Electrical field directed electropolymerization of free-standing film of polypyrrole and poly(1-(2-carboxyethyl)pyrrole at the air/liquid interface

Thin flexible films of conductive polymers are useful in biosensors and flexible batteries. These films are typically prepared through electropolymerization on the surface of electrode and are subsequently peeled off. The present work reports a novel approach of synthesizing free-standing conductive polymer films of polypyrrole and poly(pyrrole-co-(1-(2-carboxyethyl)pyrrole)) at the air/liquid interface under the control of electrical field. The films grew along the direction of the electrical field and showed unique morphology at the air-facing side of the film. SEM, XPS, ATR-FTIR, WAXD and cyclic voltammetry were used to characterize the films. A mechanism of film growth was proposed with the important experimental parameters discussed. This approach may be used for other types of conducting polymers and also for the monomers sensible to electrical field.