NMR-SPECTROSCOPY AND RELAXATION STUDIES ON LIQUID-CRYSTALLINE SIDE-CHAIN POLYSILOXANES

Two polysiloxanes with mesogenic side chains were investigated with po larization microscopy, DSC, H-1 and C-13 NMR. From proton NMR the glob al order parameter of one sample (the other does not orient itself in the magnetic field of 2.1 T) and some information about phase transiti ons was obtained. C-13 NMR yielded selective order parameters with res pect to different atomic positions. The order parameter varies slightl y also within the mesogenic unit, but much stronger within the spacer (odd-even effect). With the help of T1rho experiments some molecular m otions had been detected and characterized (main-chain motion, over-he ad rotation of the mesogenic unit, methyl rotation, side-chain rotatio n).