Aggregation of collapsed copolymer chains consisting of flexible and semi-flexible segments: A flat histogram Monte Carlo simulation

柔性与刚度的结合是自然界中一个强有力的设计原则，在材料科学中也越来越受到重视。虽然在自组装稳定型共聚物分子的合成方面取得了重大进展，但对这些分子聚集过程的统计力学理解仍处于起步阶段。在我们项目的框架内，我们研究了具有柔性和刚性组分的聚合物系统的热力学和相行为，特别强调了可用于设计分层结构材料的策略。相位行为通过先进的平面直方图蒙特卡罗方法进行研究，如随机逼近蒙特卡罗抽样（Wang-Landau抽样的最新推广），结合典型/微典型分析以及拓扑分析。在之前的联合项目中，我们研究了这种共聚物的单链行为，而在目前提出的项目中，将研究几种柔性-半柔性共聚物链在稀溶液中的聚集。我们的目标是确定能够以形状持久的方式聚集的单链形态，从而允许合理设计聚集（超分子）架构。我们还想知道，在没有特定的相互作用（如氢键）的情况下，这种聚集在多大程度上是稳定的，而这种相互作用在生物聚合物中稳定了这种结构。

Combining flexibility with stiffness is a powerful design principle in nature and increasingly also in materials science. While significant progress has been made in the synthesis of self-assembling form-stable copolymer molecules, the statistical mechanical understanding of aggregation processes of these molecules is still in its infancy. Within the framework of our project we investigate the thermodynamics and the phase behavior of polymeric systems with flexible and stiff components with special emphasis on strategies that can be used to design hierarchically structured materials. The phase behavior is investigated by advanced flat histogram Monte Carlo methods such as Stochastic Approximation Monte Carlo sampling (a recent generalization of Wang-Landau sampling) together with a combined canonical/micro-canonical analysis as well as a topological analysis. In a previous joint project we investigated the single-chain behavior of such copolymers, whereas in the present proposed project the study of aggregation of several flexible-semiflexible copolymer chains in dilute solution will be performed. Our aim is to identify single chain morphologies which are able to aggregate in a shape-persistent fashion, allowing for a rational design of aggregated (supra-molecular) architectures. We also want to learn to which degree such aggregation is stable without the presence of specific interactions (like, e.g. hydrogen bonding) which stabilize such structures in biopolymers.