Direct White-Light Reconfiguration of Dynamic Covalent Polymer Networks via Photoinsertable Spirothiopyran.

Abstract

Light offers a powerful, noninvasive tool for polymer reprocessing and recycling. However, existing strategies predominantly rely on high-energy ultraviolet (UV) irradiation, which often induces material degradation and compromises the integrity of dynamic covalent networks. Herein, we report a white-light-activated addition reaction between spirothiopyran (STP) and poly(disulfide) that enables the direct structural reconfiguration of polymer networks. Upon illumination (λ > 400 nm), STP isomerizes to its ring-opened thiomerocyanine (TMC) form, exposing a reactive ene moiety, while the poly(disulfide) backbone homolytically dissociates into sulfur-centered radicals. These intermediates undergo rapid thiol-ene coupling, establishing dynamic C-S linkages. Notably, this process operates efficiently within bulk poly(disulfide) matrices, allowing the direct incorporation of STP into the polymer backbone and subsequent topological rearrangement of the network. The resulting photoinsertion introduces additional crosslinks, which not only enhance the mechanical properties and photostability but also enable spatiotemporal control over material welding, adhesion, remolding, and recycling. Furthermore, the synergy between STP photochromism and spatially controlled photocrosslinking unlocks advanced functionalities such as dual-color encryption and biomimetic morphogenesis. This work establishes a sustainable, visible-light-driven platform for polymer reconfiguration and opens new avenues toward smart, adaptable functional materials.