The polymers shown are all linear or cyclic, comprising difunctional
units, D. In addition to these, branched polymers or
resins can be prepared if, during hydrolysis, a certain amount
of T orQunits are included, which will allow molecular expansion,
in three or four directions, as opposed to just two. For
example, consider the hydrolysis of methyltrichlorosilane in the
presence of trimethylchlorosilane, which leads to a branched
polymer as shown next: