Synthesis and properties of some new pyridinium salt models and polymers

Two monomers, 1,4-bis(4-pyridyl) and 1,4-bis(3-pyridyl) azines were synthesized and characterized. Model pyridinium salts were synthesized by condensation of azines with some bromoalkanes. Polymerization of azines with some dibromoalkanes was also carried out to form pyridinium salt polymers. The structures of both model compounds and polymers were verified from their elemental analysis, IR and ¹H NMR spectra. The liquid crystalline properties of models and polymers were studied by differential scanning calorimetry (DSC) and hot-stage polarizing microscopy. These studies revealed that some synthesized model compounds and polymers exhibit nematic liquid crystal texture having low thermal liquid crystalline stability. The terminal alkyl chains were found to produce mild effect of lowering the transition temperatures. Viscosity measurements indicate that the synthesized polymers have low molecular weight.