Journal of Polymer Science Part A: Polymer Chemistry, Vol.40, No.23, 4344-4356, 2002
Synthesis and crosslinking of a series of dimeric liquid-crystalline diglycidylester compounds containing imine groups
We used readily available commercial reagents and well-known procedures to synthesize a series of aromatic imine mesogenic diglycidylester compounds with dimeric architectures. The compounds obtained were characterized by spectroscopic techniques. Their liquid-crystalline behavior was examined by differential scanning calorimetry, hot-stage polarized optical microscopy (POM), and wide-angle X-ray scattering (WAXS) and related to the different structures that varied in the length of the central spacer. All the compounds exhibited nematic mesophases with the exception of the dimer with a three-methylene central spacer that did not reveal liquid-crystalline character. We investigated the crosslinking of the synthesized compounds and obtained liquid-crystalline thermosets (LCTs) with several primary aromatic diamines in stoichiometric ratios or a tertiary amine as a catalyst. The curing processes were measured by calorimetry, and the thermal stability of the LCTs was evaluated by thermogravimetry. The ordered character of the LCTs was confirmed by POM and WAXS. Finally, the mechanical characterization of the LCTs obtained was examined by dynamic mechanical thermal analysis.
Keywords:liquid-crystalline polymers (LCP);crosslinking;calorimetry;epoxy resins;liquid-crystalline thermosets (LCTs)