Molecular level interactions between 1-ethyl-3-methylimidazolium methanesulphonate and water: Study of physicochemical properties with variation of temperature

The role of water on bonding and structural rearrangement of a hydrophilic ionic liquid (IL), 1-ethyl-3-methylimidazolium methanesulphonate ([EMI][MS]), has been investigated. Density, sound velocity and dynamic viscosity of [EMI][MS]-water mixtures have been measured from 293.15 K to 313.15 K and the conductivity has been measured at 298.15 K. The effect of the addition of water on the surface tension and contact angle of the IL has also been studied. Molecular level dynamics has been found to be modulated by the variation of composition to exert profound influence on the bulk physicochemical properties of the [EMI][MS]-water system. Experimental data were analyzed to gain a deep insight into the interactive features of the [EMI][MS]-water system. Thermodynamic parameters such as excess molar volume, thermal expansivity, isentropic compressibility, acoustic impedance, excess viscosity etc. derived from density, ultrasonic sound velocity and viscosity have been evaluated over the entire composition range to elucidate the impact of molecular level alternation and temperature on the bulk properties. Surface properties are also influenced by the interaction between IL and water. An idea about the aggregation of ILs in the binary mixtures was obtained from sound velocity related acoustic properties and these were correlated with the conductivity, surface tension, contact angle, and propensity of ions to the air/water interface of the binary systems. These would help a fundamental understanding of the binary system and provide means to tune [EMI][MS]-water and such other binary systems for desirable properties for use in multidisciplinary areas.