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首页> 外文学位 >Partitioning and transport in complex nano-structured systems: Gradient diffusion of ionic micelles in gels and partitioning of hydrophobic aroma compounds.
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Partitioning and transport in complex nano-structured systems: Gradient diffusion of ionic micelles in gels and partitioning of hydrophobic aroma compounds.

机译：在复杂的纳米结构系统中的分配和运输：离子胶束在凝胶中的梯度扩散和疏水性香气化合物的分配。

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摘要

With the overall goal of advancing nano-scale encapsulation technology, two companion problems in the controlled release of small hydrophobic molecules have been studied: equilibrium partitioning and colloidal transport, each within nanostructured matrices.;In the first research focus, a solid phase microextraction (SPME) method was developed to measure air--water--surfactant micelle partitioning of hydrophobic analytes. Vapor--liquid partitioning (Kv ℓ) measurements were performed independently in the headspace (HS-SPME) and via direct immersion in the liquid (DI-SPME), and the results were compared. The method involves varying the total amount of analyte as well as the ratio of vapor to liquid in the closed, static system, such that the need for an external calibration is eliminated. The compounds studied cover four orders of magnitude in Kv ℓ, and agreement between DI-SPME and HS-SPME results was good, showing that these two methods were capable of providing accurate, complementary measurements. Equilibrium partitioning of limonene to sodium dodecyl sulfate (SDS) micelles was also measured using HS-SPME by varying the concentration of SDS. By fitting the data to a simple model, the cmc was accurately measured and the micelle--liquid partition coefficient was determined.;In the second research focus, the diffusion of SDS in solution and in agarose gel was measured and compared with an a priori model for colloidal transport which invokes hydrodynamic and statistical thermodynamic arguments to account for micelle--micelle and micelle--gel fiber interactions. Experimental results show that the concentration effect is enhanced considerably by the strong charge associated with SDS micelles. At high ionic strength, this concentration effect is further enhanced in 1% agarose gel, but in 2% gel the trend reverses, strongly suggesting a decrease in the micellar aggregation number. At low ionic strength, a concentration effect with a pronounced second order dependence is evident. Results show that the diffusion coefficient does not change appreciably with gel concentration up to 2%, and theoretical analysis suggests that this is due to partial canceling between the effects of solute--gel and solute--solute interactions. The pronounced second-order dependence is explained qualitatively by the changing Debye length and its influence on the thermodynamic driving force.
机译：以发展纳米级封装技术为总体目标，研究了疏水性小分子控制释放中的两个伴随问题：平衡分配和胶体运输，每个都在纳米结构基质内;;在第一个研究重点中，固相微萃取（开发了SPME）方法来测量疏水性分析物的空气-水-表面活性剂胶束分配。汽-液分配（Kv＆ell;）测量是在顶空（HS-SPME）和直接浸入液体（DI-SPME）中独立进行的，并对结果进行了比较。该方法涉及改变封闭的静态系统中分析物的总量以及蒸气与液体的比例，从而消除了对外部校准的需求。所研究的化合物的Kv＆ell;涵盖四个数量级，并且DI-SPME和HS-SPME结果之间的一致性很好，表明这两种方法能够提供准确，互补的测量结果。柠檬烯与十二烷基硫酸钠（SDS）胶束的平衡分配也使用HS-SPME通过改变SDS的浓度进行了测量。通过将数据拟合为简单模型，可以精确测量cmc并确定胶束-液体分配系数。;在第二个研究重点中，测量了SDS在溶液和琼脂糖凝胶中的扩散并将其与先验比较胶体运输模型，该模型调用流体力学和统计热力学参数来说明胶束-胶束和胶束-凝胶纤维之间的相互作用。实验结果表明，与SDS胶束相关的强电荷可大大提高浓缩效果。在高离子强度下，在1％琼脂糖凝胶中该浓缩作用会进一步增强，但在2％凝胶中，趋势会逆转，强烈表明胶束聚集数减少。在低离子强度下，具有明显的二级依赖性的浓度效应是明显的。结果表明，当凝胶浓度达到2％时，扩散系数不会发生明显变化，并且理论分析表明，这是由于溶质-凝胶和溶质-溶质相互作用之间的部分抵消所致。明显的二阶依赖性通过变化的德拜长度及其对热力学驱动力的影响进行了定性解释。

著录项

  • 作者

    Lloyd, Nathan Winter.;

  • 作者单位

    University of California, Davis.;

  • 授予单位 University of California, Davis.;
  • 学科 Chemistry Analytical.;Engineering Chemical.
  • 学位 Ph.D.
  • 年度 2010
  • 页码 146 p.
  • 总页数 146
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

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