Shunichi Osada

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

Abstract 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(ω-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°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.

Liquid-Crystalline Epoxy-Resin Cured by Mesogenic Hardening Compounds

SummaryA new type of liquid crystalline epoxy resin functionalized with mesogenic hardening agent was obtained by reacting stoichiometrically 4,4′-bis (2,3-epoxypropoxy)-3,3′5,5′-tetramethyl biphenyl (EPTB) (diepoxide monomer) with 4,4′-bis (ω-carboxy decanoxy) azoxybenzene (CDA10) (mesogenic hardening monomer) at 145°C for 10 min, using tri-n-butylamine as a catalyst. Mesomorphic phase transition behavior for EPTB-CDA10 prepolymer obtained was studied as function of curing time at 140°C by use of DSC and polarized microscopy. When the curing time is shorter than a gelling time (60 min), EPTB-CDA10 showed a liquid crystalline state reminiscent of smectic phase, while that reminiscent of nematic phase, when the curing time is longer than the gelling time. This work indicates that the new type of epoxy resin cured by mesogenic hardening compound can have a liquid crystal state.