ABSTRACT:The effect of the chemical structure and stereogeometry of mesogen on the liquid crystalline properties of thermotropic main-chain polyesters was studied by means of DSC and polarized microscopy for three series of polymers. The polyesters obtained from modified 4,4'-dihydroxybenzophenone (DHBP) and sebacoyl (SEB) or suberoyl (SUB) dichlorides did not exhibit the mesogenic properties. Modification of DHBP in this case consisted in replacement of ketone linkage by between two aromatic rings. The same bisphenol, however, when mixed with CC12 another (showing meso genic behaviour) enhanced the liquid crystalline properties of the copolyesters, namely increasing the temperature range of liquid crystalline phase. The condensation of SEB or SUB with DHBP modified by lateral substitution (at various positions) of one aromatic ring with CH3 group lead to polyesters of lower temperatures of the transition from crystal to nematic phase and mesophase to isotropic liquid, as compared to parent polymers (i.e., polyesters ofDHBP+SEB or SUB). Different shifts of those temperatures with the position of substitution have been observed and it was found less pronounced for 3-substituted than 2-substituted bisphenols. Temperature ranges of mesophases also depended on the structure of bisphenols and were broader for 3-substituted DHBP. Therefore, the stereogeometry of the polymer molecules and the bulkiness of their substituents are considered the most important parameters in controlling the mesogenic properties of thermotropic, rigid-flexible polyesters with mesogens incorporated in the main chain.

SynopsisThe antiplasticizing effect of ester derivatives of bisphenol A: l,l-bis(4-hydroxyphenyl)-2,2-propane diacetate (DAPP), 1,1-bis(4-hydroxy-3,5-dichlorophenyl)-2,2-propane diacetate (DACPP), 1,1-bis(4-hydroxy-3,5-dibromophenyl)-2,2-propane diacetate (DABPP), l,l-bis(4-hydroxy-3,5-dichlorophenyl)-2,2-propane dibenzoate (DBCPP), l,l-bis(4-hydroxy-3,5-dichlorophenyl)-2,2-propane di-2,4-dichlorobenzoate (DCBCPP) on polycarbonate was investigated. Obtained results indicate that antiplasticizing abilities of these compounds depend on the number of polar groups in the molecule, as well as on the possibility of tight filling the free volume by the molecules in polymer-antiplasticizer system.

SynopsisConsiderable deviations of molar refraction from the additivity in the solutions containing polycarbonate and its antiplasticizers symmetrical trinitrotoluene and l,l-bis(4-hydroxy-3,5-dichlorophenyl)2,2,2-trichloroethane diacetate are reported. In contrast to this, the solutions of polycarbonate with plasticizer di-n-butyl phthalate and the solutions of antiplasticizers in pure solvent show only insignificant deviation from the additivity. The calorimetric studies showed the differences in the heats of solution of the used antiplasticizers in pure solvent and in the solvent containing a constant amount of polymer, whereas there was no noticeable difference in the polycarbonate-plasticizer (di-n-butyl phthalate) system. Both deviations of the molar refraction from the additivity and differences of the heats of solution prove the existence of strong interactions between the molecules of polycarbonate and the antiplasticizer.

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