Clean surface modifications

Workpieces to be plated may be put through a variety of pretreating processes, including surface cleaning, surface modification, and rinsing. A schematic flowsheet of a typical electroplating plant, including surface treatment and waste treatment, is depicted in Fig. 2. 

Surface Modification. Plasma surface modification can include surface cleaning, surface activation, heat treatments, and plasma polymerization. Surface cleaning and surface activation are usually performed for enhanced joining of materials (see Metal SURFACE TREATMENTS). Plasma heat treatments are not, however, limited to high temperature equiUbrium plasmas on metals. Heat treatments of organic materials are also possible. Plasma polymerization crosses the boundaries between surface modification and materials production by producing materials often not available by any other method. In many cases these new materials can be appHed directly to a substrate, thus modifying the substrate in a novel way. 

Several environment-friendly surface preparation for the treatment of mbber soles with radiations have been recently studied. These treatments are clean (no chemicals or reactions by-products are produced) and fast, and furthermore online bonding at shoe factory can be produced, so the future trend in surface modification of substrates in shoe industry will be likely directed to the industrial application of those treatments. Corona discharge, low-pressure RF gas plasma, and ultraviolet (UV) treatments have been successfully used at laboratory scale to improve the adhesion of several sole materials in shoe industry. Recently, surface modification of SBR and TR by UV radiation has been industrially demonstrated in shoe industry... 

Avseenko et al. (2001) immobilized antigens onto aluminum-coated Mylar films by electrospray (ES) deposition. Various surface modifications of the metallized films were studied to determine their abilities to enhance sensitivity. The plastic surfaces were firsf cleaned by plasma discharge treatment, followed by coating with proteins (BSA and casein) or polymers such as poly (methyl methacrylate) or oxidized dextran, or they were exposed to dichlorodimethyl silane to create hydrophobic surfaces. Protein antigen was prepared in 10-fold excess sucrose and sprayed onto the surfaces to form arrays with spot diameters between 7 and 15 pm containing 1 to 4 pg protein. 

Chemical Surface Modification. In considering the interface, one must contemplate not only the possibility of moisture disrupting the bond but also the possibility of corrosion of the substrate. Corrosion can quickly deteriorate the bond by providing a weak boundary layer before the adhesive or sealant is applied. Corrosion can also occur after the joint is made and, thereby, affect its durability. Mechanical abrasion or solvent cleaning can provide adhesive joints that are strong in the dry condition. However, this is not always the case when joints are exposed to water or water vapor. Resistance to water is much improved if metal surfaces can be treated with a protective coating before being bonded. 

Exact experimental methods. Surface-pressure measurements. Nearly all the methods in use at present are modifications of Langmuir s method, of directly measuring the outward force exerted on a light floating barrier which divides the film-covered surface from a clean surface and for the manipulation of the films, and adjustment of the area available for them, modifications of Pockels s barriers are almost always used. Ths essential points requiring attention for accuracy are as follows ... 

PhotoDecomposition (APD) that occurs above a well-defined ablation threshold usually leads to removal of polymer material leaving a new fresh "clean" surface with the same composition as the untreated material. However, in the case of PET (JL) both composition and structural modifications occur even for fluences below the ablation threshold. 

Fig. 7 Effect of molecular adsorption on the EOT. Sequential surface modification with Au-MUA and albumin result in red-shifted spectra. Cleaning restores the surface response to the bare-Au spectrum. Adapted with permission from the American Chemical Society (Brolo et al. 2004)...

Plasma treatment is widely used commercially for polymer surface modification. Plasma discharge treatments are used to improve adhesiveness and printing properties, to improve cell adhesion to tissue culture substrates (1 ) and to etch or clean the surfaces of materials (removal of photoresist materials on semiconductors, for example ( ). The surface characterization of plasma-modified surfaces is important in order to provide greater insight into how the properties are changed. 

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