Highly Polymer-Repellent yet Atomically Flat Surfaces Based on Organic Monolayers with a Single Fluorine Atom

Organic monolayers or polymer brushes, often in combination with surface structuring, are widely used to prevent nonspecific adsorption of polymeric or biological material on sensor and microfluidic surfaces. Here it is demonstrated for the first time how robust, covalently attached alkyne-derived monolayers with a varying numbers of fluorine atoms, on atomically flat Si(111), effectively repel a wide range of apolar polymers without the need for micro- or nanostructuring of the surface. The antifouling property of fluoro-hydro monolayers is studied for a range of commonly used polymers with comparable molecular weight in nonaqueous solvent. Also, the effect of polymer molecular weight on the fouling behavior is investigated. A surface morphology survey by atomic force microscopy characterization that can accurately quantify the degree of fouling is developed. It is observed that especially the monofluorinated (F1) alkyne-derived monolayer shows excellent antifouling behavior, under certain conditions even more so than corresponding monolayers with perfluorinated alkyl tails. The explanation of this surprising behavior is based on a competition of solvent–solute–surface interactions. These findings and analysis offer significant potential for antifouling applications of ultrathin and covalently bound fluorine-containing coatings for a range of micro- and nanotechnological applications.