Tunable wettability of microstructured polypyrrole films

Abstract

This thesis presents the development of the conducting polymer polypyrrole as a viable material for applications requiring switchable wettability. A fabrication procedure that produces robust microstructured polypyrrole (PPy) that quickly and reversibly switches between the superhydrophobic and superhydrophilic states is discussed. The polymer is doped with perfluorooctanesulfonate ions which diffuse in and out of the film upon an electric stimulus, causing a change in the material's surface energy. The effect of changing different deposition parameters on the switchable wettability of the polymer is also investigated. A post-deposition thermal treatment that improves the electrochemical properties of polypyrrole is presented. Finally, a device that allows for the in situ wettability switch of PPy is developed, eliminating the need for polypyrrole to be immersed in an electrolyte in order to switch between wetting states. A wettability gradient created on the surface of PPy using the device is used to demonstrate a possible application requiring induced fluid movement. Electrochemical techniques are used to synthesize and characterize the polymers, and scanning electron microscopy is used to examine the surface morphology of the films.