A low-viscous and flowable zwitterionic liquid.

Zwitterionic liquids have attracted significant attention in various fields due to their low-toxicity and the ability to tune their functional properties. However, despite being liquid in thermo-dynamic definition, zwitterionic liquids are not commonly recognized as "liquids" by the general public because of their extremely high viscosity, comparable to that of peanut butter, which prevents stirring even with a strong magnetic stirrer. In this study, we developed a flowable and stirrable zwitterionic liquid, OE₂imOE₃C. Its viscosity was one-seventeenth that of traditional zwitterionic liquids. OE₂imOE₃C was able to stir and dissolve 11 wt% cellulose at 100 °C, which is a task unachievable by a typical zwitterionic liquid due to their high viscosity. Furthermore, OE₂imOE₃C exhibited low toxicity to yeast, consistent with other standard zwitterionic liquids. This study successfully achieved a significant reduction in viscosity without compromising other properties.