CAS: Harvesting Carbon Resources Locked in PVC and Polybutadiene Waste

在化学系大分子，超分子和纳米化学项目的支持下，加州大学-圣克鲁斯（UCSC）的Rebecca Braslau教授将致力于为商业聚合物聚氯乙烯（PVC）开发化学升级循环策略。一系列的化学反应将被用来将这种材料从其不可回收的形式转化为使用温和的温度和环境压力的增值产品。这些转化的目的是生产1，5-己二烯，可以收集或进一步转化为其他有价值的烷烃产品。使用由全碳骨架组成的废塑料作为丰富的原料，将为有用的有机化学品提供非石化来源，同时减轻我们环境和垃圾填埋场中持久性塑料废物的部分生态灾难。废聚氯乙烯的化学升级循环的影响将提供显着的环境效益。利用聚氯乙烯作为一种有价值的富碳资源将使聚合物主链中的碳原子具有新的用途，并导致其从垃圾填埋场转移并减少环境污染。研究经验将提供跨学科的培训，研究生和本科生在合成有机化学和材料科学。UCSC是一个西班牙裔服务机构;代表性不足的本科生将经历有意义的，令人兴奋的研究。通过向当地的初中和高中提供关于塑料的演讲并进行实践实验，积极开展外联活动，为大量代表性不足的人口提供服务，将吸引来自不同科学背景的学生，并为追求高等教育提供榜样。聚氯乙烯（PVC）是一种难以重复使用或回收的商品聚合物，因此聚合物在使用后通常会被填埋。这项工作将通过为这种商业聚合物开发升级循环策略来解决这个问题。 从PVC的（CH 2-CHCl）单元中消除HCl以形成多烯，然后通过烯烃复分解与添加的小烯烃将形成各种特定的二烯作为增值产品。同样地，烯烃复分解以上循环聚丁二烯（和具有含烯烃重复单元的相关聚合物）将允许合成橡胶的分解并提供获得衍生自聚丁二烯片段的1，5-己二烯的途径。这些二烯或其直接还原产物（不含E/Z异构体）具有长期用作化学工业原料的潜力，具有低供应链能源投资和最小的温室气体排放。开发允许烯烃形成与烯烃复分解串联的反应条件将为从使用过的/废弃的聚合物来源中目标地收获烯烃提供强大的合成工具，而且还用于塑料升级循环之外的应用。利用塑料废物作为未开发的碳资源，为持续的化学创新提供了一条对地球友好的途径，而不依赖于石化资源。该奖项反映了NSF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 Rebecca Braslau of the University of California – Santa Cruz (UCSC) will work to develop a chemical upcycling strategy for the commercial polymer, polyvinyl chloride (PVC). A series of chemical reactions will be used to transform this material from its non-recyclable form into value-added products using mild temperatures and ambient pressure. These transformations are aimed at producing 1,5-hexadiene, which can be collected or further transformed into other valuable alkane products. Use of waste plastic consisting of all-carbon backbones as a rich feedstock would provide a non-petrochemical source for useful organic chemicals, while mitigating part of the ecological catastrophe of persistent plastic waste in our environment and landfills. The impact of chemical upcycling of waste PVC would provide a significant environmental benefit. Utilizing PVC as a valued carbon-rich resource would give the carbon atoms in the polymer backbone new uses, and result in its diversion from landfills and reduce environmental contamination. The research experience will provide interdisciplinary training to graduate and undergraduate students in synthetic organic chemistry and materials science. UCSC is a Hispanic-Serving Institution; underrepresented undergraduates will experience meaningful, exciting research. Active outreach by presenting talks on plastics with hands-on experiments to local middle and high schools serving large, underrepresented populations will engage students from diverse backgrounds in science and provide role models for pursuing higher education. Polyvinyl chloride (PVC) is a commodity polymer that is notoriously difficult to reuse or recycle, hence the polymer often ends up in a landfill after use. This work will address this problem by developing an upcycling strategy for this commercial polymer. Elimination of HCl from the (CH2-CHCl) units of PVC to form polyenes followed by olefin metathesis with added small alkenes will form a variety of specific dienes as value-added products. Likewise, olefin metathesis to upcycle polybutadiene (and related polymers with olefin-containing repeat units) will allow the breakdown of synthetic rubbers and provide access to 1,5-hexadienes derived from polybutadiene fragments. These dienes, or their direct reduction products (devoid of E/Z isomers) have the long term potential of serving as feedstocks for the chemical industry with low supply chain energy investments and minimal greenhouse gas emissions. Development of reaction conditions that allow olefin formation in tandem with olefin metathesis will provide a powerful synthetic tool for targeted alkene harvesting from used/discarded polymer sources, but also for applications beyond plastics upcycling. Use of plastic waste as an untapped carbon resource provides an earth-friendly route to continued chemical innovation, without relying on petrochemical sources.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.