Effects of Dispersant Molecular Structure on the Stabilization of Dispersions Against Agglomeration and Sedimentation

许多工业上重要的过程涉及颗粒在液体中的悬浮。这些过程经常受到颗粒团聚和聚集体沉降的阻碍。工艺工程师采取措施，通过添加表面活性剂，降低两种液体之间或液体和固体之间的表面张力，包覆颗粒并抑制其团聚，来防止团聚和沉淀。然而，添加表面活性剂也会改变悬浮液的整体性质，使其更难加工。该研究项目涉及研究和替代方法，以防止团聚和沉淀，而不显着改变悬浮液的流动特性。这个想法是找到在液体中自发形成分子结构或组装体的表面活性剂，以防止颗粒团聚、沉降或两者兼而有之。研究人员正在研究一系列广泛的表面活性剂颗粒系统，并确定防止团聚的系统特性。这些结果将有助于涂料和油墨、制药和化妆品等工业领域的工艺工程师设计出长期保持稳定并保持其有益特性的产品。该项目还涉及所有学术水平的学生，包括高中生，特别是那些来自传统上代表性不足的群体的学生，他们正在通过普渡大学的种子计划被招募参加该项目。本项目的目标是筛选、评价和选择用于控制悬浮颗粒团聚和沉降的表面活性剂分散剂。表面活性剂分子结构对胶束和囊泡等组装体形成的作用正在研究中，这些组装体可以抑制颗粒的团聚和沉降。正在研究广泛的表面活性剂，包括连接到单和双极性头基的单和双烃链。碳链长度从8到16的阴离子、阳离子和非离子表面活性剂正在研究中。颗粒的特性，如大小、成分、密度和浓度，也包括在研究中。团聚体的大小是由动态光散射和分光比浊法测定，并在流变性能的变化正在使用恒定应力流变仪测量。 冷冻透射电子显微镜正在使用时，适当的囊泡和颗粒结构的特点。正在进行使用布朗动力学和随机动力学模拟的计算研究，以确定悬架稳定的机制。

Many industrially important processes involve suspensions of particles in a liquid. These processes are often hampered by agglomeration of the particles and sedimentation of the aggregates. Process engineers take steps to prevent agglomeration and sedimentation by adding surfactants, compounds that lower the surface tension between two liquids or between a liquid and a solid, that coat the particles and inhibit their agglomeration. However, adding a surfactant can also change the bulk properties of the suspension and make it more difficult to process. This research project involves studying and alternative approach to preventing agglomeration and sedimentation without changing significantly the flow properties of the suspension. The idea is to find surfactants that spontaneously form molecular structures or assemblies in the liquid that prevent particle agglomeration, sedimentation, or both. The researchers are examining a broad array of surfactant-particle systems and determining the characteristics of the system that prevent agglomeration. The results will help enable process engineers in such industrial areas as paints and inks, pharmaceuticals, and cosmetics to design products that remain stable and maintain their beneficial properties over long periods of time. The project also involves students at all academic levels, including high school students, especially those from traditionally underrepresented groups, who are being recruited to participate in the project through Purdue's SEED program. The goal of this project is to screen, evaluate, and select surfactant dispersants for controlling agglomeration and sedimentation of suspended particles. The role of surfactant molecular structure on the formation of assemblies such as micelles and vesicles that can inhibit agglomeration and sedimentation of particles is being investigated. A broad array of surfactants are being examined including single and double hydrocarbon chains connected to single and double polar head groups. Anionic, cationic, and nonionic surfactants with carbon chain lengths from 8 to 16 are being studied. Characteristics of the particles, such as size, composition, density and concentration, is also being included in the study. Agglomerate size is being determined by dynamic light scattering and spectroturbidimetry, and changes in rheological properties are being measured using a constant stress rheometer. Cryo-transmission electron microscopy is being used when appropriate to characterize vesicle and particle structures. Computational studies using Brownian Dynamics and Stochastic Dynamics simulations are being carried out to identify mechanisms of suspension stabilization.