Synthesis and curing of liquid crystalline epoxy resins based on 4,4′-biphenol

Abstract

Two liquid crystalline epoxy (LCE) resins based on biphenol mesogen, BP1 and BP2, were synthesized to produce a highly heat-resistant liquid crystalline network, and the curing behaviour of them was investigated using diaminodiphenylsulfone (DDS) and diaminodipheylester (DDE) as curing agents. The curing rate and heat of curing of LCE resins were measured with dynamic and isothermal DSC. The curing reaction of BP2 based on aromatic ester was faster than that of BP1, and the degree of cure was vice versa. A densely cross-linked BP2 network showed a much higher glass transition temperature (≈280°C) and elastic modulus than other epoxy resins reported up to now. BP2 formed a liquid crystalline network on curing with DDS and DDE, while BP1 showed a liquid crystalline network on curing with DDE. The liquid crystalline phase of the resulting network was maintained up to decomposition temperature (<300°C).