Study of Salt Effects on the Micelle–Monomer Exchange Process of Octyl-, Decyl-, and Dodecyltrimethylammonium Bromide in Aqueous Solutions by Means of Ultrasonic Relaxation Spectroscopy
✍ Scribed by Hiroyasu Nomura; Shinobu Koda; Tatsuro Matsuoka; Tadashi Hiyama; Ryukichi Shibata; Shigeo Kato
- Publisher
- Elsevier Science
- Year
- 2000
- Tongue
- English
- Weight
- 85 KB
- Volume
- 230
- Category
- Article
- ISSN
- 0021-9797
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✦ Synopsis
The effects of added salt on the micelle-monomer exchange process of octyl-and decyltrimethylammonium bromide were investigated by means of ultrasonic relaxation techniques. Using the Aniansson-Wall model, the micellar distribution width σ and the dissociation rate constant k -1 of the micelle-monomer exchange process were determined as functions of carbon number and of added salt concentration in aqueous solutions of a series of tetraalkylammonium bromide-NaBr systems and discussed on the basis of the Aniansson-Wall-Teubner model. From the rate constant of the micelle-monomer exchange process, the total energy change for the transfer of the alkyl chain of the surfactant ion from the interior of the micelle to a position where its terminal methyl groups is at the surface of the micelles was estimated and compared with those calculated by the Gouy-Chapmann model of the electric double-layer theory.