Molecular insight into wetting behavior of deep eutectic solvent droplets on ionic substrates: A molecular dynamics studyShow others and affiliations
2020 (English)In: Journal of Molecular Liquids, ISSN 0167-7322, E-ISSN 1873-3166, Vol. 319, article id 114298Article in journal (Refereed) Published
Abstract [en]
Wetting behavior of droplets made of choline chloride/urea (1:2), an archetypal deep eutectic solvent mixture, is studied using molecular dynamics simulations. The droplets are placed on a smooth model ionic substrate with positive and negative charges of the same magnitude q (0 e ≤ q ≤ 1.0 e), corresponding to a step-by-step change from a hydrophobic to hydrophilic surface. The molecular microstructure of the droplets and their spatial compositions are systematically studied in details on how they both change while gradually moving from hydrophobic to hydrophilic surface. It is observed that urea initially forms a monolayer on the surface with a planar orientation. This layer slowly shrinks while it becomes laterally more and more constrained. It becomes also molecularly more ordered when the surface becomes hydrophilic, at the same time as the contact angles become larger and larger. The anions (Cl-) are continuously pushed further away from the charged surface. While the contact angle increases and wetting decreases, and urea forms even a secondary stable layer where it changes its orientation and turns to have one of its amines facing up and carbonyl down. The average number of urea-urea H-bonds decreases linearly while the number of ion-pair contacts increases when the urea molecules are separating from the mixture. Our analysis gives a clear molecular understanding of the process and can be useful in many applications from membrane separation to catalysis.
Place, publisher, year, edition, pages
Elsevier, 2020. Vol. 319, article id 114298
Keywords [en]
Deep eutectic solvents, Solid/fluid interface, Wetting, Adsorbed layer, Molecular simulation
National Category
Energy Engineering
Research subject
Energy Engineering
Identifiers
URN: urn:nbn:se:ltu:diva-80759DOI: 10.1016/j.molliq.2020.114298ISI: 000583948500010Scopus ID: 2-s2.0-85091212214OAI: oai:DiVA.org:ltu-80759DiVA, id: diva2:1466344
Note
Validerad;2020;Nivå 2;2020-12-01 (johcin)
2020-09-112020-09-112021-03-24Bibliographically approved