| 何紫萌,岳玲,王雨琴,尚亚卓,刘洪来.化学通报,2015,78(8):710-716. |
| 十六烷基三甲基溴化铵/油酸钠混合体系蠕虫状胶束流变性研究 |
| The rheological properties of wormlike micelles formed by cetyltrimethyl ammonium bromide(CTAB) and sodium oleate(NaOA) |
| 投稿时间：2014-11-11 修订日期：2015-01-26 |
| DOI： |
| 中文关键词: 表面活性剂 蠕虫状胶束 流变性 粘弹性 |
| 英文关键词:surfactant wormlike micelle rheology viscoelasticity |
| 基金项目:国家自然科学基金项目 |
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| 中文摘要: |
| 阴、阳离子表面活性剂之间强烈的相互作用利于形成自由弯曲的蠕虫状胶束,本文利用阳离子表面活性剂十六烷基三甲基溴化氨(CTAB)和阴离子表面活性剂油酸钠(NaOA)制备了CTAB/NaOA蠕虫状胶束。系统地研究了两表面活性剂的混合比、表面活性剂总浓度的变化对蠕虫状胶束体系稳态流变性及动态粘弹性的影响。结果表明,蠕虫状胶束在剪切过程中的解缠、拟网状结构的破坏以及最终沿剪切速度方向取向等是蠕虫状胶束产生剪切稀释特性的原因。两表面活性剂的混合比及表面活性剂总浓度的变化导致表面活性剂之间的静电作用、疏水作用发生较大的变化,最终引起体系内部表面活性剂聚集体形态的差异。体系内蠕虫状胶束长度、体系结构复杂程度、蠕虫状胶束形成的网络结构的致密度等都影响着体系的流变行为。混合比R=3.6,总浓度CT=0.24mol/L时,体系中蠕虫状胶束最长,网络结构最为紧密,体系的零剪切粘度达到最大值。表面活性剂浓度一定时,混合比的提高有助于蠕虫状胶束的定向生长,弛豫时间和储能模量高频区平台模量提高,R=3.6时二者皆达到极大值,此后由于蠕虫状胶束的分枝化及(或)胶束破裂导致及下降。表面活性剂混合比一定(R=3.6)时,表面活性剂浓度的提高利于蠕虫状胶束的增长或者分枝化,增加了胶束网络结构缠绕(融合)点的密度,导致逐渐增大。Cole-Cole图证实本文研究的蠕虫状胶束体系符合Maxwell模型的线性粘弹性流体。 |
| 英文摘要: |
| The strong interactions between anionic and cationic surfactant can induce the formation of flexible wormlike micelles. The wormlike micelles were prepared by mixing cetyltrimethyl ammonium bromide (CTAB) and sodium oleate (NaOA) in this paper. The influence of molar ratio(R) and surfactant concentration on the steady-state rheological and dynamic viscoelasticity of wormlike micelles were studied systematically. The results have shown that the untangling of wormlike micelles, the broken of the network and the orientation of wormlike micelles along with the direction of shearing rate result in shear thinning. Electrostatic and hydrophobic interactions vary obviously with R and concentration and lead to the difference in morphology of surfactants’ aggregation. The rheological behavior is affected by the length of wormlike micelles, the complexity of structure and the density of network. When R=3.6, CT=0.24mol/L, the wormlike micelles are the longest and the zero-shear viscosity reaches a maximum. When the concentration is constant, the increase of molar ratio (R) benefits the growth of wormlike micelles in one dimension and thus leads to the increase of the relaxation time and the plateau value. and reach a maximum when R=3.6. Thereafter, the increase of R promotes the branching and (or) the fracture of wormlike micelles and therefore result in the decrease of and. When R is constant (R=3.6), the increase of concentration contribute to the branching and growth of wormlike micelles, increase the density of the network, which result in the enhance of . The Cole-Cole plots demonstrate that the system fits the Maxwell’s mechanical model as linear viscoelastic fluid. |
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