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SYOE: Symposium Organic Thin Film Electronics: From Molecular Contacts to Devices
SYOE 8: Poster Session SYOE
SYOE 8.28: Poster
Tuesday, March 27, 2007, 18:00–20:00, Poster B
A flexible approach to the fabrication of chemical gradients using functional monomolecular films — •Nirmalya Ballav1, Andrey Shaporenko1, Andreas Terfort2, and Michael Zharnikov1 — 1Angewandte Physikalische Chemie, Universität Heidelberg, 69120 Heidelberg, Germany — 2Anorganische und Angewandte Chemie, Universität Hamburg, 20146 Hamburg, Germany
We present a new approach for the fabrication of chemical gradients on different substrates. The key idea of the method is tuning the exchange-reaction between a self-assembled monolayer covering the substrate and a potential molecular substituent by electron irradiation. As test systems, we used alkanethiolate monolayers on gold, which are well-known to undergo an exchange-reaction with molecules capable of building self-assembled monolayer on the same substrate upon the immersion in the respective solution. We show that the rate and extent of the exchange-reaction, which is very slow at normal conditions, can be significantly influenced and precisely tuned by electron irradiation. Based on the developed approach and using the exchange reaction between the non-substituted and carboxyl-substituted alkanethiols, we were able to fabricate a hydrophilicity gradient as a test example. Generally, the irradiation-exchange approach can be used for the preparation of any gradient (biocompatibility, etc.) by a choice of a proper molecular substituent. Another advantage of the approach lies in its flexibility, since a gradient of any form and size, down to several tens of nanometers, can prewritten by electron beam and mediated by the subsequent exchange reaction.