ISSN:
0887-624X
Keywords:
liquid crystals
;
all hydrocarbon
;
side chain
;
polysiloxane polymers
;
smectic B phase
;
smectic E phase
;
X-ray diffraction
;
spin-lattice relaxation time
;
Chemistry
;
Polymer and Materials Science
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
A series of new and high-purity hydrocarbon liquid crystal monomers were synthesized through the acylation reaction, deoxygenation reaction, and Grignard reaction. 1H-NMR spectra and elemental analyses were used to examine their purity. The liquid crystalline polysiloxane polymers were obtained by grafting the monomers onto poly(methylhydrosiloxane). The thermal transition temperature, mesomorphic properties, and mesophase textures of the monomers and the polymers were determined by differential scanning calorimetry (dsc), polarized optical microscopy, and X-ray diffraction analysis. Moreover, we observed the even-odd effect of the smectic/isotropic transition temperature with the length variation of the substituents. In this study, we found by X-ray diffraction that the liquid crystalline polysiloxane polymers undergo a transition from smectic B to smectic E mesophase. However, dsc has difficulty detecting the phase transition process. By considering the spin-lattice relaxation time (T1), we can systematically explain the relation between the flexibility of the substituent with the smectic/isotropic transition temperature. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 2849-2863, 1998
Additional Material:
9 Ill.
Type of Medium:
Electronic Resource
