Preparation of novel bio-based imine-containing phthalonitrile resin through the nucleophilic reaction in green solvent

Nucleophilic reactions, as extensive and easily implementable reactions in organic chemistry, play a significant role in the molecular design of organic compounds and polymer materials. In current sustainable development strategies, nucleophilic reactions are also being shifted towards green chemistry. In this paper, phthalonitrile (PN) resin, a thermoset prepared by nucleophilic substitution reaction, was selected for a case study to investigate the application and reusability of the 'green solvent' dimethyl carbonate (DMC) in the nucleophilic substitution reaction. This research employed naturally existing vanillin and tyramine for the synthesis of a fully bio-based bisphenol bearing a Schiff base structure (VTBP). Then VTBP was converted to a novel bio-based PN (VTPN) through a nucleophilic substitution reaction in DMC, and the DMC was recovered and reused through a rotary evaporation. The structure, curing behavior, and performance of the cured resin of the synthesized VTPN were characterized. The results suggest that the Schiff base may promote and participate in the crosslinking of nitrile, with a relatively high performance achieved under moderate curing conditions. This study provides a new green implementation scheme for high-performance polymers prepared through nucleophilic reactions, as well as for the high-performance and efficient utilization of widely existing bio-based aldehydes and amines.