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The structural impact of water sorption on device-quality melanin thin films

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Abstract

The melanins are a class of pigmentary bio-macromolecules ubiquitous in the biosphere. They possess an intriguing set of physico-chemical properties and have been shown to exhibit hybrid protonic–electronic electrical conductivity, a feature derived from a process termed chemical self-doping driven by the sorption of water. Although the mechanism underlying the electrical conduction has been established, how the sorbed water interacts with the melanin structure at the physical level has not. Herein we use neutron reflectometry to study changes in the structure of synthetic melanin thin films as a function of H2O and D2O vapour pressure. Water is found to be taken up evenly throughout the films, and by employing the contrast effect, the existence of labile protons through reversible deuterium exchange is demonstrated. Finally, we determine a sorption isotherm to enable quantification of the melanin–water interactions.

Graphical abstract: The structural impact of water sorption on device-quality melanin thin films

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Publication details

The article was received on 26 Oct 2016, accepted on 05 May 2017 and first published on 15 May 2017


Article type: Paper
DOI: 10.1039/C6SM02420C
Citation: Soft Matter, 2017, Advance Article
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    The structural impact of water sorption on device-quality melanin thin films

    A. J. Clulow, A. B. Mostert, M. Sheliakina, A. Nelson, N. Booth, P. L. Burn, I. R. Gentle and P. Meredith, Soft Matter, 2017, Advance Article , DOI: 10.1039/C6SM02420C

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