Neutron and X-Ray Reflectivity Studies of the Adsorption of Aerosol-OT at the Air-Water Interface: The Structure of the Calcium Salt

We have used neutron and X-ray reflection to determine the structure of a layer of calcium bis-(2-ethyl 1-hexyl) sulphosuccinate (Aerosol-OT or AOT) adsorbed at the air/solution interface. The widths of the distributions of the chains and head groups of the molecule, and their positions in relation...

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Main Authors: Li, Z, Lee, E, Thomas, R, Penfold, J
Format: Journal article
Language:English
Published: 1997
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author Li, Z
Lee, E
Thomas, R
Penfold, J
author_facet Li, Z
Lee, E
Thomas, R
Penfold, J
author_sort Li, Z
collection OXFORD
description We have used neutron and X-ray reflection to determine the structure of a layer of calcium bis-(2-ethyl 1-hexyl) sulphosuccinate (Aerosol-OT or AOT) adsorbed at the air/solution interface. The widths of the distributions of the chains and head groups of the molecule, and their positions in relation to the underlying water, have been measured at four concentrations varying from the solubility limit (CMC) at 4 x 10(-4) M to 1 x 10(-6) M. Over this concentration range the coverage changes from 68 andplusmn; 3 to 142 andplusmn; 8 andAring;2 per AOT unit. The structure of the layer both is quite different from that of NaAOT and varies quite differently with surface concentration. The Ca(AOT)2 layer is slightly (1 andAring;) further out from the water, but the chain region is thinner for the calcium surfactant. This is reflected most in the greatly reduced chain to head separation, which drops from about 6 andAring; in NaAOT to about 4 andAring; in Ca(AOT)2.
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spelling oxford-uuid:697e6b19-f541-4386-afe1-584522e8bca42022-03-26T18:51:21ZNeutron and X-Ray Reflectivity Studies of the Adsorption of Aerosol-OT at the Air-Water Interface: The Structure of the Calcium SaltJournal articlehttp://purl.org/coar/resource_type/c_dcae04bcuuid:697e6b19-f541-4386-afe1-584522e8bca4EnglishSymplectic Elements at Oxford1997Li, ZLee, EThomas, RPenfold, JWe have used neutron and X-ray reflection to determine the structure of a layer of calcium bis-(2-ethyl 1-hexyl) sulphosuccinate (Aerosol-OT or AOT) adsorbed at the air/solution interface. The widths of the distributions of the chains and head groups of the molecule, and their positions in relation to the underlying water, have been measured at four concentrations varying from the solubility limit (CMC) at 4 x 10(-4) M to 1 x 10(-6) M. Over this concentration range the coverage changes from 68 andplusmn; 3 to 142 andplusmn; 8 andAring;2 per AOT unit. The structure of the layer both is quite different from that of NaAOT and varies quite differently with surface concentration. The Ca(AOT)2 layer is slightly (1 andAring;) further out from the water, but the chain region is thinner for the calcium surfactant. This is reflected most in the greatly reduced chain to head separation, which drops from about 6 andAring; in NaAOT to about 4 andAring; in Ca(AOT)2.
spellingShingle Li, Z
Lee, E
Thomas, R
Penfold, J
Neutron and X-Ray Reflectivity Studies of the Adsorption of Aerosol-OT at the Air-Water Interface: The Structure of the Calcium Salt
title Neutron and X-Ray Reflectivity Studies of the Adsorption of Aerosol-OT at the Air-Water Interface: The Structure of the Calcium Salt
title_full Neutron and X-Ray Reflectivity Studies of the Adsorption of Aerosol-OT at the Air-Water Interface: The Structure of the Calcium Salt
title_fullStr Neutron and X-Ray Reflectivity Studies of the Adsorption of Aerosol-OT at the Air-Water Interface: The Structure of the Calcium Salt
title_full_unstemmed Neutron and X-Ray Reflectivity Studies of the Adsorption of Aerosol-OT at the Air-Water Interface: The Structure of the Calcium Salt
title_short Neutron and X-Ray Reflectivity Studies of the Adsorption of Aerosol-OT at the Air-Water Interface: The Structure of the Calcium Salt
title_sort neutron and x ray reflectivity studies of the adsorption of aerosol ot at the air water interface the structure of the calcium salt
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AT thomasr neutronandxrayreflectivitystudiesoftheadsorptionofaerosolotattheairwaterinterfacethestructureofthecalciumsalt
AT penfoldj neutronandxrayreflectivitystudiesoftheadsorptionofaerosolotattheairwaterinterfacethestructureofthecalciumsalt