Synthesis and characterization of poly(pyridinium salt)s with oxyalkylene units exhibiting amphotropic liquid–crystalline and photoluminescence properties

Several novel poly(pyridinium salt)s with oxyalkylene moieties in the main chain with bulky organic counterions (tosylate and triflimide) were prepared by either the ring-transmutation polymerization of phenylated bis(pyrylium tosylate) salt with a series of oxyalkylene containing diamines in dimethyl sulfoxide on heating for 48 h or the metathesis reaction of the corresponding tosylate polymers with lithium triflimide in methanol. Their chemical structures were determined by elemental analysis and 1H and 13C NMR spectroscopies, and their polyelectrolyte behavior in dimethyl sulfoxide was determined by solution viscosity measurements. Their weight average molecular weights were in the range 14,000–22,000 and polydispersity indices were in the range 1.20–1.70 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. Since these polymers exhibited liquid–crystalline phase both in the melt and in solution, they can be appropriately classified as amphotropic class of ionic polymers. Their light-emitting properties were also determined by using spectrofluorometry.