Cao Xue-Zheng, Merlitz Holger, Wu Chen-Xu
Department of Physics, Zhejiang Sci-Tech University , Hangzhou 310018, P. R. China.
Department of Chemistry, University of North Carolina , Chapel Hill, North Carolina 27599, United States.
J Phys Chem Lett. 2017 Jun 15;8(12):2629-2633. doi: 10.1021/acs.jpclett.7b01049. Epub 2017 May 31.
Controlling the nanoparticle (NP) diffusion in polymers is a prerequisite to obtain polymer nanocomposites (PNCs) with desired dynamical and rheological properties and to achieve targeted delivery of nanomedicine in biological systems. Here we determine the suppression mechanism of direct NP-polymer attraction to hamper the NP mobility in adsorbing polymers and then quantify the dependence of the effective viscosity η felt by the NP on the adsorption duration τ of polymers on the NP using scaling theory analysis and molecular dynamics simulations. We propose and confirm that participation of adsorbed chains in the NP motion break up at time intervals beyond τ due to the rearrangement of polymer segments at the NP surface, which accounts for the onset of Fickian NP diffusion on a time scale of t ≈ τ. We develop a power law, η ∼ (τ), where ν is the scaling exponent of the dependence of polymer coil size on the chain length, which leads to a theoretical basis for the design of PNCs and nanomedicine with desired applications through tuning the polymer adsorption duration.
控制纳米颗粒（NP）在聚合物中的扩散是获得具有所需动态和流变特性的聚合物纳米复合材料（PNC）以及在生物系统中实现纳米药物靶向递送的先决条件。在此，我们确定了直接的NP-聚合物吸引力的抑制机制，以阻碍NP在吸附聚合物中的迁移率，然后使用标度理论分析和分子动力学模拟，量化NP感受到的有效粘度η对聚合物在NP上的吸附持续时间τ的依赖性。我们提出并证实，由于NP表面聚合物链段的重排，吸附链对NP运动的参与在超过τ的时间间隔内中断，这解释了在时间尺度t≈τ上菲克NP扩散的开始。我们推导出一个幂律，η ∼ (τ)，其中ν是聚合物线圈尺寸对链长依赖性的标度指数，这为通过调整聚合物吸附持续时间来设计具有所需应用的PNC和纳米药物提供了理论基础。
