Plasma deposition polymerization, surface materials

Plasma treatment and plasma deposition polymerization provides a unique and powerful method for the surface chemical modification of polymeric materials without altering their bulk properties. (7-5) These techniques offer the possibility to improve the performance of existing biomaterials and medical devices and for developing new biomaterials-(- -6)... 

Furthermore, in this type of plasma the polymeric materials deposit not only on the substrate but also on the electrode surfaces. Thus, the sputter deposition of metal in polymer-forming plasmas is more complicated than that in non-polymer-forming plasmas. 

Plasma deposition has also been utilized to deposit PEO-like materials from volatile precursors onto a variety of subjects. This technique involves generating a reactive plasma containing PEO-like monomers, which polymerize and deposit, often with chemical grafting, onto any surface within the plasma. The availability of large-scale vacuum apparatus makes this technique feasible on an industrial scale. The materials deposited by this technique were often shown to contain only short PEO segments yet greatly reduced protein deposition was observed and the small amounts (ng/cm) that did deposit were easily eluted. ... 

Plasma treatment for development of durable functional textiles via surface activation, deposition of active materials, and/or polymerization of coating onto the textile surface for various functionalities [1, 38, 41, 59, 72,117,152]. 

More recently, an approach for low permeability materials is to deposit parylene-C into the poly-(dimethylsiloxane). The base matrix is coated with parylene-C by chemical vapor deposition polymerization in the usual way [78]. Then the parylene-C on the surface is removed by oxygen plasma etching and only what is in the pores of the matrix remains there. 

Polymer films produced by a glow discharge often possess chemical and physical properties that are superior to conventionally polymerized materials [110,111]. They are prepared by a totally dry vapour phase deposition process and may be conformally coated onto virtually any substrate, thereby completely changing the surface properties of the substrate. Further, the substrate may be cleaned by the plasma prior to deposition and, under the correct conditions, it is often possible to graft the deposited polymeric film to the underlying substrate. 

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. 

The major polymers that make up the wall are polysaccharides and lignin. These occur together with more minor but very important constituents such as protein and lipid. Water constitutes a major and very important material of young, primary walls (2). The lignin is transported in the form of its building units (these may be present as glucosides) and is polymerized within the wall. Those polysaccharides which make up the matrix of the wall (hemicelluloses and pectin material) are polymerized in the endomembrane system and are secreted in a preformed condition to the outside of the cell. Further modifications of the polysaccharides (such as acetylation) may occur within the wall after deposition. Cellulose is polymerized at the cell surface by a complex enzyme system transported to the plasma membrane (3). 

Amount of deposited material - The difference in weight loss between coated and untreated silica corresponds to the weight of the plasma-polymerized film deposited on the surface. For the plasma-treated silicas, decomposition of the coating starts at 265°C for poly acetylene, 200°C for polypyrrole, and 225°C for poly thiophene, and is complete at 600°C. Between 265 and 600°C, PA-silica shows 6 wt% weight loss, and PPy- and PTh-silicas show 4.5 wt% and 5 wt% loss, respectively. 

The deposition of thin polymeric films from a cold plasma in a radio-frequency glow discharge apparatus has become an important means of modifying surfaces in materials applications [42], Applications receiving much attention recently have been the use of plasma polymerization to obtain biocompatible materials, and to produce functional surfaces for attachment of biologically active substances [43-45]. In this respect, many studies of protein adsorption have been... 

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