RESUMO
Ionic liquids (ILs) are becoming important solvents in commerce, but monitoring their purity and performance in industrial applications presents new challenges. Fiber welding technology utilizes ILs to mold and shape natural fibers (cotton, hemp, flax, silk, and wool) into morphologies that are typically attained only using synthetic, petroleum-based non-biodegradable plastics. The result is an atom-efficient process that up-converts fibrous substrates to value-added products and materials. A key aspect of bringing this and other IL-enabled technologies to market relies on efficient monitoring and recycling of IL-based solvents. Implementing online IL quality monitoring enhances the unit economics of these processes. Here, we characterize and report conductivity measurements, refractometry, and ATR-FTIR spectroscopy techniques for online IL monitoring during an industrial fiber welding process. The online analysis enables more efficient recycling of the IL solvent, increasing the process efficiency and product quality.
RESUMO
Transmission infrared spectroscopy (IR) and differential scanning calorimetry are used to identify and characterize multiple phase transitions of butyltrimethylammonium bis(trifluoromethylsulfonyl)imide ([N1114] [TFSI]). Phase-dependent properties are analyzed using temperature-controlled transmission IR, in which we identify changes in the molecular arrangements at and around phase transition temperatures between -80 and 30 °C, which span crystallization and melting phase transitions. Our data report the dependence of phase transition behavior across multiple heat flow rates and the resulting molecular organizations that are formed. This is significant as temperature-specific organizations and properties of ionic liquids (ILs) contribute significantly to their application in separations and in devices. We also identify and discuss the relationship between phase transition temperatures and classes of those transitions when various temperature ramp rates are applied. Our analysis indicates that these relationships of IL thermochemistry could be developed as a diagnostic for assigning phase transition types.
