title: Numerical study of homogeneous nanodroplet growth.
abstract: We investigate the axisymmetric homogeneous growth of 10-100 nm water nanodroplets on a substrate surface. The main mechanism of droplet growth is attributed to the accumulation of laterally diffusing water monomers, formed by the absorption of water vapour in the environment onto the substrate. Under assumptions of quasi-steady thermodynamic equilibrium, the nanodroplet evolves according to the augmented Young-Laplace equation. Using continuum theory, we model the dynamics of nanodroplet growth including the coupled effects of disjoining pressure, contact angle and monomer diffusion. Our numerical results show that the initial droplet growth is dominated by monomer diffusion, and the steady late growth rate of droplet radius follows a power law of 1/3, which is unaffected by the substrate disjoining pressure. Instead, the disjoining pressure modifies the growth rate of the droplet height, which then follows a power law of 1/4. We demonstrate how spatial depletion of monomers could lead to a growth arrest of the nanodroplet, as observed experimentally. This work has further implications on the growth kinetics, transport and phase transition of liquids at the nanoscale.
authors.affiliation: A∗STAR Institute of High Performance Computing, 1 Fusionopolis Way, Connexis, Singapore 138632, Singapore.
authors.forename: Tran Si Bui
authors.initials: TSB
authors.lastname: Quang
authors.affiliation: A∗STAR Institute of High Performance Computing, 1 Fusionopolis Way, Connexis, Singapore 138632, Singapore. Electronic address: leongfy@ihpc.a-star.edu.sg.
authors.forename: Fong Yew
authors.initials: FY
authors.lastname: Leong
authors.affiliation: Graphene Research Center and Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore 117551, Singapore; Center for BioImaging Sciences and Department of Biological Sciences, National University of Singapore, Science Drive 4, Singapore 117543, Singapore.
authors.forename: Utkur M
authors.initials: UM
authors.lastname: Mirsaidov
mesh_terms: D003102:Colloids / Q000737:chemistry; D007700:Kinetics; D008956:Models, Chemical; D036103:Nanotechnology; D013499:Surface Properties; D014867:Water / Q000737:chemistry*
chemical_list: D003102:Colloids; D014867:Water
keywords: Augmented Young–Laplace equation; Contact angle; Disjoining pressure; Nanodroplet growth