Synthesis, structure, and characterization of nematic liquid-crystalline thermosets based on bisacrylates

Four bisacrylate mesogenic monomers and the corresponding liquid-crystalline thermosets were synthesized. The chemical structures of the intermediate compounds and monomers obtained were confirmed by elemental analyses, Fourier transform infrared, and H-1 NMR and C-13 NMR spectra. The mesomorphic properties and thermal stability were investigated with differential scanning calorimetry, then mogravimetric analysis, polarized optical microscopy, and X-ray diffraction measurements. The influence of the curing temperatures and time on the phase behavior and thermal stability of the thermosets was discussed. All the monomers and thermosets exhibited a nematic schlieren texture. However, the monomers only showed the melting transition, and the thermosets displayed the glass transition. The experimental results demonstrated that the monomer structures strongly affected the phase behavior and the curing reaction rate, and the glass-transition temperatures and thermal stability of the thermosets increased with the curing temperature and time. (c) 2005 Wiley Periodicals, Inc.