Biobased Polystyrene Vitrimers for Thermoset Circularity
Kevin A. Stewart, Thi Minh Hue Le, Na Wei, Alexander J. Cantor, John F. Rynk, Brent S. Sumerlin
Abstract
Thermoset polymers, known for their robust thermomechanical and chemical durability, suffer from poor recyclability due to their covalent cross-linking. This study explores the tunability of covalent adaptable networks (CANs), specifically prepolymer-derived vitrimers, which offer both durability and recyclability through dynamic covalent cross-links. By utilizing biobased vanillin methacrylate (VnMA) and Priamine cross-linkers, we synthesized polystyrene (PS) vitrimers with readily tunable viscoelastic properties. The vanillin-derived PS copolymer was cross-linked with varying equivalents of Priamine to favor different exchange mechanisms: transamination for rapid processability and metathesis for enhanced dimensional stability. Extending the prepolymer chain length above the entanglement threshold also introduced physical cross-links that significantly improved creep resistance. Our findings highlight a versatile approach for creating biobased, reprocessable thermosets with high thermomechanical performance. The incorporation of primary chain entanglement and the ability to tune exchange mechanisms offer a promising pathway for sustainable and durable polymer materials suitable for various applications. This methodology enhances the recyclability and sustainability of PS-based materials, broadening their commercial utility.