Deposition and Characterization of Nanostructured Polypyrrole Films Grown at Distinct Centrifugal Accelerations

Polypyrrole (PPy) is a conductive polymer consisting of linked pyrrole monomers synthesized chemically or electrochemically.  It exhibits superhydrophobic or superhydrophilic properties which are mainly dependent on its surface roughness.  One of the factors that are known to influence the morphology of the surface of a PPy film is the centrifugal force the polymer is subjected to during its synthesis.  This study investigated the growth of nanostructures on the surface of the polymer films which were dependent on the centrifugal forces the samples experienced during synthesis.  PPy films were synthesized electrochemically (galvanostatically at a current density of 0.5 A/m²) while being submitted to specific centrifugal accelerations.  The samples were characterized using Scanning Electron Microscopy (SEM), and their dimensions and conductivity were measured.  Visual examination of the SEM micrographs revealed that the nanostructures were absent for the samples grown at normal gravity acceleration.  The samples grown at 250 RCF (relative centrifugal force) still did not show the nanostructured network, but in comparison to the previous samples, comprised of less-dispersed PPy microclusters over the bottom layer.  For the samples grown from 500 RCF and higher, the nanostructured layer completely covered the surface of the PPy films.  The nanostructures became more dense with increasing centrifugal accelerations. In summary, the density of the nanostructured network on the surface of the PPy films increased as the centrifugal accelerations they were exposed to during synthesis increased.  Therefore, the surface morphology of nanostructured PPy can be tuned by adjusting the centrifugal accelerations at which they are grown.