纳米颗粒对聚合物链及其缠结网络动力学的影响。

Nanoparticle effect on the dynamics of polymer chains and their entanglement network.

机构信息

Department of Mechanical Engineering, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208-0311, USA.

出版信息

Phys Rev Lett. 2012 Sep 14;109(11):118001. doi: 10.1103/PhysRevLett.109.118001. Epub 2012 Sep 13.

DOI:10.1103/PhysRevLett.109.118001

Abstract

We explore the dynamics of entangled polymer chains embedded into nanocomposites. From primitive path analysis, highly entangled polymer chains are found to be significantly disentangled during increment of the volume fraction of spherical nonattractive nanoparticles (NPs) from 0 to 42%. A critical volume fraction, ϕ(c)=31%, is found to control the crossover from polymer chain entanglements to "NP entanglements." While below ϕ(c), the polymer chain relaxation accelerates upon filling, above ϕ(c), the situation reverses: polymer dynamics becomes geometrically constrained upon adding NPs. Our findings provide a microscopic understanding of the dynamics of entangled polymer chains inside their composites, and offer an explanation for the unusual rheological properties of polymer composites.

摘要

我们探究了嵌入纳米复合材料中的缠结聚合物链的动力学。通过原始路径分析，发现当球形无吸引力纳米粒子（NPs）的体积分数从 0 增加到 42%时，高度缠结的聚合物链会显著解缠。发现一个临界体积分数ϕ(c)=31%，控制着从聚合物链缠结到“NP 缠结”的转变。在ϕ(c)以下，聚合物链的松弛在填充时会加速，在ϕ(c)以上，情况则相反：在添加 NPs 时，聚合物的动力学会受到几何限制。我们的发现提供了对聚合物链在其复合材料中的动力学的微观理解，并为聚合物复合材料的异常流变性质提供了解释。