Nanoindentation of inherently conductive polyaniline films.

Abstract

Conducting polymers (CPs) are similar to semiconductors in the fact that they can be used in electrical, optical, and magnetic devices. The microstructure enabling CPs to be used in these devices is the presence of #25;-electron conjugation or, more simply, the presence of double bonds in the polymer structure. This structure differentiates CPs from semiconductors. CPs, made from organic #25;-electron materials, are typically amorphous polymeric materials. This is unlike semi-conductors, which are prominently atomic solids. This structure difference allows for nearly limitless conducting mechanisms to be present in CPs. Additionally, the amorphous structure allows for varying physical and mechanical properties to fit in a variety of new applications. The study of CPs is very dynamic and has evolved from early light weight battery applications. The evolution of CPs has brought forth its use in electroluminescence, photorefractivity, electrochromism, optical nonlinearity, and sensing devices. These new and former applications are continually being applied to devices on a smaller and smaller size scale. Thus, magnifying the need to understand nano-scale properties. This thesis examines the nanoindentation and conductive properties of CPs. Nanoindentation of four polyaniline (PANI) films cast on glass slides are evaluated. The effect of carbon nanotube filler is evaluated with regard to its effect on indentation depth and conductivity of the overall film. The results show a trend of increasing conductance with higher application of pressure. This may be the result of a morphology change of the film. The addition of carbon nanotubes result in a decrease in conductivity. This non-intuitive result is likely due to porosity or voids at the carbon nanotube-polymer interface.