Alkoxysilanes, fluorinated

As well as phenyl derivatives, other products have been prepared by hydrolysis of alkoxysilanes such as cyclohexenyl or naphthyl derivatives as well as heterocyclic compounds based on thienyl rings (Table 31, entries 28-33). Few practical applications have been reported for this type of compound, except for the styryl compound T81C6H4-A-CFI = CH2]s, and the fluorinated TslCeFsJs which have been used in polymer blending (Table 31, entries 13 and 28). ... 

It has been well recognized that the hydrolysis of alkoxysilanes and chlorosilanes is effectively catalyzed when fluoride anions are present due to formation of hypercoordinated silicon intermediates.803 More in-depth studies by Bassindale et al. showed that the reaction of PhSi(OEt)3 with stoichiometric amounts of Bu4NF surprisingly yields an encapsulation complex, namely tetrabutylammonium octaphenyloctasilsesquioxane fluoride 830, in which the fluorine atom is situated inside the cubic siloxane cage (Scheme 114). The Si--F distance of average 2.65 A is shorter than the sum of van der Waals radii (3.57 A), which renders the coordination number of the silicon atoms at [4+1]. 

Oil- and water-resistant treatments have been reported which involve blends of fluoropolymers and alkoxysilane or alkoxysiloxane materials, dehvered as 100% actives (90) or from solvent or emulsion (91), fluorinated alkoxysiloxane emulsions (92), and self-emulsifying fluorinated alkoxysUane-based concentrates (93). 

Priola et al. [242] have used RBS and XPS in the study of low polarity monomers such as linear long chain hydrogenated n-alkyl acrylics, alkoxysilanes and fluorinated acrylates as modifying additives for highly polar acrylic UV-curable systems (Ebecryl 605 and Ebecryl 150) to show that the additives concentrate selectively at the surface. XPS yields information on the composition of the external layer of the film (about 100 A) and RBS on the concentration profile of some elements (up to 0.3 /um in this case). 

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