Reprocessing of cross-linked polyamide networks via catalyst-free methods under moderate conditions

Abstract

The development of renewable green synthesis methods for polyamide materials is of great significance in the chemical industry. In this context, we present the synthesis and characterization of a novel type of dynamic covalent polyamide network with exceptional repairability and recyclability. These networks exhibit remarkable dynamics attributed to internal catalysis and steric hindrance, leveraging the dissociation equilibrium between anhydrides and secondary amines containing tert-butyl groups. By investigating the reversibility and reaction mechanism of tert-butylamide-carboxylate bonds (TBCBs) using low-molecular-weight (LMW) model compounds, we establish a foundation for the rational design and optimization of TBCB-based cross-linked polyamide covalent adaptable networks. We successfully synthesize robust tung oil (TO)-based ultraviolet (UV)-curable polyamide polymers, showcasing encouraging reparability and reprocessability. The dynamic nature of the UV-curable polyamide networks is thoroughly examined through rheological analysis, stress relaxation, and temperature-dependent Fourier transform infrared (FT-IR) studies, confidently confirming their dynamic characteristics. Scratch-repairing, hot-pressing, and extrusion experiments further demonstrate the materials’ exceptional repair and reprocessing capabilities. This research represents a significant advancement in sustainable polymer development by combining high mechanical properties with easy repair and recycling.