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NMR studies of aggregation and hydration of surfactants containing amide bonds

Maria Stjerndahl (Institutionen för kemi- och bioteknik) ; Dan Lundberg (Institutionen för kemi- och bioteknik, Teknisk ytkemi) ; H. L. Zhang ; F. M. Menger
Journal of Physical Chemistry B (1520-6106). Vol. 111 (2007), 8, p. 2008-2014.
[Artikel, refereegranskad vetenskaplig]

The consequences of including amide bonds into the structure of short-chain nonionic surfactants have been studied. Of particular interest were the possible effects of the hydrogen bonding ability of the amide group on the micellar shape. The aggregate structure and hydration of two different amide-containing surfactants, C7H15CO-NH-(CH2CH2O)(4)H and C7H15CO-(NH-C3H6-CO)(2)N(CH3)(2), were investigated using NMR diffusometry (pulsed gradient spin echo NMR) as the main technique. Data from experiments on the surfactants, the hydrophobic probe molecule hexamethyldisilane (HMDS), and water were interpreted to gain information about the solution structures, and the results were compared to those on a previously studied alcohol ethoxylate surfactant of similar size, C8E4. Both of the amide-containing surfactants form small micelles within the whole investigated concentration range. At the critical micelle concentration, the aggregates are most probably spherical, and with increasing surfactant concentration there are indications of either a minor aggregate growth or agglomeration of the micelles. In addition, it was found that the presence of amide groups in the surfactant inhibits the intermicellar transport of HMDS, which occurs in the C8E4 system. From measurements on water diffusion in the three surfactant systems, it could be concluded that the surfactant hydration is higher when amide bonds are present.

Nyckelord: NUCLEAR-MAGNETIC-RESONANCE, OCTYL ETHER C(8)E(4), SELF-DIFFUSION, NONIONIC SURFACTANTS, BROWNIAN PARTICLES, MICELLAR SOLUTIONS, AQUEOUS-SOLUTIONS, LIGHT-SCATTERING, GRADIENT, SYSTEMS



Denna post skapades 2008-12-10.
CPL Pubid: 80983

 

Institutioner (Chalmers)

Institutionen för kemi- och bioteknik (2005-2014)
Institutionen för kemi- och bioteknik, Teknisk ytkemi (2005-2014)

Ämnesområden

Kemiteknik

Chalmers infrastruktur