| Self-assembly is a fundamental mechanism by which structures form in materials. This mechanism has given rise to many new technological advances in applications as diverse as structural composites, medicine, alternative energy sources and information technology. Many current approaches to self-assembly have shown promise, but each has its own unique limitations. The over-arching goal of this study is to develop self-assembly processes for nanoparticles that are simple, scalable and cost effective. In this dissertation we examine the mechanism for self assembly of nanoparticles in dispersion and at fluid-fluid interfaces.;A simple method is presented for the synthesis of amphiphilic gold nanoparticle surfactants that self-assemble into clusters of controllable structure. The technique is based on the control of particle clustering through sequential functionalization of the surface with thiol terminated polyethylene glycol to sterically stabilize particles in water and short alkane-thiols that render the particles amphiphilic. These nanoparticle surfactants are surface active and form rafts at the air-water interface and stable nanoparticle clusters in dispersion. The clusters are also reminiscent of traditional micelles with an adjustable aggregation number that is controlled via modification of the grafting density of polymer on the nanoparticle surface. The nanoparticle surfactants are also shown to be highly effective emulsifying agents due to their amphiphilicity and they adsorb strongly to oil-water interfaces with controllable inter-particle separation distances. Both the clusters and colloidosomes that can be formed with these particles exhibit tunable shifts in plasmon resonance, enhancing the near-infrared optical absorption and making them useful for a wide range of applications. |
