Journal of Polymer Science Part A: Polymer Chemistry, Vol.41, No.16, 2521-2530, 2003
Liquid-crystal line thermosets by the curing of dimeric liquid-crystal line epoxyimine monomers with 2,4-toluene diisocyanate
studied the curing processes of several series of dimeric liquid-crystalline epoxyimine monomers with 2,4-toluene diisocyanate (TDI) alone or with added catalytic proportions of 4-(N,N-dimethylamino)pyridine. We obtained isotropic materials or liquid-crystalline thermosets with different degrees of order, which depended on the structures of the monomers. To fix ordered networks, we had to do the curing in two steps when TDI was used alone as the curing agent. However, when a tertiary amine was added in catalytic proportions, the ordered networks were fixed in just one step. In this way, we were able to fix both nematic and smectic mesophases. The significance of the polarization of the mesogen for obtaining liquid-crystalline thermosets was demonstrated. (C) 2003 Wiley Periodicals, Inc.
Keywords:liquid-crystalline polymers (LCP);epoxy resins;liquid-crystalline thermosets (LCTs);isocyanates;crosslinking;high performance polymers