SILPHENYLENE AND SILPHENYLENE-SILOXANE OLIGOMERS - STRUCTURE-PROPERTY RELATIONSHIPS

Some representative oligomers were prepared by polycondensation reactions of dimethyldichlorosilane with 1,4-di-Grignard reagent prepared from 1,4-dibromobenzene in diethyl ether. The structural characterization of the oligomers was carried out by FTIR and H-1, C-13, and Si-29 NMR spectroscopy. The ($) over bar M(n) values were determined by vapor pressure osmometry. The T-g values were measured by DSC and the thermodegradation process was analyzed by TGA. In all cases the oligomers prepared in the absence of the blocking end group showed siloxane units in the main chain, which were quantified by H-1 and Si-29 NMR. Si-29 NMR was also used to determine the oligomer sequence. It was possible to correlate the ($) over bar M(n) and structure with T-g and with temperature at 3% weight loss. The results agree with these obtained for structurally similar polymers.