TY - JOUR
T1 - Excimer-monomer emission in alkylbenzenesulfonate dispersions
T2 - Effect of the surfactant structure on aggregation
AU - Aoudia, M.
AU - Wade, W. H.
AU - Rodgers, M. A.J.
N1 - Funding Information:
Work at the Center for Fast Kinetics Research (CFKR) is supported jointly by NIH Grant RR00886 from the Biotechnology Branch of the Division of Research Resources and by the University of Texas at Austin. Acknowledgment is made to the Robert A. Welch Foundation and to the Center of Oil and Gas Recovery Research at the University of Texas at Austin for partial support of this research. M. Aoudia thanks the University of Blida (Algeria) for giving him a leave.
PY - 1991/9
Y1 - 1991/9
N2 - Aqueous micellar dispersions of several alkylbenzenesulfonates (xφC12 and xφC16) where x = 1, 2, 3 ... and indicates the position of the phenyl group (φ) along the alkyl chain were prepared and examined for fluorescence emission from the benzene residues. Quantitative measurements of the intensities of the monomer and excimer contributions to the fluorescence spectrum as a function of surfactant concentration, when normalized to unit absorbance showed two linear regimes. The break point between the two occurred at a critical micellar concentration (CMC) defined by conductivity and surface tension measurements. Evidence for premicellar aggregates, at surfactant concentrations well below the CMC, was demonstrated. The CMC was related to a transition in the range of aggregation size distribution. The aggregation number was shown to depend on the surfactant structure. For a series of isomers, the aggregation number decreases when the sulfonate benzene group is moved from one end to the center of the aliphatic alkyl chain. This tendency was related to the (hydrophobic/lipophilic) balance of the surfactant.
AB - Aqueous micellar dispersions of several alkylbenzenesulfonates (xφC12 and xφC16) where x = 1, 2, 3 ... and indicates the position of the phenyl group (φ) along the alkyl chain were prepared and examined for fluorescence emission from the benzene residues. Quantitative measurements of the intensities of the monomer and excimer contributions to the fluorescence spectrum as a function of surfactant concentration, when normalized to unit absorbance showed two linear regimes. The break point between the two occurred at a critical micellar concentration (CMC) defined by conductivity and surface tension measurements. Evidence for premicellar aggregates, at surfactant concentrations well below the CMC, was demonstrated. The CMC was related to a transition in the range of aggregation size distribution. The aggregation number was shown to depend on the surfactant structure. For a series of isomers, the aggregation number decreases when the sulfonate benzene group is moved from one end to the center of the aliphatic alkyl chain. This tendency was related to the (hydrophobic/lipophilic) balance of the surfactant.
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U2 - 10.1016/0021-9797(91)90380-Q
DO - 10.1016/0021-9797(91)90380-Q
M3 - Article
AN - SCOPUS:0026219356
SN - 0021-9797
VL - 145
SP - 493
EP - 501
JO - Journal of Colloid and Interface Science
JF - Journal of Colloid and Interface Science
IS - 2
ER -