title: Evaluation the thermodynamic behavior of nonionic polyoxyethylene surfactants against temperature changes.
abstract: Micellization is the most important property of surface agents. It plays an important role in the manufacture of pharmaceutical products. The surfactants have many applications in industry, agriculture, mining and oil recovery with functional properties as wetting, foaming and emulsifier in pharmaceutical and cosmetic products. The micellization parameters of surfactants help the manufacture of pharmaceutical products to be appropriate and stable. Therefore, in this study, Polyoxyethylene lauryl ether (C12E23), Polyoxyethylene (10) cetyl ether (C16E10) and Polyoxyethylene (20) cetyl ether (C16E20) were chosen as the nonionic surfactants to examine the effect of temperature variation (10-80(°)C) on the Critical Micelle Concentration (CMC). The measurement of surface tension was done by a Du Nöuys ring method. The value of CMC was obtained from the surface tension vs. surfactant concentration curve. Since the temperature was increased, the CMC initially decreased and then increased for each surfactant because the formation of the hydrogen bond is harder in the high temperatures. The surface tension γCMC for all three surfactant solutions decreased monotonically as the temperature increased. δG(°)m, ΔH(°)m and ΔS°m as the thermodynamic parameters of micellization, were also estimated and analyzed. The ΔG(°)m was decreased (10-80(°)C) if the temperature was increased. The entropy and enthalpy correlation of micellization showed a significant linearity. For C12E23, C16E20 and C16 E10, the compensation temperature (Tc) was obtained 309.5, 313.2 and 314.4 K, respectively. The calculated thermodynamic parameters showed that the entropy influenced on the micellization process at lower temperature, but it affected by enthalpy when temperature was increased.
authors.affiliation: Pharmaceutics Research Center, Institute of Neuropharmacology, Kerman University of Medical Sciences, Kerman, Iran / Environmental Health Engineering Research Center and Department of Environmental Health, School of Public Health, Kerman University of Medical Sciences, Kerman, Iran.
authors.forename: Hadi Mahmoudi
authors.initials: HM
authors.lastname: Moghaddam
authors.affiliation: Pharmaceutics Research Center, Institute of Neuropharmacology, Kerman University of Medical Sciences, Kerman, Iran / Department of Pharmaceutics, School of Pharmacy, Kerman University of Medical Sciences, Kerman, Iran.
authors.forename: Gholamreza
authors.initials: G
authors.lastname: Dehghannoudeh
authors.affiliation: Pharmaceutics Research Center, Institute of Neuropharmacology, Kerman University of Medical Sciences, Kerman, Iran.
authors.forename: Mohammad Zaman
authors.initials: MZ
authors.lastname: Basir
mesh_terms: D002626:Chemistry, Pharmaceutical; D019277:Entropy; D006860:Hydrogen Bonding; D016014:Linear Models; D008823:Micelles; D008956:Models, Chemical; D011092:Polyethylene Glycols / Q000737:chemistry*; D013500:Surface Tension; D013501:Surface-Active Agents / Q000737:chemistry*; D013678:Technology, Pharmaceutical / Q000379:methods; D013696:Temperature
chemical_list: D008823:Micelles; D013501:Surface-Active Agents; D011092:Polyethylene Glycols