Decoupling of Interfacial Ionic Diffusion from Segmental Dynamics in Silica-Filled Silicone Gel through Experiments

This study experimentally investigates and models the ionic diffusion coefficient at inert particle/polymer interfaces in silica-filled silicone gels, aiming to elucidate the relationship between ion diffusion and segmental dynamics at interfaces. As the specific surface area of silica increases, more loop-type structure chains form at the silica-silicone gel interface. Enhanced silicone chain flexibility at the interface, coupled with a low dielectric constant, strengthens electrostatic interactions and elastic forces, increasing ion jump energy barriers and reducing ion diffusion. Consequently, the influence of polymer segmental dynamics on ion diffusion becomes more significant, shifting the decoupling index between segmental dynamics and the ionic diffusion coefficient from negative to zero. This study provides a theoretical understanding of how interfacial chain movement impacts ion diffusion at interfaces supported by experiments, which is critical to modeling electrical properties of composite polymers and optimizing the performance of relevant electronic and future bioelectronic devices.