Mesoscale Simulations of Anisotropic Patchy Nanoparticles at Oil-Water Interfaces

Cellulose is the most abundant organic material on earth, driving research for the production and use of cellulose-derived nanocrystals as Janus-particle emulsifiers. This study aimed to develop and use a mesoscale model of cellulose nanocrystals to better understand their emulsion stabilization mechanism and organization at the oil-water interface. Cellulose nanocrystals were modeled by anisotropic patchy particles consisting of two hydrophobic and four hydrophilic patches according to the experimentally-inferred structure. These nanoparticles were placed at an oil-water interface, and the effect of nanoparticles length and surface concentration on the interfacial tension and surface pressure were investigated. Interfacial tension was shown to be consistently reduced with increasing surface concentration of nanoparticles, with nanoparticles length having little influence on the final interfacial tension values. Nanoparticle organization was quantified by computing the nematic order parameter, S, at the interface. It was found that nanoparticles organize into rafts that have strong local orientational correlation, but rafts are randomly oriented at the interface, given place to a low global orientational correlation.