P. Masson et al., STRUCTURAL STUDY OF THERMOTROPIC LIQUID-CRYSTALLINE POLY(ETHYLENEIMINIUM) SALTS ALKYLATED WITH MESOGENIC SIDE-CHAINS, Macromolecular chemistry and physics, 196(11), 1995, pp. 3677-3686
Ionic liquid crystalline polymers were obtained from linear poly(ethyl
eneimine) (PEI) substituted with 6-(4-methoxy-4'-biphenylyloxy)hexyl b
romide or 12-(4-methoxy-4'-biphenylyloxy)dodecyl bromide, and quaterni
sed with dimethyl sulfate or hydrobromic acid. Their thermotropic poly
morphism was studied by means of differential scanning calorimetry (DS
C), polarising optical microscopy and X-ray diffraction. A smectic A m
esophase was identified and described from a structural point of view
with the help of computer modelling. The completely alkylated and quat
ernised PEI derivative was shown to form a single layered smectic A st
ructure with pendant groups all on the same side of the polymer backbo
ne in a double row ribbon-like configuration. The ribbon-like polymer
chains are packed side by side with the polymer backbone parallel to t
he smectic layers and the mesogenic groups perpendicular to them. For
partially alkylated or quaternised PEI derivatives, the layer spacing
in the smectic A mesophase is generally different from that of the cor
responding molecular length calculated for fully functionalised polyme
rs.