Photo-Triggerable Polymerization and Depolymerization of Stiff-Stilbene Lactones

The development of photoswitchable polymers has unlocked new avenues for controlling polymerization and depolymerization through external stimuli. In this work, we introduce a strategy that integrates stiff-stilbene-based cyclic monomers with reversible E/Z photoisomerization to dynamically modulate the ring strain of monomers for ring-opening polymerization (ROP). A series of stiff-stilbene lactones with varying linker lengths were synthesized and systematically evaluated for their polymerization behavior. The resulting polymers exhibit tunable thermal and optical properties, with select derivatives displaying liquid crystalline behavior, and can be depolymerized to recover the original monomers. Density functional theory (DFT) calculations offer insights into the crucial role of Z/E photoisomerization in governing the polymerization and depolymerization process. This photoswitchable ROP system provides a new paradigm for designing sustainable polymers materials with adaptable and responsive properties.