Phase transfer of TiO₂ nanoparticles from water to ionic liquid triggered by phosphonic acid grafting

Abstract

Controlling the interface between TiO nanocrystals and ionic liquids is of high fundamental and applied interest for energy storage and conversion devices. Phase transfer of nanoparticles from a synthesis medium to a processing or an application medium plays a significant role in nanotechnology. Here we demonstrate that surface modification with phosphonic acids bearing cationic end-groups can trigger the phase transfer of TiO nanoparticles from an aqueous sol to a typical water-immiscible ionic liquid, [Emim][NTf]. The transfer involves both the grafting of the phosphonic acid moiety and the exchange of the counter ion of the cationic end-group by NTf anions, as demonstrated by solid-state NMR, elemental analysis and independent grafting and ion exchange experiments. Furthermore, the colloidal stability of the TiO sols in [Emim][NTf] strongly depends on the hydrophobic character of the cationic end-groups.

TiO2-Based Hybrid Nanocomposites Modified by Phosphonate Molecules as Selective PAH Adsorbents

“…31 P { 1 H} MAS NMR experiments exhibited similar patterns show two distinct resonances upfield and downfield shifts (lower and higher ppm) at about 19 and 13 ppm and broadened compared to the resonance of the original ligand VPA at about 18 ppm ( Figure S4 ). These data, in agreement with the data given in the literature, did again confirm the phosphonate grafting onto the TiO 2 surface nanoparticles [ 16 , 17 ]. The width of the peaks and the presence of P=O absorption band in DRIFT spectra ( Figure 2 ) suggested a mixture of bidentate and tridentate surface grafting modes [ 11 ].…”

Thermodiffusion anisotropy under a magnetic field in ionic liquid-based ferrofluids

“…NPs either coated by polymers, [22][23][24][25][26][27] or coated with shorter surfactant chains, or even bare charged NPs [27][28][29][30][31][32][33] have been dispersed in ILs. Among the extreme variety of room temperature ionic liquids [34][35][36] , 1-Ethyl-3-methylimidazolium bistriflimide (EMIM-TFSI), which is a widely used IL in applications [37][38][39] , can be considered as an important model system, since it is not too viscous at room temperature and is stable in a large range of T 21,36,40,41 . Hydroxylcoated maghemite NPs, synthesized in water (diameter ⇠ 10 nm) are modified in order to adapt the NP/ solvent interface, i.e.…”

Selectivity in the Ligand Functionalization of Photocatalytic Metal Oxide Nanoparticles for Phase Transfer and Self‐Assembly Applications

“…It is known that organic ligands with phosphonic acid functional head groups bind strongly to both TiO 2 and ZnO. [38,41,42,36] This consolidates the fact that the nature of the ligand-nanoparticle interaction varies case by case and the selectivity is determined by both the ligand and the nanoparticle surface chemistry. It is, however, also important to have a sufficiently high ligand concentration as the contact time needed for effective attachment is inversely proportional to this concentration.…”