Rapid shape recovery and remodeling by tuning the topology of polycaprolactone-based polymer networks

Shape memory polymers (SMPs) designed with desired performance depend on a deeper understanding of network topology and macro characteristics. Although photoreversible dynamic covalent bonds are used for permanent shape reconstruction of SMPs due to their economical and rapid, the disordered network structure limits the ability to improve shape memory performance through structural adjust. In this work, the polycaprolactone networks with sliding structural components (polyrotaxane) and photoreversible components (coumarin) were prepared by preprogrammed precursors. The SMPs network topology is controlled by adjusting the length of molecular chain and sliding distance. Reversible bonding can realize complex shape designability and solid remodeling. Furthermore, the supramolecular structure of polyrotaxane can adjust the uneven stress distribution caused by network topology defects, so the material can instantly return to its original shape under more than 300 % strain, and its elongation at break is over 1600 %. Especially the thermo-mechanical properties of materials can be adjusted by simple preliminary monomer synthesis steps. The results revealed the material has excellent shape memory and controllable thermodynamic properties, which provides a new paradigm for the preparation of high performance SMPs.