Effect of added poly(oxyethylene)dodecyl ether on the phase and rheological behavior of wormlike micelles in aqueous SDS solutions.
Effect of added poly(oxyethylene)dodecyl ether on the phase and rheological behavior of wormlike micelles in aqueous SDS solutions.
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DOI：
10.1021/jp054631x
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发表时间：
2006-01
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影响因子：
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通讯作者：
Durga P. Acharya;Takaaki Sato;M. Kaneko;Y. Singh;H. Kunieda
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作者：
Durga P. Acharya;Takaaki Sato;M. Kaneko;Y. Singh;H. Kunieda
在十二烷基硫酸钠(十二烷基硫酸钠)胶束溶液中加入短EO链非离子表面活性剂聚氧乙烯十二烷基醚(C12EOn)稀释到一定浓度以上时，粘度急剧增加，形成高粘弹性胶束溶液。粘弹性溶液的振荡剪切流变行为在低剪切频率下可用Maxwell模型描述，在高剪切频率下可用Maxwell-Rouse组合模型描述。这一特性是蠕虫状胶束缠绕形成瞬时网络的典型特征。发现当混合体系中的C12EO4被C12EO_3取代时，胶束的生长更有效。然而，随着EO链长的进一步减小，在形成粘弹性溶液之前会发生相分离。结果表明，在SDS-C_(12)EO_3体系中，当表面活性剂的混合分数适当时，体系的零剪切粘度最大。我们还用小角X射线散射(SAXS)的方法研究了混合表面活性剂体系中胶束的生长。SAXS数据表明，胶束在所有的SDS-C12EOn(n=0-4)水溶液中均以一维方式生长。在短EO链C12EOn体系中，当非离子表面活性剂的混合分数较低时，胶束生长较快。
Upon the addition of a short EO chain nonionic surfactant, poly(oxyethylene) dodecyl ether (C12EOn), to dilute micellar solution of sodium dodecyl sulfate (SDS) above a particular concentration, a sharp increase in viscosity occurs and a highly viscoelastic micellar solution is formed. The oscillatory-shear rheological behavior of the viscoselastic solutions can be described by the Maxwell model at low shear frequency and combined Maxwell-Rouse model at high shear frequency. This property is typical of wormlike micelles entangled to form a transient network. It is found that when C12EO4 in the mixed system is replaced by C12EO3 the micellar growth occurs more effectively. However, with the further decrease in EO chain length, phase separation occurs before a viscoelastic solution is formed. As a result, the maximum zero-shear viscosity is observed at an appropriate mixing fraction of surfactant in the SDS-C12EO3 system. We also investigated the micellar growth in the mixed surfactant systems by means of small-angle X-ray scattering (SAXS). It was found from the SAXS data that the one-dimensional growth of micelles was obtained in all the SDS-C12EOn (n=0-4) aqueous solutions. In a short EO chain C12EOn system, the micelles grow faster at a low mixing fraction of nonionic surfactant.