Mechanism of the formation of polyphenylpolysiloxanes from terfunctional ?monomers?

Abstract

1. Is has been shown that, when terfunctional organosilicon monomers are hydrolyzed in an aqueous medium in presence of mineral acids, complex cyclic polymeric products which do not readily pass, when heated, into three-dimensional polymers, since further condensation occurs by two competing reactions-intramolecular dehydration and intermolecular condensation. The first reaction predominates when the organic radical attached to silicon is large, and the second when it is small. 2. Hydrolysis of triacetoxyphenylsilane in a weakly acid medium (acetic acid) yielded the crystalline trimer 1,3,5-triphenyltrisiloxane-1,1,3,5,5-pentols: 3. Hydrolysis of terfunctional monomers in a weakly acid medium (in presence of organic acids) results in the formation of linear polymers. This view is confirmed by the isolation of the crystalline products 1,3,5-triphenyltrisiloxane-1,1,3,5,5-pentol and by the analytical data on the more complex polymers.