Stable nanoreactors for material fabrication using the aggregation of fluorinated ionic liquid surfactants in ionic liquid solvents

Abstract

The design of thermostable and efficient self-assembly nanoreactors is highly desirable for the fabrication of nanomaterials. Benefiting from the tunable properties and nonvolatility of ionic liquids (IL), IL-in-IL self-assembly systems show a flexible structure and thermostability under extreme conditions. Inspired by this hypothesis, stronger hydrophobic fluorinated ILs are expected to fabricate nonvolatile IL-in-IL self-assembly systems. In this work, two series of fluorinated ILs were synthesized and characterized by NMR, FTIR, DSC, and TGA. Then, the aggregation of these fluorinated ILs in protic and aprotic IL solvents was studied by surface tension and 19F NMR methods. The microstructure of these IL-in-IL aggregation systems was characterized by DLS and SAXS. The fluorinated ILs exhibit excellent surface activity even in aprotic ILs. Furthermore, protic ILs display superior ability to promote the self-assembly of ILs surfactants. These IL-in-IL aggregation systems display the typical morphology of ellipsoidal or multilayer spherical micelles with diameters of approximately 10 nm ∼ 60 nm. A typical IL-in-IL aggregation system was proposed as an efficient nanoreactor to prepare nanoscale MOFs without using any volatile organic solvents or autoclaving. The synthesized HKUST-1 exhibits larger surface areas and nanoscale morphology by XRD, SEM, TEM, BET, and XPS characterization. The results presented in this study offer key information to design new thermostable IL-based colloidal systems and their applications.