Synthesis, Degradation Behavior, and Recyclability Property of Novel Bio-Based Polyimine Thermosets

Given the challenges in recycling, degradation, flammability and environmental protection of most petroleum-based thermosets, it is of great significance to develop degradable, recyclable, and flame-retardant thermosets from renewable feedstocks for material safety and promote sustainable development. Herein, novel Polyimine thermosets (PIts) were prepared from renewable vanillin and their degradation behavior and recyclability properties were systematically investigated. The prepared PIts exhibited excellent thermal properties (Tg: 91–158 °C and T5% above 250 °C), degradability and high monomer recovery rates (above 80 %). Meanwhile, the PIts demonstrated outstanding flame retardancy with a UL-94 V-0 rating achieved by forming noncombustible gas, phosphorus-containing species and nitrogen-containing hexatomic rings. Additionally, these PIts displayed high malleability with Ea ranging from 77.0-118.8 kJ.mol−1 and could be recycled via hot pressing without altering their chemical structure and original mechanical properties. This work presents a new strategy for fabricating bio-based advanced thermosets from renewable resources.