Silicones are the synthetic organois licone polymers which contains Si-O-Si linkages. These are represented by the general formula `(R_(2) SiO)_(x)`, Here R may be alkyl or phenyl group. In general, silicones are formed by reacting Grignar reagent with `SiCl_(4)` and this is followed to hydrolysis.
(i) How are linear silicones formed?
(ii) How are cross- linked silicones prepared?
(iii) What is the value associated with silicones?

Explanation

(i) Linear silicones are formed by the hydrolysis of dichlorosilances followed by polymerisation.
(ii) Cross-linked silicones are formed by the hydrolysis of trichlorosilanes followed by polymerisation.
(iii) Silicones have wide range of applications. Silicone-rubbers retain their elasticity over a range of temperature These are used as insulating materials for electrical motorws and other appliances. Silicones are also used inmaking greases that act as lubircants in acroplnaes.