Computer simulations of underwater oil adhesion of self-assembled monolayers on Au (111). Issue 9 (12th June 2020)

• Record Type: Journal Article
• Authors: Liao, Mingrui; Li, Yingtu; Chen, Zheng; Zhou, Jian
• Is Part Of: Molecular simulation. Volume 46:Issue 9(2020)
• Page Start: 713
• Page End: 720
• Publication Date: 2020-06-12
• Subjects: Adhesion -- oleophobicity -- self-assembled monolayer -- molecular simulation -- protein adsorption; Molecular dynamics -- Computer simulation -- Periodicals; Statistical mechanics -- Computer simulation -- Periodicals; 539.6
• DOI: 10.1080/08927022.2018.1498974
• Languages: English
• ISSNs: 0892-7022

Abstract

ABSTRACT: Molecular dynamics and steered molecular dynamics (SMD) simulations are used to investigate the underwater adhesive forces of 1, 2-dichloroethane (DCE) on ionic and non-ionic self-assembled monolayers (SAMs) grafted on Au (111). The non-ionic SAMs containing hydroxyl group include ethanolamine-terminated SAM (ETA-SAM), dopamine-terminated SAM (DOPA-SAM), hydroxyl-terminated SAM (OH-SAM) and oligo(ethylene glycol)-terminated SAM (OEG-SAM); the ionic SAMs contain mixed-charged zwitterionic SAM ( C O O − / N ( C H 3 ) 3 + − S A M ) and zwitterionic phosphorylcholine-terminated SAM ( P O 4 − @ N ( C H 3 ) 3 + − S A M ) . Simulation results show that the order of underwater oleophobicity of SAMs is OEG-SAM < ETA-SAM < OH-SAM < DOPA-SAM < PO 4 − @ N ( C H 3 ) 3 + − S A M < CO O − / N ( C H 3 ) 3 + − S A M, while the order of underwater DCE oil droplet adhesion forces on different SAMs is CO O − / N ( C H 3 ) 3 + − S A M < PO 4 − @ N ( C H 3 ) 3 + − S A M < ETA-SAM < DOPA-SAM < OH-SAM < OEG-SAM. The ionic SAMs show stronger underwater oleophobicity and lower oil adhesion than non-ionic SAMs. Generally, a more underwater oleophobic surface is less adhesive. The underwater oil droplet desorption behaviours on ionic and non-ionic SAMs are also different. With the oil droplet being pulled away from ionic SAMs, the oil contact lines gradually shortened and disappeared finally; whereas the oil contact lines on non-ionic SAMs almost kept an initial state even the main part of oil droplet separated from the SAMs. This work systematically proved that a zwitterionic surface was less underwater oil adhesive than a non-ionic surface and provided a new insight for their oil desorption behaviours. The above results will be helpful for the design of underwater oleophobic surfaces with tuneable adhesion.