Aggregation behavior of N-alkyl perfluorooctanesulfonamides in dimethyl sulfoxide solution

Journal Article

N-alkyl perfluorooctanesulfonamides (C8F17SO2NHCnH2n+1, FC8{single bond}HCn, n = 2, 4, 6, 8) were shown to form aggregates in dimethyl sulfoxide (DMSO). Surface tension results revealed that the dissolution of FC8{single bond}HCn reduced the surface tension of DMSO in a manner analogous to common surfactants in aqueous solutions. Maximum surface excess amount (Γmax) and minimum surface area per molecule (Amin) at the air-liquid interface were estimated. Γmax decreases and Amin increases with an increase of the hydrocarbon chain length of FC8{single bond}HCn. Steady-state fluorescence and NMR measurements demonstrated that both fluorocarbon and hydrocarbon chains of FC8{single bond}HCn molecules were incorporated inside the aggregates. UV-vis spectroscopy confirmed the formation of aggregates and determined the critical micelle concentration (cmc) of FC8{single bond}HC6 and FC8{single bond}HC8 solutions. The thermodynamic parameters Δ Gagg0, Δ Hagg0, and Δ Sagg0 for the aggregate formation of FC8{single bond}HCn in DMSO derived from the temperature dependence of the cmc revealed that the aggregate formation is an enthalpy-driven process, which was further confirmed by isothermal titration calorimetry (ITC) measurements. Moreover, the absolute values of Δ Gagg0 and Δ Hagg0 increase with an increase of the hydrocarbon chain length of FC8{single bond}HCn at 298 K. © 2009 Elsevier Inc. All rights reserved.

Full Text

Duke Authors

Cited Authors

  • Li, G-L; Gao, Y-A; Li, X-W; Liu, J; Zheng, L-Q; Xing, H; Xiao, J-X

Published Date

  • 2010

Published In

Volume / Issue

  • 342 / 2

Start / End Page

  • 372 - 381

International Standard Serial Number (ISSN)

  • 0021-9797

Digital Object Identifier (DOI)

  • 10.1016/j.jcis.2009.10.058