CAREER: Novel Approaches to Hyperbranched Polymers

在化学系大分子、超分子和纳米化学项目的支持下，弗吉尼亚理工学院和州立大学的Michael D.Schulz正在开发自缩合开环复分解聚合(ROMP)来制备超支化聚合物。高支化和超支化聚合物是树状的3D大分子，与线性聚合物相比具有非常不同的粘度特性。因此，超支化聚合物被广泛应用于各种领域，包括用作添加剂、涂料和传感器、组合化学中的高负载载体和均相催化剂。在这项研究中，将首先合成亚胺-既可以作为引发剂又可以作为单体的小分子。还将进行结构调整，以优化聚合活性。成功制备的亚胺随后将用于自缩聚反应，以制备几种具有有趣结构和机械性能的超支化聚合物。本研究有可能为合成新型可控大分子结构塑料奠定基础。该项目还将成为培训学生学习聚合物化学和催化的绝佳工具。以化学为主题的教育推广活动将在西弗吉尼亚州科学博物馆进行演示，重点是现代世界中的聚合物以及它们的性能如何依赖于化学结构。还将开发旅行工具包，用于访问科学教育资源不足的农村社区。该项目将专注于使用Ru催化的自缩合开环复分解聚合(ROMP)来控制合成超支化聚合物。中心方法将包括制备潜伏期引发的烯烃歧化催化剂，该催化剂带有修饰的亚甲基配体，将偶联到ROMP单体上，产生烯烃歧化异构体。将对合成的亚胺进行系统的研究，以考察结构修改对潜伏期控制、激活和聚合性能的影响。然后，成功的候选者将被用于制备超支化聚合物。重点将集中在研究聚合条件、聚合动力学、超支化结构和端基修饰策略之间的相互作用。最后，我们将系统地研究合成聚合物中的结构-性质关系。该项目有可能产生一种强大的策略来合成具有受控支化、重复单元功能和末端基团的超支化ROMP聚合物。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势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, Michael D. Schulz of Virginia Polytechnic Institute and State University is developing self-condensing ring opening metathesis polymerization (ROMP) to prepare hyperbranched polymers. Highly and hyperbranched polymers are tree-like 3D macromolecules that have very different viscosity characteristics when compared to linear polymers. As a result, hyperbranched polymers have been applied in various applications ranging from their use as additives to coatings and as sensors, as high loading supports in combinatorial chemistry, and as homogeneous catalysts. In this research, inimers—small molecules that can act as both an initiator and a monomer—will first be synthesized. Structural modifications will also be conducted to optimize polymerization activity. Successfully prepared inimers will then be used in self-condensing polymerization to prepare several hyperbranched polymers with interesting structural and mechanical properties. This research has the potential to lay the foundation for the synthesis of new class of plastics with controlled macromolecular structures. The project will also serve as an excellent vehicle for training students in polymer chemistry and catalysis. A chemistry-themed educational outreach with demonstrations at the Science Museum of West Virginia will focus on polymers in the modern world and how their properties are dependent on chemical structure. A travelling kit will also be developed for visits to rural communities that are under-resourced in science education. The project will focus on controlled synthesis of hyperbranched polymers using ruthenium-catalyzed self-condensing ring opening metathesis polymerization (ROMP). The central approach will involve the preparation of latent-initiating olefin metathesis catalysts with modified benzylidene ligands that will be coupled to a ROMP monomer, producing an olefin metathesis inimer. The synthesized inimers will be systematically investigated to examine the effects of structural modification on latency control, activation, and polymerization properties. Successful candidates will then be used to prepare hyperbranched polymers. A strong focus will be on investigating the interplay among polymerization conditions, polymerization kinetics, hyperbranched structures, and strategies for end-group modification. Lastly, structure-property relationships in the synthesized polymers will be systematically investigated. This project has the potential to produce a powerful strategy to synthesize hyperbranched ROMP polymers with controlled branching, repeat-unit functionality, and end-groups.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.