LIQUID-CRYSTALLINE POLYETHERS BASED ON CONFORMATIONAL ISOMERISM .19. SYNTHESIS AND CHARACTERIZATION OF FLEXIBLE POLYETHERS BASED ON 1-(4-HYDROXYPHENYL)-2-(2-R-4-HYDROXYPHENYL) ETHANE WITH H, F, CH3, BR, CL, AND CF3 AS R GROUPS

The synthesis of 1-(4-hydroxyphenyl)-2-(2-fluoro-4-hydroxyphenyl)ethane (FBPE), 1-(4-hydroxyphenyl)-2-(2-chloro-4-hydroxyphenyl)etane (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.