Processable, Regioregular, and Clickable Monomer and Polymers Based on 3,4-Propylenedioxythiophene with Tunable Solubility

Clickable monomer and polymers based on 3,4-propylenedioxythiophene, ProDOT, which can be functionalized either at the monomer stage or after the polymerization, were synthesized and characterized for the first time. The Solubility of these polymers can be fine-tuned front organic to aqueous solvents by functionalization with an appropriate side chain. In fact, the clickable functionality allows us to synthesize and characterize water-soluble ProDOT-based cationic polymer which were hitherto unknown. Chemical polymerization of propargyl-functionalized ProDOT (ProDOT-propargyl) resulted in an insoluble polymer which could be made water-soluble by reacting it with 1-azido-ethanoic acid sodium salt or 3-azidopropyltrimethylammonium iodide using click chemistry. Interestingly, the chemical copolymerization of ProDOT-propargyl with 25 mol % of dihexyl-ProDOT resulted in an organic soluble polymer which was characterized using NMR, FTIR, UV-vis spectroscopy, Solution doping, and GPC. This polymer was then used Successfully for click chemistry in solution. The click reaction that was performed on this polymer by using 2-azidoacetic acid sodium salt or 3-azidopropyltrimethylammonium iodide resulted in the complete reversal of solubility from organic solvent of the parent polymer to water solubility of the resulting polymers. In order to study the electrochemical properties, thin films of poly(ProDOT-propargyl) were prepared using electrochemical polymerization and were characterized by electrochemical, spectrochemical, optical switching, and in situ conductance measurements. Electropolymerization resulted in the formation of an electroactive film on the electrode surface. Spectroelectrochemical studies indicated that the polymer switched from opaque blue to a transmissive oxidized state with a contrast of 75%. In situ conductance Studies showed a maximum conductance of 0.03 S.