Self-assembled Monolayers for Surface Engineering

In addition, these thin films have been important in studies of electron transfer, relevant for catalytic systems [64], molecular recognition [65], biomaterial interfaces [66], cell growth [67], crystallization [68], adhesion [69], and many other aspects [70]. SAMs provide ideal model systems, because fine control of surface functional group concentration is possible by preparing mixed SAM systems of two or more compounds, evenly distributed over the surface [71, 72], as two- or 

The dotted line on the left is a bond in a possible precursor trimer. X-ray data suggest an area of 21 3 per alkyl chain, with a thickness of 25 2 A. FTIR spectroscopy suggest that the alkyl chains in -octadecyltrichlorosi-lane SAMs are perpendicular to the surface (Reprinted with permission from [5] A. Ul-man, Introduction to Thin Organic Films From Langmuir-Blodgett to Self Assembly, Academic Press, Boston, 1991. p. 257 and 258. Copyright 1991 Academic Press/Elsevier Science) 

In many supported catalytic systems, it is nearly impossible to determine either the specific species, responsible for the observed catalytic activity, or the mechanistic pathway of the reaction. Using a defined SAM system in which careful molecular design is followed by controlled deposition into a solid-supported catalyst of known morphology, surface coverage, mode of binding and molecular orientation, allows direct correlation of an observed catalytic activity with the structure on the molecular scale. SAM and LB-systems allow detailed and meaningful studies of established surface bound catalysts to understand their behavior in heterogeneous 

Surface Reconstruction A Dynamic View of Self-assembled Monolayer Systems 

Recently, Genzer and coworkers [85] presented an interesting new approach for the preparation of stable silane-based SAM systems. As a substrate, cross-linked polydimethylsiloxane (PDMS) was oxidized by UV/ozone treatment to yield a thin sihcon dioxide surface. The surface was then treated with fluorinated alkyltrichlo-rosilanes from the gas phase while being mechanically stretched by a certain length Ax. After modification, the elastomer was allowed to relax resulting in a mecdianically assembled monolayer (MAM) at the surface (Fig. 9.8). 

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