Polyaniline/poly(vinyl alcohol) (PAN/PVA) composite films: the synergy of film structural stiffening, redox amplification, and mobile species compositional dynamics

In this work, we report an unexpected but significant improvement of the redox behavior of conducting polyaniline (PAN) films by trapping intrinsically nonconducting poly(vinyl alcohol) (PVA) in the matrix of the polymer acting as stiffening and/or cross-linking agents. Film structural stiffening of PAN/PVA inclusion was studied in relation to film compositional dynamics. PAN and PAN/PVA composite films were potentiodynamically deposited using high-frequency electrochemical quartz crystal microbalance under electrochemical potentiodynamic control. From the simultaneously obtained measurements of nanogravimetric and cyclic voltammetric data, it has been found that the presence of PVA in the deposition solution increased the rate of PAN film growth as a function of PVA concentration. Characterization of the resultant composite films in monomer-free acidic electrolyte solutions showed significantly enhanced redox behavior of PAN/PVA composite films (with different PVA contents) compared to pure PAN by a factor of similar to 2-4. For the study of structure-composition relationships of composite polymer films, fluxes of instantaneous mobile species dynamics (ion/solvent) as a function of film redox conversion and potential cycling were correlated with film structural stiffening and the observed unusual redox enhancement of PAN/PVA composite films. Using various experimental timescales, we were able to resolve bound (associated with ion transfer) and free solvent compositional dynamics (associated with thermodynamic activity balance).