Metallization of polymer films

A second already mentioned application is the metallization of polymer films. As shown in Fig. 3.78, is the thermal treatment of a TMC-polycarbonate film onto which gold metal clusters were deposited [164], Upon annealing above Tg, the metal particles are in parts sunken into the softened film, thereby reducing the surface roughness. It was also concluded that the embedded clusters were covered with a thin polymer layer. 

Vacuum metallizing of polymer films, such as cellulose acetate, butyrate, and Mylar, is performed in essentially the same way. Film rolls are unreeled and rewound during the deposition process to metallize the desired surface. A protective abrasion-resistant coating is then applied to the metallized surface in an automatic coating machine. 

Stagnation flames are also being used to modify the surface properties of various materials. For example, premixed methane-air flames can beneficially alter the properties of polymer films [41,358,381,382,388]. Flames can also modify surface properties of ferrous and nonferrous metals, for example, improving surface hardness [360] by creating... 

Si(Li) detectors without Be windows ("windowless") or with thin metal-coated polymer films (Ultra-Thin Window UTW) have become an important peripheral to modern-day AEMs for the qualitative detection of elements with 5vacuum requirements because the removal of the Be window increases the probability of detector contamination (from the specimen or column environment) and consequent degradation of performance [12]. Windowless and UTW Si(Li) detectors are commonly installed with additional airlock mechanisms and only on instruments with acceptable levels of vacuum cleanliness. Thus, design constraints on modern AEMs preclude placement of the UTW detector close to the sample. In addition, loss of detection efficiency at low energies (light-element K-lines with the L-lines of transition metals all conspire to limit windowless or UTW EDS analysis of minerals to a qualitative basis only. 

As outlined above, the electrochemical properties of this redox species are strongly pH-dependent and this behavior can be used to illustrate the supramolecular nature of the interaction between the polymer backbone and the pendent redox center. The cyclic voltammetry data shown in Figure 4.17 are obtained at pH = 0, where the polymer has an open structure and the free pyridine units are protonated (pKa(PVP) = 3.3). The cyclic voltammograms obtained for the same experiment carried out at pH 5.7 are shown in Figure 4.18. At this pH, the polymer backbone is not protonated and upon aquation of the metal center the layer becomes redox-inactive, since protons are involved in this redox process. This interaction between the redox center and the polymer backbone is typical for these types of materials. Such an interaction is of fundamental importance for the electrochemical behavior of these layers and highlights the supramolecular principles which control the chemistry of thin films of these redox-active polymers. Finally, it is important to note that the photophysical properties of polymer films are very similar to those observed in solution. Since the layer thickness is much more than that of a monolayer, deactivation by the solid substrate is not observed. 

As the presented data are of rather poor quality, we would not like presently to discuss at length the problem we would prefer waiting for other sets of high resolution spectra that are scheduled for the near future (161... However in the meantime, we studied the origin of the HREELS broadening (Fig.7), to discover that other authors (2b.8.111 already stressed upon an influence of the substrate spectra of polymer films deposited onto a metallic substrate are of better quality than when deposited onto silicon or germanium. 

The activation of nonconducting materials by the deposition of metal-containing polymer films could improve the autocatalytic metallization process by eliminating the aqueous etching and sensitizing steps. In addition, substrates that are hard to etch and activate by the aqueous process could be plated by this technique. 

PAP cycle at room temperature the inset shows the same experiment for a DRl/PMMA guest host system. Details of ATR EO modulation experiments can be found elsewhere.Briefly, the EO coefficients of polymer films are determined by applying an ac voltage (ViCosQt) between two metallic layers that sandwich the polymer film, and by recording the modulation of the reflectivity at Q, for the Pockels effect, and at 2Q, for the Kerr effect. A computer program evaluates the amplitudes of modulation of the film s thickness, and the refractive indices, , (i = x, y, 2 which represent the principal axes of the film), from which the Pockels, e.g., and Kerr, e.g., s y, EG coefficients are obtained. These are given by... 

Such bilayers can conveniently be built up by successive electropolymerization of complexes containing ligands with vinyl substituents, e.g. 4-vinylpyridine or 4-vinyl-4 -methyl-2,2 -bipyridyl. The films may be deposited on metallic or semiconductor electrodes (e.g. Pt, glassy carbon, Sn02, Ti02). More efficient metallation of the films is obtained by polymerization of coordinated ligand than by subsequent metallation of a preformed polymer film. An alternative to discrete films would be a copolymer with distinct redox sites, or a combination of a single polymer film with a copolymer film in a bilayer device. 

The Incorporation of metals Into polymer films produced by plasma techniques Is an attractive prospect since It can be envisaged that careful choice of the metal and organic phases, and close control of the overall composition of the product would greatly extend the scope of these plasma polymerized materials In, for example, electrical, magnetic and optical applications. In a previous paper (1) we have outlined a convenient method for the preparation of such materials derived from fluorinated monomers by simultaneous chemical plasma etching and polymerization in the same system. 

The synthesis of the metal containing polymer films involves a capacitively coupled diode reactor configuration in which one electrode is grounded, (the anode). 

Electropolymerization methods are already established for two purposes—the coating of polymer films onto electrodes and the electroinitiation of bulk polymerization. Future prospects are probably brighter for the use of these processes in new coating technology, both for protection of metallic surfaces and for designed modification of electrodes in the manner discussed earlier. 

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