Industrial Applications of Other Organosilicon Polymers

Macromolecular carbosilanes can be prepared from vinyl, allyl or hydroorganosi-lanes, or from siletanes, and attain molecular weights of 100000. They are, as a rule, resistant to heat and hydrolysis. Their boiling points and viscosities are higher than those of silicones with similar molecular weights. The viscosity of a carbosilane depends strongly on the temperature. This is an important point in the use of macromolecular carbosilanes as copolymers. For example, the copolymers of triorganovinylsilanes and isoprene or 1,3-butadiene, which are prepared at 10 to 

80 °C in the presence of alkyllithium, can be used to make membranes with selective permeability [531]. 

Pure macromolecular organosilazanes are applied only in exceptional cases. 

When heated to about 450 C, hexaphenylcyclotrisilazane forms an infusible polymer (Eq. 4.5)  

4 Bis (aminodimethylsilyl) benzene reacts with glycol to form a polymer which is alkali-resistant and thermally stable to about 400 °C [533]. 

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