A New Approach to Develop Di‐Imidazole Cored Polybenzoxazine/Epoxy Hybrid Matrices for High Thermal, Low Dielectric, and Corrosion Resistant Applications

ABSTRACT New di‐imidazole cored bisphenol (DIBP)‐based benzoxazines (DIBP‐BZ) were synthesized using three different amines, like furfuryl amine (fa), lauryl amine (la), and stearyl amine (sa), separately with paraformaldehyde through the Mannich condensation reaction. Incorporation of the imidazole core into the polymer backbone imparts self‐catalytic activity, significantly lowering the curing temperatures (205°C–224°C) compared to that of conventional benzoxazines (typically above 250°C). The prepared DIBP‐BZ monomers are capable of curing at lower temperatures by blending with fossil‐based bisphenol‐F‐epoxy (BFE) resin and bio‐based cardanol‐bisphenol epoxy (CBE) resin in a weight ratio of 1:1 to obtain hybrid polybenzoxazine‐epoxy networks. These hybrid systems exhibit enhanced thermal stability, lower dielectric constant and dielectric loss, minimal moisture absorption, and superior hydrophobicity relative to conventional benzoxazine–epoxy blends. The poly(DIBP‐sa)/CBE hybrid shows an exceptional corrosion protection, attaining an inhibition efficiency of 99% after 15 days, followed by a marginal reduction thereafter, according to electrochemical corrosion studies conducted in 3.5 wt% solution of NaCl, for a period of 30 days (evaluated at 15‐day intervals). Further, the poly (DIBP‐sa)/CBE system exhibits excellent dielectric performance, with a dielectric constant of 2.93 and a dielectric loss of 0.052, highlighting its potential as a high‐performance material for advanced coating and low‐k microelectronics applications.