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2024 (English)In: Langmuir, ISSN 0743-7463, E-ISSN 1520-5827, Vol. 40, no 9, p. 4801-4810Article in journal (Refereed) Published
Abstract [en]
Strongly attractive forces act between superhydrophobic surfaces across water due to the formation of a bridging gas capillary. Upon separation, the attraction can range up to tens of micrometers as the gas capillary grows, while gas molecules accumulate in the capillary. We argue that most of these molecules come from the pre-existing gaseous layer found at and within the superhydrophobic coating. In this study, we investigate how the capillary size and the resulting capillary forces are affected by the thickness of the gaseous layer. To this end, we prepared superhydrophobic coatings with different thicknesses by utilizing different numbers of coating cycles of a liquid flame spraying technique. Laser scanning confocal microscopy confirmed an increase in gas layer thickness with an increasing number of coating cycles. Force measurements between such coatings and a hydrophobic colloidal probe revealed attractive forces caused by bridging gas capillaries, and both the capillary size and the range of attraction increased with increasing thickness of the pre-existing gas layer. Hence, our data suggest that the amount of available gas at and in the superhydrophobic coating determines the force range and capillary growth. © 2024 The Authors.
Place, publisher, year, edition, pages
American Chemical Society, 2024
Keywords
Coatings; Flame spraying; Hydrophobicity; Molecules; Sols; Surface properties; water; Attractive force; Capillary force; Capillary interactions; Coating cycles; Different thickness; Gas layers; Gas molecules; Layer thickness; Super-hydrophobic surfaces; Superhydrophobic coatings; adult; article; capillary; confocal laser scanning microscopy; flame; gas; liquid; middle aged; thickness; Gases
National Category
Chemical Sciences
Identifiers
urn:nbn:se:ri:diva-72784 (URN)10.1021/acs.langmuir.3c03709 (DOI)2-s2.0-85186451464 (Scopus ID)
Note
Paxton Juuti and Janne Haapanen (Tampere University, Tampere, Finland) are acknowledged for preparing the LFS coatings and Oskar Karlsson (Swerim, Stockholm, Sweden) for cross-sectional SEM imaging. M.E. thanks SSF, the Swedish Foundation for Strategic Research (grant no. FID15-0029) and Omya International AG for funding. H.T. acknowledges the Alexander von Humboldt Foundation for financial support. D.V. would like to acknowledge financial support via the Priority Programme 2171. A.S. is a researcher in Pro2BE at Karlstad University, a research environment for processes and products for a circular forest-based bioeconomy.
2024-05-162024-05-162024-05-16Bibliographically approved