Effect of organic additives on micellar systems studied by positron annihilation techniques

Journal Article · Thu Apr 06 00:00:00 EST 1978 · J. Phys. Chem.; (United States)

DOI:https://doi.org/10.1021/j100496a010· OSTI ID:6939799

Jean, Y C; Ache, H J

The rate constants for the reactions of positronium with nitrobenzene and cupric chloride in various aqueous micellar systems, such as sodium dodecylsulfate, hexadecyltrimethylammonium bromide, sodium octylsulfonate, hexadecylpyridinium chloride, and Tergitol-NPX, were measured in the presence of organic additives, such as benzene, benzyl alcohol, n-hexane, and 1-hexanol. The results show that the positronium reactivity toward nitrobenzene or cupric chloride substantially increases, when benzene or benzyl alcohol are added to sodium dodecylsulfate, hexadecyltrimethylammonium bromide, and hexadecylpyridinium chloride solutions, whereas only a slight increase was observed in Tergitol-NPX and no increase in sodium octylsulfonate solutions. In the former systems the rate constants are generally higher in the presence of benzene or benzyl alcohol than in aqueous solutions of nitrobenzene or cupric chloride and approach in the case of nitrobenzene values obtained for positronium reactions with nitrobenzene in benzene solution, whereas n-hexane or 1-hexanol generally exhibit only a small effect. A possible explanation for the observed behavior may be that the aromatic additives become incorporated into the micelle, possibly close to the micelle-water interface where they form clusters or aggregates in which the nitrobenzene probe molecules resides. In this benzene-like microenvironment the nitrobenzene molecule exhibits the same reactivity toward positronium as in benzene solutions. By the same token in the case of n-hexane or 1-hexanol additives, the corresponding rates slightly decrease with additive concentration and approach rate constants observed in a n-hexane-like environment. It appears that the positron annihilation technique can provide a sensitive method of studying the microenvironment of probe molecules in micellar systems.

• Research Organization: Virginia Polytechnic Inst. and State Univ., Blacksburg
• OSTI ID: 6939799
• Journal Information: J. Phys. Chem.; (United States), Vol. 82:7
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
COPPER CHLORIDES
CHEMICAL REACTION KINETICS
MICELLAR SYSTEMS
NITROBENZENE
POSITRONIUM
ALCOHOLS
ALKANES
AROMATICS
CHLORIDES
CHLORINE COMPOUNDS
COPPER COMPOUNDS
COPPER HALIDES
HALIDES
HALOGEN COMPOUNDS
HYDROCARBONS
HYDROXY COMPOUNDS
KINETICS
NITRO COMPOUNDS
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
REACTION KINETICS
TRANSITION ELEMENT COMPOUNDS
400201* - Chemical & Physicochemical Properties