Al Harraq Ahmed, Hymel Aubry A, Lin Emily, Truskett Thomas M, Bharti Bhuvnesh
Cain Department of Chemical Engineering, Louisiana State University, Baton Rouge, LA, 70803, USA.
McKetta Department of Chemical Engineering, University of Texas at Austin, Austin, TX, 78712, USA.
Commun Chem. 2022 Jun 9;5(1):72. doi: 10.1038/s42004-022-00687-3.
Competition between attractive and repulsive interactions drives the formation of complex phases in colloidal suspensions. A major experimental challenge lies in decoupling independent roles of attractive and repulsive forces in governing the equilibrium morphology and long-range spatial distribution of assemblies. Here, we uncover the 'dual nature' of magnetic nanoparticle dispersions, particulate and continuous, enabling control of the short-range attraction and long-range repulsion (SALR) between suspended microparticles. We show that non-magnetic microparticles suspended in an aqueous magnetic nanoparticle dispersion simultaneously experience a short-range depletion attraction due to the particulate nature of the fluid in competition with an in situ tunable long-range magnetic dipolar repulsion attributed to the continuous nature of the fluid. The study presents an experimental platform for achieving in situ control over SALR between colloids leading to the formation of reconfigurable structures of unusual morphologies, which are not obtained using external fields or depletion interactions alone.
吸引力与排斥力之间的竞争驱动了胶体悬浮液中复杂相的形成。一个主要的实验挑战在于区分吸引力和排斥力在控制聚集体的平衡形态和长程空间分布方面的独立作用。在这里，我们揭示了磁性纳米颗粒分散体的“双重性质”，即颗粒性和连续性，从而能够控制悬浮微粒之间的短程吸引力和长程排斥力（SALR）。我们表明，悬浮在水性磁性纳米颗粒分散体中的非磁性微粒同时经历了由于流体的颗粒性质而产生的短程耗尽吸引力，以及与流体的连续性质相关的原位可调长程磁偶极排斥力。该研究提供了一个实验平台，用于实现对胶体之间SALR的原位控制，从而导致形成具有不寻常形态的可重构结构，而仅使用外部场或耗尽相互作用是无法获得这些结构的。
