The straight-chain polymer is formed by the

Options

A. hydrolysis of `CH_(3)SiCl_(3)` followed by cendensation polymerization
B. hydrolysis of`(CH_(3))_(4) Si addition polymerization
C. hydrolysis of `(CH_(3))_(2)SiCl_(2)` followed by condensation polymerization
D. hydrolysis of `(CH_(3))_(3)SiCl` followed by condensation polymerization

Answer

C

Explanation

The hydrolysis of `(CH_(3))_(2)SiCl_(2)` gives `(CH_(3))_(2)Si(OH)_(2)` which undergoes condensation polymerization to yield a straight-chain polymer:
`(CH_(3))_(2)SiCl_(2)+2H_(2)O rarr (CH_(3))_(2)Si(OH)_(2)+2HCl`
`HO-underset(CH_(3))underset(|)overset(CH_(3))overset(|)(Si)-OH+HO-underset(CH_(3))underset(|)overset(CH_(3))overset(|)(Si)-OHoverset(-H_(2)O)rarr`
`underset("Linear polymer")(-O-underset(CH_(3))underset(|)overset(CH_(3))overset(|)(Si)-O-underset(CH_(3))underset(|)overset(CH_(3))overset(|)(Si)-O-)`
(1) The hydrolysis of `CH_(3)SiCl_(3)` gives a very complex cross-linked polymer.
(2) `(CH_(3))_(2)Si` does not undergo hydrolysis.
(4) The hydrolysis of `(CH_(3))_(3)SiCl` gives `(CH_(3))_(3)SiOH` which condenses to give a dimer:
`CH_(3)-underset(CH_(3))underset(|)overset(CH_(3))overset(|)(Si)-OH+HO-underset(CH_(3))underset(|)overset(CH_(3))overset(|)(Si)-CH_(3)overset(-H_(2)O)rarr`
`CH_(3)-underset(CH_(3))underset(|)overset(CH_(3))overset(|)(Si)-O-underset(CH_(3))underset(|)overset(CH_(3))overset(|)(Si)-CH_(3)`