Tailoring nanoparticles and polymers for cooperative interfacial and surface interactions

This thesis describes the synthesis of chemically functionalized nanoparticles and their behavior at interfaces and in conjunction with polymers. Solid-liquid, liquid-liquid, and air-liquid interfaces are useful platforms for studying nanoparticle assembly, especially when nanoparticles are functionalized to enable their segregation to the interface. At the liquid-liquid interface, double emulsions droplets, both oil-in-water-in-oil and water-in-oil-in-water, stabilized with nanoparticles were prepared. This involved gold nanoparticles stabilizing oil-in-water droplets, and CdSe quantum dots stabilizing water-in-oil droplets. These double emulsion droplets were by simply shaking to give polydisperse droplets, or in a well-defined fashion by microcapillary flow focusing. When nanoparticle-stabilized double emulsions were sized using glass microcapillary devices, they formed a variety of interesting structures that demonstrated the importance of having nanoparticles in the emulsion. Ligand-functionalized nanoparticles proved emenable to triggered disruption and inversion processes. Two different tetrahydropyranyl protecting groups were employed in the ligand shell of gold nanoparticles enabling an ‘in situ’ droplet inversion, in the presence of acid using either added H+ or photogenerated acid to trigger the desired inversion. Considering the liquid-solid interface, amphiphilic phosphorylcholine substituted polyolefins stabilized droplets were used to pick up various types of nanoparticles from substrates, and transport the nanoparticles in a fluid driven system. Specifically, decoration of oil-in water droplets with pentafluorophenyl ester groups enabled efficient removal of amine functionalized silica nanoparticles adsorbed on a substrate. At the air-liquid interface, Langmuir films of gold nanoparticles were prepared where the nanoparticles contained cyclic olefins in their ligand periphery. The films were crosslinked by introduction of a water soluble ruthenium benzylidene catalyst to the aqueous sub-phase, affording two-dimensional elastic networks at the air-water interface