Theory of Polymer Crystallization

该奖项支持理论研究和教育，旨在通过采用模拟技术和统计力学来发展聚合物结晶和定向聚合物组装的理论。聚合物从溶液和熔体中结晶是聚合物科学长期研究的领域之一。聚合物链如何组织成层次结构的基本理解仍然难以捉摸。柔性聚合物分子的构象熵使聚合物的结晶现象区别于小分子体系的有序现象。相同的熵方面的聚合物表现在各种定向组装的二嵌段共聚物和生物聚合物。PI以前的工作是解决构象熵的影响，导致了解释聚合物结晶丰富现象学的新方法。这些是对文献中传统观点的补充，传统观点基本上忽略了构象熵。该奖项支持的研究将建立在最近的新想法，以探索聚合物的几个相关的有序现象。具体来说，(a)聚合物球粒中的片层形态，(b)聚合物溶液和熔体中的生长前沿动力学，以及(c)聚合物的定向组装将被解决。该项目旨在建立新的概念模型并发现聚合物组装的新规律。提出的理论工作补充了世界各地实验室正在积极进行的实验研究。该奖项支持综合计算和理论研究和教育，旨在了解聚合物，由许多较小的重复分子单元组成的大长链分子如何组织成有序状态。特别有趣的是它们是如何结晶的。长链分子扭曲和弯曲的多种方式使得聚合物的结晶过程不同于许多其他材料。PI将使用计算机模拟，并以他自己和其他人之前的工作为基础，发展对聚合物结晶的理解。这项研究的结果可能会对许多应用领域产生影响，例如聚合物加工，聚合物材料的制造，尺寸缩小到比人类头发小一万倍，以及分子和其他材料的“构建块”自行组装形成生物结构和生命物质的过程。许多（如果不是大多数的话）现代材料都是由加工过的半结晶聚合物制成的，这也是本文提出的理论和模型研究的主题。对这类重要材料行为的基本理解将有助于设计和加工新型聚合物材料，为我们的社会带来更大的利益。这项活动为研究生在这一具有挑战性的研究领域的培训和21世纪的劳动力提供了支持。

TECHNICAL SUMMARYThis award supports theoretical research and education with an aim to develop theories of polymer crystallization and directed polymer assembly, by employing simulation techniques and statistical mechanics. Crystallization of polymers from solutions and melts is one of the longstanding research areas in polymer science. A fundamental understanding of how polymer chains organize into hierarchical structures remains elusive. The conformational entropy of flexible polymer molecules makes the crystallization phenomenon of polymers distinct from ordering of small molecular systems. The same entropic aspects of polymers are manifest in various directed assemblies of diblock copolymers and biological polymers. Previous work by the PI to address the effects of the conformational entropy has resulted in novel ways of interpreting the rich phenomenology of polymer crystallization. These are complementary to the traditional arguments in the literature, which essentially ignore the conformational entropy. This award supports research that will build on recent new ideas to explore several related ordering phenomena of polymers. Specifically, (a) lamellar morphology in polymeric spherulites, (b) kinetics of growth fronts in polymer solutions and melts, and (c) directed assembly of polymers will be addressed. This project is aimed at building new conceptual models and discovering new laws of polymer assembly. The proposed theoretical work complements experimental investigations being actively pursued in laboratories worldwide.NON-TECHNICAL SUMMARYThis award supports integrated computational and theoretical research and education aimed to understand how, polymers, large long-chain molecules made of many smaller repeating molecular units, organize into ordered states. Of particular interest is how they crystallize. The many ways long-chain molecules can twist and bend makes the crystallization process of polymers distinct from that of many other materials. The PI will use computer simulations and build on previous work, his own and that of others, to develop an understanding of polymer crystallization. The results of this research may have impact in numerous applied areas such as polymer processing, the fabrication of polymeric materials down to scales some ten thousand times smaller than a human hair, and the process by which molecules and other 'building blocks' of materials assemble themselves to form biological structures and living matter. Many, if not most, modern materials are made from processed semicrystalline polymers, which are the subjects of the proposed theoretical and modeling investigation. A fundamental understanding of the behavior of this important class of materials will help to design and process novel polymeric materials with enhanced benefits to our society. This activity provides support for training of graduate students in this challenging research area and the workforce of the twenty first century.