CAS: Collaborative Research: Processive Ring-Opening Metathesis Polymerization Through Molecularly Confined Catalysts

CAS：合作研究：通过分子限域催化剂进行开环易位聚合

• 批准号: 2305566
• 负责人: Jia Niu
• 金额: $ 34万
• 依托单位: Boston College
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2023
• 资助国家: 美国
• 起止时间: 2023-07-01 至 2026-06-30
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2305566&HistoricalAwards=false
• 关键词: CAS; Collaborative; Research; Processive; Ring; CAS; Collaborative; Research; Processive; Ring

With the support of the Macromolecular, Supramolecular and Nanochemistry (MSN) program and the Chemical Catalysis (CAT) program in the Division of Chemistry, Jia Niu of Boston College and Wenyu Huang of Iowa State University are developing ring-opening metathesis polymerization (ROMP) catalyzed by organometallic ruthenium complexes confined within molecularly defined cages. Despite the significance of ROMP in producing a plethora of functional polymers, existing techniques still cannot completely prevent chain transfer and termination, in particular when low-strain monomers are involved. As a result, mixtures of linear and cyclic macromolecules of different sizes are formed that are difficult to separate. This research endeavors to directly address this unmet challenge and introduce a distinct strategy for processive ROMP. In this strategy, polymerization catalysts will be encapsulated in molecularly defined cage structures, such that, ideally only monomers, but not nascent polymers, can access the catalyst. This will thereby inhibit the chain transfer and termination caused by the interaction between the catalyst and the nascent polymer, resulting in linear macromolecules with controlled molecular weights. The developed methodology will also be applied to ROMP of sustainability-oriented monomers that are considered challenging for ROMP due to their low strain. These monomers include cyclic alkenes with low ceiling temperatures and those consisting of degradable functionalities. This research will provide interdisciplinary training for students in polymer synthesis and sustainability. The collaborative team will additionally develop a hybrid three-week summer workshop aimed to introduce polymer chemistry principles and practices into 3D-printing. The workshop will be integrated with existing outreach programs to stimulate interest in polymer science and catalysis among college and high school students in the communities served by Boston College and Iowa State University.Synthetic polymers ranging from commodity products to specialty goods are at the center of modern society. Among many properties, molecular weight, sequence, and dispersity are essential in determining the material performance of polymers. Therefore, the precise control over these properties is the central goal in modern synthetic polymer chemistry. This research will focus on developing processive ring-opening metathesis polymerization (ROMP) of low-strain cyclic alkenes through confining organometallic ruthenium catalysts into molecularly defined cages. Such an approach is expected to allow access to monomer molecules but prevent the nascent polymer chains from accessing these confined catalysts. As a result, well-defined, high, and ultra-high molecular weight, low dispersity polymers from ROMP could be realized. The first objective will focus on design of homogeneous and heterogeneous Zr-based cages using the reversable aperture opening/closing approach. These cages will then be utilized to encapsulate ruthenium-based Grubbs and Hoveyda-Grubbs ROMP catalysts. The second objective will leverage molecularly confined catalysts to enable polymerization of sustainability-oriented monomers containing degradable functionalities. Lastly, kinetic behaviors of ROMP mediated by molecularly confined catalysts will be systematically investigated. The basic guiding principles associated with this project are general and have the potential to be applied to various other catalyst-mediated chain-growth polymerization techniques in which the control of termination and/or chain-transfer events is desirable.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.

With the support of the Macromolecular, Supramolecular and Nanochemistry (MSN) program and the Chemical Catalysis (CAT) program in the Division of Chemistry, Jia Niu of Boston College and Wenyu Huang of Iowa State University are developing ring-opening metathesis polymerization (ROMP) catalyzed by organometallic ruthenium complexes confined within molecularly defined cages. 尽管ROMP在产生大量功能聚合物方面具有重要意义，但现有技术仍然无法完全防止链的传递和终止，特别是当涉及低晶体单体时。 结果，形成了很难分离的不同尺寸的线性和环状大分子的混合物。 这项研究努力直接应对这一未满足的挑战，并引入了一项与众不同的策略。 在这种策略中，聚合催化剂将封装在分子定义的笼子结构中，因此，理想情况下，只有单体而不是新生的聚合物才能访问催化剂。 因此，这将抑制由催化剂与新生聚合物之间的相互作用引起的链转移和终止，从而导致具有控制分子量的线性大分子。 开发的方法还将应用于以可持续性为导向的单体的romp，由于其低应变而被认为对ROMP充满挑战。这些单体包括天花板温度低的环状烯烃和由可降解功能组成的烯烃。 这项研究将为聚合物合成和可持续性的学生提供跨学科培训。 合作团队还将开发一个三周的混合动力夏季研讨会，旨在将聚合物化学原理和实践引入3D打印。该研讨会将与现有的外展计划融合，以刺激波士顿学院和爱荷华州立大学为聚合物科学和高中生之间的聚合物科学和催化的兴趣。从商品产品到特殊产品的共同聚合物在现代社会的中心。在许多特性中，分子量，序列和分散性对于确定聚合物的材料性能至关重要。因此，对这些特性的精确控制是现代合成聚合物化学的核心目标。 这项研究将着重于通过将有机金属弦催化剂限制在分子定义的笼子中，从而将低压环烷烃的加工环化离子化聚合（ROMP）开发。 这种方法有望允许进入单体分子，但可以防止新生的聚合物链进入这些粘附的催化剂。 结果，可以实现，定义明确的，高和超高的分子量，可以实现低分散性聚合物。 第一个目标将着重于使用可逆的孔径开放/关闭方法设计均质和异类的基于ZR的笼子。 然后，这些笼子将用于封装基于钌的grubbs和hoveyda-grubbs romp催化剂。 第二个目标将利用分子限制的催化剂来实现含有可持续性的含有降解功能的聚合。 最后，将系统地研究由分子限制的催化剂介导的ROMP的动力学行为。 The basic guiding principles associated with this project are general and have the potential to be applied to various other catalyst-mediated chain-growth polymerization techniques in which the control of termination and/or chain-transfer events is desirable.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.