Size and Shape of Micelles Studied by Means of SANS, PCS, and FCS
Size and Shape of Micelles Studied by Means of SANS, PCS, and FCS
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DOI：
10.1021/la100181d
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发表时间：
2010-06-15
期刊：
影响因子：
3.9
通讯作者：
Holyst, Robert
中科院分区：
文献类型：
--
作者：
Gapinski, Jacek;Szymanski, Jedrzej;Holyst, Robert
用小角中子散射（SANS）和光子相关谱（PCS）研究了浓度为10%的六甘醇单十二烷基醚（C12 E6）胶束在各向同性相（10-48 ℃）的性质。在低温下获得的SANS数据可以明确地解释为从一个紧凑的球形胶束悬浮液的形状的三轴椭球或短的端盖椭圆棒的散射的结果。不同的模型已被应用于分析在较高的温度下获得的SANS数据：（i）细长的棒状胶束与纯粹的空间相互作用，（ii）紧凑的球状胶束与弱吸引力的潜力，和（iii）球状胶束的影响，在整个温度范围内的临界现象的研究。实验数据的良好质量表明模型（i）是我们数据的最佳模型。从PCS测量获得的扩散系数进行了比较的棒状胶束的SANS数据分析的结果计算的扩散系数。一个很好的协议，实现了使用溶剂粘度，与空间相互作用的球状胶体颗粒的理论预测。最后，在24 ℃下获得的SANS结果与先前通过荧光相关光谱法（FCS）在该温度下测量的胶束自扩散系数进行比较。缩放的数据与溶液粘度后得到的良好的协议支持的有效性的广义斯托克斯-爱因斯坦关系在空间相互作用系统的胶体粒子的自扩散系数和宏观粘度的产品保持恒定在一个很宽的浓度范围。它已得出结论，结合简单的粘度测量的FCS技术可能作为一种工具，用于估计胶束的大小和形状。
The hexaethylene glycol monododecyl ether (C12E6) micelles at concentrations up to 10% have been studied in their isotropic phase (10-48 degrees C) by means of small angle neutron scattering (SANS) and photon correlation spectroscopy (PCS). The SANS data obtained at low temperatures could be unequivocally interpreted as a result of scattering from a suspension of compact globular micelles with the shape of a triaxial ellipsoid or a short end-capped elliptical rod. Different models have been applied to analyze the SANS data obtained at higher temperatures: (i) elongated rod-like micelles with purely sterical interactions, (ii) compact globular micelles with a weak attractive potential, and (iii) globular micelles influenced by the critical phenomena in the whole temperature range studied. The good quality of the experimental data indicated model (i) as the best it for our data. The diffusion coefficients obtained from the PCS measurements have been compared to the diffusion coefficients calculated for the rod-like micelles-results of the SANS data analysis. A good agreement was achieved using the solvent viscosity, in agreement with the theoretical predictions for sterically interacting globular colloidal particles. Finally, the SANS results obtained at 24 degrees C were compared to the micelle self-diffusion coefficients previously measured by means of fluorescence correlation spectroscopy (FCS) at this temperature. The good agreement obtained after scaling the data with solution viscosity supports the validity of the generalized Stokes-Einstein relation in sterically interacting systems: the product of the colloidal particle self-diffusion coefficient and the macroscopic viscosity remains constant in a broad range of concentrations. It has been concluded that the FCS technique in combination with simple viscosity measurements might serve as a tool for estimating the micellar size and shape.