Silicone Resin-Based Covalent Adaptive Networks Additionally Cross-Linked by Si–O–Ph Bonds

Silicone resins, known for their exceptional properties across various industries, are traditionally nonreprocessable due to their permanent cross-linked networks. Herein, we propose a method to turn a disadvantage into an advantage by converting silanol (Si–OH) groups─adverse factors for thermal stability─into dynamic Si–O–Ph bonds, thereby endowing silicone resin with reprocessability. Polysiloxane oligomers with benzoxazine side groups (PBTS) were formed via hydrolysis–condensation reactions between monofunctional benzoxazine-containing siloxane (P-mdes) monomers and triethoxymethylsilane (MTES). The curing behaviors of PBTS are analyzed using DSC and FTIR, confirming the formation of silicone resin-based covalent adaptive networks (CANs) through the introduction of dynamic Si–O–Ph bonds. The resulting silicone resin-based CANs exhibit reprocessability and significantly improved mechanical and thermal properties. The tensile strength of the original silicone resin-based CANs reaches 23.34 MPa, and even after five cycles of reprocessing, the strength remains at 22.98 MPa, demonstrating excellent mechanical retention. The Tg and Td5 of the silicone resin-based CANs reach up to 132 °C, 424 °C, and 425 °C in nitrogen or air atmospheres, respectively. Notably, the reprocessed samples maintain excellent heat resistance and thermal stability even after five reprocessing cycles, with Tg and Td5 values around 130 and 380 °C.