Interfacial Analysis of Imidazolium Styrene [TF2N] and Ionic Liquids for Self-Emulsifying Polyhipe Foam

A polyHIPE is a high internal phase emulsion (HIPE) polymer foam with an external phase consisting of a polymerized monomer. To prevent phase separation while the external phase polymerizes, a surfactant is added to the solution and removed once the polyHIPE is made. Removing the surfactant is time consuming with no guarantee of complete removal, which is problematic when the foam is used for water treatment. As a filter, water contaminants adsorb to the foam as it passes through, cleaning the water. Different contaminants require different polymers or different functionality to adsorb them, so the foams must be catered towards the individual water treatment needs of an area. This study aims to identify an ionic liquid solvent that could create a self-emulsifying polyHIPE foam with imidazolium styrene [TF2N] for water filtration. When added to a solvent, imidazolium styrene [TF2N] causes a decrease in the interfacial tension between the monomer and IL solution and an immiscible internal phase such as water. Three ionic liquids were used as solvents, PEG1-MIM[TF2N], C₄MIM[TF2N], and BnMIM[TF2N]. Imidazolium styrene [TF2N] was selected due to its similar chemical structure to known surfactants consisting of a hydrophilic head and hydrophobic chain of carbons.The interfacial tension of each IL was measured with increasing concentrations of imidazolium styrene [TF2N] added to each solution. Although the solutions containing C₄MIM[TF2N] and BnMIM[TF2N] caused a decrease in interfacial tension with increasing concentrations of monomer, the interfacial tensions were still too high for the solution to be self-emulsifying. When a known surfactant such as Span 80 or CTAB were added to the solution, the interfacial tension decreased to an acceptable value for making a stable emulsion, so it is possible to lower the interfacial tension of a solution containing imidazolium styrene [TF2N]. The resulting interfacial data on imidazolium styrene [TF2N] may prove useful to other future projects.The ionic liquids used in this project have many other applications where the interfacial tension may be necessary, as well as determining that their interface can be stabilized with known surfactants. Imidazolium styrene [TF2N] with longer hydrophobic chains that more closely resemble the structures of surfactants should be investigated for use as a self-emulsifying solvent.