Graft polymerization metal-containing complexes

The fact that silsesquioxane molecules like 2 7 contain covalently bonded reactive functionalities make them promising monomers for polymerization reactions or for grafting these monomers to polymer chains. In recent years this has been the basis for the development of novel hybrid materials, which offer a variety of useful properties.3,4 This area of applied silsesquioxane chemistry has been largely developed by Lichtenhan et al.4 With respect to catalysis research, the chemistry of metallasilsesquioxanes also receives considerable current interest.1,2,10,21 As mentioned above, incompletely condensed silsesquioxanes of the type R7Si7Og(OH)3 (2-7, Scheme 4) share astonishing structural similarities with p-tridymite and p-cristobalite and are thus quite realistic models for the silanol sites on silica surfaces.1,2,21 26 Metal complexes derived from 2-7 are therefore commonly regarded as realistic models for industrially important metal catalysts immobilized on silica surfaces.1,2,22 It is... 

The previous example illustrates that quantification on entirely polymeric systems is difficult to achieve and often requires elaborate post-modification steps. XPS analysis, however, can provide straightforward information on the presence of hetero-atoms from the graft polymer (e.g., phosphorus, nitrogen, and sulfur) if the substrate polymer does not contain these elements. Moreover, complexation of metal cations such as Fe ", Ni ", and Cu " can also be investigated. XPS is therefore complementary to other analysis techniques, such as UV spectroscopy and ATR-IR spectroscopy. 

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