTPB, and the mechanical properties and shape memory capabilities of the material can be tailored. Small-molecule simulation experiments confirm the dynamic nature of the thiol-based carbamate bonds; due to the exchange properties of the dynamic bonds at lower temperatures, the cross-linked network is prone to rearrangement, enabling the shape memory material to easily achieve permanent shape reconfiguration and facilitating the recycling and reprocessing of the material. The topology freezing transition temperature (Tv) and the operational temperature can be determined by identifying the abrupt plateau in the Tan Delta curve. This design merges plasticity with reprocessability within a shape memory network, offering greater possibilities for the deformation performance of shape memory materials.