The Role of Chemical Heterogeneity in Surfactant Adsorption at Solid-Liquid Interfaces

Chemical heterogeneity of solid surfaces disrupts the adsorption of surfactants from the bulk liquid. While its presence can hinder the performance of some formulations, bespoke chemical patterning could potentially facilitate controlled adsorption for nanolithography applications. Although some computational studies have investigated the impact of regularly patterned surfaces on surfactant adsorption, in reality many interesting surfaces are expected to be stochastically disordered and this is an area unexplored via simulations. In this paper we describe a new algorithm for the generation of randomly disordered chemically heterogeneous surfaces and use it to explore the adsorption behaviour of four model nonionic surfactants. Using novel analysis methods we interrogate both the global surface coverage (adsorption isotherm) and behaviour in localised regions. We observe trends in adsorption characteristics as surfactant size, head/tail ratio, and surface topology are varied and connect these to underlying physical mechanisms. We believe that our methods and approach will prove useful to researchers seeking to tailor surface patterns to calibrate nonionic surfactant adsorption.