TEMPERATURE-INFLUENCED ORDERING OF MESOGENS IN COMB-LIKE LIQUID-CRYSTALLINE POLY(METHYLSILOXANE) MACROMOLECULES WITH SIDE-GROUPS CONSISTINGOF PHENYL BENZOATE MOIETIES IN SOLUTION

Comb-like poly(methylsiloxane) macromolecules P4, P6, and P11, with si de groups consisting of ''phenyl benzoate'' moieties and different alk yl spacers (from 4 to 11 C-atoms) between the backbone and the mesogen ic side groups have been synthesized and investigated as well as low-m olar-mass compounds M4, M6, and M11, as model molecules analogous to s ide chains of the macromolecule. The liquid-crystalline phase transiti on temperatures have been determined. Mobility of the mesogens and the macromolecule as a whole in dilute solution was studied in external f ields (electric and mechanical shear field). In dilute solution under the influence of a sinusoidal electric field, the polymer behaviour is typical of flexible-chain polymer molecules where each mesogenic unit is oriented independently of the other ones. This is in contrast to t he effect observed in a mechanical shear flow field. The Maxwell const ant is positive for the solutions of compounds M4, M6, M11 and negativ e in polymers P4, P6, P11. This indicates the orientation of the macro molecule as a whole in the shear flow field, the mesogenic group main axis being oriented in the direction preferably normal to the macromol ecular axis of primary polarizability. Temperature effects are also di scussed.