Enhanced B-N coordinated dynamic boronate chemistry for recyclable thermosets with elevated stability.

Abstract

Translate Article

The environmental impact of non-recyclable thermoset waste demands sustainable polymer solutions. Existing dynamic covalent boronic ester chemistries operate at relatively low temperatures (<150 °C), resulting in insufficient stability to meet thermoset performance requirements. Here, we overcome these limitations through a N-iminodiacetic acid (N-IDA) boronate system featuring a strengthened internal B-N coordination bond. This enhanced B-N bond (~1.65 Å) endows the dynamic covalent bonds with both exceptional thermal stability and controllable exchange above 150 °C. We leverage this chemistry to develop radical crosslinkers compatible with commercial monomers and thermoplastics. The resulting recyclable thermosets demonstrate exceptional thermal stability, chemical durability under harsh environments (85 °C/85% RH, 7 days), and excellent dimensional stability. This stability-exchange dichotomy is exemplified in heat-shrinkable crosslinked polyethylene (XLPE), where the enhanced B-N coordination maintains network integrity at service temperatures (<150 °C) while enabling thermal reprocessability above 150 °C. By extending the operational range of boronic ester-based dynamic chemistry to high temperature domains, this work provides a scalable pathway toward recyclable thermosets without stability compromises.