Facile synthesis of “digestible”, rigid-and-flexible, bio-based building block for high-performance degradable thermosetting plastics†
Plastics are indispensable in modern society, but are non-sustainable resources, releasing hazardous chemicals during their service life, and post-disposal issues make traditional plastics a risk. Herein, we report a “digestible”, rigid-and-flexible, bio-sourced building block for high-performance degradable plastics. This building block was synthesized from the bioresources vanillin (lignin derivative) and glycerol through solvent-free acetalization with a high conversion rate and high selectivity. It could be extremely rapidly degraded into non-toxic vanillin and glycerol under mild acidic conditions even at a similar pH and temperature to gastric juice in the human stomach (“digested”), resulting in the outstanding chemical degradability of its corresponding epoxy thermosets, which is beneficial for their recycling. By virtue of the benzene ring, heterocycle, and methoxyl group-related hydrogen bond, the degradable thermosetting plastic showed much higher mechanical properties (stronger and tougher) and comparable thermal properties relative to a commercial high-performance counterpart based on bisphenol A (BPA). This favorable performance combination has never been reported for plastics. Thus, this bio-derived building block exhibits great potential as a sustainable and upgraded alternative to petroleum-sourced aromatic chemicals such as BPA for high-performance plastics.