Temperature-influenced ordering of mesogens in comb-like liquid-crystalline poly(methylsiloxane) macromolecules with side groups consisting of “phenyl benzoate” moieties in solution
✍ Scribed by Peter Lavrenko; Natalia Yevlampieva; Olga Okatova; Galina Kolbina; Michael Olbrich
- Publisher
- John Wiley and Sons
- Year
- 1997
- Tongue
- English
- Weight
- 814 KB
- Volume
- 198
- Category
- Article
- ISSN
- 1022-1352
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✦ Synopsis
Comb-like poly(methylsi1oxane) macromolecules P4, P6, and P11, with side groups consisting of "phenyl benzoate" moieties and different alkyl spacers (from 4 to 11 C-atoms) between the backbone and the mesogenic side groups have been synthesized and investigated as well as low-molar-mass compounds M4, M6, and M11, as model molecules analogous to side chains of the macromolecule. The liquid-crystalline phase transition temperatures have been determined. Mobility of the mesogens and the macromolecule as a whole in dilute solution was studied in external fields (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 the effect observed in a mechanical shear flow field. The Maxwell constant is positive for the solutions of compounds M4, M6, MI1 and negative in polymers P4, P6, P11. This indicates the orientation of the macromolecule as a whole in the shear flow field, the mesogenic group main axis being oriented in the direction preferably normal to the macromolecular axis of primary polarizability. Temperature effects are also discussed.