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Curved colloidal crystals of discoids at near-critical liquid–liquid interface
Soft Matter ( IF 3.4 ) Pub Date : 2021-07-06 , DOI: 10.1039/d1sm00765c Ashis Mukhopadhyay 1
Soft Matter ( IF 3.4 ) Pub Date : 2021-07-06 , DOI: 10.1039/d1sm00765c Ashis Mukhopadhyay 1
Affiliation
The assembly of disc-shaped particles at curved liquid–liquid interfaces was studied by using confocal microscopy. The interface is formed by a phase-separating critical liquid mixture of 2,6-lutidine and heavy water, where the colloids spontaneously assembled forming a dome. The novelty of this system is three-fold. First, the domes can be constructed and annihilated remotely and reversibly, which allows dynamic control of the colloidal assembly. Second, the effect of curvature can be investigated by analyzing domes of different radii ranging from 5 μm to 125 μm. Third, the slow dynamics due to hydrodynamic interaction among the particles can be utilized to investigate the time-evolution of defect morphology. Unlike the widely studied repulsive colloids, the interparticle potential near the critical point has an attractive component. I contrasted the packing and defects morphology of a solid-like and liquid-like dome differing in particle number density. In the solid-like dome, a chain of 5- and 7-fold coordinated particles was observed. The analysis of trajectories showed that particles were bound in a potential well of a depth of about ten times the thermal energy, which matched well with the calculation of the pair-potential by considering the attractive critical Casimir force among the particles. In the liquid-like dome, 6-fold particles separated by clusters of 5- and 7-coordinated particles were observed, which is suggestive of liquid–solid coexistence. The uniqueness of this system will open up a new research avenue to investigate the effect of varying curvature on the crystallization, defects, and phase diagram of colloidal assemblies.
中文翻译:
近临界液-液界面处的盘状弯曲胶体晶体
通过使用共聚焦显微镜研究了圆盘状颗粒在弯曲的液-液界面处的组装。界面由 2,6-二甲基吡啶和重水的相分离临界液体混合物形成,其中胶体自发组装形成圆顶。该系统的新颖性体现在三方面。首先,圆顶可以远程和可逆地建造和消灭,这允许对胶体组件进行动态控制。其次,可以通过分析从 5 μm 到 125 μm 的不同半径的圆顶来研究曲率的影响。第三,由于粒子之间的流体动力学相互作用导致的缓慢动力学可用于研究缺陷形态的时间演变。与广泛研究的排斥胶体不同,临界点附近的粒子间电位具有有吸引力的成分。我对比了颗粒数密度不同的固体状和液体状圆顶的堆积和缺陷形态。在类似固体的圆顶中,观察到了 5 倍和 7 倍配位粒子链。轨迹分析表明,粒子被束缚在深度约为热能十倍的势阱中,这与考虑粒子之间的吸引力临界卡西米尔力计算的对势的计算非常吻合。在类似液体的圆顶中,观察到由 5 和 7 配位粒子簇分隔的 6 重粒子,这表明液固共存。该系统的独特性将为研究不同曲率对胶体组件的结晶、缺陷和相图的影响开辟一条新的研究途径。
更新日期:2021-07-12
中文翻译:
近临界液-液界面处的盘状弯曲胶体晶体
通过使用共聚焦显微镜研究了圆盘状颗粒在弯曲的液-液界面处的组装。界面由 2,6-二甲基吡啶和重水的相分离临界液体混合物形成,其中胶体自发组装形成圆顶。该系统的新颖性体现在三方面。首先,圆顶可以远程和可逆地建造和消灭,这允许对胶体组件进行动态控制。其次,可以通过分析从 5 μm 到 125 μm 的不同半径的圆顶来研究曲率的影响。第三,由于粒子之间的流体动力学相互作用导致的缓慢动力学可用于研究缺陷形态的时间演变。与广泛研究的排斥胶体不同,临界点附近的粒子间电位具有有吸引力的成分。我对比了颗粒数密度不同的固体状和液体状圆顶的堆积和缺陷形态。在类似固体的圆顶中,观察到了 5 倍和 7 倍配位粒子链。轨迹分析表明,粒子被束缚在深度约为热能十倍的势阱中,这与考虑粒子之间的吸引力临界卡西米尔力计算的对势的计算非常吻合。在类似液体的圆顶中,观察到由 5 和 7 配位粒子簇分隔的 6 重粒子,这表明液固共存。该系统的独特性将为研究不同曲率对胶体组件的结晶、缺陷和相图的影响开辟一条新的研究途径。