Small-Angle Neutron Scattering and Fluorescence Studies of Mixed Surfactants with Dodecyl Tails.
Small-Angle Neutron Scattering and Fluorescence Studies of Mixed Surfactants with Dodecyl Tails.
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十二烷基尾混合表面活性剂的小角中子散射和荧光研究。
DOI：
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发表时间：
1999
影响因子：
9.9
通讯作者：
Heenan
中科院分区：
文献类型：
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作者：
Griffiths;Whatton;Abbott;Kwan;Pitt;Howe;King;Heenan
用表面张力、荧光和小角中子散射研究了阴离子表面活性剂十二烷基硫酸钠（SDS）和非离子表面活性剂十二烷基丙二酸双-N-甲基葡萄糖酰胺（DBNMG）在水溶液中形成的混合胶束。用表面张力法和荧光法测定了两种表面活性剂的临界胶束浓度（CMC），结果表明这两种表面活性剂的混合是非理想的。所有组合物的表面活性剂混合物的CMC的实验值都小于克林特提出的理想预测（J. Chem. Soc. 71，1327（1975））。正规溶液理论（例如，Penfold等人，Langmuir 11，2498（1995））可用于计算CMC下胶束的组成。由此计算的胶束组合物显着不同，在较高的总表面活性剂浓度，后者更接近化学计量组成。胶束环境的极性，如通过溶解的荧光探针所感知的，对于单组分和混合胶束是相同的。散射数据表明，混合胶束的大小与纯非离子胶束相当，略大于阴离子胶束。与氘代SDS的平行研究表明，没有证据的隔离或本地订购内的混合胶束。混合胶束上的有效电荷由胶束内离子表面活性剂的量决定。添加0.1 M NaCl到这些系统中没有CMC，胶束椭圆率和聚集数的影响，从观察到的简单SDS溶液的行为非常不同。版权所有1999学术出版社。
The mixed micelles formed in solutions of the anionic surfactant sodium dodecylsulfate (SDS) and the nonionic surfactant dodecylmalono-bis-N-methylglucamide (DBNMG) were studied by surface tension, fluorescence, and small-angle neutron scattering. Measurements of the critical micelle concentration (CMC) by surface tension and fluorescence show that these two surfactants mix nonideally. The experimental values of the CMCs for surfactant mixtures for all compositions are less than the ideal prediction proposed by Clint (J. Chem. Soc. 71, 1327 (1975)). Regular solution theory (for example, Penfold et al., Langmuir 11, 2498 (1995)) can be used to calculate the composition of the micelle at the CMC. The micellar composition thus calculated differs significantly from that at higher total surfactant concentrations, the latter being much closer to the stoichiometric composition. The polarity of the micellar environment, as perceived by a solubilized fluorescence probe, is identical for both the single-component and the mixed micelles. The scattering data show that the mixed micelles are comparable in size to the pure nonionic micelle and slightly larger than the anionic micelle. Parallel studies with deuterated SDS showed no evidence of segregation or local ordering within the mixed micelle. The effective charge on the mixed micelle is determined by the amount of ionic surfactant within the micelle. Addition of 0.1 M NaCl to these systems has no effect on the CMC, micelle ellipticity, and aggregation number-a behavior very different from that observed for simple SDS solutions. Copyright 1999 Academic Press.