Influence of Nano-Structure on the Degradation Pathways of Ethylene-Co-Vinyl Acetate Polymer

Polymeric encapsulants are essential materials in photovoltaic modules, protecting sensitive electronics from the environment while providing mechanical integrity to the multilayered assembly. However, these polymeric materials are susceptible to degradation processes driven by the ingress of environmental species, ultraviolet radiation, thermal stresses, and mechanical loading. In this study, we employ molecular dynamics (MD) simulations to investigate the molecular-scale mechanisms of encapsulant degradation, with a specific focus on the nano-structure dependence of ethylene-co-vinyl acetate (EVA) polymer. Classical MD simulations were used to quantify the diffusion of environmental (water) and degradation (acetic acid) species through the polymer matrix, producing nano-state specific diffusion coefficients. Additionally, using Reactive MD, we compute the reaction rate and activation energy of deacetylation and beta-scission kinetics with nano-state dependency. We establish a quantitative correlations between polymer composition, species diffusivity and concentration with chemical kinetics. These relationships and quantitative values could serve as high-fidelity inputs to reaction-diffusion models, enabling physics-informed lifetime predictions and guiding the design of more durable encapsulant materials for solar energy applications.