Theory of Polymer Crystallization and Melting

非技术总结该奖项支持关于链状分子或聚合物结晶长度的理论和计算研究和教育。考虑一组缠绕在一起的电线，并考虑将它们组织成有序的晶体。然而，这种看似困难的任务在现实世界中自然而容易地发生，即使是对于最简单的聚合物，如聚乙烯。事实上，今天的大多数材料都是由这种半结晶聚合物制成的，这构成了一个数十亿美元的产业。了解聚合物的结晶过程是材料领域长期面临的研究挑战之一，这主要是由于聚合物分子在形成晶体之前的随机构型。因此，聚合物结晶现象具有挑战性，几乎没有统一的概念主题。这项研究计划旨在开发基本概念，以了解聚合物是如何结晶和熔化的，使用理论和模型。对这类重要材料行为的基本了解将有助于设计和加工具有更大社会效益的新型聚合物材料。该项目包括在这一具有巨大社会价值的具有挑战性的研究领域培训研究生。技术总结该奖项支持有关聚合物结晶的理论和计算研究和教育。聚合物从溶液和熔体中结晶是聚合物科学中一个由来已久的研究领域，具有巨大的工业价值，充满了阴谋，但没有统一的概念主题。对聚合物链如何组织成分层晶体结构的基本理解仍然难以捉摸。柔性聚合物分子最重要的天赋是它们的构象熵。这一属性使聚合物的结晶和熔融行为有别于小分子体系的其他有序化现象。这项研究的目的是通过考虑高分子链的构象熵和非平衡条件下的拓扑缺陷来发展聚合物结晶和熔融的基本概念。主要研究人员将运用统计力学、场论和各种模拟技术来发展聚合物结晶和熔融的新理论。更具体地说，该研究项目将研究(A)单晶形态--驱动片层中扇形化的拓扑缺陷以及扁片、中空金字塔、涡卷和扭曲片层的相对稳定性，(B)聚合物晶体的熔融和重结晶动力学，以及(C)聚合物结晶中熔体记忆的大分子起源。该研究计划的结果可能对聚烯烃数十亿美元的行业以及许多应用领域产生影响，如聚合物加工和聚合物纳米材料的制造。在这一具有挑战性的研究领域对研究生进行培训是该研究计划的一个重要教育组成部分。

NONTECHNICAL SUMMARYThis award supports theoretical and computational research and education on how long chain-like molecules or polymers, crystallize. Consider a collection of tangled wires and think about organizing them into well-ordered crystals. Such a seemingly difficult task, however, occurs naturally and readily in the real world even for the simplest polymers such as polyethylenes. In fact, most of the materials today are made from such semicrystalline polymers, which constitute a multi-billion-dollar industry. An understanding of the crystallization process of polymers is one of the longstanding research challenges in the materials world, primarily due to the haphazard and random configurations of the polymer molecules before they organize into crystals. As a result, the phenomenon of polymer crystallization is challenging with few unifying conceptual themes. This research program is geared towards development of fundamental concepts to understand how polymers crystallize and melt, using theory and modelling. A fundamental understanding of the behaviours of this important class of materials will help to design and process novel polymeric materials with enhanced benefits to our society. This project includes training graduate students in this challenging research area of tremendous societal value.TECHNICAL SUMMARYThis award supports theoretical and computational research and education on how polymers crystallize. Crystallization of polymers from solutions and melts is one of the longstanding research areas in polymer science with tremendous industrial value, full of intrigue without unifying conceptual themes. A fundamental understanding of how polymer chains organize into hierarchical crystalline structures remains elusive. The most significant endowment of flexible polymer molecules is their conformational entropy. This attribute sets the crystallization and melting behaviours of polymers to be distinct from other ordering phenomena of small molecular systems. This research project is aimed to develop fundamental concepts behind polymer crystallization and melting, by accounting for conformation entropy of polymer chains and topological defects under non-equilibrium conditions. The principal investigator will employ statistical mechanics, field theory, and various simulation techniques in the development of new theories of polymer crystallization and melting. More specifically, the research project will address (a) single crystal morphology - topological defects driving sectorization in lamellae and relative stabilities of flat lamellae, hollow pyramids, scrolls, and twisted lamellae, (b) kinetics of melting and recrystallization of polymer crystals, and (c) macromolecular origin of melt-memory in polymer crystallization.The results from the research program may have impact in the multi-billion-dollar industry of polyolefins and also in numerous applied areas such as polymer processing, and fabrication of polymeric nanomaterials. Training graduate students in this challenging research area is a strong educational component of the research program.