Improved electrical properties, hydrophobicity, and degradability of ortho-vanillin-based epoxy resin: Roles of Schiff base

Conventional diglycidyl ether of bisphenol A epoxy resins (DGEBA) are made from non-renewable fossil resources, which caused severe resource waste and environmental issues. It is of great importance to develop degradable epoxy resins with excellent physicochemical and electrical properties. In this work, a novel vanillin-based epoxy resin (VEP) with Schiff base bond is synthesized from Ortho-vanillin (OVA) and L-phenylalanine (PHE) through a two-step procedure. After cured with 4, 4’-diaminodiphenylmethane (DDM), the vanillin-based epoxy resin (VEP/DDM) exhibits a high char yield of 31.15%, and 110% enhancement in storage modulus comparing to DGEBA/DDM. Meanwhile, VEP/DDM presents excellent electrical properties with breakdown strength of 33.16 kV/mm, dielectric constant of 4.00 and dielectric loss of 0.0059 at 50 Hz, respectively. Furthermore, the degradable Schiff base and hydrophobic groups on the side chain of PHE enable the VEP/DDM with good acid-catalytic degradation and hydrophobic properties. This work provides a new route for fabricating bio-based epoxy resins with promising physicochemical and electrical performance in practical engineering applications. • Bio-based epoxy resin with Schiff base bond (VEP/DDM) was synthesized from Ortho-vanillin and L-phenylalanine. • VEP/DDM showed high residual char yield, almost 2-fold than DGEBA/DDM. • VEP/DDM exhibited great electrical properties with breakdown strength of 33.16 kV/mm, dielectric constant of 4.00 and dielectric loss of 0.0059. • Under acid condition, VEP/DDM can degrade in organic solvents within 12 h.