An addition-curable hybrid phenolic resin containing silicon and boron with improved thermal stability

Abstract In this work, an addition-curable hybrid phenolic resin containing silicon and boron was synthesized via the addition-condensation reaction between 4-hydroxyphenylboronic acid and formaldehyde to obtain boron hybrid novolac resin (BN), which was followed by esterification with vinyltrimethoxysilane. Boron and silicon were introduced into the phenolic resin skeleton by forming C-B-OH, B-O-C, B-O-Si, and Si-O-Ph bonds, so the hybrid resin not only realized uniform molecular-level dispersion of hybrid elements but also achieved addition curing via the presence of vinyl groups. The hybrid resin's residual weight in an N2 atmosphere at 800°C was improved to 81.02%. The high residual weight arose from the formation of a three-dimensional continuous oxide framework composed of B-O-B-O-Si-O-Si. In addition, we characterized the pyrosis production of the materials with the combination of FT-IR, Raman, SEM/SEM-EDX, XPS, and solid-state NMR spectroscopy to develop a detailed understanding of the synergistic effects of boron-silicon modified phenolic resin.