Liquid crystalline phases of 1,2-dimethyl-3-hexadecylimidazolium bromide and binary mixtures with water

► 1,2-dimethyl-3-hexadecylimidazolium bromide exhibits thermotropic SmA2 phase behavior. ► The layer spacing in SmA2 phase displays linear temperature dependence. ► H1 phase forms in the mixtures of 1,2-dimethyl-3-hexadecylimidazolium bromide and water. ► In the H1 phase, the cylinder units with D about 4.97 ± 0.04 nm nearly reach the most dense and highest-ordered columnar structure.