Preparation of PDMS/SiO₂ nanocomposites via ultrasonical modification and miniemulsion polymerization

In this paper, the ultrasonic dispersion process was utilized to modify the silica sol nanoparticles by a certain amount of hydroxyl silicone oil (HSO), then in the presence of the modified silica sol, miniemulsion polymerization of octamethylcyclotetrasiloxane (D₄) was conducted with dodecylbenzene sulfonic acid (DBSA) as the emulsifier and catalyst, and finally polydimethylsiloxane (PDMS)/silica (SiO₂) nanocomposite latex was obtained. The modified silica sol particles, diameter and morphology of the composite latex particles, mechanical properties and thermal stabilities of the composite films were characterized and discussed, respectively. The results showed that the ultrasonic dispersion was an effective method to modify the silica sol particles, the grafted degree of HSO onto silica surface was about 5 %. The morphology of composite latex particles was shown core-shell structure with grafted SiO₂ particles encapsulated by PDMS, the introduction of SiO₂ improved the mechanical properties and thermal stabilities of polysiloxane composite films.