Calorimetric study on interaction of water-soluble copolymers with ionic surfactant.
Using isothermal titration microcalorimetry (ITC), we examined the aggregation behavior of water-soluble copolymers, poly(methoxypolyethylene glycol methacrylate-co-ethyl acrylate)s (PME-EA)s, with ionic surfactant, sodium dodecyl sulfate (SDS). From ITC measurements the values of critical aggregation concentration (cac) and saturation concentration (C(2)), the concentration at which the aggregation of the copolymers starts to form and reaches saturation, respectively, were determined. Thermodynamic parameters such as DeltaG(0)(agg), DeltaH(agg), and TDeltaS(0)(agg) of the aggregation were deduced. Results indicate that cac of the PME-EA remained constant with increase in the concentration of the copolymers, while C(2) increased linearly. On the other hand, the effect of the weight ratio of the EA unit in the copolymer was such that cac of the PME400-EA decreased, while C(2) increased with increase in the weight ratio. The results suggested that the EA units are the main binding sites of the copolymer with SDS.
Yan
Hu
H
Department of Materials Science and Environmental Engineering, Tokyo University of Science, Yamaguchi, SanyoOnoda-shi, Yamaguchi 756-0884, Japan. yanhu@yamanashi.ac.jp
Kawamitsu
Hiroka
H
Kushi
Yoshinori
Y
Kuwajima
Teruaki
T
Ishii
Keizo
K
Toshima
Naoki
N
D001665:Binding Sites; D002151:Calorimetry / Q000379:methods; D057927:Hydrophobic and Hydrophilic Interactions; D008689:Methacrylates / Q000737:chemistry*; D011092:Polyethylene Glycols / Q000737:chemistry*; D012967:Sodium Dodecyl Sulfate / Q000737:chemistry*; D012995:Solubility; D013499:Surface Properties; D013501:Surface-Active Agents / Q000737:chemistry*; D013816:Thermodynamics; D014867:Water / Q000737:chemistry*
D008689:Methacrylates; D013501:Surface-Active Agents; D014867:Water; D012967:Sodium Dodecyl Sulfate; D011092:Polyethylene Glycols; C005044:hydroxyethyl methacrylate