Phase studies of ethyl ammonium nitrate (EAN)/sugar surfactant microemulsions: effect of chain length of alkanes and length of the hydrophobic chain of the non-ionic surfactant

Abstract Microemulsions were formulated with the ionic liquid ethylammonium nitrate (EAN) used instead of water as the polar phase, hydrocarbon solvents ( n -alkanes) and sugar-based non-ionic surfactants, and their phase behaviour and microstructure were investigated. The sugar-based non-ionic surfactants used are non-toxic, biodegradable and environmentally friendly. Due to these properties, their use in microemulsion systems is a clear alternative to the conventionally used non-ionic surfactants from the class of alkyl polyoxyethylene ethers (C i E j ). The influence of n -alkanes with different chain lengths and of sugar-based nonionic surfactants with hydrophobic chains of different lengths on the microemulsion system was also investigated. The results obtained for the microemulsions with EAN described here are similar to those obtained for microemulsion systems formulated with water as the polar solvent. Liquid crystalline ( LC ) phases were observed in microemulsion systems with sugar-based nonionic surfactants having longer hydrocarbon chains, at lower temperatures and higher surfactant mass fraction.