Boron-Modified Phenolic Resin: Thermal Stability and Decomposition Mechanisms via Experiments and Simulations

Abstract In this study, a boron-modified phenolic resin system with enhanced thermal stability was developed through the incorporation of 4-hydroxyphenylboronic acid pinacol ester (4-HPBAPE). A multiple-scale methodology integrating experimental characterization with classical molecular dynamics (MD) and reactive force field molecular dynamics (ReaxFF MD) was employed to systematically investigate the Tg, thermal conductivity, and pyrolysis mechanisms of modified phenolic resins. Differential scanning calorimetry (DSC) measurements showed a 30 ℃ increase in Tg (159 → 189 ℃), while thermal conductivity testing revealed a 10% reduction (0.2154 → 0.1920 W/(m·K)). The errors between the results obtained from MD simulation and the experimental results were all less than 10%. Thermogravimetric analyzer (TGA) measurements indicated that the char yield decreased with increasing 4-HPBAPE doping ratio. ReaxFF MD simulations demonstrated that boron modification of phenolic resins enhanced the production of light hydrocarbons (C₁-C₅) during pyrolysis, resulting in higher mass loss. This occured via boron-mediated ring-opening and suppression of large aromatic cluster formation. Future efforts could focus on controlling the bonding form of boron to suppress ring-opening reactions, thereby enhancing the char yield.