6533b833fe1ef96bd129c0b9

RESEARCH PRODUCT

Molecular Association of a Nonionic and an Ionic-Induced Surfactant:  Cryptand (221D) NaCl in Water

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The cryptand 5-decyl-4,7,13,16,21-pentaoxa-1,10-diazabicyclo-[8.8.5] tricosane [221D] strongly resembles a surfactant in its characteristics:  it contains a hydrophilic headgroup, the cryptand unit, and a hydrophobic unit, the decyl chain. It is insoluble in water, but in the presence of an appropriate amount of NaCl, as a consequence of the complex formation between 221D and Na+, it becomes soluble and forms aggregates. The aggregates, depending on the NaCl-221D molar ratio, can be considered as mixed ionic nonionic micelles or ionic micelles. The evolution of the aggregate dimensions and their shape has already been studied at two NaCl-221D molar ratios as a function of the 221D concentration. In the present work, to obtain information on the aggregation behavior of 221D in water on varying the NaCl concentration from one third up to four times the 221D content, the system has been studied by small-angle neutron scattering. Increasing the NaCl-221D molar ratio up to 1, the aggregation number rapidly fal...