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Synthesis and properties of high temperature mesomorphic polysiloxane solvents biphenyl and terphenyl based nematic systems


, : Synthesis and properties of high temperature mesomorphic polysiloxane solvents biphenyl and terphenyl based nematic systems. Analytical Chemistry 57(3): 651-658

The synthesis and characterization of a variety of mesomorphic (liquid-crystalline) side-chain polysiloxane (MEPSIL) solvents, said to be useful as gas chromatographic stationary phases, were described and discussed. The synthetic scheme was based upon the hydrosilation reaction that occurred when 4-(allyloxy)benzoyl esters were contacted with poly(methylsiloxane) in the presence of a dicyclophentadienylplatinum(II) catalyst, while product characterization was carried out by IR, NMR, GC [gas chromatography], DSC [differential scanning calorimetry], elemental analysis and direct-observation hot-stage light-polarized microscopy. Selectivity of the MEPSIL phase differed substantially from those exhibited by all other common GC solvents. The MEPSIL found overall to be the best suited as a GC stationary liquid exhibited a melting point of 139.degree. C (k .fwdarw. n) and a nematic/isotropic (n .fwdarw. i) transition temperature of 319.degree. C, while the practical operating limits of the material spanned 150-300.degree. C.

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