New class of liquid crystalline epoxy resins: Synthesis and properties

A new class of liquid crystalline epoxy resins has been developed by reacting the diglycidyl ether of bisphenol A (DGEBA) with two new mesogenic diols, 3,3′-dimethoxy-4,4′-di(hydroxyhexoxy)-N-benzylidene-o-tolidine and 4,4′-di(6-hydroxyhexoxy)-N-benzylidene-o-tolidine, containing azomethine groups. Fourier transformed infra-red (FT-IR), nuclear magnetic resonance (NMR) spectroscopy and CHN elemental analysis were used to confirm the chemical structures of these azomethine mesogenic diols. Cure reaction between DGEBA and the mesogenic diols were carried out with different ratios 1:1, 1:2 and 2:1. The mesogenic phase transitions for azomethine mesogenic diols and cured polymers were examined by differential scanning calorimetry (DSC) and polarized optical microscopy (POM). Thermal, mechanical and adhesion properties were then investigated for the cured polymers based on new azomethine mesogenic diols. The cured polymers were found to exhibit high thermal stability, flexibility and good adhesion properties compared to conventional resins.