Collaborative Research: Dynamic Clustering and Rheology of Magnetic Janus Particles with Shifted Dipoles

该项目的目标是设计流体的流动性，即，通过添加具有独特磁性的活性磁性颗粒，使流体易于流动。这些粒子可以通过外部磁场和内部化学梯度的组合来操纵。具有不同流动性的流体对于诸如打印机、流体减震器、流体特性传感器、生物医学设备和防弹衣等常见技术是重要的。对流动性的控制将使流体和装置的寿命更长、适用性更广、成本更低、稳定性更高。该研究将利用实验和计算技术研究活性磁性胶体的组装特性。这些研究的其他好处是创建了一个工具箱，用于设计具有特定应用的流动性的流体。 这项研究解决了需要深入了解的组装行为的主动磁性Janus粒子与移动偶极子。在具有偏移偶极子的系统中，磁偶极子轴偏移远离粒子的质心，从而提供对粒子取向和响应的额外控制。与机载推进相结合，具有移动偶极子的粒子代表了一类新的令人兴奋的活性材料。所描述的研究将推进我们对磁性粒子相互作用、活性物质和复杂磁性流体流变学的理解。这项工作将使未来的研究，例如，布朗动力学模拟用于预测长时间的动态，并发现新的结构，难以完成或检测实验。更广泛地说，提案中描述的研究将促进我们对复杂流体结构中力和扭矩的内在作用的理解，从而为失衡系统的统计物理学提供重要见解，并使研究人员能够更好地设计和利用微观体系中的许多身体动力学。该提案的教育目标将利用两个参与机构之间的合作环境，加强各个阶段的学生教育，从而加强STEM劳动力管道的多样性。

The goal of the project is to engineer the flowability of a fluid, i.e., the ease with which a fluid flows, by addition of active magnetic particles with unique magnetic properties. These particles can be manipulated by a combination of an external magnetic field and an internal chemical gradient. Fluids with varying flowability are important for common technologies, such as printers, fluid shock absorbers, fluid property sensors, biomedical devices, and body armor. Control of the flowability will enable longer lifetimes, broader applicability, reduced cost, and increased stability of the fluids and devices. The proposed research will investigate the assembly properties of active magnetic colloids using experimental and computational techniques. Additional benefits of these studies are the creation of a toolbox for the design of fluids that have their flowability tailored to a particular application. The research addresses the need for an in-depth understanding of the assembly behavior of active magnetic Janus particles with shifted dipoles. In systems with shifted dipoles, the magnetic dipole axis is shifted away from the center of mass of the particle, thereby providing additional control over particle orientation and response. In combination with on-board propulsion, particles with shifted dipoles represent a new and exciting class of active materials. The research described will advance our understanding of magnetic particle interaction, active matter, and the rheology of complex magnetic fluids. This work will enable future studies in which, for example, Brownian Dynamics simulations are used to predict long-time dynamics and to discover novel structures that are difficult to accomplish or detect experimentally. More broadly, research described in the proposal will advance our understanding of the intrinsic role of forces and torques in the structure of complex fluids, thus providing important insights into the statistical physics of out-of-equilibrium systems and enabling researchers to better engineer and utilize many body dynamics in the microscopic regime. The educational goals of this proposal will leverage the collaborative environment between the two participating institutions to enhance student education at various stages and thereby strengthen the diversity of the STEM workforce pipeline.