Conducting-polymer microcontainers: Controlled syntheses and potential applications

We have demonstrated the controlled synthesis of conducting-polymer microcontainers through the electrochemical generation of surfactant (i.e., beta-naphthalenesulfonic acid, beta-NSA)-stabilized H-2 gas bubbles on the working electrode, followed by electrochemical polymerization of pyrrole around the wall of the "soap-bubble" template. It was noticed that the density, shape, and wall thickness of the polypyrrole microcontainers thus prepared could be regulated by controlling the electrochemical potential applied for the generation of H-2 gas and the experimental conditions (e.g., the surfactant concentration, number of the cyclic voltammetric scanning) for the electropolymerization of pyrrole. By pre-patterning the working electrode surface with non-conducting polymers using microcontact printing (muCP) or plasma patterning, we have also produced conducting-polymer microcontainers in a patterned fashion. Furthermore, potential applications of the patterned and non-patterned conducting-polymer microcontainers have been demonstrated; for example, through the encapsulation of appropriate fluorescence-labeled molecules (e.g., fluorescein cadaverin) into the conducting-polymer microcontainers by sealing their opened mouths with sequential electropolymerization of pyrrole. The resulting closed microcontainers could then be used for controlled releases.