Interfacial thermodynamics of spherical nanodroplets: molecular understanding of surface tension via a hydrogen bond network. Issue 36 (7th September 2020)

• Record Type: Journal Article
• Authors: Kim, QHwan; Jhe, Wonho
• Is Part Of: Nanoscale. Volume 12:Issue 36(2020)
• Page Start: 18701
• Page End: 18709
• Publication Date: 2020-09-07
• Subjects: Nanoscience -- Periodicals; Nanotechnology -- Periodicals; 620.505
• DOI: 10.1039/d0nr04533k
• Languages: English
• ISSNs: 2040-3364

Abstract

Abstract : Change of surface tension of nanodroplet originates dominantly from the configurational energy of interfacial molecules, which is evidenced by the increasingly disrupted hydrogen bond network as the droplet size decreases. Abstract : Surface tension plays a ubiquitous role in phase transitions including condensation or evaporation of atmospheric liquid droplets. In particular, understanding of interfacial thermodynamics of the critical nucleus of 1 nm scale is important for molecular characterization of the activation energy barrier of nucleation. Here, we investigate surface tension of spherical nanodroplets with both molecular dynamics and density functional theory and find that surface tension decreases appreciably below 1 nm radius, whose analytical expression is consistently derived from the classic Tolman's equation. In particular, the free energy analysis of nanodroplets shows that the change of surface tension originates dominantly from the configurational energy of interfacial molecules, which is evidenced by the increasingly disrupted hydrogen bond network as the droplet size decreases. Our result can be applied to the interface-related phenomena associated with molecular fluctuations such as biomolecule adsorption at the sub-nm scale where macroscopic thermodynamic quantities are ill-defined.