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

Abstract

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.

Antifouling Properties of Fluoropolymer Brushes toward Organic Polymers: The Influence of Composition, Thickness, Brush Architecture, and Annealing

“…This surface coverage by fouling polymers was quantified by an AFM-based method (blueyellow images in Figure 2). 11 The surface coverage of the polymer brushes by fouling polymers decreases with increased polymer brush thickness. The numerical value of the obtained surface coverage is, of course, dependent on the arbitrarily chosen threshold value, but the point is that the order of the extent of fouling for the different surfaces does not change with the threshold value ( Figure S1A and B), i.e., the trends in the antifouling characteristics (effects of thickness, composition, Langmuir XXXX, XXX, XXX−XXX etc.)…”

Self-healing fluoropolymer brushes as highly polymer-repellent coatings

“…12 Recently, we reported the rst systematic study of the fouling of high-quality uorinated monolayers onto ultraat Si surfaces by a wide range of polymers with variable molecular weights. 13 This choice was based on the high degree of control that is available in the construction of such monolayers, whereas ultraat substrates rigorously decouple the contributions of the molecular structure and surface roughness. In addition, the choice of Si was practically driven by the fact that small-scale orices used in industry are increasingly lithographically prepared from Si.…”

“…The polymer fouling was studied by XPS, CA and a previously developed bimodal atomic force microscopy (AFM) based approach. 13 For each surface, the fouling experiments were conducted on three different samples, and on each sample the ellipsometry, XPS and AFM measurements were carried out at at least three different places. Fig.…”

Rapid Surface Functionalization of Hydrogen-Terminated Silicon by Alkyl Silanols

“… 67 Fouling is generally defined as the deposition or accumulation of unwanted materials on a solid surface, causing severe damage of equipment, 68 and is particularly relevant for reduced flow, such as in orifices in next-generation Si-based printer heads and SiN-based microsieves (typically pore size: 400–4000 nm). Both monolayers 51 and polymer brushes 69 have been used to minimize such organic polymer fouling, but all previously made coatings took many hours and (for the brushes) multistep surface-bound conversions. Therefore, the antifouling properties of the prepared monolayers were studied toward a selection of commonly used polymers with similar molecular weight ( M n ∼ 5000 g/mol), namely poly(ethylene glycol) (PEG), poly(acrylic acid) (PAA), poly(vinyl acetate) (PVA), polystyrene (PS), poly(2-vinylpyridine) (P2VP) and poly( N -isopropylacrylamide (PNIPAM).…”