Electrical conductivity response of dodecylbenzene sulfonic acid-doped polypyrrole films to SO2–N2 mixtures

Abstract The effects of using dodecylbenzene sulfonic acid as a dopant on electrical conductivity of polypyrrole films were investigated in N 2 atmosphere and SO 2 –N 2 mixtures. For a film with a higher doping level, the time for the specific electrical conductivity σ dc to reach its equilibrium value when exposed to SO 2 was reduced; and consistently, the short time response (d σ dc /d t ) at zero exposure time increased. The temporal response of conductive polypyrrole films was improved with the films having higher doping levels. On the other hand, the gas sensitivity or change in the specific electrical conductivity from its base value when exposed to SO 2 was independent of dopant concentration, if it was below a critical doping level. Above this critical doping level, the change in the specific electrical conductivity climbed to a maximum value and then declined slightly as the doping level was increased. The dependence of the specific electrical conductivity on dopant concentration can be well correlated with changes in morphology observed. The conductive polymer chains changed from assuming three dimensional random-coil structures to rod-like fabrillar structures.

[1]  M. McBride.  Environmental Chemistry of Soils , 1994 .

[2]  I. Lundström,et al.  The effect of ammonia on the physical properties of polypyrrole , 1987 .

[3]  Jonathan M. Slater,et al.  Examination of ammonia–poly(pyrrole) interactions by piezoelectric and conductivity measurements , 1991 .

[4]  M. Ayad.  Quartz crystal microbalance study for chemical synthesis of polypyrrole , 1994 .

[5]  C. R. Martin,et al.  Unusual Gas-Transport Selectivity in a Partially Oxidized Form of the Conductive Polymer Polypyrrole , 1997 .

[6]  G. Mathys,et al.  Spectroscopic study of thermo-oxidative degradation of polypyrrole powder by FT-IR , 1997 .

[7]  D. Y. Kim,et al.  Synthesis of soluble polypyrrole of the doped state in organic solvents , 1995 .

[8]  T. Hanawa,et al.  Gas sensitiveness of polypyrrole films doped chemically in the gas phase , 1989 .

[9]  Joo,et al.  Microwave dielectric response of mesoscopic metallic regions and the intrinsic metallic state of polyaniline. , 1994, Physical review. B, Condensed matter.

[10]  A. Ricard,et al.  Influence of the dopant on the polypyrrole moisture content: Effects on conductivity and thermal stability , 1998 .

[11]  K. Wynne,et al.  The Structure and Mechanical Properties of Polypyrrole , 1985 .

[12]  Alan Hooper,et al.  Conducting polymer gas sensors , 1986 .

[13]  K. Khulbe,et al.  Polymerization of pyrrole by potassium persulfate , 1982 .

[14]  G. Zerbi,et al.  Lattice dynamics and vibrational spectra of polypyrrole , 1990 .

[15]  J. Stenger-Smith.  Intrinsically electrically conducting polymers. Synthesis, characterization, and their applications , 1998 .

[16]  Joo,et al.  Crossover in Electrical Frequency Response through an Insulator-Metal Transition. , 1996, Physical review letters.

[17]  Charles J. Pouchert.  The Aldrich library of FT-IR spectra , 1985 .

[18]  M. Wan,et al.  In situ doping polymerization of pyrrole with sulfonic acid as a dopant , 1998 .

[19]  G. Street,et al.  Optical study of polypyrrole perchlorate , 1983 .

[20]  M. Krounbi,et al.  Preparation and characterization of neutral and oxidized polypyrrole films , 1982 .

[21]  Chen C. Ku,et al.  Electrical properties of polymers , 1987 .

[22]  Jonathan M. Slater,et al.  Gas and vapour detection with poly(pyrrole) gas sensors , 1992 .

[23]  Göran Gustafsson,et al.  The interaction between ammonia and poly(pyrrole) , 1989 .