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Coupling of Nanoparticle Dynamics to Polymer Center-of-Mass Motion in Semidilute Polymer Solutions
Macromolecules ( IF 5.1 ) Pub Date : 2018-02-22 00:00:00 , DOI: 10.1021/acs.macromol.7b02441
Renjie Chen 1 , Ryan Poling-Skutvik 1 , Arash Nikoubashman 2 , Michael P. Howard 3 , Jacinta C. Conrad 1 , Jeremy C. Palmer 1
Affiliation  

We investigate the dynamics of nanoparticles in semidilute polymer solutions when the nanoparticles are comparably sized to the polymer coils using explicit- and implicit-solvent simulation methods. The nanoparticle dynamics are subdiffusive on short time scales before transitioning to diffusive motion on long time scales. The long-time diffusivities scale according to theoretical predictions based on full dynamic coupling to the polymer segmental relaxations. In agreement with our recent experiments, however, we observe that the nanoparticle subdiffusive exponents are significantly larger than predicted by the coupling theory over a broad range of polymer concentrations. We attribute this discrepancy in the subdiffusive regime to the presence of an additional coupling mechanism between the nanoparticle dynamics and the polymer center-of-mass motion, which differs from the polymer relaxations that control the long-time diffusion. This coupling is retained even in the absence of many-body hydrodynamic interactions when the long-time dynamics of the colloids and polymers are matched.

中文翻译:

半稀释聚合物溶液中纳米粒子动力学与聚合物质心运动的耦合

当使用显式和隐式溶剂模拟方法将纳米粒子的尺寸与聚合物线圈进行比较时,我们研究了半稀释聚合物溶液中纳米粒子的动力学。纳米粒子动力学在短时间尺度上是亚扩散的,然后过渡到长时间尺度上的扩散运动。长期扩散率根据基于与聚合物链段弛豫的完全动态耦合的理论预测进行缩放。然而,与我们最近的实验一致,我们观察到在较大的聚合物浓度范围内,纳米粒子的亚扩散指数显着大于偶联理论所预测的指数。我们将这种差异归因于亚扩散机制的存在,这是由于纳米粒子动力学与聚合物质心运动之间存在附加的耦合机制,这与控制长时间扩散的聚合物弛豫不同。当胶体和聚合物的长期动力学相匹配时,即使在没有多体流体动力学相互作用的情况下,也可以保持这种偶联。
更新日期:2018-02-22
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