Poly(pyridinium salt)s with organic counterions derived from an aromatic diamine containing oxyethylene unit exhibiting amphotropic liquid-crystalline and photoluminescence properties

Pradip K. Bhowmik, University of Nevada, Las Vegas
Haesook Han, University of Nevada, Las Vegas
Alexi K. Nedeltchev, University of Nevada, Las Vegas
Hari D. Mandal, Texas A and M International University
Jose A. Jimenez-Hernandez, Texas A and M International University
Patrick M. McGannon, Texas A and M International University


Several poly(pyridinium salt)s containing various organic counterions and oxyethylene unit in their backbones were synthesized by either the ring-transmutation polymerization reaction of 4,4′-(1,4-phenylene)bis(2,6-diphenylpyrylium tosylate) with 1,2-bis(4-aminophenoxy)ethane on heating in dimethyl sulfoxide or the metathesis reaction of the tosylate polymer with the corresponding lithium or sodium salts in acetonitrile. Their chemical structures were determined by 1H and 13C NMR spectroscopy, and elemental analyses. Their number-average molecular weights and polydispersity indices were in the range of 59,000-63,000 and 1.41-1.65, respectively, as determined by gel permeation chromatography. They were characterized for their thermotropic and lyotropic liquid-crystalline properties by using differential scanning calorimetry and polarizing optical microscopy. Since these polymers exhibited liquid-crystalline phase both in the melt and in solutions, they belong to an amphotropic class of ionic polymers. Their light-emitting properties both in polar organic solvents and in films cast from methanol and acetonitrile were also studied by using spectrofluorometry. © 2009 Elsevier Ltd. All rights reserved.