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首页> 外文期刊>The journal of physical chemistry, B. Condensed matter, materials, surfaces, interfaces & biophysical >Binding Characteristics of Hydrophobic Ethoxylated Urethane (HEUR) and an Anionic Surfactant: Microcalorimetry and Laser Light Scattearing Studies
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Binding Characteristics of Hydrophobic Ethoxylated Urethane (HEUR) and an Anionic Surfactant: Microcalorimetry and Laser Light Scattearing Studies

机译：疏水性乙氧基化氨基甲酸乙酯（HEUR）与阴离子表面活性剂的结合特性：微量量热法和激光划痕研究

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摘要

The binding behaviors of an anionic surfactant, sodium dodecyl sulfate (SDS), to an associative polymer, hydrophobic ethoxylated urethane (HEUR) were studied by isothermal titration calorimetric (ITC) and laser light scattering (LLS) techniques. Static and dynamic light scattering results suggest that HEUR polymers form flowerlike micelles with an average aggregation number of about 20. Isothermal titration calorimetric studies of SDS and HEUR solutions were conducted by varying both the concentrations of SDS and HEUR. For the titration of SDS into HEUR solutions, the thermograms display an endothermic peak after the critical aggregation concentration (cac), followed by an exothermic peak that eventually merges with the SDS dilution curve. The endothermic and exothermic peaks are interpreted by different binding mechanisms at different surfactant concentrations. Although the values of cac are independent of HEUR concentrations, the saturation concentration C_2 is strongly dependent on HEUR concentrations. With increasing HEUR concentrations, C_2 increases proportionately. Dynamic light scattering results corroborate with the findings from ITC studies. The apparent hydrodynamic radii increase with increasing SDS concentrations for cac < C_SDS < C2, and remained constant at C_SDS> C_2. However, the thermograms for titration of HEUR into SDS micellar solutions differ from those of titrating SDS into HEUR, suggesting that different binding mechanism must be in operation. The binding enthalpy changes increase with SDS concentration and decrease with HEUR concentration when titrating HEUR into SDS solutions.
机译：通过等温滴定热法（ITC）和激光散射（LLS）技术研究了阴离子表面活性剂十二烷基硫酸钠（SDS）与缔合聚合物疏水性乙氧基化尿烷（HEUR）的结合行为。静态和动态光散射结果表明，HEUR聚合物形成花状胶束，平均聚集数约为20。通过改变SDS和HEUR的浓度进行SDS和HEUR溶液的等温滴定热研究。对于将SDS滴定到HEUR溶液中，热谱图在临界聚集浓度（cac）之后显示一个吸热峰，然后是一个放热峰，最终与SDS稀释曲线合并。吸热峰和放热峰由在不同表面活性剂浓度下的不同结合机理解释。尽管cac的值与HEUR浓度无关，但是饱和浓度C_2强烈取决于HEUR浓度。随着HEUR浓度的增加，C_2成比例地增加。动态光散射结果与ITC研究的结果相符。当cac C_2处保持恒定。但是，将HEUR滴定至SDS胶束溶液的热分析图与将SDS滴定至HEUR的热分析图不同，这表明必须使用不同的结合机制。当将HEUR滴定到SDS溶液中时，结合焓的变化随SDS浓度的增加而增加，随HEUR浓度的减少而减小。

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