SYNTHESIS OF QMD AND QD POLYORGANOSILOXANES FROM TETRAKIS(TRIMETHYLSILOXY)SILANE AND PALABORA VERMICULITE

Tetrakis(trimethylsiloxy)silane (QM4) (Q = SiO4/2 and M = MeSiO1/2) re acts with dimethyldichlorosilane in the presence of an iron(III) chlor ide hexahydrate catalyst to give chlorinated intermediates, e.g. QM3Y (Y = Me2SiO1/2Cl), which upon hydrolysis give products which range fro m viscous liquid QMD (D = Me2SiO2/2) systems to QD elastomeric solids. Chlorinated Q(x)Y(y) intermediates have also been synthesized from hi gh-molecular-weight Q(x)M(y) polyorganosiloxanes derived from palabora vermiculite, and which react with hydroxy-terminated poly(dimethylsil oxanes) (HOD(n)OH) to give a range of QD polymers. The Lentz trimethyl silylation of vermiculite has been modified with the hexamethyldisilox ane replaced by HOD(n)OH as the capping agent to give QD polyorganosil oxanes via a one-pot reaction. Selected QD polymers have undergone a f lame test at 1100-degrees-C to assess their potential as fire-retardan t materials.