Magnetic field enabled in situ control over the structure and dynamics of colloids interacting via SALR potentials
Magnetic field enabled in situ control over the structure and dynamics of colloids interacting via SALR potentials
复制标题
磁场能够原位控制通过 SALR 电位相互作用的胶体的结构和动力学
DOI：
10.1039/d3sm00354j
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发表时间：
2023
期刊：
影响因子：
3.4
通讯作者：
Bharti, Bhuvnesh
中科院分区：
文献类型：
--
作者：
Gauri, Hashir M.;Sherman, Zachary M.;Al Harraq, Ahmed;Truskett, Thomas M.;Bharti, Bhuvnesh
胶体悬浮液是研究结晶、成核和玻璃化转变机制的理想模型，因为它可以通过改变颗粒的形状、电荷或体积分数来精确控制颗粒间的相互作用。然而，这些调整参数对粒子间相互作用和组装结构的可重构性提供的主动控制不足。对粒子间相互作用的动态控制可以通过应用非接触和化学惰性的外部磁场来获得。在这项工作中，我们展示了磁性纳米颗粒分散的双重性质，以利用外部磁场编程悬浮非磁性微球之间的相互作用。纳米颗粒分散体在微尺度上表现为连续的磁性介质，在纳米尺度上表现为由单个颗粒组成的离散介质。这使得可以控制耗尽吸引势和引入磁排斥势，通过施加外部磁场，允许在富相图中胶体结构的可逆转变。对竞争相互作用的主动控制使我们能够创建一个包含一系列状态的模型系统，从大型分形簇到低密度维格纳玻璃状态。监测胶体颗粒的动力学揭示了动态非均匀性和与接近维格纳玻璃状态相关的显著减速。
Colloidal suspensions are an ideal model for studying crystallization, nucleation, and glass transition mechanisms, due to the precise control of interparticle interactions by changing the shape, charge, or volume fraction of particles. However, these tuning parameters offer insufficient active control over interparticle interactions and reconfigurability of assembled structures. Dynamic control over the interparticle interactions can be obtained through the application of external magnetic fields that are contactless and chemically inert. In this work, we demonstrate the dual nature of magnetic nanoparticle dispersions to program interactions between suspended nonmagnetic microspheres using an external magnetic field. The nanoparticle dispersion simultaneously behaves as a continuous magnetic medium at the microscale and a discrete medium composed of individual particles at the nanoscale. This enables control over a depletion attractive potential and the introduction of a magnetic repulsive potential, allowing a reversible transition of colloidal structures within a rich phase diagram by applying an external magnetic field. Active control over competing interactions allows us to create a model system encompassing a range of states, from large fractal clusters to low-density Wigner glass states. Monitoring the dynamics of colloidal particles reveals dynamic heterogeneity and a marked slowdown associated with approaching the Wigner glass state.