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Published on: April 21, 2017
Study of the interaction between a nonyl phenyl ether and beta-cyclodextrin: declouding nonionic surfactant solutions
Andrés Guerrero-Martínez1, Teresa Montoro, Montserrat H Viñas
1Departamento de Química-Física I, Facultad de Ciencias Químicas, Universidad Complutense de Madrid, 28040, Madrid, Spain.
The Journal of Physical Chemistry. B
|January 27, 2007
Summary
Beta-cyclodextrin (beta-CD) addition disrupts pentaoxyethylene nonyl phenyl ether (NPE5) surfactant aggregation and excimer formation in aqueous solutions. Complexation with beta-CD alters NPE5
Area of Science:
- Physical Chemistry
- Supramolecular Chemistry
- Colloid and Surface Science
Background:
- Pentaoxyethylene nonyl phenyl ether (NPE5) is a nonionic surfactant whose aggregation behavior is crucial for its applications.
- Beta-cyclodextrin (beta-CD) is a cyclic oligosaccharide known for its ability to form inclusion complexes with hydrophobic molecules.
- Understanding surfactant aggregation and its modification by complexing agents is vital for controlling solution properties.
Purpose of the Study:
- To investigate the effect of beta-cyclodextrin (beta-CD) complexation on the aggregation and micellar behavior of pentaoxyethylene nonyl phenyl ether (NPE5).
- To characterize the formation of inclusion complexes and their influence on surfactant self-assembly and clouding phenomena.
- To determine the binding stoichiometry and structural aspects of the beta-CD:NPE5 complexes.
Main Methods:
- Absorption and fluorescence spectroscopy to study excimer formation and binding interactions.
- Static light scattering and 1H NMR diffusion-ordered spectroscopy (DOSY) to characterize cloud point and diffusion.
- Two-dimensional rotating-frame Overhauser enhancement spectroscopy (ROESY) to elucidate complex structure and stoichiometry.
Main Results:
- In binary systems, NPE5 forms excimers within micellar cores, indicated by new emission bands and isoemissive points.
- beta-CD addition prevents excimer formation by forming inclusion complexes that disrupt NPE5 aggregates.
- Complexation with beta-CD increases the cloud-point concentration of NPE5, with dominant 2:1 (beta-CD:NPE5) stoichiometry observed in excess beta-CD.
Conclusions:
- beta-CD effectively inhibits NPE5 micellar aggregation and excimer formation through host-guest complexation.
- The interaction between beta-CD and NPE5 aggregates significantly influences the surfactant's clouding behavior.
- A detailed structural model of the 2:1 beta-CD:NPE5 complex is proposed, involving the threading of the NPE5 hydrophobic tail through two beta-CD molecules.
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