Thiol−Isocyanate−Epoxy Covalent Adaptable Networks with Versatile Dual-Curing Processing and Tunable Stress Relaxation

Dual-curing covalent adaptable networks (CANs) provide a powerful platform to tailor thermomechanical properties through controlled network architecture and dynamic bond exchange. In this work, a thiol−isocyanate−epoxy system is employed to construct networks via a sequential photo- and thermally activated curing strategy, enabling precise control over intermediate and final network structures. The resulting materials exhibit composition-dependent stress relaxation behavior governed by the interplay of transthiocarbamoylation and transesterification mechanisms. By systematically varying the stoichiometric ratios, the relative contribution of each dynamic process is tuned, providing insight into structure−dynamics relationships in dual-curing networks. A simplified structural model is evaluated against experimental stress relaxation data, demonstrating its ability to capture key trends while highlighting its limitations in systems involving multiple concurrent exchange mechanisms. This work establishes a framework for the design of dual-curing CANs with tunable relaxation behavior and reprocessing capabilities.