Influence of binding strength of added electrolytes on the properties of micelles and of micellized radical pairs

Journal Article · Fri Jan 31 23:00:00 EST 1992 · Langmuir; (United States)

DOI:https://doi.org/10.1021/la00038a028· OSTI ID:5845255

Lei, X G; Zhao, G H; Liu, Y C ^[1]; Turro, N J ^[2]

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1. Lanzhou Univ. (China)
2. Columbia Univ., New York, NY (United States)

p-Methyldibenzyl ketone (1), pyrene (2), and 1,3-di-[alpha]-napthylpropane (3) have been employed as probes of the effects of added electrolytes on the properties of micelles and of the effects of an applied magnetic field on the reactivity of micellized radical pairs. The effect of added electrolytes depends on the structure of the surfactant head group, the length of the hydrocarbon chain of surfactants, the added gegenions, and the temperature. The electrolytes added were found to exhibit both a [open quotes]salt effect[close quotes] on the physical properties of micelles, which is related to the strength of their binding to the micellar surface, and a [open quotes]magnetic effect[close quotes], which is related to the ability of a bound cation to relax the triplet state of a micellized radical pair and thereby modify the reactivity of the pair. In aqueous solutions of anionic surfactants, Gd[sup 3+] causes a large magnetic field dependent internal magnetic field effect in addition to a salt effect on micellar properties. The internal magnetic field effect is independent of the length of hydrocarbon chain, but is dependent on the surface density of bound Gd[sup 3+] ions. The salt effect on micellar properties decreases with the increase of the length of hydrocarbon chain of the surfactants and with the surface density of added ions. In aqueous solutions containing neutral TX-100 micelles or cationic micelles (cetyltrimethylammonium bromide, CTAB), Gd[sup 3+] shows only a small salt and a small internal magnetic field effect. Addition of lanthanide salts results in a dramatic increase in the aggregation number of sodium dodecyl sulfate (SDS) micelles. 28 refs., 6 figs., 1 tab.

• OSTI ID: 5845255
• Journal Information: Langmuir; (United States), Journal Name: Langmuir; (United States) Vol. 8:2; ISSN LANGD5; ISSN 0743-7463
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400102 -- Chemical & Spectral Procedures
400201* -- Chemical & Physicochemical Properties
400500 -- Photochemistry
AROMATICS
CHARGED PARTICLES
CHEMICAL REACTIONS
CONDENSED AROMATICS
DATA
DECOMPOSITION
ELECTROLYTES
EXPERIMENTAL DATA
GADOLINIUM IONS
HYDROCARBONS
INFORMATION
IONS
KETONES
MAGNETIC FIELDS
MICELLAR SYSTEMS
NUMERICAL DATA
ORGANIC COMPOUNDS
PHOTOCHEMICAL REACTIONS
PHOTOLYSIS
PYRENE
RADICALS
SPECTROSCOPY
SURFACTANTS