Formation of viscoelastic wormlike micellar solutions in mixed nonionic surfactant systems
Formation of viscoelastic wormlike micellar solutions in mixed nonionic surfactant systems
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DOI：
10.1021/jp0353237
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发表时间：
2003-09-18
影响因子：
3.3
通讯作者：
Kunieda, H
中科院分区：
文献类型：
--
作者：
Acharya, DP;Kunieda, H
在聚氧乙烯胆固醇醚(CHEO(M)，m=10和15)稀溶液中加入短链聚氧乙烯十二烷基醚(C12EOn)表面活性剂，可诱导一维胶束生长，形成粘弹性溶液。粘弹性体系在很宽的剪切频率范围内表现出Maxwell行为，并被认为是由蠕虫状胶束组成的瞬时网络。在胶束溶液中，随着C12EOn(n=1-4)浓度的增加，胶束相中CHO(10)浓度一定时，零剪切粘度(ETA(O))先逐渐增大，然后急剧增大。增加ETA(O)或促进胶束生长的C12EOn的混合分数按如下顺序增加：C12EO1近似于C12EO2和lt；C12E03和lt；C12EO4。在CHEO(M)-C12EO_3体系中，当CHEO(M)的m从10增加到15时，ETA(O)的急剧增加被转移到相对较高的C_12EO_3混合分数。这些结果表明，加入短链C12EOn后，每个表面活性剂在胶束中的平均截面积减小，胶束长大形成长棒状胶束。假设每个两亲分子在疏水界面的截面积a是恒定的(理想表面混合)，利用实验数据计算了棒状胶束长度，它是C12EOn在总的两亲分子中混合分数X的函数。胶束生长的计算结果很好地解释了流变学测量结果。
The addition of short-EO-chain polyoxyethylene dodecyl ether (C12EOn) surfactants to a dilute solution of polyoxyethylene cholesteryl ether (ChEO(m), m = 10 and 15) induced unidimensional micellar growth leading to the formation of viscoelastic solutions. The viscoelastic systems show Maxwellian behavior over a wide range of shear frequency and are considered to consist of a transient network of wormlike micelles. With increasing concentration Of C12EOn (n = 1-4) at fixed ChEO(10) concentration in a micellar solution phase, at first a gradual and then a steep increase in zero-shear viscosity (eta(o)) was observed. The mixing fraction of C12EOn to increase eta(o) or induce the micellar growth increases in the following order: C12EO1 approximate to C12EO2 < C12EO3 < C12EO4. On increasing m of ChEO(m) from 10 to 15 in the ChEO(m)-C12EO3 system, a sharp increase in eta(o) is shifted to relatively higher mixing fraction Of C12EO3. These results indicate that the average section area per surfactant in a micelle decreases upon the addition of short-EO-chain C12EOn and that micelles grow to form long rod micelles. Assuming that the cross-sectional area of each of the amphiphiles at the hydrophobic interface, a, is constant (ideal surface mixing), the rod micellar length was calculated as a function of the mixing fraction Of C12EOn in the total amphiphile, X, using the data obtained from experimental results. The calculated results on micellar growth well explained the results of rheological measurements.