A quantitative structure property relationship; QSPR was preformed as a means to predict critical micelle concentration of nonionic surfactants via correlating properties to parameters calculated from molecular structure. Such parameters; molecular weight, M w , hydrophobichydrophilic fragments molecular weight ratio, x, polarizability, a, partition coefficient, log P, energy of hydration, E H , Van der Waal's surface area, G, and dipole moment,m. Principal component analysis PCA and multiple linear regression technique MLR were performed to examine the relationship between multiple variables of the above parameters and the critical micelle concentration of nonionic surfactants. The results of PCA explain the interrelationships between log cmc and different variables. The linear relationship between the selected parameters and the critical micelle concentration was modeled according to the better statistical results. The best regressed model has highest coefficient of determination (R 2 5 0.9889), highest statistical significance (F 5 391.599), and lowest standard errors (s 2 5 0.2358). The obtained a QSPR model allows estimating of critical micelle concentration for nonionic surfactants using theoretical-calculated descriptors.Keywords Anionic surfactants, critical micelle concentration, principal component analysis, multiple linear regression, quantitative structure property relationship (QSPR) computational chemistry
INTRODUCTIONObviously, the surface tension decreases as the surfactant concentration increases. Surfactant molecules first adsorbed at the liquid air interface until the surface of the solution is completely saturated. Then, the excess molecules start to from micelles over a narrow range of concentration at which critical micelle concentration is determined.Comprehensive studies were performed to understand the effect of the chemical structure of different surfactants, anionic, [1] cationic, [2,3] amphoteric, [4] and nonionic [5] on their adsorption and micellization processes and thermodynamic properties. Some empirical relationships based on experimental data between the chemical structural of surfactants and cmc have been developed for surfactant types. [6] In a previous study, the structural effect of N-alkyl sulfoacetates on surface and thermodynamic properties of their solutions has been studied. [7] It correlates the logarithm of cmc to the number of carbon atoms. log cmc ¼ A þ Bn, n is the number of carbon atoms and A and B are constants depending on temperature and homologous series. The same empirical equation was obtained for N-alkyl M-trimethylsilane Ammonium