Electrical Conductance of Hydrophobic Membranes or What Happens below the Surface
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- 作者：Ivan Vlassiouk ; Fabian Rios ; Sean A. Vail ; Devens Gust ; Sergei Smirnov
- 刊名：Langmuir
- 出版年：2007
- 出版时间：July 3, 2007
- 年：2007
- 卷：23
- 期：14
- 页码：7784 - 7792
- 全文大小：221K
- 年卷期：v.23,no.14(July 3, 2007)
- ISSN：1520-5827
文摘
Nanoporous alumina membranes rendered hydrophobic by surface modification via covalent attachment of hydrocarbonor fluorocarbon chains conduct electricity via surface even when the pores are not filled with electrolyte. The resistanceis many orders of magnitude higher than for electrolyte-filled membranes and does not depend on the electrolyteconcentration or pH, but it does depend on the type of hydrophobic monolayer and its density. The correspondingsurface resistance varies from greater than 1018 
per square to less than 3 × 109 per square. When the hydrophobicmonolayer contains a small proportion of photoactive spiropyran that is insufficient to switch the surface to hydrophilicafter spiropyran photoisomerization to the merocyanine form, the membrane resistance also becomes light-dependentwith a reversible increase of surface resistance by as much as 15%. Surface conduction is ascribed to hydration andionization of the alumina surface hydroxyls and the ionizable groups of the hydrophobic surface modifiers.
per square to less than 3 × 109 per square. When the hydrophobicmonolayer contains a small proportion of photoactive spiropyran that is insufficient to switch the surface to hydrophilicafter spiropyran photoisomerization to the merocyanine form, the membrane resistance also becomes light-dependentwith a reversible increase of surface resistance by as much as 15%. Surface conduction is ascribed to hydration andionization of the alumina surface hydroxyls and the ionizable groups of the hydrophobic surface modifiers.