Catalog Home Page

Water nanodroplet on a hydrocarbon “Carpet”—The mechanism of water contact angle stabilization by airborne contaminations on Graphene, Au, and PTFE surfaces

Terzyk, A.P., Bryk, P., Korczeniewski, E., Kowalczyk, P., Zawadzka, A., Płóciennik, P., Wiśniewski, M. and Wesołowski, R.P. (2019) Water nanodroplet on a hydrocarbon “Carpet”—The mechanism of water contact angle stabilization by airborne contaminations on Graphene, Au, and PTFE surfaces. Langmuir, 35 (2). pp. 420-427.

Link to Published Version: https://doi.org/10.1021/acs.langmuir.8b03790
*Subscription may be required

Abstract

Wetting is very common phenomenon, and it is well documented that the wettability of a solid depends on the surface density of adsorbed airborne hydrocarbons. This “hydrocarbon hypothesis” has been experimentally confirmed for different surfaces, for example, graphene, TiO2, and SiO2; however, there are no scientific reports describing the influence of airborne contaminants on the water contact angle (WCA) value measured on the polytetrafluoroethylene (PTFE) surface. Using experimental data showing the influence of airborne hydrocarbons on the wettability of graphene, gold and PTFE by water, together with Molecular Dynamics simulation results we prove that the relation between the WCA and the surface concentration of hydrocarbons (n-decane, n-tridecane, and n-tetracosane) is more complex than has been assumed up until now. We show, in contrast to commonly approved opinion, that adsorbed hydrocarbons can increase (graphene, Au) or decrease (PTFE) the WCA of a nanodroplet sitting on a surface. Using classical thermodynamics, a simple theoretical approach is developed. It is based on two adsorbed hydrocarbon states, namely, “carpet” and “dimple”. In the “carpet” state a uniform layer of alkane molecules covers the entire substrate. In contrast, in the “dimple” state, the preadsorbed layer of alkane molecules covers only the open surface. Simple thermodynamic balance between the two states explains observed experimental and simulation results, forming a good starting point for future studies.

Item Type: Journal Article
Murdoch Affiliation: School of Engineering and Information Technology
Publisher: American Chemical Society
Copyright: © 2018 American Chemical Society
URI: http://researchrepository.murdoch.edu.au/id/eprint/43093
Item Control Page Item Control Page