| Summary: | Surfactants comprise one of the largest volume commodity chemicals in the world and have multifarious uses from pharmaceuticals, agrochemicals, food, fuel and lubricant additives, paints and inks as well as detergents and cleaning agents. The ability to control surfactants once they are in solution is of great importance not only for scientific reasons but also because of environmental and economic interest. To this end, surfactants sensitive to changes in pH, temperature, C02, light and redox have already been developed. This thesis investigates a new class of surfactants designed to be magnetically active, whereby the composition and physico-chemical properties of a system may be perturbed simply by the switching "on" and "off" of a magnetic switch and with no significant energy input. The thesis demonstrates that these new magneto-responsive surfactants behave like conventional surfactants but are now bifunctional allowing for new magnetic approaches where previously magnetic nanoparticles have been employed. For example, the magnetic properties makes it easier to round up and remove the surfactant from a system once it has been added. By developing the first nanoparticle-free magnetic emulsions the potential for further applications in environmental clean ups (e.g. oil spills), water treatment or drug delivery have been demonstrated. In addition to this, the combination of surfactant adsorption and intrinsic magnetism has allowed for the control and manipulation of biomolecules without the need for magnetic nanoparticles. This work explores both the fundamental properties of these novel surfactants and also takes significant steps to optimize the surfactants for potential applications.
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