Adsorption of polyelectrolyte/surfactant mixtures at the air-water interface: modified poly(ethyleneimine) and sodium dodecyl sulfate.
Adsorption of polyelectrolyte/surfactant mixtures at the air-water interface: modified poly(ethyleneimine) and sodium dodecyl sulfate.
复制标题
聚电解质/表面活性剂混合物在空气-水界面的吸附：改性聚（乙烯亚胺）和十二烷基硫酸钠。
DOI：
10.1021/la104698w
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发表时间：
2011
期刊：
影响因子：
--
通讯作者：
J. Penfold
中科院分区：
文献类型：
--
作者：
X. L. Zhang;D. Taylor;R. Thomas;J. Penfold
用中子反射率和表面张力研究了十二烷基硫酸钠(十二烷基硫酸钠)和不同改性的聚乙二亚胺(PEI)聚电解质在空气-水界面上的吸附行为。通过添加环氧乙烷(EO)或环氧丙烷(PO)基团对PEI进行改性，对其表面吸附行为产生了影响。这是由于聚合物/表面活性剂相互作用的改变、改性聚电解质的固有表面活性的增加以及表面和溶液络合物形成的相对重要性的变化。对于聚电解质PEI，在加入单一EO基团和加入(EO)3基团之间，表面吸附行为发生了明显的变化。在PEI中加入单一的EO或PO基团会导致与未经修饰的PEI/SDS混合物在行为上大致相似的十二烷基硫酸钠浓度和溶液pH吸附依赖关系。也就是说，在低浓度的十二烷基硫酸钠溶液中有很强的表面络合和吸附作用，除了在低pH值下有很强的静电吸引外，在高pH值下还有很强的相互作用。加入较大的环氧乙烷基团三环氧乙烷(EO)3，表面吸附行为更接近于中性聚合物/离子表面活性剂混合物的吸附行为，类似于观察到的具有较大环氧乙烷基团的PEI，特别是PEI-(EO)7。在这种情况下，聚合物/表面活性剂络合物的吸附要不明显得多。吸附主要来自聚合物和表面活性剂之间的竞争，表明随着pH的增加，聚合物/表面活性剂的相互作用减弱。也就是说，增加环氧乙烷基团的大小会导致从强表面聚合物/表面活性剂相互作用向弱聚合物/表面活性剂相互作用的转变。
The adsorption of surfactant/polyelectrolyte mixtures of sodium dodecyl sulfate (SDS) and different modified poly(ethyleneimine) (PEI) polyelectrolytes at the air-water interface has been studied using neutron reflectivity and surface tension. Modification of the PEI by the addition of short ethylene oxide (EO) or propylene oxide (PO) groups is shown to have an impact upon the surface adsorption behavior. This is due to a modification of the polymer/surfactant interaction, an increase in the intrinsic surface activity of the modified polyelectrolyte, and changes in the relative importance of surface and solution complex formation. For the polyelectrolyte PEI, there is a marked change in the surface adsorption behavior between the addition of a single EO group and that of the (EO)3 group. The addition of a single EO or PO group to the PEI results in an SDS concentration and solution pH adsorption dependence that is broadly similar in behavior to that of the unmodified PEI/SDS mixture. That is, there is strong surface complexation and adsorption down to low SDS concentrations, and there is evidence of a strong interaction at high pH in addition to the strong electrostatic attraction at low pH. The addition of a larger ethylene oxide group, triethylene oxide (EO)3, results in a surface adsorption behavior that more closely resembles that of a neutral polymer/ionic surfactant mixture, similar to that observed for PEI with a larger ethylene oxide group, notably PEI-(EO)7. In that case, the adsorption of the polymer/surfactant complex is much less pronounced. The adsorption arises predominantly from competition between the polymer and surfactant and indicates a decrease in the polymer/surfactant interaction with increasing pH. That is, increasing the size of the ethylene oxide group induces a transition from a strong surface polymer/surfactant interaction to a weak polymer/surfactant interaction.