Anomalous Proton Conductivity in Chitin-Chitosan Mixed Compounds

Abstract

In order to investigate a key factor for the appearance of proton conductivity in chitin-chitosan mixed compounds, the chitin-chitosan mixed compounds (chitin) x (chitosan) 1-x were prepared and these proton conductivities have been investigated. DC proton conductivity σ is obtained from Nyquist plot of impedance measurement data, and the relationship between σ and mixing ratio x has been made clear. It was found that the x dependence of σ is non-monotonous. That is, σ shows the anomalous behavior, and has peaks around x = 0.4 and 0.75. This result indicates that there exist optimal conditions for the realization of high-proton conductivity in the chitin-chitosan mixed compound in which the number of acetyl groups is different. From the FT-IR measurement, we have found that the behavior of proton conductivity in (chitin) x (chitosan) 1-x is determined by the amount of water content changed by x . Using these results, proton conductivity, which is important for the application of conducting polymers in chitin-chitosan mixed compounds, will be able to be easily controlled by adjusting the mixing ratio x .