Peter HESEMANN1, Nicole ABDOU1, Bruno ALONSO1, Périne LANDOIS2, Andreas TAUBERT3, Ahmad MEHDI1, Nicolas BRUN1, Sabine DEVAUTOUR-VINOT1, Matthieu PAILLET2
1Institut Charles Gerhardt de Montpellier, Montpellier, France
2Laboratoire Charles Coulomb, Montpellier, France
3Universität Potsdam, Potsdam, Germany
Due to their unique physicochemical properties and their huge potential for a multitude of applications, ionic liquids (ILs) are nowadays among the most investigated systems in chemistry. However, one of the key issues that limit their applications is the fact that ILs are liquid. Therefore, ILs were immobilized within a solid host matrix forming composite materials also called ionogels (IGs) . IGs were thoroughly investigated in the last decade for their polyvalence that combines the properties of ILs with those of the host matrix.
In our ongoing effort to immobilize ILs in solid devices, we report herein Ionosilica Ionogels (ISIGs), as a combination of ionic liquid guest confined in an ionosilica host (Figure 1). Indeed, Ionosilicas are silica-based hybrid materials that are exclusively constituted of ionic fragments . Ionosilicas should therefore be particularly suitable host matrices for the immobilization of ionic liquid guests.
ISIG were synthesized via non-hydrolytic sol-gel (NHSG) processes starting from various silylated ionic ammonium precursors using the IL [BMIM] NTf2 as solvent, resulting in the formation of brittle and nearly colorless monoliths. Special confinement effects between the ionosilica host and IL guest could be evidenced using solid state NMR, Raman spectroscopy and impedance spectroscopy. In a second time, we synthesized ionosilica ionogel thin films following hydrolytic sol-gel procedures, resulting in the formation of self-standing and flexible films [3,4].
Both systems, monoliths and films, can contain more than 80 wt.-% of IL while maintaining a mechanically robust morphology. The obtained ISIGs are highly polyvalent materials with adaptable properties that may find applications in catalysis, gas sorption, and energy storage. Our work therefore opens the route to functional ionosilica ionogel combinations for specific applications in various domains.
 Le Bideau J.; Viau L.; Vioux A.; Chem. Soc. Rev. 2011, 40, 907-925.
 Thach U.-D.; Prelot B.; Pellet-Rostaing S.; Zajac J.; Hesemann P.; ACS Appl. Nano. Mater. 2018, 1, 2076−2087.
 Abdou, N.; Alonso, B.; Landois, P.; Brun, N.; Taubert, A.; Hesemann, P.; Mehdi, A.; Materials Chemistry Frontiers 2022, 6, 939-947.
 Abdou, N.; Alonso, B.; Brun, N.; Devautour-Vinot, S.; Paillet, M.; Landois, P.; Mehdi, A.; Hesemann, P.; J. Phys. Chem. C, 2022, asap, DOI: 10.1021/acs.jpcc.2c06565