Initiation of 2-Hydroxyethyl Methacrylate Polymerization by Tert-Butyl Peroxide in a Planar PECVD System

This article reports on the deposition conditions and characterization of poly(2-hydroxyethyl methacrylate) thin films grown by initiated plasma enhanced chemical vapor deposition process. The plasma power is inductively coupled into the process chamber with a planar-coil antenna through a quartz window, and the substrate is cooled to promote physical adsorption of monomers on its surface. The introduction of the initiator allowed for film deposition at very low plasma powers (1W) and greatly improves the deposition rates. Fourier transform infrared (FTIR) and X-ray photoelectron spectroscopy (XPS) analyses confirmed that the chemical functionalities of the monomers are preserved to a good extent during the depositions that were carried out at low plasma powers. The deposition kinetics of PECVD-produced films from HEMA can be tailored by varying the substrate temperature. The apparent activation energies observed from PHEMA deposition kinetics with varying substrate temperatures are observed to be negative, which supports the hypothesis of the free radical polymerization mechanism in the PECVD PHEMA deposition.