Brij 30 Induced Transition of Rodlike Micelles to Wormlike Micelles and Gels in the Imidazole Ionic Liquid Surfactants: The Alkyl Chain Length Effect

ABSTRACT: The effect of the hydrocarbon chain length of ionic liquid surfactants 1-hexadecyl-3-alkyl imidazolium bromide [C16imCn]Br (n = 1???16) on their aggregation behavior with polyoxyethylene lauryl ether (Brij 30) in aqueous solution was inspected. The rheological behavior, thermal properties, and microstructures of the different samples were studied using freeze-fractured electron microscopy. The interactions between [C16imCn]Br and Brij 30 were studied using nuclear magnetic resonance spectroscopy and theoretical simulation. With the addition of Brij 30, the rodlike micelles of [C16imCn]Br (n = 1, 2, 4, and 6) transition into wormlike micelles. The effects of the molar ratio of Brij 30 and [C16imCn]Br and the hydrocarbon chain length of [C16imCn]Br on the Brij 30/[C16imCn]Br (n = 1, 2, 4, and 6) wormlike micelles were studied. When Brij 30 was mixed with the rodlike micelles of [C16imC8]Br, the Brij 30/[C16imC8]Br mixtures form wormlike micelles at low Brij 30 concentration and gels at high Brij 30 concentration. The [C16imCn]Br (n = 10, 12, 14, and 16) rodlike micelles were induced by Brij 30 to turn into the Brij 30/[C16imCn]Br gels. The effect of the [C16imCn]Br hydrocarbon chain length on their rodlike micelles with the addition of Brij 30 is also theoretically discussed.

Automated summary

The effect of the hydrocarbon chain length of ionic liquid surfactants on the aggregation behavior with polyoxyethylene lauryl ether in aqueous solution was studied. The results showed that the chain length had a significant impact on the micelle structure.