Adsorption of polyelectrolyte/surfactant mixtures at the air-solution interface: Poly(ethyleneimine)/sodium dodecyl sulfate
Adsorption of polyelectrolyte/surfactant mixtures at the air-solution interface: Poly(ethyleneimine)/sodium dodecyl sulfate
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DOI：
10.1021/la0505014
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发表时间：
2005-10-25
期刊：
影响因子：
3.9
通讯作者：
Zhang, J
中科院分区：
文献类型：
--
作者：
Penfold, J;Tucker, I;Zhang, J
中子反射率和表面张力已被用来表征聚电解质/离子表面活性剂混合物聚（乙烯亚胺）（PEI）和十二烷基硫酸钠（SDS）在空气-水界面的吸附。表面张力行为和吸附模式显示出对溶液 pH 值的强烈依赖性。然而，当 pH 值较高时（当聚合物本质上是中性聚合物时）以及当聚合物结构为支化而不是线性时，界面处的 SDS 吸附出乎意料地最明显。对于支化和线性 PEI 聚合物/表面活性剂复合物的形成，导致界面处 SDS 的量显着增加，表面活性剂浓度低至类似于 10(-6) M。对于支化 PEI，观察到从单层吸附到多层吸附的转变，这取决于表面活性剂浓度和 pH 值。相反，对于线性聚合物，仅观察到单层吸附。通过与 PEI 络合，SDS 的表面活性显着增加，导致十六烷在水中自发乳化，并有效润湿疏水性基材（如特氟龙）。在接近电荷中和的区域，多层吸附增强，并且更广泛的有序结构，在反射率数据中产生布拉格峰，是显而易见的。
Neutron reflectivity and surface tension have been used to characterize the adsorption of the polyelectrolyte/ionic surfactant mixture of poly(ethyleneimine) (PEI) and sodium dodecyl sulfate (SDS) at the air-water interface. The surface tension behavior and adsorption patterns show a strong dependence upon the solution pH. However, the SDS adsorption at the interface is unexpectedly most pronounced when the pH is high (when the polymer is essentially a neutral polymer) and when the polymer architecture is branched rather than linear. For both the branched and the linear PEI polymer/surfactant complex formation results in a significant enhancement of the amount of SDS at the interface, down to surfactant concentrations similar to 10(-6) M. For the branched PEI a transition from a monolayer to a multilayer adsorption is observed, which depends on surfactant concentration and pH. In contrast, for the linear polymer, only monolayer adsorption is observed. This substantial increase in the surface activity of SDS by complexation with PEI results in spontaneous emulsification of hexadecane in water and the efficient wetting of hydrophobic substrates such as Teflon. In regions close to charge neutralization the multilayer adsorption is accentuated, and more extensively ordered structures, giving rise to Bragg peaks in the reflectivity data, are evident.