MICROBIAL-DEGRADATION OF POLYMERIC COATINGS MEASURED BY ELECTROCHEMICAL IMPEDANCE SPECTROSCOPY

This paper reports results of biodegradation studies of polyimide coat ings exposed to a mixed fungal culture using electrochemical impedance spectroscopy (EIS). The fungal consortium was originally isolated fro m degraded polyimides and identified species include Aspergillus versi color, Cladosporium cladosporioides, and a Chaetomium species. Activel y growing fungi on polyimides yield distinctive EIS spectra through ti me, indicative of failure of the polymer integrity compared to the uni noculated controls. An initial decline in coating resistance was relat ed to the partial ingress of water molecules and ionic species into th e polymeric matrices. This was followed by further degradation of the polymers by activity of the fungi. The relationship between the change s in impedance spectra and microbial degradation of the coatings was f urther supported by scanning electron microscopy, showing extensive co lonization of the polyimide surfaces by the fungi. Our data indicate t hat EIS can be a sensitive and informative technique for evaluating th e biosusceptibility of polymers and coatings.