Supporting Information

Influence of the cation alkyl chain length of imidazolium-based room temperature ionic liquids on the dispersability of TiO2 nanopowders

Alexandra Wittmara,c, Martyna Gajdaa, Devendraprakash Gautamb,c, Udo Dörflerb,c, Markus Wintererb,c, Mathias Ulbrichta,c,*

aLehrstuhl für Technische Chemie II, Universität Duisburg-Essen, 45141 Essen, Germany, bNanoparticle Process Technology, Universität Duisburg-Essen, 47057 Duisburg, Germany,

cCeNIDE – Centre for Nanointegration Duisburg-Essen, 47057 Duisburg, Germany

*Fax: x49 – 201 – 183 3147, e-mail:

Figure SI-1. X-ray diffraction patterns of the TiO2 powders

Figure SI-2. FT-IR spectra of the [Cnmim][BF4] ionic liquids (n = 2, 4, 6)

Table SI-1. IR bands of [Cnmim][BF4] and their assignments: ip … in plane, op … out of plane, sym … symetric, asym … antisymetric, str … structure, vib … vibration[S1, S2]

Frequency, cm-1 / Vibrational assignment
~ 699 / Ring ip asym bending vib
~ 750 / BF4- stretching vib
~ 845 / Ring ip bending vib
~ 1018 / Alkyl chain ip wagging vib
~ 1170 / Ring ip asym stretching
~ 1286 / Ring sym vib
~ 1335 / Ring ip sym stretching vib
~ 1390 / Ring ip asym stretching vib
~ 1573 / Ring ip asym/sym stretching vib
~ 2991 / Alkyl chain sym stretching vib
~ 3123 / Ring stretching vib
~ 3167 / Ring asym stretching vib

Figure SI-3. Viscosity dependency on the shear rate for [C2mim][BF4] at varied NP concentration

Figure SI-4. Viscosity dependency on the shear rate for [C4mim][BF4] at varied NP concentration

Figure SI-5. Viscosity dependencey on the shear rate for [C6mim][BF4] at varied NP concentration

Figure SI-6. Viscosity dependency on shear rate in the three ionic liquids at higher concentrations; case study: nanopowder TiO2 (3)

Figure SI – 7. TiO2 dispersions in [C6mim][BF4]: fresh (left) and after 264 h (right),

0.1 wt% TiO2, 1 h ultrasound treatment

Figure SI – 8. Aggregate sizes in dispersion vs. time for TiO2 (2) and TiO2 (3) in [C6mim][BF4], 0.1 wt% TiO2, 1 h ultrasound treatment

Figure SI-9. Influence of the period of ultrasound treatment on the dispersion rheology at 0.5 wt% TiO2 in [C4mim][BF4]

References

(S1) Talaty E.R., Raja S., Storhaug V.J., Dölle A., Carper W.R., Raman and infrared spectra and ab initio calculations of C2-4MIM imidazolium hexafluorophosphate ionic liquids, J. Phys. Chem. B 2004, 108, 13177

(S2) Shi F., Deng Y., Abnormal FT-IR and FT Raman spectra of ionic liquids confined in nano-porous silica gel, Spect. Acta A 2005, 62, 239