Surface Roughness Explains the Observed Water Contact Angle and Slip Length on 2D Hexagonal Boron Nitride

Kumar Verma, A and Govind Rajan, A (2022) Surface Roughness Explains the Observed Water Contact Angle and Slip Length on 2D Hexagonal Boron Nitride. In: Langmuir : the ACS journal of surfaces and colloids, 38 (30). pp. 9210-9220.

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Abstract

Hexagonal boron nitride (hBN) is a two-dimensional (2D) material that is currently being explored in a number of applications, such as atomically thin coatings, water desalination, and biological sensors. In many of these applications, the hBN surface comes into intimate contact with water. In this work, we investigate the wetting and frictional behavior of realistic 2D hBN surfaces with atomic-scale defects and roughness. We combine density functional theory calculations of the charge distribution inside hBN with free energy calculations using molecular dynamics simulations of the hBN-water interface. We find that the presence of surface roughness, but not that of vacancy defects, leads to remarkable agreement with the experimentally observed water contact angle of 66° on freshly synthesized, uncontaminated hBN. Not only that, the inclusion of surface roughness predicts with exceptional accuracy the experimental water slip length of ∼1 nm on hBN. Our results underscore the importance of considering realistic models of 2D materials with surface roughness while modeling nanomaterial-water interfaces in molecular simulations.

Item Type:	Journal Article
Publication:	Langmuir : the ACS journal of surfaces and colloids
Publisher:	NLM (Medline)
Additional Information:	The copyright for this article belongs to the NLM (Medline).
Department/Centre:	Division of Mechanical Sciences > Chemical Engineering
Date Deposited:	30 Aug 2022 05:42
Last Modified:	30 Aug 2022 05:42
URI:	https://eprints.iisc.ac.in/id/eprint/76271

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