title: Paramagnetic ionic liquids for measurements of density using magnetic levitation.
abstract: Paramagnetic ionic liquids (PILs) provide new capabilities to measurements of density using magnetic levitation (MagLev). In a typical measurement, a diamagnetic object of unknown density is placed in a container containing a PIL. The container is placed between two magnets (typically NdFeB, oriented with like poles facing). The density of the diamagnetic object can be determined by measuring its position in the magnetic field along the vertical axis (levitation height, h), either as an absolute value or relative to internal standards of known density. For density measurements by MagLev, PILs have three advantages over solutions of paramagnetic salts in aqueous or organic solutions: (i) negligible vapor pressures; (ii) low melting points; (iii) high thermal stabilities. In addition, the densities, magnetic susceptibilities, glass transition temperatures, thermal decomposition temperatures, viscosities, and hydrophobicities of PILs can be tuned over broad ranges by choosing the cation-anion pair. The low melting points and high thermal stabilities of PILs provide large liquidus windows for density measurements. This paper demonstrates applications and advantages of PILs in density-based analyses using MagLev.
authors: Department of Chemistry and Chemical Biology, Harvard University, 12 Oxford St., Cambridge, Massachusetts 02138, USA.
authors: David K
authors: DK
authors: Bwambok
authors: Martin M
authors: MM
authors: Thuo
authors: Manza B J
authors: MB
authors: Atkinson
authors: Katherine A
authors: KA
authors: Mirica
authors: Nathan D
authors: ND
authors: Shapiro
authors: George M
authors: GM
authors: Whitesides
mesh_terms: D004578:Electron Spin Resonance Spectroscopy / Q000379:methods*; D052578:Ionic Liquids / Q000737:chemistry*; D060526:Magnetic Fields; D013046:Specific Gravity
chemical_list: D052578:Ionic Liquids