Poly(pyridinium salt)s with organic counterions derived from an aromatic diamine containing tetraoxyethylene units 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 tetraoxyethylene units in their backbones were synthesized by either ring-transmutation polymerization reaction of 4, 4'-(1, 4-phenylene)- bis(2, 6-diphenylpyrylium tosylate) with bis(2-(2-(4-aminophenoxy)ethoxy)ethyl) ether on heating in dimethyl sulfoxide or metathesis reaction of the tosylate polymer with the corresponding lithium or sodium salts in acetonitrile. Their chemical structures were determined by 1H-NMR and 13C-NMR spectroscopy, and elemental analyses. Their number-average molecular weights and polydispersity indices were in the range of 34, 000-52, 000 and 1.14-1.38, respectively, as determined by gel permeation chromatography. They were characterized both for their thermotropic and lyotropic liquid-crystalline properties by using differential scanning calorimetry and polarizing optical microscopy. As these polymers exhibited liquid-crystalline phase both in the melt and in solutions, they are classified as an amphotropic class of ionic polymers. Their light-emitting properties in a large number of organic solvents that ranged from nonpolar to polar solvents and in films cast from methanol and acetonitrile were also studied by using spectrofluorometry. © 2009 Wiley Periodicals, Inc.