Dynamics of Nanoparticles in Entangled Polymer Solutions.
Dynamics of Nanoparticles in Entangled Polymer Solutions.
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DOI：
10.1021/acs.langmuir.7b03418
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发表时间：
2018-01
期刊：
影响因子：
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通讯作者：
Pooja Nath;R. Mangal;Ferdinand F. E. Kohle;Snehashis Choudhury;S. Narayanan;Ulrich B Wiesner;L. Archer
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文献类型：
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作者：
Pooja Nath;R. Mangal;Ferdinand F. E. Kohle;Snehashis Choudhury;S. Narayanan;Ulrich B Wiesner;L. Archer
纳米粒子探针分散在简单的各向同性液体和聚合物溶液中的均方位移ε r2 ε询问使用荧光相关光谱和单粒子跟踪（SPT）实验。探针动力学在不同制度的颗粒直径（d），相对于特征聚合物的长度尺度，包括相关长度（λ），缠结网格尺寸（a），和回转半径（Rg），进行了研究。在简单的流体和聚合物溶液中，其中d = Rg，长时间粒子动力学服从随机游走统计，聚合物溶液的体积零剪切粘度决定了对粒子运动的摩擦阻力。与此相反，在聚合物溶液中与DA，纳米粒子动力学过渡从扩散到subdiffusive在很长的时间尺度上，让人想起在一个领域的颗粒运输障碍。这最后一个发现是在纠缠聚合物熔体中观察到的纳米粒子动力学，其中X射线光子相关光谱测量揭示更快，但hyperdiffusive动态形成鲜明对比。我们分析了这些结果的帮助下，由蔡等人提出的聚合物中的粒子动力学的跳跃模型，并在此基础上，讨论了纠缠聚合物溶液中的纳米粒子所经历的局部阻力的物理起源。
The mean square displacement ⟨r2⟩ of nanoparticle probes dispersed in simple isotropic liquids and in polymer solutions is interrogated using fluorescence correlation spectroscopy and single-particle tracking (SPT) experiments. Probe dynamics in different regimes of particle diameter (d), relative to characteristic polymer length scales, including the correlation length (ξ), the entanglement mesh size (a), and the radius of gyration (Rg), are investigated. In simple fluids and for polymer solutions in which d ≫ Rg, long-time particle dynamics obey random-walk statistics ⟨r2⟩:t, with the bulk zero-shear viscosity of the polymer solution determining the frictional resistance to particle motion. In contrast, in polymer solutions with d a, nanoparticle dynamics transition from diffusive to subdiffusive on long timescales, reminiscent of particle transport in a field with obstructions. This last finding is in stark contrast to the nanoparticle dynamics observed in entangled polymer melts, where X-ray photon correlation spectroscopy measurements reveal faster but hyperdiffusive dynamics. We analyze these results with the help of the hopping model for particle dynamics in polymers proposed by Cai et al. and, on that basis, discuss the physical origins of the local drag experienced by the nanoparticles in entangled polymer solutions.