Phase transfer of TiO2 nanoparticles from water to ionic liquid triggered by phosphonic acid graftingElectronic supplementary information (ESI) available: Experimental procedures, dLS and solid-state NMR details, elemental analysis. See DOI: 10.1039/c7sm01424d

• Main Authors: Bhandary, R, Alauzun, J. G, Hesemann, P, Stocco, A, In, M, Mutin, P. H
• Format: Article
• Language: English
• ISSN: 1744-683X; 1744-6848
• DOI: 10.1039/c7sm01424d

Controlling the interface between TiO 2 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 2 nanoparticles from an aqueous sol to a typical water-immiscible ionic liquid, [Emim][NTf 2 ]. 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 2 anions, as demonstrated by solid-state NMR, elemental analysis and independent grafting and ion exchange experiments. Furthermore, the colloidal stability of the TiO 2 sols in [Emim][NTf 2 ] strongly depends on the hydrophobic character of the cationic end-groups. Hydroxylated TiO 2 nanoparticles can be transferred from water to [Emim][NTf 2 ] ionic liquid by reaction with a phosphonic acid bearing a cationic group; this phase transfer involves both grafting and anion exchange.