Surface Dynamics of Amorphous Polymers Used for High-Voltage Insulators
PT Shernella and T Laino and O Fritz and A Curioni, JOURNAL OF PHYSICAL CHEMISTRY B, 115, 13508-13512 (2011).
Amorphous siloxane polymers are the backbone of high-voltage insulation materials. The natural hydrophobicity currents and dielectric breakdown. As these surfaces are exposed their surface is a necessary property for avoiding leakage posed to the environment, electrical discharges or strong mechanical impact can temporarily destroy their water-repellent properties. After such events, however, a self-healing process sets in and restores the original hydrophobicity within some hours. In the present study, we investigate possible mechanisms of this restoration process. Using large-scale, all-atom molecular dynamics simulations, we show that molecules on the material surface have augmented motion that allows them to rearrange with a net polarization. The overall surface region has a net orientation that contributes to hydrophobicity, and charged groups that are placed at the surface migrate inward, away from the vacuum interface and into the bulk-like region. Our simulations provide insight into the mechanisms for hydrophobic self-recovery that repair material strength and functionality and suggest material compositions for future high-voltage insulators.
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