Single-Crystalline Poly(disulfide)s Enabled by PhotoTriggered Topochemical Ring-Opening Polymerization of 1,2-Dithiolane

Topochemical polymerization offers a versatile approach to producing single-crystalline polymers by in situ polymerization in the preorganized solid state. Despite the existing examples of topochemical polymerization based on the formation of strong covalent bonds (e.g., C-C, C-N, and C-O), the construction of single-crystalline polymers mediated by weak yet dynamic covalent bonds, e.g., disulfide bonds, remains elusive. Here, we report a single-crystalline poly(disulfide) by phototriggered topochemical ring-opening polymerization mediated by disulfide exchange. The key design is to control the spatial distance and geometry of the 1,2-dithiolane ring by elaborating side-chain moieties that determine the supramolecular self-assembling. It is found that zigzag-like preorganization facilitates the quantitative single-crystal-to-single-crystal polymerization triggered by UV/visible light or X-ray. The resulted single-crystalline poly(disulfide)s exhibit superior thermostability and solvent resistance compared to the state-of-the-art amorphous poly(disulfide)s. Upon dissolving the crystals with trifluoroacetic acid, the intrinsic dynamicity of poly(disulfide)s could be reactivated to enable depolymerization and yield origin-quality crystalline monomers for polymer regeneration. We anticipate this work as a starting point, bridging dynamic polymers with topochemical polymerization toward dynamic molecular crystals and smart materials.