Radiation & Photochemistry Division, Bhabha Atomic Research Centre, Mumbai 400 085, India.
J Phys Chem B. 2010 Mar 25;114(11):3818-26. doi: 10.1021/jp909333q.
Interaction of cationic surfactant, cetyl trimethyl ammonium bromide (CTAB), with pluronics F88 (EO(103)-PO(39)-EO(103)) and P105 (EO(37)-PO(56)-EO(37)) micelles and its effect on modulating the location of an anionic solute in the mixed micelles have been investigated using time-resolved fluorescence and small angle neutron scattering (SANS) studies. SANS results indicate the formation of pluronic-CTAB supramolecular assemblies, in which the hydrophobic chains of CTAB occupy the hydrophobic core of the pluronic micelle while the positively charged head groups reside at the micellar core-corona interface. Rotational correlation time of the anionic probe in these supramolecular assemblies increases with an increase in the CTAB concentration, and the observed results are explained on the basis of the probe movement from the surface to the interior of the micelle due to the increased electrostatic attraction. Dynamic Stokes' shift measurements also support the movement of the probe due to the addition of the surfactant to the supramolecular assemblies. From the studies with different pluronics, it is indicated that the concentration of CTAB required to drag the probe molecule into the interior of the micelles is linearly correlated to the thickness of the corona region of the respective micelles.
使用时间分辨荧光和小角中子散射（SANS）研究了阳离子表面活性剂十六烷基三甲基溴化铵（CTAB）与两亲性嵌段共聚物 F88（EO(103)-PO(39)-EO(103)) 和 P105（EO(37)-PO(56)-EO(37)）胶束的相互作用及其对调节阴离子溶质在混合胶束中位置的影响。SANS 结果表明形成了两亲性嵌段共聚物-CTAB 超分子组装体，其中 CTAB 的疏水链占据两亲性嵌段共聚物胶束的疏水核，而带正电荷的头基位于胶束核-冠界面。这些超分子组装体中阴离子探针的旋转相关时间随 CTAB 浓度的增加而增加，观察到的结果基于探针由于静电引力从表面向胶束内部的移动来解释。动态斯托克斯位移测量也支持由于表面活性剂添加到超分子组装体中探针的运动。通过与不同两亲性嵌段共聚物的研究表明，将探针分子拖入胶束内部所需的 CTAB 浓度与相应胶束的冠区厚度呈线性相关。
