New dimeric LC-epoxyimine monomers with oxyethylene central spacers. Crosslinking study

Abstract

We have studied how substituting alkylene by oxyethylene spacers influences the mesomorphic behavior of LC-dimeric epoxy resins with imine groups in the mesogens. This structural variation has been shown to diminish the mesomorphic characteristics of the dimeric epoxy resins containing oxyethylene spacers. These compounds only show mesomorphic behavior when the mesogens are polarized by the presence of an ester and an ether group at their ends. When the ester group is located in the inner position, smectic mesophases have been observed. Depending on the parity of the central spacer, these smectic mesophases are of type A or C. Moreover, when the ether group is in the inner position only monotropic nematic mesophases are formed. By curing these compounds with primary or tertiary amines, the monotropic character and the low isotropization temperatures of compounds with the ether group in the central position prevent an ordered network from becoming fixed. However, LC-epoxy resins with ester groups in the inner position lead to the fixation of homogeneous smectic-C like networks only when the spacer was diethylene oxide.