Influence of Local Sequence Architecture on the Hydrolysis Pathways and Dielectric Property Evolution of Butyl Acrylate- co -Acrylonitrile Adhesives

Acrylate-nitrile adhesives are used in electronics, aerospace, and defense applications, but the chemical mechanisms responsible for age-induced degradation of assemblies that use these adhesives are difficult to characterize directly. This work identifies acrylonitrile (AN)-rich local environments associated with the proposed 5:12 butyl acrylate-co-acrylonitrile (BA-AN) composition as important structural and electronic contributors to degradation in acrylate-nitrile adhesives. To interpret aging in this cross-linked adhesive, we developed an integrated workflow combining ensemble quantum-based steered molecular dynamics (SMD), multivariate spectral deconvolution, and electronic structure analysis. This approach links local sequence arrangement to hydrolysis pathways, product speciation, and assembly property degradation, allowing complex attenuated total reflectance Fourier transform infrared (ATR-FTIR) aging data to be interpreted at the molecular level. The modeled AN-rich environment exhibits approximately orthogonal neighboring nitrile dipoles that suppress interdipole coupling and favor cyclic amidine formation over terminal hydrolysis products. Spectral deconvolution of aged ATR-FTIR data estimates a total hydrolysis level of 45.3%, with the degraded matrix dominated by nitrogen-containing intermediates. Composition-guided electronic estimates give the pristine 5:12 HOMO–LUMO gap (Eg) nearly 1.0 eV below that of the 1:1 alternating model. In the computed aged-state, Eg decreases slightly from 6.77 to 6.66 eV, while the intensity-derived transition dipole moment (TDM) increases by 16.9%, from 3.34 to 3.90. This electronic shift is consistent with an enhanced dipolar dielectric loss and energy dissipation in the model aged state. The corresponding electronic quality factor, χ = Eg/TDM, is in good agreement with the experimentally observed 15.5% reduction in dielectric breakdown strength. Together, these results connect AN-rich local environments to hierarchical adhesive degradation and provide a broadly applicable framework for analyzing aging chemistry in complex polymer systems.