Plasma polymerization of 1,3,5,7-tetravinyl-1,3,5,7-tetramethylcyclotetrasiloxane onto silicone oils

Abstract Vapor phase deposition of polymer films onto liquid substrates can be used to fabricate ultrathin films for a range of applications. However, a significant challenge arises when the monomer is soluble into the liquid substrate due to their similar chemical structures, which can prevent successful film formation. In this study, we investigated the plasma-enhanced chemical vapor deposition (PECVD) of 1,3,5,7-tetravinyl-1,3,5,7-tetramethylcyclotetrasiloxane onto silicone oils. We examined the effect of the ratio of plasma power to the monomer flow rate (W/F) on film formation. We also systematically varied the viscosity of the silicone oil to determine how this parameter affects film growth. Our study showed increasing the ratio of the plasma power to the monomer flow rate promotes ring-opening reactions, increases monomer fragmentation, and higher polymer cross-linking. These factors reduce polymer chain mobility and thereby enhance film formation by decreasing polymer diffusion and solubility into the liquid substrate. We also illustrated that increasing the viscosity of the silicone oil decreases the diffusion of the polymer chains which leads to film formation.