title: High-accuracy vapor pressure data of the extended [C(n)C1im][Ntf2] ionic liquid series: trend changes and structural shifts.
abstract: For the first time, two distinct trends are clearly evidenced for the enthalpies and entropies of vaporization along the [Cnmim][Ntf2] ILs series. The trend shifts observed for Δ(l)(g)H(m)(o) and Δ(l)(g)S(m)(o), which occur at [C6mim][Ntf2], are related to structural modifications. The thermodynamic results reported in the present article constitute the first quantitative experimental evidence of the structural percolation phenomenon and make a significant contribution to better understanding of the relationship among cohesive energies, volatilities, and liquid structures of ionic liquids. A new Knudsen effusion apparatus, combined with a quartz crystal microbalance, was used for the high-accuracy volatility study of the 1-alkyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide series ([Cnmim][Ntf2], where n = 2, 3, 4, 5, 6, 7, 8, 10, 12). Vapor pressures in the (450–500) K temperature range were measured, and the molar standard enthalpies, entropies, and Gibbs energies of vaporization were derived. The thermodynamic parameters of vaporization were reported, along with molecular dynamic simulations of the liquid phase structure, allowing the establishment of a link between the thermodynamic properties and the percolation phenomenon in ILs.
authors.affiliation: Centro de Investigação em Química, Departamento de Química e Bioquímica, Faculdade de Ciências da Universidade do Porto, R. Campo Alegre 687, P-4169-007 Porto, Portugal.
authors.forename: Marisa A A
authors.initials: MA
authors.lastname: Rocha
authors.forename: Carlos F R A C
authors.initials: CF
authors.lastname: Lima
authors.forename: Lígia R
authors.initials: LR
authors.lastname: Gomes
authors.forename: Bernd
authors.initials: B
authors.lastname: Schröder
authors.forename: João A P
authors.initials: JA
authors.lastname: Coutinho
authors.forename: Isabel M
authors.initials: IM
authors.lastname: Marrucho
authors.forename: José M S S
authors.initials: JM
authors.lastname: Esperança
authors.forename: Luís P N
authors.initials: LP
authors.lastname: Rebelo
authors.forename: Karina
authors.initials: K
authors.lastname: Shimizu
authors.forename: José N Canongia
authors.initials: JN
authors.lastname: Lopes
authors.forename: Luís M N B F
authors.initials: LM
authors.lastname: Santos
mesh_terms: D052578:Ionic Liquids / Q000737:chemistry*; D058525:Quartz Crystal Microbalance Techniques; D013449:Sulfonamides / Q000737:chemistry*; D013696:Temperature; D013816:Thermodynamics; D055548:Vapor Pressure; D014835:Volatilization
chemical_list: D052578:Ionic Liquids; D013449:Sulfonamides; C545574:bis(trifluoromethanesulfonyl)amide