Siloxane-Mediated Schiff Base Bio-Based Curing Agent: Achieving Epoxy Vitrimer with Excellent Mechanical Properties, Low Dielectric Constant and Rapid Degradation Characteristics

Abstract

Epoxy resin is indispensable in various applications due to its outstanding properties. However, its limited recyclability and associated environmental issues pose significant challenges for sustainable development. To address this issue, integrating recyclable Schiff base groups into epoxy resin systems to construct epoxy vitrimer with dynamic properties has become a promising strategy. Herein, a rapid degradation, enhanced mechanical properties, and low dielectric constant epoxy vitrimer (EP-BOB) is proposed through a unique rigid-flexible structure bio-based curing agent (BOB). BOB is synthesized using siloxane as a flexible chain to bridge with vanillin in a one-pot process. The incorporation of the Schiff base structure imparted exceptional degradability to EP-BOB, allowing it to fully degrade within 45 min. In addition, due to the unique rigid-flexible structure, EP-BOB exhibited lower dielectric constant (1.2–2.6) and outstanding mechanical properties (60.5 MPa tensile strength). Furthermore, Raman spectroscopy and scanning electron microscopy shows that EP-BOB can be completely degraded in the amine solution to recycle carbon fibers (CFs) without damage. Especially, the Schiff base can endow EP-BOB UV-shielding and antibacterial properties. This work opens up a new strategy for designing a rigid-flexible structure epoxy vitrimer using silicone to achieve multifunctional and high-performance EP.