Journal Article

FZJ-2016-02240

http://join2-wiki.gsi.de/foswiki/pub/Main/Artwork/join2_logo100x88.png Ionic dye–surfactant nanoassemblies: interplay of electrostatics, hydrophobic effect, and π–π stacking

Kutz, A. ; Mariani, G. ; Gröhn, F. (Corresponding author)

2016
Springer Berlin

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Please use a persistent id in citations: doi:10.1007/s00396-015-3814-2

Abstract: The interplay of several non-covalent interaction forces is used as key to supramolecular structures. Combining cationic alkyltrimethylammonium bromide surfactants and the divalent anionic azo dye Acid Red 26 (Ar26) as small building blocks in aqueous solution, electrostatic interactions of the oppositely charged building blocks in combination with hydrophobic effect and π–π interactions play a major role in aggregate formation. Static and dynamic light scattering and small-angle neutron scattering (SANS) revealed different sizes of aggregates in the range of 2 nm ≤ R H ≤ 420 nm depending on surfactant length, concentration and of dye to surfactant loading ratio. A strong relationship of assembly size with surfactant concentration has been found, where initial surfactant monomers and micelles influence the aggregate formation differently. The stability of dye–surfactant aggregates which also shows a dependency on surfactant tail length has been related to ζ-potential measurements. Small-angle neutron scattering elucidated that dye–surfactant aggregates possess cylindrical shapes with different aspect ratios. UV/Vis spectroscopy gave information on the dye–dye π–π stacking geometry and extent, while the thermodynamic parameters for micellization and dye–surfactant binding ΔH, ΔG, and ΔS as well as stoichiometry and binding constant obtained by isothermal titration calorimetry revealed insight into the interplay of interactions.

Keyword(s): Polymers, Soft Nano Particles and Proteins (1st) ; Soft Condensed Matter (2nd)

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Contributing Institute(s):

1. JCNS-FRM-II (JCNS (München) ; Jülich Centre for Neutron Science JCNS (München) ; JCNS-FRM-II)

Research Program(s):

1. 6G15 - FRM II / MLZ (POF3-6G15) (POF3-6G15)
2. 6G4 - Jülich Centre for Neutron Research (JCNS) (POF3-623) (POF3-623)

Experiment(s):

1. KWS-2: Small angle scattering diffractometer (NL3ao)

Appears in the scientific report 2016

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Database coverage:
; Current Contents - Physical, Chemical and Earth Sciences ; IF < 5 ; JCR ; Nationallizenz ; No Authors Fulltext ; SCOPUS ; Science Citation Index ; Science Citation Index Expanded ; Thomson Reuters Master Journal List ; Web of Science Core Collection

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