PhD, University of Cincinnati, 2002, Engineering : Materials Science

This work was focused on the investigation of charge and discharge properties of polypyrrole/polyimide (PPy/PI) composites. Capacitive and accumulative properties of PPy/PI composites were studied in details targeting application of the composite in polymer based charge storage devices: supercapacitors and polymer batteries. Polyimide was chosen as a matrix because of its excellent mechanical properties and electroactivity. Composites were prepared electrochemically on stainless steel, and studied by potential step amperometry and electrochemical impedance spectroscopy. The composition of the composite was studied by FTIR. Mechanism for PAAc conversion to PI was studied by FTIR ands DSC. Morphology was determined by SEM. Doping-dedoping of PPy in the composite in competition with doping-dedoping of PI along with formation of double electric layers were found to be responsible for a difference between discharge behaviors of PPy and PPy/PI composite. Charge storage ability was greatly affected by PPy. PPy along with factor of preconversion of poly(amic acid) (PAAc) matrix to PI was found to play a key role in charge storage properties of PPy/PI composite. DC polarization was found to alter the supercapacitance of the composite. Two mechanisms: orientation polarization and ion jump polarization were suggested to be responsible for supercapacitance in double electric layer. PPy/PI composite can be considered as a promising material for use in supercapacitors as a material for active polymer electrodes in polymer batteries. Additional advantage of use of PPy as a filler for PI matrix is the reduction of activation energy to conversion to polyimide. This was shown by differential scanning calorimetry and FTIR. Activation energy of the reaction of imidization can be reduced significantly by the presence of PPy.

Committee: Dr. Jude O. Iroh (Advisor) Subjects: