ISSN:
0887-624X
Keywords:
1-(4-hydroxyphenyl)-2-(2-R-4-hydroxyphenyl)ethane (RBPE), with H, F, CH3, Cl, Br, CF3 as R groups, polyethers
;
phase transitions
;
molecular breadth
;
Chemistry
;
Polymer and Materials Science
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
The synthesis of 1-(4-hydroxyphenyl)-2-(2-fluoro-4-hydroxyphenyl)ethane (FBPE), 1-(4-hydroxyphenyl)-2-(2-chloro-4-hydroxyphenyl)ethane (CIBPE), 1-(4-hydroxyphenyl)-2-(2-bromo-4-hydroxyphenyl)ethane (BrBPE), and 1-(4-hydroxyphenyl)-2-(2-trifluoromethyl-4-hydroxyphenyl)ethane (CF3BPE), of the corresponding polymers based on 1,5-dibromopentane (RBPE-5), 1,8-dibromooctane (RBPE-8), and of the copolymers based on various ratios of 1,5-dibromopentane and 1,8-dibromooctane [RBPE-5/8(A/B)] is described. The phase transition temperatures and thermodynamic parameters of RBPE-5 and RBPE-8 polymers were compared to those of the corresponding polyethers based on 1,2-bis(4-hydroxyphenyl)ethane (BPE) and 1-(4-hydroxyphenyl)-2-(2-methyl-4-hydroxyphenyl)ethane (MBPE) which were reported previously. Both isotropic-nematic transition temperatures and corresponding thermodynamic parameters (i.e., enthalpy and entropy changes) decrease in the following order of the substituent R: H 〉 F 〉 CH3 〉 Cl 〉 Br 〉 CF3. This order corresponds to the increase of the breadth of the RBPE molecules, and agrees with the similar trends observed in low molar mass liquid crystals.
Additional Material:
7 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/pola.1992.080300606
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