Synthesis of QMD and QD polyorganosiloxanes from tetrakis(trimethylsiloxy)silane and palabora vermiculite

Abstract

Tetrakis(trimethylsiloxy)silane (QM₄)(Q = SiO_4/2 and M = Me₃SiO_1/2) reacts with dimethyldichlorosilane in the presence of an iron(III) chloride hexahydrate catalyst to give chlorinated intermediates, e.g. QM₃ Y (Y = Me₂SiO_1/2Cl), which upon hydrolysis give products which range from viscous liquid QMD (D = Me₂SiO_2/2) systems to QD elastomeric solids. Chlorinated Q_xY_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_nOH) to give a range of QD polymers. The Lentz trimethylsilylation of vermiculite has been modified with the hexamethyldisiloxane replaced by HOD_nOH as the capping agent to give QD polyorganosiloxanes via, a one-pot reaction. Selected QD polymers have undergone a flame test at 1100 °C to assess their potential as fire-retardant materials.