Effects of Electric Field and Temperature on Interfacial Properties of Nano-SiO Doped Silicone Rubber Composites: A Molecular-Dynamics Study

It is of great significance to clarify the effect of external environment, such as electric field and temperature, on interface region of nano-dielectric materials, which not only help us understand the operational mechanism of nano-dielectric but also guide us to design new nano-dielectric. Based on classical molecular dynamics method, the effects of electric field and temperature on interfacial properties of nano-SiO2 doped silicone rubber composites are studied. The mean square displacement results show that increasing temperature will cause the increase of the movement of SR chains in interface region, which impair the mechanical properties and thermal stability. Meanwhile, the increasing electric field will decrease the movement of chains. The free volume fractions calculations show that the electric field and temperature have little effect on the total free volume fractions. However, the higher electric field and higher temperature both lead to a larger pore size in free volume region, in which the free electron will accelerate to obtain a higher energy. As a result, the increasing temperature and increasing electric field have a synergistic effect on damaging the dielectric properties of nano-SiO2 doped silicone rubber composites. The analysis of interfacial interaction energy shows that the molecular interaction between SR and nanoparticles is dominated by van der Waals interaction and supplemented by electrostatic interaction. The increasing temperature will weaken the van der Waals interaction, while the increasing electric field will enhance the electrostatic interaction.