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

Tetrakis(trimethylsiloxy)silane (QM4) (Q = SiO4/2 and M = MeSiO1/2) reacts with dimethyldichlorosilane in the presence of an iron(III) chloride hexahydrate catalyst to give chlorinated intermediates, e.g. QM3Y (Y = Me2SiO1/2Cl), which upon hydrolysis give products which range from viscous liquid QMD (D = Me2SiO2/2) systems to QD elastomeric solids. Chlorinated Q(x)Y(y) intermediates have also been synthesized from high-molecular-weight Q(x)M(y) polyorganosiloxanes derived from palabora vermiculite, and which react with hydroxy-terminated poly(dimethylsiloxanes) (HOD(n)OH) to give a range of QD polymers. The Lentz trimethylsilylation of vermiculite has been modified with the hexamethyldisiloxane replaced by HOD(n)OH as the capping agent to give QD polyorganosiloxanes via a one-pot reaction. Selected QD polymers have undergone a flame test at 1100-degrees-C to assess their potential as fire-retardant materials.