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Incorporation of substituted acrylamides to the lamellar mesophase of Aerosol OT

Esteban, Isabel LU ; Renamayor, CS ; Horta, A ; Lindman, Björn LU and Thuresson, Krister LU (2006) In Journal of Colloid and Interface Science 299(1). p.378-387
Abstract
The structure and stability of the lamellar liquid crystal formed by the surfactant sodium bis-2ethylhexyl sulfosuccinate (AOT) in water is perturbed by small amounts of the substituted acrylamides N-isopropyl, N,N-diethyl, N-acryloylmorpholine, and N,N-dimethyl methacrylamide, as revealed by small angle X-ray scattering (SAXS), deuterium NMR, and microscopy. These molecules are water soluble and stay mostly in the water layers between lamellae, but a small fraction of them (5-19%) are incorporated into the AOT bilayers, thereby producing dramatic changes. Both, the degree of anisotropy in the water molecules hydrating AOT (quadrupolar splitting in H-2 NMR) and the long period spacing between lamellae (SAXS), decrease with addition of this... (More)
The structure and stability of the lamellar liquid crystal formed by the surfactant sodium bis-2ethylhexyl sulfosuccinate (AOT) in water is perturbed by small amounts of the substituted acrylamides N-isopropyl, N,N-diethyl, N-acryloylmorpholine, and N,N-dimethyl methacrylamide, as revealed by small angle X-ray scattering (SAXS), deuterium NMR, and microscopy. These molecules are water soluble and stay mostly in the water layers between lamellae, but a small fraction of them (5-19%) are incorporated into the AOT bilayers, thereby producing dramatic changes. Both, the degree of anisotropy in the water molecules hydrating AOT (quadrupolar splitting in H-2 NMR) and the long period spacing between lamellae (SAXS), decrease with addition of this molecules at low concentrations, which is attributed to the lower average headgroup, density at the AOT/water interface when the acrylamide is incorporated. The strength of these perturbations depends on the acrylamide, and goes in parallel with the hydrophobic character of the alkyl side groups in its molecule, which suggests that the acrylamides incorporated to the bilayer enter into contact with the lipophilic tails of the AOT molecule. An interaction with the hydrated heads of AOT is also suggested in the particular case of N-isopropylacrylamide. On increasing the molecule concentration an incipient melting of the lamellar phase towards an isotropic solution takes place, first at the microscopic level, then macroscopic. Near this phase transition, the ordered domains lose the random orientation prevailing at lower acrylamide concentrations, and adopt a preferred orientation, perpendicular to the magnetic field. (c) 2006 Elsevier Inc. All rights reserved. (Less)
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author
; ; ; and
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
deuterium NMR, lamellar mesophase, substituted acrylamides, AOT, SAXS
in
Journal of Colloid and Interface Science
volume
299
issue
1
pages
378 - 387
publisher
Elsevier
external identifiers
  • wos:000238227700041
  • scopus:33646856646
  • pmid:16542669
ISSN
1095-7103
DOI
10.1016/j.jcis.2006.01.070
language
English
LU publication?
yes
id
f136c91e-ba0d-4676-b63f-876244e760bf (old id 406021)
date added to LUP
2016-04-01 11:36:51
date last changed
2021-08-11 01:28:23
@article{f136c91e-ba0d-4676-b63f-876244e760bf,
  abstract     = {The structure and stability of the lamellar liquid crystal formed by the surfactant sodium bis-2ethylhexyl sulfosuccinate (AOT) in water is perturbed by small amounts of the substituted acrylamides N-isopropyl, N,N-diethyl, N-acryloylmorpholine, and N,N-dimethyl methacrylamide, as revealed by small angle X-ray scattering (SAXS), deuterium NMR, and microscopy. These molecules are water soluble and stay mostly in the water layers between lamellae, but a small fraction of them (5-19%) are incorporated into the AOT bilayers, thereby producing dramatic changes. Both, the degree of anisotropy in the water molecules hydrating AOT (quadrupolar splitting in H-2 NMR) and the long period spacing between lamellae (SAXS), decrease with addition of this molecules at low concentrations, which is attributed to the lower average headgroup, density at the AOT/water interface when the acrylamide is incorporated. The strength of these perturbations depends on the acrylamide, and goes in parallel with the hydrophobic character of the alkyl side groups in its molecule, which suggests that the acrylamides incorporated to the bilayer enter into contact with the lipophilic tails of the AOT molecule. An interaction with the hydrated heads of AOT is also suggested in the particular case of N-isopropylacrylamide. On increasing the molecule concentration an incipient melting of the lamellar phase towards an isotropic solution takes place, first at the microscopic level, then macroscopic. Near this phase transition, the ordered domains lose the random orientation prevailing at lower acrylamide concentrations, and adopt a preferred orientation, perpendicular to the magnetic field. (c) 2006 Elsevier Inc. All rights reserved.},
  author       = {Esteban, Isabel and Renamayor, CS and Horta, A and Lindman, Björn and Thuresson, Krister},
  issn         = {1095-7103},
  language     = {eng},
  number       = {1},
  pages        = {378--387},
  publisher    = {Elsevier},
  series       = {Journal of Colloid and Interface Science},
  title        = {Incorporation of substituted acrylamides to the lamellar mesophase of Aerosol OT},
  url          = {http://dx.doi.org/10.1016/j.jcis.2006.01.070},
  doi          = {10.1016/j.jcis.2006.01.070},
  volume       = {299},
  year         = {2006},
}