Multiscale Modeling of Self-assembled Nanoparticle Superstructures

In this thesis, we describe our modeling of structure, stability, and material properties of membranes, super-structures, and superlattices formed of self-assembled colloidal nanoparticles (NPs) interacting by many competing forces (Coulombic, magnetic, van der Waals, solvation, entropic, etc.). Most of the studies were done in close collaborations with experimentalists. First, using classical atomistic molecular dynamics (MD) simulations, we have studied a molecular filtration in realistic gold NPs membranes, a complex behavior of supercharged gold NPs at aqueous-organic liquid interfaces, a pH-dependent stabilization of CdS NP nanoshells, and a transfer of chirality from individual NPs to their nanoribbons. These simulations demonstrate the importance of atomistic descriptions for a precise modeling of realistic self-assembled NP systems (ligands, electric fields, ionic solutions, etc.). Second, using coarse-grain MD simulations, we have studied a mechanical stretching of stressed self-standing gold NP membranes and capsules, and an inclusion of hydrophobic ligated gold NPs inside lipid bilayers. These simulations demonstrate the possibility to describe large structural deformations of stressed self-standing membranes, and the stabilization of large nanoparticle-lipid hybrid systems. Finally, using mean-field semi-analytical calculations and Monte Carlo simulations, we have studied the stabilization of superlattices formed of regular and truncated Pt nanocubes, and the self-assembly of many different superparamagnetic magnetite super-structures, such as chiral helices. These calculations demonstrate the description of large systems with complex interactions between their components.