Nanoparticle deposition on heterogeneous surfaces : random sequential adsorption modeling and experiments

The deposition of positively charged polymer nanoparticles on heterogeneous surfaces formed by a controlled self-assembly of larger particles on silica sensors was quantitatively described. Applying the Monte-Carlo type, random sequential modeling, the kinetics of particle deposition, their maximum coverage and the structure of the layers were determined. It is shown that the maximum coverage of the nanoparticles linearly decreases with the heterogeneity degree quantified in terms of the larger particle coverage. It is also confirmed that the nanoparticle layers exhibit a pronounced short-range ordering analogous to a two-dimensional liquid phase. The theoretical results derived from the modeling are used to interpret nanoparticle deposition kinetics acquired by the atomic force microscopy and the quartz microbalance (QCM). This allowed to determine the hydration function, which enables a proper interpretation of the QCM signal for the heterogeneous systems, extending the applicability range of this technique. Given that the kinetics of nanoparticle deposition on geometrically heterogeneous surfaces was not treated in the literature before, the results obtained in this work significantly advance the field of colloid science.