Colloidal Dynamics in Turbid Suspensions

浑浊悬浮液中的胶体动力学

• 批准号: 450537114
• 负责人: Professor Dr. Thomas Palberg
• 金额: --
• 依托单位: Institut für Physik
• 依托单位国家: 德国
• 项目类别: Research Grants
• 资助国家: 德国
• 项目状态: 未结题
• 来源: https://gepris.dfg.de/gepris/projekt/450537114?language=en
• 关键词: Colloidal; Dynamics; Turbid; Suspensions

Depending on the range and strength of their mutual interactions, suspensions of colloidal particles can develop complex dynamics on different time and length scales as well as a rich and fascinating phase behaviour. Charged spheres in particular have emerged as excellent models for a vast variety of charge-stabilized globular colloids encountered in chemical industry, biology, and medicine. Investigations on the dynamics of these mainly water based systems by conventional homodyne time domain dynamic light scattering (DLS) are often limited by the onset of multiple scattering at larger concentrations and by spatial and temporal heterogeneity upon structure formation. Some alternative techniques to cope with one or both of these challenges exist. Examples include cross-correlation, echo-experiments or X-ray scattering. However, most of these are instrumentally rather demanding. A facile frequency domain approach to the intermediate scattering function is, however, possible usingSuper-Heterodyning Doppler Velocimetry, which is a standard technique in electro-kinetics and flow analysis. In our preliminary work we developed an effective way of ensemble averaging as well as an empirical, post-recording, multiple scattering correction for a small angle variant of this method. Here we propose to combine this promising technique with the versatility of a conventional Dynamic Light Scattering goniometer setup for investigations over a large range of scattering vectors. Using a prototype machine, we have already given proof of concept for this approach in our preliminary work. Now, a PhD student shall construct an improved version of this instrument, develop the necessary data processing and implement suitable evaluation algorithms. In a first stage, focus will be on demonstrating its robust and reliable performance as well as on mapping out its range of accuracy and precision. Using model systems, industrial and biological systems, we will comprehensively test the machine against time domain reference experiments like conventional and cross correlation DLS. In the second stage, we will exploit the instrumental features demonstrated before, i.e. multiple scattering correction, facile ensemble averaging and accessibility of complex scale and time dependent dynamics. We will apply the new approach to two selected examples identified in our preliminary work. Both the melt dynamics during the late stages of colloidal crystallization and the relaxation processes encountered in low density charged sphere glasses pose a number of interesting open questions. Our studies will thereby also highlight the versatility of our approach and its potential applicability for a broader range of Soft Matter systems.

根据它们相互作用的范围和强度，胶体颗粒的悬浮液可以在不同的时间和长度尺度上发展复杂的动力学，以及丰富而迷人的相行为。特别是带电球体已经成为化学工业、生物学和医学中遇到的各种电荷稳定的球状胶体的极好模型。传统的零差时域动态光散射（DLS）对这些主要基于水的系统的动力学的研究通常受到在较大浓度下的多重散射的开始以及结构形成时的空间和时间异质性的限制。存在科普这些挑战中的一个或两个的一些替代技术。例子包括互相关、回声实验或X射线散射。然而，其中大多数都是工具性的要求。然而，使用超外差多普勒测速法（Super-Heterodyning Doppler Velocimetry），这是电动力学和流动分析中的标准技术，可以实现对中间散射函数的简便频域方法。在我们的初步工作中，我们开发了一种有效的方法，合奏平均以及经验，记录后，多次散射校正这种方法的一个小角度变量。在这里，我们建议结合联合收割机这种有前途的技术与传统的动态光散射测角仪设置的多功能性，在大范围的散射矢量的调查。使用原型机器，我们已经在我们的初步工作中给出了这种方法的概念证明。现在，博士生将构建该仪器的改进版本，开发必要的数据处理并实施合适的评估算法。在第一阶段，重点将是展示其强大和可靠的性能，并绘制出其准确度和精度范围。使用模型系统，工业和生物系统，我们将全面测试机器对时域参考实验，如传统和互相关DLS。在第二阶段，我们将利用仪器的功能之前，即多次散射校正，简易的合奏平均和复杂的尺度和时间依赖的动力学的可访问性。我们将采用新的方法，在我们的初步工作中确定的两个选定的例子。胶体结晶后期的熔体动力学和低密度带电球形玻璃中遇到的弛豫过程都提出了一些有趣的开放性问题。因此，我们的研究也将突出我们的方法的多功能性及其对更广泛的软物质系统的潜在适用性。