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Joerg Lahann,1Samir Mitragotri,2Thanh-Nga Tran,1Hiroki Kaido,1Jagannathan Sundaram,2Insung S. Choi,1*Saskia Hoffer,3Gabor A. Somorjai,3Robert Langer1
We report the design of surfaces that exhibit dynamic
changes in interfacial properties, such as wettability, in responseto
an electrical potential. The change in wetting behavior wascaused by
surface-confined, single-layered molecules undergoingconformational
transitions between a hydrophilic and a moderatelyhydrophobic state.
Reversible conformational transitions wereconfirmed at a molecular
level with the use of sum-frequency generationspectroscopy and at a
macroscopic level with the use of contactangle measurements. This type
of surface design enables amplificationof molecular-level
conformational transitions to macroscopic changesin surface properties
without altering the chemical identity ofthe surface. Such reversibly
switching surfaces may open previouslyunknown opportunities in
interfacial engineering.
1 Department of Chemical Engineering,
Massachusetts Institute of Technology (MIT), 45 Carleton
Street, Cambridge, MA 02139, USA.
2 Department of
Chemical Engineering, University of California at Santa Barbara, Santa
Barbara, CA 93106, USA.
3 Department of Chemistry,
University of California at Berkeley, Material Science Division,
Lawrence Berkeley Laboratory, Berkeley, CA 94720, USA.
*
Present address: Department of Chemistry and School of Molecular
Science (BK21), Korean Advanced Institute of Science andTechnology,
Daejeon 305-701, Korea.
To whom correspondence should be addressed. E-mail:
rlanger{at}mit.edu
