Protic ionic liquids: physicochemical properties and behavior as amphiphile self-assembly solvents.
The physicochemical properties of 22 protic ionic liquids (PILs) and 6 protic molten salts, and the self-assembly behavior of 3 amphiphiles in the PILs, are reported. Structure-property relationships have been explored for the PILs, including the effect of increasing the substitution of ammonium cations and the presence of methoxy and hydroxyl moieties in the cation. Anion choices included the formate, pivalate, trifluoroacetate, nitrate, and hydrogen sulfate anions. This series of PILs had a diverse range of physicochemical properties, with ionic conductivities up to 51.10 mS/cm, viscosities down to 5.4 mPa.s, surface tensions between 38.3 and 82.1 mN/m, and densities between 0.990 and 1.558 g/cm3. PILs were designed with various levels of solvent cohesiveness, as quantified by the Gordon parameter. Fourteen PILs were found to promote the self-assembly of amphiphiles. High-throughput polarized optical microscopy was used to identify lamellar, hexagonal, and bicontinuous cubic amphiphile self-assembly phases. The presence and extent of amphiphile self-assembly have been discussed in terms of the Gordon parameter.
Greaves
Tamar L
TL
CSIRO Molecular and Health Technologies, Bag 10 Clayton, Vic 3169, Australia.
Weerawardena
Asoka
A
Krodkiewska
Irena
I
Drummond
Calum J
CJ
D000838:Anions / Q000737:chemistry; D002412:Cations / Q000737:chemistry; D002627:Chemistry, Physical / Q000379:methods*; D005561:Formates / Q000737:chemistry; D006878:Hydroxides / Q000737:chemistry; D052578:Ionic Liquids / Q000737:chemistry*; D008859:Microscopy, Polarization; D015394:Molecular Structure; D009566:Nitrates / Q000737:chemistry; D010421:Pentanoic Acids / Q000737:chemistry; D000644:Quaternary Ammonium Compounds / Q000737:chemistry; D012997:Solvents / Q000737:chemistry*; D013431:Sulfates / Q000737:chemistry; D013501:Surface-Active Agents / Q000737:chemistry*; D013696:Temperature; D014269:Trifluoroacetic Acid / Q000737:chemistry; D014783:Viscosity
D000838:Anions; D002412:Cations; D005561:Formates; D006878:Hydroxides; D052578:Ionic Liquids; D009566:Nitrates; D010421:Pentanoic Acids; D000644:Quaternary Ammonium Compounds; D012997:Solvents; D013431:Sulfates; D013501:Surface-Active Agents; C030544:formic acid; C005566:pivalic acid; C031356:hydroxide ion; D014269:Trifluoroacetic Acid