EFRI E3P: CAS: Transformative Upcycling of Polymers by Activating Chemistries

该项目设想通过使用“激活”化学物质实现解聚（即解构）机制，对常见的报废塑料（elp）进行变革性的“升级回收”。这些活化化学反应是直接的、可扩展的化学反应，它们修饰废弃聚合物，使随后的解聚产物比通过常规回收或已建立的解聚化学反应获得的产物更有价值和有用。该项目的重点是实现两种最难回收的聚合物——聚氯乙烯（PVC）和聚氨酯（PU）材料的解聚和升级回收。尽管缺乏任何可行的回收方法，但全球对PVC和PU产品的需求仍在继续增长。该项目将开发将废弃PVC转化为小分子的新方法，这些小分子现有用途包括化学中间体、消费品、溶剂和其他最终用途。同样，聚氨酯（PU）材料将通过在最终产品中产生碳-碳双键的反应分解成更有价值的分子。由PVC和聚对苯二甲酸乙酯（PET）衍生的低聚物（部分解聚产物）将用于形成热塑性弹性体（TPEs）。与热固性弹性体不同，tpe可以熔化、成型、再加工，可能更容易回收，并且比典型的热固性弹性体和塑料更有价值。该项目为研究生和本科生提供高度跨学科的研究培训，并为塔斯卡卢萨的高中生创造了一年一度的夏季沉浸体验。夏季沉浸体验有望在帮助消除环境中的elp方面灌输个人投资，并探索学生将工程作为职业的兴趣。爱荷华州立大学计划为高中生开展一项与美国化学学会SEED项目一致的协同活动。在工程理事会新兴前沿和多学科活动部门以及化学部门的支持下，该项目将通过使用激活化学物质，使elp产生新的解聚产物，从而恢复elp“锁定”的内在价值。这些技术将鼓励回收而不是处置（这是一个特别关注的“难以回收”的材料，如PVC和PU），减少对石油资源的依赖，并防止塑料废物污染环境。该项目将通过激活化学物质和随后解聚成增值小分子，为普通elp的升级利用创造变革性的新途径，包括将这些分子重新组合成更有用、更耐用的聚合物产品的方法。如何将这些废物转化为有价值的小分子的基本理解将通过综合实验-计算方法来获得，该方法检查PVC和PU活化和解聚的适当条件。通过PET和PVC的部分解聚以及随后这些低聚物的重组来合成TPE材料有望从废物中创造出更有价值和有用的聚合物材料。研究计划强调了解反应机理和选择性，产品分析/鉴定，PVC和PU解聚产物的分离，以及TPE材料的表征。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。

This project envisions a transformative “upcycling” of common end-of-life plastics (ELPs) by depolymerization (i.e., deconstruction) mechanisms that are achieved using “activating” chemistries. These activating chemistries are straightforward, scalable chemical reactions that modify the waste polymers such that the subsequent depolymerization products are much more valuable and useful than products obtained through conventional recycling or established depolymerization chemistries. This project focuses on enabling depolymerization and upcycling of two of the most difficult to recycle polymers - poly(vinyl chloride) (PVC) and polyurethane (PU) materials. The global demand for PVC and PU products continues to grow despite the lack of any viable recycling methods for these materials. This project will develop novel methods for converting waste PVC to small molecules that have existing uses as chemical intermediates, consumer products, solvents, and other end-uses. Similarly, polyurethane (PU) materials will be broken down into more valuable molecules via reactions that yield carbon-carbon double bonds in the final products. Oligomers (the products of partial depolymerization) derived from PVC and poly(ethylene terephthalate) (PET) will be used to form thermoplastic elastomers (TPEs). Unlike thermoset elastomers, TPEs can be melted, molded, reprocessed, are potentially easier to recycle, and are much more valuable than typical thermoset elastomers and plastics. The project provides highly interdisciplinary research training for graduate and undergraduate students and creates an annual summer immersion experience for high school students in Tuscaloosa, AL. The summer immersion experience is expected to instill a personal investment in helping to eliminate ELPs from the environment and to explore the students’ interest in pursuing engineering as a career. A synergistic activity for high school students aligned with the American Chemical Society Project SEED is planned at Iowa State University.With support from the Engineering Directorate's Division of Emerging Frontiers and Multidisciplinary Activities and the Division of Chemistry, this project will recover the intrinsic value “locked away” within ELPs by using activating chemistries that enable new depolymerization products from ELPs. These enabling technologies will incentivize recovery rather than disposal (which is a particular concern for “hard to recycle” materials such as PVC and PU), reduce dependence on petroleum resources, and prevent plastic wastes from polluting the environment. The project will create transformative new avenues for upcycling common ELPs via activating chemistries and subsequent depolymerization into value-added small molecules, including methods that recombine these molecules into more useful and durable polymer products. A fundamental understanding of how to convert these wastes into valuable small molecules will be gained through an integrated experimental-computational approach that examines the proper conditions for PVC and PU activation and depolymerization. The synthesis of TPE materials via partial depolymerization of PET and PVC and subsequent recombination of these oligomers promises to create much more valuable and useful polymer materials from waste. The research plan emphasizes understanding reaction mechanisms and selectivity, product analysis/identification, separation of the depolymerization products of PVC and PU, and characterization of TPE materials.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.