New types of liquid crystalline epoxy resins cured by a mesogenic hardening compound

The new epoxy resins, EPD-CAA10 and EPTB-CAA10, were synthesized by reacting stoichiometrically the diepoxides, 4,4'-bis(2,3-epoxypropoxy)bisphenol A (EPB) and 4,4'-bis-2,3-epoxypropoxy)-3,3',5,5'-tetramethylbiphenol (EPTB), respectively, with a mesogenic hardening compound, 4,4'-bis(omega-carboxydecanoxy)azoxybenzene (CAA10), using tri-n-butylamine as a catalyst. The reaction procedures and the mesogenic phase transitions for the two epoxy resins were studied by the use of infra-red (i.r.), spectroscopy, differential scanning calorimetry (d.s.c.) polarizing microscopy and X-ray diffraction spectroscopy. It was found that both of the differential EPB-CAA10 and EPTB-CAA10 systems had a mesophase which was functionalized by the mesogenic hardening compound; EPB-CAA10 showed a smectic-like mesophase between 70 and 90 degrees C when the polymer was not gelated but had no mesophase when gelated, while EPTB-CAA10 also had a smectic-like mesophase when not gelated, but showed a nematic phase when gelated. Copyright (C) 1996 Published by Elsevier Science Ltd.