A novel series of cyclophosphazene derivatives containing imidazolium ionic liquids with variable alkyl groups and their physicochemical properties

A series of substituted cyclophosphazene derivatives containing imidazolium ionic liquids having variable alkyl groups were successfully synthesized and characterized by different spectroscopic techniques. The synthesized ionic liquids with butyl, pentyl, hexyl, heptyl, octyl and decyl groups were designated as IL1, IL2, IL3, IL4, IL5, and IL6 respectively. Physicochemical studies in terms of viscosity, density, thermal stability and conductivity were carried out as a function of temperature and molecular weight to see the lengthening effect of the alkyl group. The viscosity and density of the ionic liquids tend to decrease linearly with temperature. Further, experimental values of viscosity and density calculated the viscosity index, thermal expansion coefficient and molar volume. Similarly, all other physicochemical properties were evaluated to study structure-property correlation. (C) 2019 Elsevier B.V. All rights reserved.