Ionic liquids:: First direct determination of their cohesive energy

Molar enthalpies of vaporization, delta H-g(1)m(0)(T), of a homologous series of 1-alkyl-3-methylimidazolium bis(trifluoromethyl sulfonyl)imides, [C(n)mim][NTf2], (with 2 <= n <= 8) were directly determined for the first time. The results obtained in this study emphasize and constitute clear experimental support for the novel concept that these liquid salts are composed of polar and nonpolar domains; that is, they exhibit microphase segregation.