Characterization of plasma polymerized silicone coatings useful as biomaterials.

Plasma polymerization techniques were used to deposit a layer of filler-free silicone rubber on a variety of substrate materials. The thickness of the deposited film was 0.5-0.8 micron. As it is the surface of the biomaterial that comes in direct contact with the body fluids, the surface of the biomaterial is of paramount importance. In this study, the plasma polymerized biomaterials were characterized. Thus, the scanning electron microscope (SEM) showed the surfaces to be smooth. To study the surface layer of the deposited polymer, Fourier-transform infrared spectrometry in the attenuated total reflection (ATR) mode was used. The deposited material was indeed silicone polymer with adsorption bands at 1262, 1020, and 802 cm-1 for the Si-CH3 bending, Si-0-Si stretching, and Si-CH3 bending, respectively. To find the bonding nature of the polymer, electron spectrometry for chemical analysis (ESCA) was used. The silicone polymer was shown to be highly cross-linked. To find the molecular weight between cross-links, swelling studies were done. Thus the results of the study show that the plasma polymerization could produce a filler-free silicone layer on a variety of substrate materials.