Metathesis cascade depolymerization of enyne self-immolative polymers

Self-immolative polymers (SIPs) are a promising class of degradable polymers that can undergo triggered head-to-tail depolymerization in the presence of external stimuli. Despite significant advances in the past decade, existing SIPs such as polycarbamates, polyphthalaldehydes, and polyglyoxylates are still limited by chemical incompatibility, toxicity, nonoptimal material performance, and inefficient depolymerization. In this presentation, we will discuss a novel class of enyne SIPs that employ rapid and energetically favored olefin metathesis cascade reaction to trigger depolymerization. Model studies revealed a 1,6-enyne motif consisting a p-pentylbenzosulfonamide linker enabled efficient metathesis cascade cyclization. The SIPs incorporating this motif were readily prepared via polycondensation and iterative exponential growth approaches. These SIPs were stable in strong acid, base, nucleophiles, or at elevated temperatures, and could undergo efficient and complete depolymerization once triggered by a metathesis catalyst. Temperature-triggered depolymerization of the enyne SIPs was demonstrated using thermally responsive second-generation Grubbs catalyst, highlighting the potential for these enyne SIPs to be used as stimuli-responsive materials.