Silane high polymers synthesis

Synthesis is typically by alkali metal-mediated coupling of dichlorosilanes or 1,2-dichlorodisilanes, although electrochemical coupling of chlorosilanes and dehydrocoupling of primary and secondary silanes also often lead to oligomeric (as opposed to high polymer) fractions. 

The conventional methods for the synthesis of organosilanols can be accomplished by the hydrolysis of the appropriate substituted silane in the presence of catalysts such as an acid or a base.1 This synthetic route, however, had some difficulty when applied to the synthesis of silanol polymers which demanded not only high conversion of the functional groups for polymer modification but also resistance to the transformation of silanols to siloxane by self- or catalytic condensation during the preparation. 

The disadvantages of the synthesis routes 1-4 are the application of highly reactive and expensive metals (Li, Na, K, Mg) and the enormous quantity of solvents. Particularly, as result of the dehalocoupling reactions, the polymers are unreactive at room temperature. To overcome these problems we synthesized spinnable reactive poly(silanes/-carbosilanes) via heterogeneous catalytic disproportionation of methylchlorodisilanes which have been wasted as a byproduct of the "Direct synthesis" of methylchlorosilanes so far. 

Propyl trimethoxysilane 4a exhibits a much lower reaction rate than that of trimethoxy vinyl silane 4b. This is the result of a reduced electron density at the silicon atom in 4a compared to 4b bearing the vinyl groiq). In contrast, the high reactivity in die case of 5, the saturated counterpart of 3a, is not only retained, but enhanced. This can be explained by a more effective electron transfer from the ester moiety to silicon in the case of 5 compared to 3a due to the missing electron delocalization. The high hydrolysis speed found for compound 5 indicates that the high reactivity of 3a can be transferred into a polymer in the case of a copolymer synthesis. 

Disperse oxides unmodified or modified by organics (OC) or OSC are used as fillers, adsorbents, or additives [1-11]. OSCs are used as promoters of adhesion, inhibitors of corrosion, for the stabilization of monodisperse oxides and the formation of the nanoscaled particles. Oxide modification by alcohols or other OC is of interest for synthesis of polymer fillers, as such modification leads to plasticization and reinforcement of the filled coating, but in this case a question arises about hydrolyz-ability of the =M—O—C bonds between oxide surface and alkoxy groups, as those are less stable than =M—O— M= formed, for example, upon the silica modification by silanes or siloxanes. The high dispersity, high specific surface area, and high adsorption ability of fumed oxides have an influence on their efficiency as fillers of polymer systems. 

Silane-terminated poiysiioxanes are a new class of high reactive rtv-1 silicone systems. The synthesis of these polymers is shown in Eq. 1. In a first step a hydroxy-terminated polydimethylsiloxane is converted to the corresponding aminopropyl-polydimethylsiloxane by reaction with stoichiometric amounts of 3-[(2,2-dimethyl-l,2-a2asiiolidin-l-yl)dimethylsilyl]-l -propylamine at room temperature. The silane termination reaction in a second step is carried out under the same conditions without adding further catalysts, due to the fast reaction of NCO groups with the primary amino groups. 

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