Underwater Adhesion of Oil Droplets to Surfaces Grafted with Hydrophilic Polymer Brushes: Many-Body Dissipative-Particle Simulations

A droplet probe atomic force microscopy (AFM) simulation using many-body dissipative particle dynamics is employed to investigate the effects of polymer hydrophilicity and grafting density on the underwater adhesion behavior of oil droplets at hydrophilic polymer brush layers. The results show that increasing the grafting density suppresses oil penetration, leading to reduced adhesion. Moreover, a higher polymer hydrophilicity weakens the sensitivity of adhesion behavior to grafting density, causing adhesion forces to converge under strong polymer-water interactions. Further analysis reveals that interfacial properties, including contact area, penetration depth, and contribution of polymers at the interface, significantly influence oil droplet adhesion. Additionally, polymer hydrophilicity plays a key role in regulating the relative contribution of polymers at the contact interface, ultimately determining the adhesion and its sensitivity to interfacial properties.