Hua Dao-Yang, Luo Meng-Bo
School of Physics, Zhejiang University, Hangzhou 310027, China.
Phys Chem Chem Phys. 2023 Oct 25;25(41):28252-28262. doi: 10.1039/d3cp03641c.
The diffusion of polymer chains in a crowded environment with large and small immobile, attractive nanoparticles (NPs) is studied using Langevin dynamics simulations. For orderly distributed NPs on the simple cubic lattice, our results show that the diffusion of polymer chains is dependent on the NP-NP distance or lattice distance . At low where NPs are placed closely, subdiffusion occurs at a sufficiently high polydispersity of NPs, PD. Both the apparent diffusion coefficient and subdiffusion exponent of polymer chains decrease with increasing PD, attributed to the adsorption of polymers on NP clusters formed by larger NPs. At large , normal diffusion is always observed, and the diffusion coefficient increases with increasing PD. The reason is that, at high PD, the difference between single large NP adsorption and double large NP adsorption is reduced, which increases the exchange of a polymer between the two adsorption states. Finally, the impact of size polydispersity of NPs on the diffusion of polymer chains in a crowded environment with randomly distributed NPs is also investigated. The results show that the position disorder of NPs enhances the subdiffusion of the system.
利用朗之万动力学模拟研究了聚合物链在存在大小不一、固定不动且具有吸引力的纳米颗粒（NP）的拥挤环境中的扩散情况。对于简单立方晶格上有序分布的NP，我们的结果表明聚合物链的扩散取决于NP - NP距离或晶格距离。在NP紧密排列的低间距情况下，当NP的多分散性（PD）足够高时会发生亚扩散。聚合物链的表观扩散系数和亚扩散指数均随PD的增加而降低，这归因于聚合物在由较大NP形成的NP簇上的吸附。在大间距情况下，总是观察到正常扩散，且扩散系数随PD的增加而增大。原因是，在高PD时，单个大NP吸附和双个大NP吸附之间的差异减小，这增加了聚合物在两种吸附状态之间的交换。最后，还研究了NP的尺寸多分散性对聚合物链在NP随机分布的拥挤环境中扩散的影响。结果表明，NP的位置无序增强了系统的亚扩散。
