Solvent-Free Synthesis of High-Performance Polyhexahydrotriazine (PHT) Thermosets

Polyhexahydrotriazines (PHT) are promising high-performance thermosets exhibiting enhanced thermal and mechanical properties. Here, we demonstrate a new solvent-free approach for the fabrication of PHT based on low-melting-point diamines enabling the production of adhesives with comparable properties to well-established epoxy adhesives. Structure property relationships were supported by small molecule model reactions that mimic the cross-linking hexahydrotriazine (HT) cores and allowed the unique reactivity of benzylamine building blocks to be demonstrated. Through a variety of spectroscopic and physical techniques, this increased molecular level understanding of monomer design led to the ability to tune acidic degradation and thermal properties.