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 (C2C2), the concentration at which the aggregation of the copolymers starts to form and reaches saturation, respectively, were determined. Thermodynamic parameters such as ΔGagg0, ΔHaggΔHagg, and TΔSagg0 of the aggregation were deduced. Results indicate that cac of the PME-EA remained constant with increase in the concentration of the copolymers, while C2C2 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 C2C2 increased with increase in the weight ratio. The results suggested that the EA units are the main binding sites of the copolymer with SDS.

Graphical abstractUsing isothermal titration microcalorimetry (ITC), the aggregation behaviors of water-soluble copolymers, poly(methoxypolyethylene glycol methacrylate-co  -ethyl acrylate)s (PME-EA)s, with ionic surfactant, sodium dodecylsufate (SDS) were investigated. From ITC measurements the values of critical aggregation concentration (cac) and saturation concentration (C2C2), respectively, were determined.Figure optionsDownload full-size imageDownload as PowerPoint slide