Deposited polymeric films, effect

In earlier work, Vaswani et al. [40] verified the effectiveness of plasma deposition of polymerized fluorocarbon films on paper and regenerated cellulose surfaces for the purpose of enhancing barrier properties as well as achieving hydrophobic surface properties. The monomers used for the plasma polymerization process were pentafiuoroethane (CF3CHF2) and octafiuorocyclobutane (C4F8). Although the deposited polymerized films allowed water vapor diffusion, the deposited films were hydrophobic and therefore remained unwetted by water contact. Contact angle studies confirmed that a small fluorocarbon film thickness at 70 nm was only needed to completely envelop the paperboard surface and its near-surface fibers. Aside from this hydrophobic surface characteristic, it was also confirmed that plasma deposited films imparted improved barrier to lipophilic materials. 

When optical anisotropies form spontaneously in the polymeric film during deposition, the situation is more complicated. Significant effects are observed in optical and spectroscopic properties, such as LED emission [17] and waveguide propagation [45-50,52,64], For these films, accurate evaluation of the optical constants is more difficult and must be based on variable incidence angle measurements, as in the case of surface plasmon resonance [45-47], waveguide propagation [48-50,52], ellipsometry [64,67], and reflectance/transmittance [68]. 

Stancell et. al. ( 0) reported the possible use of ultrathin films deposited onto relatively permeable substrates as permselective membranes. Ultrathin and highly crosslinked coatings effectively distinguish between molecules of different sizes and increase the permselectivity of the substrate film. Chang et. al. ( ) demonstrated that the permeability coefficient of silicone rubber to oxygen decreased noticeably after depositing a plasma-polymerized ethylene film on the surface. Colter, et. al. (92.93) found similar effects of plasma polymerized films as diffusion barriers in controlled-released drug delivery systems. 

Nishimori H., Tatsumisago M., Minami T. Preparation of thick silica films by the electrophoretic sol-gel deposition on a stainless steel sheet. J. Ceram. Soc. Jpn 1995 103 78-80 Schulze-Bergkamen H., Yamane M. Effects of reaction parameters on the preparation of thick silica gel films by an interfacial polymerization I. Effects of pH and type of catalyst. J. Sol-Gel Sci. Technol. 1995 5 185-191... 

Electrochemical polymeriza tion of heterocycles is useful in the preparation of conducting composite materials. One technique employed involves the electro-polymerization of pyrrole into a swollen polymer previously deposited on the electrode surface (148—153). This method allows variation of the physical properties of the material by control of the amount of conducting polymer incorporated into the matrix film. If the matrix polymer is an ionomer such as Nation (154—158) it contributes the dopant ion for the oxidized conducting polymer and acts as an effective medium for ion transport during electrochemical switching of the material. 

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