Synthesis and properties of a water-soluble ionic conjugated polymer with carboxylic acids.

A new water-soluble ionic conjugated polymer, poly[N-(carboxymethyl)-2-ethynylpyridinium bromide], was prepared by the activated polymerization of 2-ethynylpyridine by using bromoacetic acid. This polymerization proceeded well in mild reaction conditions without any additional initiator or catalyst. The polymer structure was characterized by various instrumental methods to have a conjugated polymer backbone system with the designed functional groups. The photoluminescence spectrum of polymer showed that the PL peak is located at 603 nm corresponding to the photon energy of 2.06 eV. The cyclovoltammograms of polymer exhibited the irreversible electrochemical behaviors between the oxidation and reduction peaks. The oxidation current density of polymer versus the scan rates is approximately linear relationship in the range of 30 mV/sec-150 mV/sec. It was found that the kinetics of the redox process of polymer is almost controlled by the reactant diffusion process from the oxidation current density of polymer versus the scan rates.