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

本课题将研究基于氢键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建立在具有首尾结合基序的线性前驱体上时，熔体的性质将取决于所得到的链长度分布以及熔体中存在的环的比例和长度分布。此外，还需要探索分支可能性对聚合统计的影响。实验结果表明，熔体聚集并不总是可以从溶液中的聚集行为推断出来，而且理论上对这些体系中的聚集统计量的理解也很有限。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，这也在Forschungszentrum j<e:1> lich的Ana博士Brás申请的平行实验项目中进行了研究。我们将进一步在选定的状态点对这些系统进行动态蒙特卡罗模拟，研究它们的弛豫行为，并将这些动态实验（中子散射、介电光谱和核磁共振实验）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).