Vanillin-based degradable epoxy vitrimers: Reprocessability and mechanical properties study

The preparation of vanillin-based epoxy thermosets has attracted great attention in recent years, however, most of them could not be reprocessed once after curing procedures. In the present work, a vanillin-based epoxy vitrimer (Van-Ep/IPDA) with dynamic imine covalent bonds was prepared by curing mono-glycidyl structure of vanillin (Van-Ep) with isophorone diamine (IPDA) hardener, which simultaneously exhibits the excellent reprocessability and acid degradable behavior. The mechanical properties of Van-Ep/IPDA vitrimers and cured bisphenol A (E51) epoxy are kept at the same level, which the Young's modulus, elongation and tensile strength at break of Van-Ep/IPDA vitrimers reach 2.30 GPa, 4.4% and 65.0 MPa, respectively. Importantly, compared with these of original vitrimers, all reprocessed Van-Ep/IPDA vitrimers exhibit the same level of mechanical properties even after three times of hot pressing. Thanks to the imine structure, epoxy vitrimers also exhibit degradable property under acid solution. This facile approach of imine chemistry for preparing vanillin-based epoxy vitrimers sets up an important framework for designing sustainable polymer materials with excellent reprocessability and degradability.