Tracer Transport Probes Relaxation and Structure of Attractive and Repulsive Glassy Liquids
Tracer Transport Probes Relaxation and Structure of Attractive and Repulsive Glassy Liquids
复制标题
示踪输运探测吸引和排斥玻璃状液体的弛豫和结构
DOI：
10.1021/acs.jpclett.8b01074
复制
发表时间：
2018
期刊：
影响因子：
--
通讯作者：
Conrad, Jacinta C.
中科院分区：
文献类型：
--
作者：
Roberts, Ryan C.;Poling-Skutvik, Ryan;Palmer, Jeremy C.;Conrad, Jacinta C.
小渗透剂与拥挤细胞、过冷液体和聚合物基质内缓慢、协同松弛的动态耦合对于从药物输送到纳米复合材料加工等应用具有广泛的影响。这些介质和其他无序介质的成分之间的相互作用改变了合作弛豫，但它们对渗透动力学的影响仍不完全清楚。我们使用分子动力学模拟来表明，硬球示踪粒子的运动可探测具有相同堆积分数和长时间扩散率的吸引和排斥玻璃状液体基质中局部结构和协同弛豫过程的差异。示踪剂动力学与每个矩阵中的集体弛豫的耦合会影响示踪剂轨迹的形状，示踪剂轨迹在排斥矩阵内是分形的，而在吸引矩阵中则更加紧凑。这些结果表明，弛豫结构控制着协同弛豫系统中的渗透剂传输和色散，并提供了对玻璃液体内动力学异质性的深入了解。
Dynamic coupling of small penetrants to slow, cooperative relaxations within crowded cells, supercooled liquids, and polymer matrices has broad consequences for applications ranging from drug delivery to nanocomposite processing. Interactions between the constituents of these and other disordered media alter the cooperative relaxations, but their effect on penetrant dynamics remains incompletely understood. We use molecular dynamics simulations to show that the motions of hard-sphere tracer particles probe differences in local structure and cooperative relaxation processes in attractive and repulsive glassy liquid matrices with equal bulk packing fractions and long-time diffusivities. Coupling of the tracer dynamics to collective relaxations in each matrix affects the shape of tracer trajectories, which are fractal within the repulsive matrix and more compact in the attractive. These results reveal that the structure of relaxations controls penetrant transport and dispersion in cooperatively relaxing systems and provide insight into dynamical heterogeneity within glassy liquids.