UCLA

Oil-in-water nanoemulsions are aqueous dispersions of oil which have a < 100 nm and are an intriguing model system to study fundamental chemical and physical science. Nanoemulsions have a broad range of utilities and applications, not only in academic research, but in industry as well. Due to the small size of droplets inherent in nanoemulsions, they have an incredibly large surface area-to-volume ratio. This small droplet size also leads to decreased multiple scattering, even at large volume fractions, which can yield translucent elastic solids. In this dissertation, we present methods to measure the thermodynamic partitioning of sodium dodecyl sulfate molecules in nanoemulsions between the aqueous phase and oil-water interface, as well as an exciting novel route to produce crystalline and non-crystalline photonic size-fractionated nanoemulsions. Both gravimetric and electrical conductivity measurement analyses have been developed which can accurately determine what fraction of the total surfactant in both unfractionated and size-fractionated nanoemulsion resides on the oil-water interface or in the bulk continuous phase as either monomer or micelles. A theory of this partitioning, based off the Langmuir isotherm, has been developed and is presented in terms relevant to emulsion science. Furthermore, through a process of both hot emulsification and competitive surfactant exchange, we have developed methods where poorly screened ultrastable nanoscale liquid droplets can self-assemble to form brilliant opals, where the Debye layer D is greater than the diameter of the droplet (a/D < 1). This poorly screened ultrastable nanoemulsion can also form non-crystalline hyperuniform structures where intense monochromatic colors are observed in backscatter, without the addition of any optically absorbing chemicals or compounds.