CAREER: Using numerical simulation to investigate the influence of collective behaviors on the sequences of step-grown copolymers

聚合物是由许多称为单体的重复分子亚基连接在一起而形成的长分子链。共聚物是一类特殊的聚合物。它们是由两种（或更多）不同的单体制成的，根据单体的组合方式，共聚物可以表现出独特的性能。在生物共聚物中，如DNA和蛋白质，单体的序列是由细胞精确控制的。相比之下，在实验室中控制单体的序列仍然是一个重大挑战，这限制了合成共聚物的实用性。在大分子、超分子和纳米化学以及化学、结构动力学和机制A系的支持下，弗吉尼亚大学的DuBay教授正在使用计算机模拟来研究逐步生长的共聚物。DuBay教授和她的学生开发了一个计算机模型来模拟共聚物的生长。他们正在使用该模型来更好地理解决定单体序列的因素。从他们的研究中获得的见解可以实现更好的序列控制，这可能会影响从能量转换到水净化和药物输送的技术。该研究项目由一个由本科生和研究生组成的多元化团队进行，培训他们在化学工业中从事生产性职业。此外，下一代专业传播者被嵌入实验室，使他们能够更好地了解科学过程，并识别和报告突破性成果。最后，本项目的重点是提高当前大学生的科学信息素养，使他们能够更好地从各种公共资源中仔细评估信息。聚合链之间的突发集体行为，如链排列、自模板化或相分离，可以显著影响共聚过程中不同反应物质相遇的频率和发生反应的概率。因此，这些行为预计会影响链中不同单体的掺入频率和位置。然而，目前的理论框架理解什么支配共聚物序列并没有考虑到这种复杂性。DuBay教授正在利用阶梯生长共聚的粗粒度模拟来研究这种行为对共聚物序列的影响。通过将朗之万动力学与允许聚合物键形成的反应截止距离方法相结合，这些模拟能够全面研究各种单体特性和反应条件对所得共聚物序列的影响。通过与合成聚合物化学家的合作，人们正在研究对这种非常规的序列偏倚机制敏感的共聚物和反应体系。此外，DuBay教授正在开发一个项目，将未来的作家和传播者嵌入到以聚合物为重点的研究实验室中，并为化学入门课程提供一个基于聚合物案例研究的新课程。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Polymers are long molecular chains formed by linking together many repeating molecular sub-units called monomers. Copolymers are a special class of polymers. They are made by using two (or more) different monomers and, depending on how the monomers are combined, the copolymers can exhibit unique properties. In biological copolymers, such as DNA and proteins, the sequence of monomers is precisely controlled by the cell. In contrast, controlling the sequence of monomers in the laboratory remains a significant challenge, and this limits the usefulness of synthetic copolymers. With support from the Macromolecular, Supramolecular and Nanochemistry and the Chemical, Structure Dynamics, and Mechanisms A Programs in Division of Chemistry, Professor DuBay at the University of Virginia is using computer simulations to study copolymers that are grown step-by-step. Professor DuBay and her students have developed a computer model to simulate copolymer growth. They are using the model to better understand the factors that determine the monomer sequence. Insights gained from their studies could enable better sequence control, which could impact technologies ranging from energy conversion, to water purification and drug delivery. This research project is conducted by a diverse team of undergraduate and graduate researchers, training them for productive careers in the chemical industry. In addition, the next generation of professional communicators are embedded into the lab, enabling them to better understand the scientific process and recognize and report on breakthrough achievements. Finally, this project focuses on improving the scientific information literacy of current college students to better equip them to carefully assess information from a variety of public sources. Emergent collective behaviors among the polymerizing chains, such chain alignment, self-templating, or phase separations, can significantly influence how often different reactive species encounter one another during a copolymerization and the probability of a reaction when they do. As a result, such behaviors are expected to affect the incorporation frequency and placement of different monomers in the chain. However, the current theoretical framework for understanding what governs copolymer sequences does not account for such complexities. Professor DuBay is utilizing coarse-grained simulations of step-growth copolymerizations to study the influence of such behaviors on copolymer sequence. By combining Langevin dynamics with a reactive cutoff distance approach that allows for the formation of polymer bonds, these simulations enable a comprehensive investigation of the influence of various monomer characteristics and reaction conditions on the resulting copolymer sequences. Copolymers and reaction regimes that are shown to be sensitive to this unconventional mechanism of sequence biasing are being studied through a collaboration with synthetic polymer chemists. In addition, Professor DuBay is developing a program to embed future writers and communicators in polymer-focused research labs as well as a novel polymer case-study based curriculum for introductory chemistry courses.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.