Enhancement of conductivity stability of polypyrrole films modified by valence copper and polyethylene oxide in an oxygen atmosphere

The degradations of polypyrrole (PPy)-based films in conductivity are examined in an oxygen atmosphere for 50 days. The results reveal that polymerization potential, solvents used in polymerization, modification of PPy with valence Cu, and introduction of polyethylene oxide (PEO) into PPy influence the conductivities of PPy films and their corresponding stabilities significantly. Pure PPy, prepared in water at an over-oxidized potential, shows a serious decrease in conductivity. However, valence Cu-modified PPy and PEO-modified PPy, resulting in an electron transfer from Cu to N⁺ of PPy and a more compact, dense surface and hydrogen bonds forming, respectively, behave more stable. The changes of surface mean roughness before and after aging are quantitatively measured via atomic force microscopy (AFM) analysis. Meanwhile, SERS experiments provide a deeper insight into the aging mechanism of PPy in conductivity.