Bio-based Recyclable Polydithioacetal Covalent Adaptable Networks with Activation Temperature-Tunable Shape Memory Property

Abstract

The extensive development of polymer materials from fossil resources poses serious environmental challenges. Therefore, developing recyclable functional materials from biomass is crucial. Here, we confirmed the reversible exchange ability of dithioacetal bonds by model compounds exchange reaction. Crosslinked polydithioacetal (PDTA) was prepared via solvent-free polycondensation of biomass benzaldehyde and tetra-thiol monomer at room temperature. The self-healing and multi-mode recycling including mechanical reprocessing, chemical recycling, and back-to-monomer recycling were achieved at mild condition with no mechanical performance reduction. The solid-state plasticity by the dynamic nature of polydithioacetal endowed PDTA with reconfigurable shape memory capability, which ensured the flexible application of PDTA by reconfiguring its permanent shape and recovery route direction. Moreover, the activation temperature for shape memory can be facilely tuned by adjusting the crosslinking densities of PDTA to meet medical application needs. With facile tunability, great hydrolytic resistance and biocompatibility, PDTA exhibited outstanding performance in vascular stent demonstration experiment, in which the shrunken stent of body temperature-responsive PDTA expanded and provided support within the vessel, showing promises as an environmentally and biologically friendly material for the implanted biomedical stent.