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Application of topological indices in estimating of the CMC value of surfactants in aqueous solutions

100%

Zielinski R.

2015

nr 2

Krytyczne stężenie micelarne i metody jego wyznaczania

84%

Piotrowska-Kirschling A. , Drzeżdżon J. , Chmurzyński L. , Jacewicz D.

tom [Z] 72, 11-12

815--828

Surfactants are substances, which have surface activity in aqueous solutions [1–3]. By adsorbing on the surface (boundary of phase separation) of the system, they change the surfactant properties of the liquid. Surfactants consist of a hydrophobic part (non-polar, called “tail”) and a hydrophilic part (polar, called “head”) [1–3]. The overall structure of the surfactant molecule is shown in Figure 1. In aqueous solution after exceeding one critical micellar concentration of the CMC surfatant (Critical Micelle Concentration), the surfactant molecules aggregate to form micelles [1–5]. Knowledge of CMC values and the micelle formation in solution, it determines the properties of surfactants and their subsequent use in the chemical industry. Surfactants are used in the chemical industry, inter alia, for the production of many detergents, cosmetics, paints, dyes, agrochemicals, pharmaceuticals, food or oil [2, 3].

ESR study of micellization process of N,N,N-trimethylglycinetetradecyl ester chloride

84%

Podolak M. , Man D. , Przestalski S.

1997

tom 02

nr 1

Formation of micelles of the fourteen-carbon amphiphilic ammonium salt (N,N,N - trimethylglycinetetradecyl ester chloride - AS V-14), was studied using the ESR spin probe method. The probe used was 2-hexyl-2-[11-methoxy-11-oxoundecyl]-4,4-dimethyl-3oxazolidinyloxy [Met (5,10)]. The micelles formation process was signalized by changes in ESR spectra of a probe. The probe spectrum in aqueous environment has the shape of one broad line, whereas three narrow lines are observed in a hydrophobic environment. The study showed that the critical micellar concentration (CMC) of the AS V-14 compound amounts to about 1.7 mM. This agrees approximately with the value obtained from calorimetric measurements (1.9 ± 0.1 mM). After addition of oleic acid into the solution (by intensive shaking) it was found that AS V-14 micelles start to form at concentration of about 0.07 mM. The reduction in the CMC value may be caused by formation of mixed micelles, containing AS V-14 and fatty acid.