Liquid crystalline thermosets (LCT) from diaromatic mesogenic diepoxides and aromatic diamines: synthesis and phase behaviour of model compounds and intermediate structures

摘要

Two mesogenic monoepoxides, nematogenic 4-(2,3-epoxypropoxy)-4'-ethoxy-biphenyl (1) and smectic-A 4-butoxyphenyl-4-(2,3-epoxypropoxy)-benzoate (2) were synthesized and reacted with 4,4'-diaminobiphenyl (3), or 4-aminophenyl-4-aminobenzoate (4) to obtain model compounds for the chain extended and branched intermediates (cross-link sites) formed in the amine curing of epoxides. All epoxy/amine-adducts have higher clearing points than the original epoxide/amine mixtures, though with one exception only monotropic mesophases were observed. The order of the clearing points for a given epoxide/amine combination is symm. 2:1 > 4:1 > 1:1 approximate to 3:1 > non symm. 2:1. The type of mesophase of the adducts is that of the monoepoxide used except for the 1:1 adduct of smectic 2 and 4, where a nematic phase was obtained. (C) 1998 Elsevier Science Ltd. All rights reserved. [References: 16]