Characterization of stationary phases for gas chromatography by 29Si nuclear magnetic resonance spectroscopy: III. Carborane–siloxane copolymers

Five bis(dimethylsilyl)-m-carborane–siloxane polymers with methyl, phenyl, and 2-cyanoethyl ligands were characterized by 1H, 11B, 13C, and 29Si nuclear magnetic resonance (NMR) spectroscopy. All relevant chemical shifts are reported, whereas signal assignment was confirmed by 2D NMR spectroscopy. The chemical composition of the polymers was calculated from the 1H and 29Si NMR spectra. Only 29Si NMR spectroscopy was able to quantify the methoxy end group, from which the average molecular weights were calculated. The copolymer Dexsil 300 turned out to have a regular microstructure, whilst the terpolymers Dexsil 400 and Dexsil 410 have only partly regular sequences. 11B NMR spectroscopy confirmed the m-carborane structure and revealed some low molecular weight impurities.