Molecular Engineering of Voltage-Stabilizer Grafting Polydimethylsiloxane for Superior Electrical Insulation and Environmental Stability

The present theoretical study represents molecular simulation insights to a chemical modification of polyisobutylene (PDMS) by grafting a functional molecule (MB) as the voltage stabilizer for ameliorating electrical insulation performance, oxygen resistance, and thermal stability of the PDMS material applied in power insulator or transformer. It is demonstrated by first-principles calculations that chemical-grafting MB can introduce deep and shallow charge traps to inhibit impede charge transport and restrict hot electron production respectively into PDMS macromolecule. Through molecular dynamics and Monte Carlo simulation, the chemical-graft modifier is verified to enhance aggregation and decrease oxygen compatibility of PDMS macromolecules due to its much higher dipole moment, leading to reduction in oxygen permeation and improvement in thermal stability of PDMS material. It is indicated from first-principles oxidation reaction pathways that chemical-grafting MB contributes positively rather than impacts negatively to the oxidative stability of PDMS. The improved abilities of charge trapping and withstanding high temperatures together with the enhanced resistances to oxygen infiltration and oxidation in PDMS material, as unraveled on molecular-scale in this research, opens an avenue for developing advanced polymer dielectrics used in harsh environments.