8th Liquid Matter Conference September 6-10, 2011 Wien, Austria ...

P1.6Fri 911:10-14:00Structure and dynamics of ionic liquids entrapped innanoporous silicaBenoit Coasne, 1 Lydie Viau, 1 and Andre Vioux 11 CNRS - Institut Charles Gerhardt Montpellier, 8 rue de l Ecole Normale, 34096,Montpellier, FranceThe simplest definition of ionic liquids (ILs) is ”liquids composed solely of ions”. Usually theterm is restricted to salts having melting points below 100 ◦ C (higher temperature melts are commonlyreferred to as molten salts). An important strategy for using ILs is to immobilize them byimpregnation of supports or incorporation in porous solids; the IL being used as an adsorbed filmor by incorporation into a silica substrate, typically as solid-like systems called ionogels. In orderto gain insights into the physical and chemical properties of ionogels, we performed a molecularsimulation study of an imidazolium-based IL entrapped within a cylindrical silica nanopore. Ourresults show a significant stiffening of the confined IL controlled by the loading. A decrease in theself-diffusivity and ionic conductivity, which are always lower than the bulk due to strong interactionswith the hydroxylated surface, is observed upon decreasing the loading. Such a slowing downof the dynamics and transport is associated with an increase in the residence time at the surfaceas the pore center becomes depleted in ionic liquid. Despite the ordering of the ionic liquid at thesurface, the pair correlation functions and magnitude of the dynamics evidence a liquid behavior.6