Characterization of stationary phases for gas chromatography by Si-29 NMR spectroscopy II. Silphenylene-siloxane copolymers

A series of tetramethyl-p-silphenylene-siloxane copolymers with dimethyl, 1 H,1H,2H,2H-perfluorodecylmethyl and diphenyl siloxy groups was prepared. H- 1 and Si-29 nuclear magnetic resonance spectroscopy showed that the chosen reaction conditions provided polymers with diphenyl content up to 85%. The theoretical content of the monomer units correlated well with the measured content. Signal assignments of the copolymers and their corresponding chemi cal shifts are summarized. Information about alternating, randomized or blo ck sequences was obtained by Si-29 nuclear magnetic resonance spectroscopy. Limitations of the method for the determination of microstructure paramete rs are discussed. (C) 2001 Elsevier Science B.V. All rights reserved.