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The authors construct a multiscale computational framework combining first-principles quantum simulations with classical molecular dynamics to quantify how radio-oxidation defects alter the dielectric response of semicrystalline polyethylene across electronic, vibrational, and mesoscale regimes (down to 10–100 MHz). Resolving these cross-scale defect interactions is essential for predicting degradation and dielectric breakdown in polymer insulation used in extreme environments. The analysis reveals that defect–defect interactions dominate the total dielectric response, with ketone groups driving the largest dielectric loss while alcohol defects exhibit an unexpected negative cross-correlation with the host matrix that partially dampens their dielectric footprint.
Chemical defects in polymer insulators do not degrade performance uniformly: while ketone groups drive peak dielectric loss, alcohol defects exhibit negative dipolar cross-correlations with the host polyethylene matrix that actively dampen their dielectric impact.
Polymers are widely used as functional insulating materials, but predicting their dielectric behavior is challenging because multiple mechanisms, acting across different spatial and temporal scales, contribute to their response. In polyethylene (PE), one of the most common polymers, electronic, atomic, and mesoscale dynamics must all be considered. In this work, semicrystalline models of polyethylene were developed and investigated using a multiscale approach. Quantum simulations were employed to describe electronic and vibrational contributions to the dielectric response, while classical molecular dynamics simulations captured the behavior of polymer chains at room temperature and frequencies down to the 10-100 MHz range. The study focuses on the impact of radio-oxidation defects on the dielectric properties of polyethylene. Quantum calculations reveal how electronic and vibrational contributions depend on the local atomic environment surrounding these defects. Comparison with molecular dynamics results highlights the influence of temperature on the static dielectric constant. Structural analyses further assess the effect of each defect type on PE crystallinity. Analysis of dipolar correlation functions shows that different defects interact with one another and with the polymer matrix in distinct ways, affecting permittivity and dielectric loss peaks. For all defect types, defect-defect interactions provide the largest contribution to dielectric response. While most oxidized groups exhibit positive coupling with the PE matrix, alcohol defects display a negative cross-correlation, partially offsetting their impact on the dielectric properties. Our results also show that ketone groups produce the largest dielectric loss between the defects studied.