CAS: Lewis Pair Polymerization: Compounded Sequence and Spatiotemporal Controls for Precision Synthesis of Sustainable Linear and Cyclic Block Copolymers

在化学系大分子、超分子和纳米化学项目的支持下，科罗拉多州立大学的Eugene Y. Chen教授正在开发新的合成路线，用于从生物基可再生单体中构建技术上重要的环状聚合物和共聚物。环状聚合物是一类有趣的大分子，没有链端。与线性聚合物相比，这些聚合物通常具有较低的粘度，更快的结晶动力学，有时具有更高的耐化学和热降解性。这些特性使环状聚合物非常适合各种重要的工业应用。该项目将利用合成、催化和机械方法制备各种环状聚合物和共聚物，目的是精确控制单体单元的结构和序列。通过建立国际合作的计算方法将进一步指导实验设计。这项合成工作有可能帮助提供精确的规则和嵌段环状聚合物，其规模足够大，可以用于更广泛的聚合物群落进行结构/性质关系研究。从可持续发展的角度来看，与这个项目相关的设计原则有可能帮助形成一个巨大的变化，即可回收和可升级回收的聚合物被更广泛地生产和用作商品塑料。与此项目相关的活动旨在扩大参与范围，使本科生和研究生能够接受聚合物化学方面的培训，并努力开发和推广比今天通常实践的更可持续的方法。在这项工作中，路易斯对聚合（LPP）将用于定制合成环聚合物和共聚物。LPP利用Lewis对（LP）的酸和碱之间的协同作用和协同作用来影响单体活化、链起始、传播、终止和转移事件。与其他聚合方法相比，这种合作的双组分催化机制提供了一些优势，特别是在一步精确合成的复合序列控制和时空控制方面。与线性聚合物相比，环状聚合物（CPs）的研究一直较少，这主要是由于这种有趣的聚合物的合成途径有限。该项目的具体目标包括：(1)更好地了解精密CPs和环嵌段共聚物（cBCPs）合成过程中决定空间和时间控制的因素；(2)利用生物基丙烯酸单体的LPP在一炉一步中合成高阶多嵌段共聚物；(3)利用手性双核LPs作为启动子，从可再生乙烯基内酯中衍生出立体规则和可回收的CPs。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。

With the support of the Macromolecular, Supramolecular and Nanochemistry program in the Division of Chemistry, Professor Eugene Y. Chen of Colorado State University is developing new synthetic routes for the construction of technologically important cyclic polymers and copolymers from bio-based renewable monomers. Cyclic polymers are an intriguing class of macromolecules that lack chain ends. When compared to linear counterparts, these polymers typically have lower viscosity, faster crystallization kinetics, and sometimes higher resistance to chemical and thermal degradation. These properties make cyclic polymers ideally suited for a variety of industrially important applications. The project will utilize synthetic, catalytic, and mechanistic approaches to prepare a variety of cyclic polymers and copolymers with the aim of precisely controlling the structures and sequences of monomer units. Computational methods through established international collaborations will further guide experimental design. The synthetic work has the potential to help provide precision regular and block cyclic polymers at a scale large enough for structure/property relationship studies to be conducted by the broader polymer community. From the point of view of sustainability, the design principles associated with this project have the potential to help nucleate a sea change, whereby recyclable and upcyclable polymers are more widely produced and used as commodity plastics. The activities associated with this project are intended to broaden participation and enable the training of undergraduate and graduate students in polymer chemistry, with a distinct effort to develop and promote more sustainable approaches than are typically practiced today.In this work, Lewis pair polymerization (LPP) will be used for tailored synthesis of cyclic polymers and copolymers. LPP exploits the synergy and cooperativity between an acid and a base of a Lewis pair (LP) to effect monomer activation, chain initiation, propagation, termination, and transfer events. This cooperative two-component catalytic mechanism provides several advantageous features when compared to other polymerization methods, particularly with respect to compounded sequence control and spatiotemporal control in one-step precision synthesis. Cyclic polymers (CPs) have historically been less studied than their linear counterparts, which is mainly due to limited synthetic access to this interesting class of polymers. Specific objectives of the project include: (1) developing a better fundamental understanding of the factors that determine spatial and temporal control in the synthesis of precision CPs and cyclic block copolymers (cBCPs), (2) synthesizing higher-order multi-BCPs by LPP of bio-based acrylic monomers in one pot and one step, and (3) constructing stereoregular and recyclable CPs derived from renewable vinyl lactones utilizing chiral dinuclear LPs as promoters.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.