Synergistic Effect of Catalyst Structure on Recycling Efficiency and Mechanical Properties of Imine-Based Epoxy Vitrimer

Abstract

Epoxy (EP) vitrimers with dynamic imine bonds have attracted great attention because of their catalyst-free nature and diverse dynamic reactions. However, developing catalysts that promote stress relaxation to improve self-healing or recycling properties of vitrimers is still of great significance to practical value. In this work, a hardener (AP) containing imine bonds was synthesized and then used to prepare an EP vitrimer (EPV-AP) with promising mechanical properties. By incorporating five similar types of catalysts into the EPV-AP cross-linking network, we found that 2,4,6-tris(dimethylaminomethyl)phenol (DMP30) and N,N-dimethylbenzylamine (BMDA) could effectively promote the exchange rearrangement of the imine metathesis. We propose a mechanistic hypothesis to explain the promoting effect of these two catalysts on the imine bond exchange. These imine metathesis catalysts are expected to be applicable to other imine bond-based EP vitrimers for higher recyclability or milder recycling environments.