Superhydrophobic surfaces can be quickly formed with supramolecular materials. Incorporating low-molecular-weight gelators (LMWGs) with perfluorinated chains generates xerogel coatings with low surface energies and high roughness. Here, we examine and compare the properties of the xerogel coatings formed with eight different LMWGs. These LMWGs all have a trans-1,2-diamidocyclohexane core and two perfluorinated ponytails, whose lengths vary from three to ten carbon atoms (CF3 to CF10). Investigation of the xerogels aims to provide in-depth information on the chain length effect. LMWGs with a higher degree of fluorination (CF7 to CF10) form superhydrophobic xerogel coatings with very low surface energies. Scanning electron microscopy images of the coatings show that the aggregates of CF5 and CF7 are fibrous, while the others are crystal-like. Aggregates of CF10 are particularly small and further assemble into a porous structure on the micrometer scale. To test their stabilities, the xerogel coatings were flushed multiple times with a standardized water flush test. The removal of material from the surface in these flushes was monitored by a combination of the water contact angle, contact angle hysteresis, and coating thickness measurements. A new method based on image processing techniques was developed to reliably determine the change of the coating thickness. The CF7, CF9, and CF10 surfaces show consistent hydrophobicity and coating durability after repetitive flushing tests. The length of the perfluorinated side chains thus has a significant effect on the morphology of the deposited xerogel coatings, their roughness, and, in consequence, their hydrophobicity and mechanical durability.

This Minireview discusses recent developments in research on the interfacial phenomena of fluorinated amphiphiles, with a focus on applications that exploit the unique and manifold interfacial properties associated with these amphiphiles. Most notably, fluorinated amphiphiles form stable aggregates with often distinctly different morphologies compared to their nonfluorinated counterparts. Consequently, fluorinated surfactants have found wide use in high-performance applications such as microfluidic-assisted screening. Additionally, their fluorine-specific behaviour at solid/liquid interfaces, such as the formation of superhydrophobic coatings after deposition on surfaces, will be discussed. As fluorinated surfactants and perfluorinated materials in general pose potential environmental threats, recent developments in their remediation based on their adsorption onto fluorinated surfaces will be evaluated.

Abbildung 4. a) Allgemeine chemische Struktur der Gelatoren auf der Grundlage des Cyclohexyl-Diamid-Kerns. b) Vorgeschlagener Aufbaumechanismus für den C 7 F 15 -substituierten Gelator. [31] c)-e) Zweistufige hierarchische Struktur der selbstorganisierten Strukturen von Gelatoren mit verschiedenen Seitenketten. [31,32] f)-h) Selbstreinigung gegenüber Blut auf geschmierter gleitfähiger Oberfläche. [31] i) und j) Lichtmikroskopische Aufnahmen, die das unterschiedliche Ausmaß der Beeinträchtigung während der Wasserflussstabilitätstests der hergestellten Beschichtungen zeigen. [32] k) und l) Veränderung des makroskopischen Aussehens der Beschichtungen in (i) bzw. (j), analysiert anhand der Pixelhelligkeit. [32] Abbildung adaptiert mit Genehmigung von Wei et al. [31] und Lee et al. [32]