Melts of supra-molecular polymers: A study of their thermodynamics, structure and dynamics by Monte Carlo simulations

本项目主要研究基于氢键作用的超分子聚合物熔体的热力学、结构和动力学。当人们将这些聚合物基于具有头-尾结合基序的线性前体时，熔体的性质将取决于所得的链长分布以及熔体中存在的环的分数和长度分布。此外，分支的可能性对聚集统计的影响需要探讨。实验结果表明，熔体聚集并不总是可以推断出在溶液中的聚集行为，也存在到目前为止，理论上只有有限的理解，在这些系统中的聚集统计。通过采用先进的Wang-Landau Monte Carlo模拟，我们将确定超分子聚乙二醇（PEG）和聚丁二醇（PBG）熔体的简单模型的平衡行为，这也是由Ana Brás博士从Forschungszentrum Jülich申请的平行实验项目中研究的。我们还将在选定的状态点对这些系统进行动态Monte Carlo模拟，以研究它们的弛豫行为，并将其与动态实验（中子散射，介电谱和核磁共振实验）进行比较。

In this project we will study the thermodynamics, structure and dynamics of melts of supra-molecular polymers based on hydrogen bonding. When one bases these polymers on linear precursors with a head-tail binding motif, the properties of the melt will depend on the resulting chain length distribution and the fraction and length distribution of rings present in the melt. Also, the effects of branching possibility on the aggregation statistics need to be explored. Experimental results indicate that melt aggregation can not always be inferred from the aggregation behavior in solution, and also theoretically there exists so far only a limited understanding of the aggregation statistics in these systems. By employing advanced Wang-Landau Monte Carlo simulations we will determine the equilibrium behavior of simple models for supra-molecular polyethylene-glycol (PEG) and polybutylene-glycol (PBG) melts, which are also studied in a parallel experimental project applied for by Dr. Ana Brás from the Forschungszentrum Jülich. We will furthermore perform dynamic Monte Carlo simulations of these systems at selected state points to study their relaxation behavior and compare these the dynamic experiments (neutron scattering, dielectric spectroscopy and nuclear magnetic resonance experiments).