Jastrzebska M M, Isotalo H, Paloheimo J, Stubb H
Department of Biochemistry and Biophysics, Silesian Medical Academy, Sosnowiec, Poland.
J Biomater Sci Polym Ed. 1995;7(7):577-86. doi: 10.1163/156856295x00490.
The dependence of the d.c. conductivity on the hydration and temperature (293-343 K) for synthetic DOPA-melanin polymer is presented. The hydration state of the melanin has been changed by varying the humidity conditions around the sample. It has been shown, that in the range of relative humidity values (0-100%), changes in the hydration state of melanin have predominant influence on electrical conductivity (10(-13)-10(-5)S cm-1) in comparison to temperature. The influence of the two forms of water on the conductivity--the first form adsorbed mainly on the melanin surface and easily removed by drying, and the second one incorporated into the inner structure of the polymer, has been investigated. The temperature dependence of the conductivity in vacuum (0.8 and 0.04 mb) and thermal activation energy values (0.49-0.76 eV) for cooling and heating curves have been determined. The relationship between thermal activation energy and preexponential factor sigma 0 (compensation effect) and possible charge transport mechanisms are discussed.
本文介绍了合成的多巴黑色素聚合物的直流电导率与水合作用及温度（293 - 343K）之间的关系。通过改变样品周围的湿度条件来改变黑色素的水合状态。结果表明，在相对湿度值范围（0 - 100%）内，与温度相比，黑色素水合状态的变化对电导率（10⁻¹³ - 10⁻⁵S cm⁻¹）具有主要影响。研究了两种形式的水对电导率的影响——第一种形式主要吸附在黑色素表面，通过干燥容易去除；第二种形式则融入聚合物的内部结构。测定了在真空（0.8和0.04毫巴）下电导率的温度依赖性以及冷却和加热曲线的热活化能值（0.49 - 0.76电子伏特）。讨论了热活化能与指前因子σ₀之间的关系（补偿效应）以及可能的电荷传输机制。
