Unique self-catalyzed bio-benzoxazine derived from novel renewable acid-containing diamines based on levulinic acid and furfurylamine: Synthesis, curing behaviors and properties

Abstract 4,4-bis[5-(aminomethyl)furan-2-yl]pentanoic acid (BAFP), brand new renewable acid-containing diamines, was first utilized as feedstock for preparing fully biomass-based benzoxazine with self-catalytic characteristic. The resulting acid-containing bio-benzoxazine was prepared through Schiff base strategy. The onset ring-opening polymerization temperature of resulting benzoxazine is 173 °C determined by DSC, much lower than that of analogous bisfurfurylamine-based biobenzoxazine free of carboxylic group. The curing kinetics of as-prepared benzoxazine was probed by non-isothermal DSC method. The curing reaction consisted of three stages with overlapped regions with each other. The first stage was ascribed to initiation reaction triggered by protons of acid, with a activation energy of 116.9 KJ/mol calculated by Flynn-Wall-Ozawa method; the second stage was named combination-catalyzed stage for the fact that acid proton and phenolic proton was co-catalyzed the chain propagation, with a activation energy of 118.0 KJ/mol; The third stage was diffusion-controlled curing reaction with a activation energy of 137.3 KJ/mol. More interesting, the calculated apparent activation energy of three reactions decreased with the increase of monomer conversion.