Low‐Temperature Curable Thermosetting Resins with Cycloaddition‐Driven Cross‐Linking Based on Sydnone and Silylacetylene

Silicon–alkyne hybrid resins (PSA) possess considerable potential in aerospace and electronic applications. However, their practical use is limited by high curing temperatures (>350°C) and complex cross‐linking processes. To address these challenges, a click chemistry approach based on the 1,3‐dipolar cycloaddition of sydnones is introduced to replace the conventional self‐curing of alkynes. A monofunctional model compound is synthesized to elucidate the structural evolution during curing. A solution‐based prepolymerization strategy is developed to produce B‐stage prepolymers capable of efficient cross‐linking upon mild thermal activation. This method significantly reduces the curing temperature, minimizes processing risks, and enables precise control over the polymer network. The final cross‐linked structure forms stable pyrazole rings with carbon dioxide as the only by‐product. The cured resin exhibits excellent thermal stability with a decomposition temperature ( T d5 ) exceeding 450°C, providing a promising strategy for the advancement of PSA resins.