Fluorinated Ionic Liquids as Task-Specific Materials: An Overview of Current Research

Abstract

This chapter is focused on the massive potential and increasing interest on Fluorinated Ionic Liquids (FILs) as task-specific materials. FILs are a specific family of ionic liquids, with fluorine tags equal or longer than four carbon atoms, that share and improve the properties of both traditional ionic liquids and perfluoro surfactants. These compounds have unique properties such as three nanosegregated domains, a great surfactant power, chemical/biological inertness, easy recovery and recyclability, low surface tension, extreme surface activity, high gas solubility, negligible vapour pressure, null flammability, and high thermal stability. These properties allied to the countless possible combinations between cations and anions allow the design and development of FILs with remarkable properties to be used in specific applications. In this review, we highlight not only the unique thermophysical, surfactant and toxicological properties of these fluorinated compounds, but also their application as task-specific materials in many fields of interest, including biomedical applications, as artificial gas carries and drug delivery systems, as well as solvents for separations in engineering processes.

Disclosing the Potential of Fluorinated Ionic Liquids as Interferon-Alpha 2b Delivery Systems

“…To study the influence of IFN-α 2b on the aggregates of FILs, two FILs were selected: [C 2 C 1 Im][C 4 F 9 SO 3 ] and [N 1112(OH ][C 4 F 9 SO 3 ]. These FILs have outstanding surface-active properties, full miscibility in water, and negligible toxicity [ 31 , 32 , 38 ]. Both FILs can form different aggregates that were identified by the determination of distinct CACs in water [ 38 ].…”

“…The use of ILs as DDSs has been under investigation due to their capacity to stabilize and enhance the solubilization of macromolecules such as proteins [ 27 , 28 ], especially the surface-active ionic liquids (SAILs) [ 29 , 30 ]. Fluorinated ionic liquids (FILs) are a family of SAILs and have shown promising results in the biopharmaceutical field [ 31 , 32 ]. These compounds are characterized by the introduction of perfluoroalkyl chains with equal or more than four carbon atoms in the cation and/or anion.…”

“…These compounds are characterized by the introduction of perfluoroalkyl chains with equal or more than four carbon atoms in the cation and/or anion. This structural feature can promote the formation of three nano-segregated domains (one polar and two non-polar: hydrogenous and fluorous), which grant improved properties to FILs [ 31 , 32 , 33 , 34 , 35 , 36 ]. They are mainly characterized by impressive surfactant power, chemical and biological inertness, low surface tension, negligible vapour pressure, tuneability, and high thermal stability, along with other excellent properties that are common in the conventional ILs and perfluoroalkyl compounds, such as high solubility of gases [ 31 , 32 , 33 , 34 , 35 , 36 , 37 ].…”

“…This structural feature can promote the formation of three nano-segregated domains (one polar and two non-polar: hydrogenous and fluorous), which grant improved properties to FILs [ 31 , 32 , 33 , 34 , 35 , 36 ]. They are mainly characterized by impressive surfactant power, chemical and biological inertness, low surface tension, negligible vapour pressure, tuneability, and high thermal stability, along with other excellent properties that are common in the conventional ILs and perfluoroalkyl compounds, such as high solubility of gases [ 31 , 32 , 33 , 34 , 35 , 36 , 37 ]. FILs constituted by perfluoroalkyl anions with only four carbon atoms have shown enhanced self-aggregation behaviour that aids the formation of self-assembled structures in aqueous solutions [ 31 , 32 , 38 ], which combined with the low surface tension [ 31 ] make FILs highly surface-active compounds.…”

“…This superior surfactant behaviour allows those FILs to be completely miscible in aqueous solutions [ 38 ]. Moreover, FILs can be customized to have negligible cytotoxicity in four different human cell lines [ 31 , 32 , 39 , 40 ], high acceptance of red blood lysis [ 32 ], and insignificant ecotoxicity to several aquatic species and bacteria [ 31 , 32 ]. These properties have been key to considering the use of FILs in the biological field, especially in the formulation of DDSs for therapeutic proteins.…”