Electrochemically controlled swelling properties of nanoporous templated polypyrrole and layer by layer polypyrrole

Electrochemically controlled swelling properties of polypyrrole (PPy) are investigated by comparing the performance of layer-by-layer (LbL) assembled and nanoporous templated (NT) systems. The swelling behavior was improved for the NT and LbL systems over that of unmodified PPy. Reversible swelling of about 20% in 120 s on the first cycle was measured with the NT PPy via the electrochemical quartz crystal microbalance (EQCM). The changes in the morphology and roughness that occur with swelling and shrinking were measured using in situ electrochemical atomic force microscopy (EC-AFM). Electrochemical impedance spectroscopy (EIS) measurements showed that both the LbL and NT systems exhibited increased surface area relative to unmodified PPy thin films. The understanding of the changes occurring due to molecular and nanostructural reconfiguration in response to electrochemical stimuli may lead to potential applications in the development of a new generation of smart materials, in particular, more effective switchable materials.

► We examined the EQCM response of PPy films with increased surface area over unmodified PPy. ► The surface area was increased with nanoporous templating and layer-by-layer assembly. ► Increasing the surface area of the PPy resulted in increased actuator response revealed by EQCM. ► EC-AFM shows that morphological changes are different for each modified PPy surface with cycling.