Khan, N.; Price, D. M.; Bashir, Z.; Synthesis and mesophase characterisation of liquid crystalline polyesters with bulky, rigid, lateral substituents. Journal of Polymer Science, Part B: Polymer Physics 32(15) (1995) 2509-2518
The synthesis and characterisation of aromatic polyesters containing various symmetrically di-substituted hydroquinone monomers is described. The homopolyesters made from these monomers and terephthalic acid did not melt. Copolyesters of terephthalic acid with mono- and di-substituted hydroquinone formed liquid crystalline melts. Optical microscopy showed Schlieren, marbled, and droplet textures characteristic of the nematic phase. DSC experiments were also in accord with mesophase formation as multiple transitions characteristic of first-order phase changes were found. In general, the crystal-nematic transition was about 300°C, whereas the nematic-isotropic change was over 400°C. All the polyesters were prone to decomposition near or above the isotropisation temperature.
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