Polysilane specific forms

Figure 4. shows the route from the high boiling residue of the direct synthesis to silicon carbo-nitride fibers. Methylchlorodisilanes and trichlorosilanes as additives are mixed in a specific ratio and react with methylamine and a small amount of ammonia to form an aminodisilane/oligosilazane. The subsequent polycondensation reaction of this mixture by heating to 250 °C yields a soluble and melt spinnable polysilazane. In comparision with the polysilane the properties of the polysilazane depend on the ratios of the disilanes/silanes and methylamine/ammonia and also on the reaction conditions. 

Specifically, the chloro and alkoxy groups of multifunctional organosilanes undergo bulk hydrolysis and condensation, forming polysilane networks in an aqueous environment prior to depositing onto the substrate. As a result, the fraction of initial surface silanols that reacts with the functional organosilane is quite small, and the silylation process is usually non-uniform and difficult to control [181]. 

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