Polymer chemistry, high-resolution direct

Another modeling approach involves the deposition of an ultrathin film onto a solid substrate. If the film is thin enough, XPS can then be used to look through the film to observe interfacial chemistry directly. Such an approach was first tried in a study of the process of polymer metallization for Cr, Fe, Ni [83,84], Ti [85] and A1 [86] and has recently been extended to the use of thin polymer films on metallic substrates [87], The best results have been achieved using very dilute polymer solutions (0.01-0.025 w/w/ 7f). polished substrates and very high resolution (monochromatic A1 Kq) XPS [88]. The information that can be gleaned from such studies is impressive but relies on careful peal-fitting of the Cls. spectra, as will be discussed in the. section on acid-ba.se interactions. 

The concept that by carrying out a surface analysis on a model specimen one can obtain direct access to the interphase chemistry is a potentially very exciting and rewarding idea. The interaction of PMMA with various metals (as exemplified hyO Fig. 10.14 above) has been studied in some detail using high resolution XPS (Leadley and Watts 1997). In this work the manner in which PMMA formed specific interactions with oxidized metal surfaces was studied by the nature of the fine structure in the XPS spectrum. In this manner, it was possible to show that the polymer formed hydrogen bonds with oxidised silicon (an acidic substrate), a bidentate structure with oxidised aluminum (an amphoteric substrate) and would undergo acyl nucleophilic attack with oxidised nickel (a basic substrate). 

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