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Structural study of thermotropic liquid crystalline poly(ethyleneiminium) salts alkylated with mesogenic side chains
Author(s) -
Masson Patrick,
Gramain Philippe,
Guillon Daniel
Publication year - 1995
Publication title -
macromolecular chemistry and physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.57
H-Index - 112
eISSN - 1521-3935
pISSN - 1022-1352
DOI - 10.1002/macp.1995.021961120
Subject(s) - thermotropic crystal , mesophase , mesogen , side chain , differential scanning calorimetry , polymer chemistry , polymer , chemistry , bromide , crystallography , materials science , organic chemistry , phase (matter) , liquid crystalline , physics , thermodynamics
Ionic liquid crystalline polymers were obtained from linear poly(ethyleneimine) (PEI) substituted with 6‐(4‐methoxy‐4′‐biphenyloxy)hexyl bromide or 12‐(4‐methoxy‐4′‐biphenylyloxy)dodecyl bromide, and quaternised with dimethyl sulfate or hydrobromic acid. Their thermotropic polymorphism was studied by means of differential scanning calorimetry (DSC), polarising optical microscopy and X‐ray diffraction. A smectic A mesophase was identified and described from a structural point of view with the help of computer modelling. The completely alkylated and quaternised PEI derivative was shown to form a single layered smectic A structure with pendant groups all on the same side of the polymer backbone in a double row ribbon‐like configuration. The ribbon‐like polymer chains are packed side by side with the polymer backbone parallel to the 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 corresponding molecular length calculated for fully functionalised polymers.