Physico-Chemical nanomaterials science

Features of hysteresis of wetting of a solid substrate by a nanodroplet
Burian S.A.1,2, Zubariev O.M1, Kovalchuk V.I2, Yaroshchuk A.E3, Isaiev M.V.4
1 Faculty of Physics, Taras Shevchenko National University of Kyiv, Volodymyrska str. 64/13, Kyiv-01601, Ukraine
E-mail: burian_sergii@knu.ua
2 F.D. Ovcharenko Institute of Biocolloidal Chemistry of the National Academy of Sciences of Ukraine, Vernadskoho Ave. 42, Kyiv-03142, Ukraine
3 Institució Catalana de Recerca i Estudis Avançats, pg. L.Companys 23, Barcelona-08010, Spain
4 Université de Lorraine, CNRS, LEMTA, 54000 Nancy, France

Understanding the dynamics of three-phase contact-line movement is crucial for the description of processes important for numerous technological issues related to nuclearization, evaporation, percolation etc [1,2]. In this context, from a microscopic point of view, phenomena of hysteresis of wetting angle on smooth surfaces are still not fully understood. 
In our talk, we will consider the shape of a nanoscopic droplet located on a solid substrate in an external force field applied parallel to the surface. The cylindrical cap shape of the droplet was chosen to minimise the impact of three-phase line curvature. Molecular dynamics simulations were chosen as the main tool for the evaluation of droplet shape.
As a main result of our simulations, a contact-angle hysteresis on atomistic smoothed surfaces was observed. Dependences of droplet velocity, receding and advancing contact angle on the magnitude of external field were also investigated. An analytical model postulating adsorption of water molecules on the solid substrate was developed to explain the characteristic features of the droplet shape.

1.	Wang, H., Lou, Q., Liu, G., & Li, L. Effects of contact angle hysteresis on bubble dynamics and heat transfer characteristics in saturated pool boiling // International Journal of Thermal Sciences-2022.-178.-P.107554.
2.	Khadka, K., & Ferguson, G. S. Does the Roll-off Angle Depend on Work of Adhesion? // Langmuir-2022.-38, N 16.-P. 4820-4825.