Department of Materials Science and Engineering, Rensselaer Polytechnic Institute , Troy, New York 12180, United States.
Langmuir. 2017 Oct 24;33(42):11845-11850. doi: 10.1021/acs.langmuir.7b02901. Epub 2017 Oct 2.
We conducted molecular dynamics (MD) simulations to study how solvent chains affect the diffusion of linear polymers in the unentangled regime. For monodisperse solvent chains, the self-diffusivity of a tagged chain scales with its chain length. The solvent chain length affects both the prefactor and the exponent, the latter of which ranges from -0.79 to -0.85. The scaling exponent here deviates from -1 as predicted by the Rouse model, which may suggest that the friction coefficient increases with the solvent chain length. In addition, we carried out diffusion simulations on two polydisperse melts, one with the Flory-Schulz distribution and the other with the Gaussian distribution. The measured diffusivity as a function of the tagged chain length agrees with a simple proposed model accounting for the heterogeneous medium.
我们进行了分子动力学（MD）模拟，以研究溶剂链如何影响无缠结状态下线性聚合物的扩散。对于单分散溶剂链，标记链的自扩散系数与其链长成正比。溶剂链长影响前因子和指数，后者的范围为-0.79 至-0.85。此处的标度指数偏离了 Rouse 模型预测的-1，这可能表明摩擦系数随溶剂链长增加而增加。此外，我们对两种多分散熔体进行了扩散模拟，一种是具有 Flory-Schulz 分布，另一种是具有高斯分布。标记链长度的测量扩散系数与一个简单的提出的模型一致，该模型考虑了非均相介质。
