Electrical conductance of hydrophobic membranes or what happens below the surface
Nanoporous alumina membranes rendered hydrophobic by surface modification via covalent attachment of hydrocarbon or fluorocarbon chains conduct electricity via surface even when the pores are not filled with electrolyte. The resistance is many orders of magnitude higher than for electrolyte-filled m...
| Veröffentlicht in: | Langmuir : the ACS journal of surfaces and colloids. - 1992. - 23(2007), 14 vom: 03. Juli, Seite 7784-92 |
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| 1. Verfasser: | |
| Weitere Verfasser: | , , , |
| Format: | Aufsatz |
| Sprache: | English |
| Veröffentlicht: |
2007
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| Zugriff auf das übergeordnete Werk: | Langmuir : the ACS journal of surfaces and colloids |
| Schlagworte: | Journal Article Research Support, N.I.H., Extramural Research Support, U.S. Gov't, Non-P.H.S. Benzopyrans Electrolytes Indoles Lipid Bilayers Nitro Compounds Spiro Compounds spiro-merocyanine |
| Zusammenfassung: | Nanoporous alumina membranes rendered hydrophobic by surface modification via covalent attachment of hydrocarbon or fluorocarbon chains conduct electricity via surface even when the pores are not filled with electrolyte. The resistance is many orders of magnitude higher than for electrolyte-filled membranes and does not depend on the electrolyte concentration or pH, but it does depend on the type of hydrophobic monolayer and its density. The corresponding surface resistance varies from greater than 10(18) Omega per square to less than 3 x 10(9) Omega per square. When the hydrophobic monolayer contains a small proportion of photoactive spiropyran that is insufficient to switch the surface to hydrophilic after spiropyran photoisomerization to the merocyanine form, the membrane resistance also becomes light-dependent with a reversible increase of surface resistance by as much as 15%. Surface conduction is ascribed to hydration and ionization of the alumina surface hydroxyls and the ionizable groups of the hydrophobic surface modifiers |
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| Beschreibung: | Date Completed 14.09.2007 Date Revised 08.01.2019 published: Print-Electronic Citation Status MEDLINE |
| ISSN: | 1520-5827 |