Evidence of nanostructuration from the heat capacities of the 1,3-dialkylimidazolium bis(trifluoromethylsulfonyl)imide ionic liquid series

• Tipo: Artigo em Revista Científica Internacional
• Data: 2013

Autores

Marisa A A Rocha (Autor) Outra; Joao A P Coutinho (Autor) Outra; Luis M N B F Santos (Autor) FCUP

Revista

Título: Journal of Chemical Physics

Vol. 139

Página Final: 104502

ISSN: 0021-9606

Editora: American Institute of Physics

Indexação

ISI Web of Knowledge - 36 Citações

Scopus - 36 Citações

Classificação Científica

FOS: Ciências exactas e naturais > Física

Outras Informações

ID Authenticus: P-006-7B0

DOI: 10.1063/1.4820825

Abstract (EN): In the present work, the heat capacities at T = 298.15 K of 1,3-dialkylimidazolium bis(trifluoromethylsulfonyl)imide, [C(N/2)C(N/2)im][NTf2], were measured, for the first time, using a high-precision heat capacity drop calorimeter, with an uncertainty of less than 0.15%. Based on the obtained results, it was possible to evaluate the effect of the cation symmetry on the heat capacity data through a comparative analysis with the [C(N-1)C(1)im][NTf2] ionic liquid series. The molar heat capacities of the [C(N/2)C(N/2)im][NTf2] ionic liquids series present a less pronounced deviation from the linearity along the alkyl chain length than the asymmetric based ionic liquids series. Lower molar heat capacities for the symmetric than the asymmetric series were observed, being this difference more evident for the specific and volumic heat capacities. As observed for the [C(N-1)C(1)im][NTf2] series, a trend shift in the heat capacities at [C(6)C(6)im][NTf2] was found that reflects the impact of nonpolar region nanostructuration on the thermophysical properties of the ionic liquids. The profile of the two regions is in agreement with the expected effect arising from the nanostructuration in ionic liquids. The results obtained in the present work show a clear indication that for the symmetric series, [C(N/2)C(N/2)im][NTf2], the starting of the liquid phase nanostructuration/alkyl chain segregation occurs around [C(6)C(6)im][NTf2]. (C) 2013 AIP Publishing LLC.

Idioma: Inglês

Tipo (Avaliação Docente): Científica

Nº de páginas: 5