Preparation and characterisation of polymer films from polymerizable microemulsions
This thesis is concerned with the microemulsion phase behaviour of polymerizable surfactants with polymerizable oils and water, and the effect of various properties and characteristics of the equilibrium microemulsion phases and their components on the structure of solid polymers prepared by polymerisation of the liquid microemulsion phases. The polymerizable surfactants each contain a polymerizable methacrylate group in one of two possible locations. In two of the surfactants, the methacrylate group is located on the head group of the surfactant and on one the methacrylate group is located on the surfactant tail group. Three oils were used, each possessing an acrylate polymerizable group at either end of the oil molecule. The characterisation of polymerizable surfactants in aqueous/ polymerizable oil systems at low [surfactant] was observed initially. It was found that the solubility of the surfactants is similarly low in each of the three oils and each surfactant was found to be soluble in water. Stable o/w emulsions were prepared using each of the surfactants with no evidence of phase inversion with temperature observed in any system but phase inversion with electrolyte was observed in some systems. Salt was found to affect the partitioning of each surfactant between water and oil and C3/11-M surfactant was found to exhibit an electrolytic effect of its own. Winsor I microemulsion systems were prepared at low [salt] and Winsor II microemulsions were prepared at high [salt] for systems containing HDDA or DPGDA oils for each of the surfactants. The effects of each of the components present in each system on surfactant partitioning and cmc in water and oil and were observed. High surfactant concentration microemulsion phases were then prepared using each of the three surfactants with each of the three oils (nine systems) so that the effect of surfactant and oil molecular structure on phase equilibration (location of aggregates, equilibrium phase composition etc.) could be determined. A broad range of phase types were observed, dependent on the structures of the surfactant and oil molecules. Phase inversion due to increasing initial [surfactant] alone (i.e. no added salt) was observed in several systems. The possibility of control of equilibrium water content of the equilibrium microemulsion phases with surfactant concentration was studied. Systems that did not demonstrate phase inversion with initial [surfactant] displayed control of equilibrium water content of the equilibrium microemulsion phases with initial [surfactant]. It was thought that control of porosity of the solid polymers may be possible by controlling the equilibrium water content of the liquid microemulsion. Solid polymer films were prepared by polymerisation of equilibrium microemulsion phases containing high initial [surfactant] using a photopolymerisation method. 0.1 min using 1 wt. % Darocur 1173 initiator was sufficient UV irradiation time to prepare sold films. The opacity of the polymer films was seen to increase with increasing water content of the parent microemulsion. The strength of the films was seen to decrease with increasing water content of the parent microemulsion. Three different microstructures of polymer films were observed by SEM and were dependent on the structures of the surfactants and oils in the microemulsion. The pore volume fraction of the polymers was found to be dependent on the microemulsion phase type, including surfactant and oil types and was controllable in several cases by equilibrium water content of the parent microemulsion, therefore by initial [ surfactant] in the microemulsion.