Molecular dynamic study of radiation-moisture aging effects on the interface properties of nano-silica/silicone rubber composites

The influence of radiation-moisture aging on the thermodynamic and interface properties of nano-silica/silicone rubber (PDMS) composites was investigated using molecular dynamics simulation. The deterioration of polymer matrix was incorporated into the PDMS-silica interface models based on the hydrolysis products and the dominant role of cross-linking over chain scission. The results indicate that the long-chain structure with the higher molecular weight and the stronger intermolecular interactions are formed by incorporating multi-chain cross-linking and more hydroxyl groups. The coupling effects of the long-chain structure and stronger intermolecular interactions enhance the binding strength between the silica and PDMS matrix owing to the formation of more hydrogen bonds, and restrict the diffusion mobility of PDMS chains and water molecules. The aging of the PDMS matrix facilitates water molecules to adsorb on the surface of the silica and the PDMS matrix to form hydrogen bonds, and eventually weakens the bonding strength of the silica-PDMS interface.