MRI: Colloidal Characterization Capability through Combined DLS-ACS Analysis

该奖项来自主要研究仪器计划，资助在单个铁磁样品上建立一个集成的粒子属性分布测量系统。 胶体动力学是特别复杂的，当悬浮粒子之间的强相互作用可以压倒波动耗散和热化。 这个问题在铁磁流体中非常明显，在铁磁流体中，长程磁偶极相互作用会导致逐渐凝聚和失去所需的胶体特性。 一种特殊类型的铁磁流体被称为铁磁流体，其中特别制造的铁磁纳米颗粒悬浮在液晶基质中，由于其强磁光响应而越来越受欢迎。 亚铁离子的长期稳定性取决于表面活性剂的掺入，所述表面活性剂支持足够的电荷或空间效应以抵消颗粒间的磁吸引力。 正确的动力学表示的铁磁需要修改的数学动力学方程，以纳入粒子间的力量，并平均在整个合奏的粒子的物理，磁性和电气性能。 具有zeta电位能力的动态光散射用于确定颗粒尺寸和表面电荷，然后将该信息前馈到具有扫频能力的交流磁化率测量，该扫频能力表征颗粒磁性作为其物理尺寸的函数。 结合的分布，然后用于开发和验证先进的动力学模型，并评估胶体对凝聚和沉降的稳定性。非技术随着纳米粒子的科学和技术的发展，各类液体悬浮纳米粒子（胶体）被证明是特别重要的科学，工程和环境应用。 了解关键的纳米粒子参数，区分分散悬浮沉淀或团聚将导致上级类工程材料，如铁磁流体，纳米药物输送剂，生物燃料，以及改善环境的理解，在海洋和湖泊的水文流动。 主要研究仪器计划的这一奖项为建立一对互补的表征仪器提供资金。 第一种工具使用动态光散射（DLS）确定颗粒尺寸和表面电荷分布。 然后，该信息被前馈到磁性测量，AC磁化率（ACS），该测量利用相同的胶体样品并表征颗粒磁化强度分布和磁开关行为。 DLS还将用于研究水文沉积研究，如动力学密度和浊流。 除了胶体研究，化学，物理，大气和水文科学系的几个本科班将在他们的教学实验室中采用这些表征技术。

TechnicalThis award from the Major Research Instrumentation Program funds the establishment of an integrated particle property distribution measurements system on a single ferronematic sample. Colloid dynamics are particularly complex when strong interactions amongst the suspended particles can overwhelm the fluctuation-dissipation and thermalization. This problem is prominently manifest in ferrofluids where long range magnetic dipole interactions can lead to gradual agglomeration and loss of desirable colloidal characteristics. A particular class of ferrofluids known as ferronematics, where specially fabricated ferromagnetic nano-particles are suspended in liquid crystal host matrices, is gaining increasing popularity due to their strong magneto-optical response. Long term stability of ferronematics depend on the incorporation of surfactants that support sufficient electric charge or steric effects to counteract the inter-particle magnetic attraction. Proper dynamical representation of ferronematics requires that the mathematical dynamical equation be modified to incorporate the inter-particle forces and be averaged over the entire ensemble of particle physical, magnetic, and electric properties. Dynamic light scattering with zeta-potential capability is used to determine particle size and surface charge and then that information is fed forward to the ac susceptibility measurement with swept frequency capability that characterizes particle magnetics as a function of its physical dimension. The combined distributions are then used to develop and validate advanced dynamical models and to evaluate colloid stability against agglomeration and sedimentation.Non TechnicalAs the science and technology of nanoparticles evolve, various classes of liquid suspended nanoparticles (colloids) are proving to be of particular importance to science, engineering, and environmental applications. Understanding the critical nanoparticle parameters that differentiate dispersed suspension from sedimentation or agglomeration will lead to superior classes of engineered materials such as ferrofluids, nano-drug delivery agents, and biofuels, as well as improved environmental understanding of hydrologic flows in oceans and lakes. This award from the Major Research Instrumentation program funds the establishment of a complementary pair of characterization instruments. The first tool determines particle size and surface charge distributions using Dynamic Light Scattering (DLS). That information is then fed forward to a magnetic measurement, AC Susceptibility (ACS), that utilizes the same colloid sample and characterizes the particle magnetization distribution and magnetic switching behavior. DLS will also be used for studying hydrologic sedimentation research such as dynamics density and turbidity flows. In addition to colloidal research, several undergraduate classes in the departments of chemistry, physics, and atmospheric and hydrological sciences will incorporate these characterization techniques in their instructional laboratories.