Multiscale‐Guided Molecular Engineering of Aromatic Charge‐Trap Epoxy Dielectrics for Synergistic Electro–Hygro–Thermal Resilience

ABSTRACT Escalating demands of modern high‐voltage power grids necessitate epoxy‐based electrical insulation materials with simultaneously enhanced dielectric withstand capability, moisture resistance, and thermal durability. A multiscale molecular design strategy integrating first‐principles calculations, classical/reactive molecular dynamics, and Monte Carlo simulations is presented experimentally validated through dielectric and hygrothermal aging experiments, to rationally engineer phenolphthalein‐cured bisphenol‐A epoxy resins via covalent grafting of two architecturally distinct polar‐functionalized molecules: 2‐amino‐5‐chlorophenyl‐2‐fluorophenyl methanone (ACFM) and N‐methylmaleimide (NMM). First‐principles calculations reveal that grafting ACFM introduces deep electron traps of 1.0 eV depth derived from polarized conjugated‐π phenylene that couples molecular vibrations with electronic bound states merged at the conduction band minimum that increase carrier effective masses, thereby restraining hot charge carrier generation and suppressing electron avalanche breakdown. Molecular dynamics and Monte Carlo simulations demonstrate that the planar, multi‐dipolar ACFM architecture acts as transient pinning points that enhance cohesive energy density by 24%–32% while reducing fractional free volume by 2.2%–2.9%, synergistically inhibiting water infiltration. Reactive molecular dynamics further elucidates that ACFM grafting mitigates severe thermal‐impact pyrolysis above ~2100 K, whereas NMM grafting delays pyrolysis inception by 300 K but aggravates high‐temperature decomposition. Experimental validation confirms that EP‐g‐ACFM achieves a characteristic AC breakdown strength of 21.92 kV/mm (19.9% enhancement) with a Weibull modulus β of 16.10 (149.2% improvement), alongside a 74.2% increase in 1% failure‐probability design value, and the suppression of electric conductivity by 26.3% at 10 kV/mm. Under 1008 h of hygrothermal aging (85°C/85% RH), EP‐ g ‐ACFM retains 98.2% of its breakdown strength with an integrated aging index of 0.51, substantially outperforming EP‐ g ‐NMM (0.42) and pristine epoxy (0.31). This work establishes the quantitative structure–property correlations governing graft architecture, charge trapping, chain packing, and degradation resistance, providing fundamental mechanistic insights and a predictive computational framework for the rational molecular design of next‐generation polymer dielectrics with multifunctional electro‐hygro‐thermal stability.