EFFECT OF SMECTOGENICITY OF THE IONIC GROUPS ON THE THERMOTROPIC LIQUID-CRYSTALLINE BEHAVIOR OF PYRIDINIUM AND POLY(4-VINYLPYRIDINIUM) SALTS QUATERNIZED WITH MESOGENIC GROUPS

In order to demonstrate the important smectic power of the ionic funct ions present in mesogenic molecules, a series of N-alkylpyridinium bro mides omega-substituted with (4-cyanobiphenylyl) oxy or [4-(2-methyl-1 -butoxy) biphenylyl] oxy mesogenic group and their analogous 4-vinylpy ridinium polymers were synthesized and characterized. The liquid cryst alline behavior was studied by differential scanning calorimetry, pola rizing optical microscopy, and X-ray diffraction. Smectic mesophases, namely A, B, and E, were identified for the low molecular weight compo unds, whereas smectic A and E mesophases were identified for the analo gous polymers. Both structures were found to be very similar. They con sist of single layers of upright molecules laterally arranged head-to- tail; the polymer backbone is inserted in between the layers. The mono layer smectic ordering observed in spite of the presence of the intera cting cyano and chiral groups demonstrates the prevailing effect of th e electrical interactions upon the structural organization. (C) 1997 J ohn Wiley & Sons.