Capillary Interaction and Self-Assembly of Tilted Magnetic Ellipsoidal Particles at Liquid Interfaces.
Capillary Interaction and Self-Assembly of Tilted Magnetic Ellipsoidal Particles at Liquid Interfaces.
复制标题
液体界面处倾斜磁性椭球粒子的毛细管相互作用和自组装。
DOI：
10.1021/acsomega.8b01818
复制
发表时间：
2018
期刊：
影响因子：
4.1
通讯作者：
Newton BJ
中科院分区：
文献类型：
--
作者：
Newton BJ
吸附在液体界面处的磁性椭圆体颗粒为产生可切换功能材料提供了令人兴奋的机会，其中可以使用外部场来打开和关闭自组装[Davies等人，高级材料，2014，26，6715]。为了更深入地了解这种新的系统在外场的存在下，我们研究了毛细管相互作用和自组装的倾斜椭球体使用分析理论和有限元模拟。我们推导了椭圆极坐标系中倾斜椭球体间偶极毛细相互作用的解析表达式，该表达式在远场表现出1/r2幂律依赖性（即，大颗粒分离SR）并正确地捕获近场中毛细管相互作用的取向依赖性。使用这种偶极子势和有限元模拟，我们进一步分析了由多达8个倾斜的椭球体接触的粒子簇的能量景观。对于两个粒子的团簇，我们发现侧到侧的配置是稳定的，而尖端到尖端的配置是不稳定的。然而，对于超过三个粒子的集群，我们发现，侧到侧粒子的圆形回路成为全局稳定，而侧到侧粒子的线性链成为亚稳态。此外，线性到回路过渡的能量势垒随着粒子数的增加而降低。我们的研究结果解释了为什么倾斜的椭球体组装侧到侧本地，但有很强的倾向，形成较大的长度尺度上的循环。
Magnetic ellipsoidal particles adsorbed at a liquid interface provide exciting opportunities for creating switchable functional materials, where self-assembly can be switched on and off using an external field [Davies et al.,Adv. Mater.,2014,26, 6715]. In order to gain a deeper understanding of this novel system in the presence of an external field, we study the capillary interaction and self-assembly of tilted ellipsoids using analytical theory and finite element simulations. We derive an analytical expression for the dipolar capillary interaction between tilted ellipsoids in elliptical polar coordinates, which exhibits a 1/r2power law dependence in the far field (i.e., large particle separationsr) and correctly captures the orientational dependence of the capillary interactions in the near field. Using this dipole potential and finite element simulations, we further analyze the energy landscape of particle clusters consisting of up to eight tilted ellipsoids in contact. For clusters of two particles, we find that the side-to-side configuration is stable, whereas the tip-to-tip configuration is unstable. However, for clusters of more than three particles, we find that circular loops of side-to-side particles become globally stable, whereas linear chains of side-to-side particles become metastable. Furthermore, the energy barrier for the linear-to-loop transition decreases with increasing particle number. Our results explain both thermodynamically and kinetically why tilted ellipsoids assemble side-to-side locally but have a strong tendency to form loops on larger length scales.