CONTROLLED POLYMERIZATION OF SILICIC ACIDS DERIVED FROM MINERAL SILICATES .3. FORMATION AND REACTIONS OF QXMY(O1 2R)Z/

The preparation of reactive intermediates, of the type QxMy(O1/2R)z (w here Q = SiO4/2; M = Me3SiO1/2; R = Et), has been studied. The interme diates (partially trimethylsilylated silicic acid esters) have been ch aracterised and average structures have been determined. The formation and stability, and hence reactivity, of the intermediates, have been studied with respect to inter- or intra-molecular condensations under various reaction conditions: temperature, acidity and phase-transfer a gent. The stability of the intermediates has been attributed to the fo rmation of micelles in solution. The intermediates have been shown to undergo condensations with silicic acids from another source, e.g. a s ilicate mineral, yielding higher-molecular-weight polyorganosiloxanes. The intermediates have also been shown to react with various heteromo lecules, yielding polymers which contain aluminium, phosphate, silicon es, tetraethylsilicate, ethylenediaminetetraacetic acid and phenol gro ups.