Fabrication and Properties of Silicon-Containing Resin-Based Covalent Adaptable Networks via Hybrid Exchange Reaction between Ph–OH Groups and Si–O–Si Bonds

The introduction of dynamic covalent bonds imparts reprocessability to the thermosets. However, achieving reprocessing in conventional thermosets, which lack dynamic bonds in their cross-linked networks, remains a significant challenge. Herein, we propose a strategy to fabricate silicon-containing resin-based covalent adaptable networks (CANs) from fully cured phenolic resin and silicone resin via the hybrid exchange reaction between phenolic hydroxyl groups (Ph–OH) and siloxane (Si–O–Si) bonds. This hybrid exchange reaction was validated by the degradation of the silicone resin by phenolic compounds. Subsequently, silicon-containing resin-based CANs were prepared from the two fully cured resins by utilizing this reaction. The resulting CANs demonstrate exceptional mechanical and thermal properties, including a tensile strength reaching up to 25.7 MPa, a glass transition temperature (Tg) exceeding 400 °C, and thermal decomposition temperatures (Td5 and Td10) of 410 and 452 °C, respectively, under a nitrogen atmosphere, along with a high char yield (Yc) of 63.7% at 800 °C. Moreover, the materials demonstrate excellent reprocessability, retaining 91.4% and 87.5% of their original tensile strength after the first and second recycling cycles, respectively, while maintaining a Tg consistently above 400 °C throughout. The silicon-containing resin-based CANs presented here offer a promising new strategy for overcoming the reprocessing challenges associated with traditional thermosets.