TOF-SIMS CHARACTERIZATION OF ELECTROCHEMICALLY SYNTHESIZED POLYPYRROLE FILMS

A time-of-flight secondary ion mass spectrometry (ToF-SIMS) instrument was used to perform a systematic characterization of a range of polypyrrole (PPy) films prepared electrochemically with a variety of dopant anions. The dopant anions used were chloride, bromide, sulfate and tosylate. This study was successful in characterizing PPy films in the negative ion mode, with the molecular specificity of SIMS enabling the distinction between the different dopant anions. The halide dopants were characterized by ions attributed to the isotopic halide clusters, i.e., Cl- at m/z 35 and 37 for chloride-doped PPy, and Br- at m/z 79 and 81 for bromide-doped PPy. The molecular specificity of SIMS enabled the unambiguous identification of the sulfate and tosylate dopants. An ion attributed to the dopant tosylate anion was observed at m/z 171 in the negative ion spectrum (CH3C6H4SO3-) of the tosylate-doped PPy. This ion was not observed in the spectrum of the sulfate-doped PPy, which showed the characteristic sulfate fragment at m/z 80 (SO3-).