Phase behaviour of polymer emulsions during the phase inversion process in the presence of non-ionic surfactants

A phase inversion map for polyisobutene–water–nonionic surfactant system showing the behaviour of the emulsion system as a function of the hydrophobic–lipophilic balance (HLB) and water volume fraction is developed. The apparatus and the different experimental techniques used to characterise the emulsion system is described. It was found that, using information from the phase inversion map, it is possible to produce stable polymer emulsions with sub-micron polymer drops via the transitional inversion route. The drop size distribution before transitional inversion was wide, while after transitional inversion it was much narrower. An average drop size of ∼200 nm was obtained for a mixture of polyoxyethylene nonylphenyl ether (NPE) surfactants (5% overall concentration by weight). It is, also, possible to produce small polymer drops via stable catastrophic inversion as the emulsion becomes more concentrated. The unstable multiple emulsion drops were found to decrease in size as we get closer to the transitional inversion line.