Plasma polymerizations (under 13.5‐MHz radiofrequency inductively coupled glow discharge) of some organic compounds are investigated by their properties (elemental analysis, surface energy, and infrared spectra) and their relations to the concentrations of free radicals in the polymers as detected by electron spin resonance (ESR) spectroscopy. Monomers that have been investigated are hexamethyldisiloxane, tetrafluoroethylene, acetylene, acetylene/N2, acetylene/H2O, acetylene/N2/H2O, allene, allene/N2, allene/H2O, allene/N2/H2O, ethylene, ethylene/N2, ethylene oxide, propylamine, allylamine, propionitrile, and acrylonitrile. Plasma‐polymerized polymers generally contain oxygen, even if the starting monomers do not contain oxygen. This oxygen incorporation is related to the free‐radical concentration in the polymer. Molecular nitrogen copolymerizes with other organic monomers such as acetylene, allene, and ethylene, and their properties are very similar to those of plasma‐polymerized polymers from nitrogen‐containing compounds such as amines and nitriles. The addition of water to the monomer mixture reduces in a dramatic manner the concentration of free radicals in the polymer and consequently the oxygen‐incorporation after the polymer is exposed to air. The concentrations of free radicals (by ESR) are directly correlated to the change of the properties of plasma‐polymerized polymers with time of exposure to the atmosphere. These changes are primarily the introduction of carbonyl (and possibly hydroxyl) groups. The addition of water to the plasma introduces these groups during the polymerization.

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SynopsisPolymerizations of acetylene with nonpolymerizing gases and vapors such as HzO, Nz, and CO in a plasma generated by inductive coupling of 13.5 MHz radio frequency are investigated. It is found that acetylene copolymerizes with those comonomers and that properties of copolymers are distinctly different from that of plasma polymer of acetylene. The copolymerization with H20 has a significant effect in reducing the trapped free radicals in the plasma polymer (to a nonexistent level). Infrared and electron spin resonance (ESR) spectroscopies and elemental analysis of polymers are used to investigate the incorporation of HzO, NO, and CO into the plasma polymers.

Plasma coating (deposition of polymer under the influence of plasma) is utilized to modify the surface properties of corneal contact lens. An ultrathin layer (thickness of roughly 200 A) of plasma polymer of acetylene/H20/N2 is applied to poly(methyl methacrylate) (PMMA) corneal contact lenses. The surface becomes highly wettable with water compared to uncoated lens. When coated and uncoated contact lenses are placed on rabbit eyes, a remarkable difference in accumulation of mucous matter is observed. With the control lenses, the accumulation of mucous matter in a week is sufficient to affect the optical clarity of the lenses, whereas the coated lenses show no change after three months continuous wearing. The comparative degree of adhesion of the corneal epithelium cells onto glass, modified glass, PMMA, and coated PMMA surfaces is studied using tissue cultures and phase contrast microscopy. The coated PMMA surface exhibits a degree of tissue adhesion lower than that of control PMMA and higher than that of glass surface, and no sign of toxicity of the coated surface is observed by the tissue cultures.