Mesoscale modeling and computer simulation of tethered nanorod 'shape amphiphile' assemblies

The goal of this thesis is to elucidate the parameters that strongly influence the self-assembled morphologies formed by tethered nanoparticle, "shape amphiphiles". Minimal models are developed which capture the geometry and rigidity of the particles, the immiscibility between the particle and tether, and the tether connectivity and flexibility. This work focuses on the self-assembly of tethered rods a class of shape amphiphile where the rigid block is rod-like.; The work presented here demonstrates that in addition to forming micelles, cylinders, bicontinuous, and sheet-like morphologies additional local ordering arises due to the geometry or anisotropy of the rigid block. For example, at high concentrations tethered rods are observed to form monolayer smectic morphologies when the solvent is good for the tether and poor for the rod, while, mono-tethered spheres self-assemble into bilayer structures. The number of tethers also influences the self-assembly. For example, di-tethered spheres self-assemble into monolayers in contrast to the bilayers formed when only a single tether is attached to the sphere.; For the tethered rods in selective solvent, our simulations predict several novel phases. In the case of end-tethered rods, a novel hexagonally arranged chiral cylinder morphology was observed. Other morphologies such as the tetragonally perforated and hexagonally perforated lamellar phases were observed. These phases have been observed in experimental rod coil copolymers but have not been previously predicted by simulation or theory. In the case of side-tethered rods several novel phases have been identified in this work including rectangular centered stepped ribbons, and bilayer phases, one with P2 symmetry and the other with Cmm symmetry, are predicted. Of particular interest may be the orientation of the rods in the stepped ribbon phase, wherein the long axis of the rod is parallel to the major axis of the ribbon.; For end-tethered rods in a neat system two bilayer arrowhead phases are identified that are consistent with the arrowhead phases observed for rod coil copolymers. Additionally a novel monolayer arrowhead phase is identified for the end-tethered rods. The rich phases predicted in this study demonstrate the complex coupling of the rigid and flexible blocks of the shape amphiphiles.