Wood Zachary A, Castro Eunice C, Nguyen Angelyn N, Fieser Megan E
Department of Chemistry, University of Southern California Los Angeles CA 91706 USA.
Wrigley Institute for Environment and Sustainability University of Southern California Los Angeles CA 91706 USA
Chem Sci. 2024 May 14;15(23):8766-8774. doi: 10.1039/d4sc00130c. eCollection 2024 Jun 12.
Full dechlorination of poly(vinyl chloride) (PVC) in a controlled manner to yield useful polymeric and chlorinated products is of great interest for the processing of PVC waste. Forming polyethylene (PE) without corrosive by-products would allow for a pre-treatment of PE wastes that are often contaminated with PVC. Herein, full dechlorination of PVC has been achieved generation of silylium ions , to furnish PE products. Complete dechlorination of PVC can be achieved in 2 hours, yielding organic polymer that has similar spectroscopic and thermal signatures of branched PE, with no observable chlorine. The degree of branching can be tuned between 31 and 57 branches per 1000 carbons, with melting temperatures ranging from 51 to 93 °C. This method is applicable to not only pure PVC, but also commercial PVC products. Depending on if the PVC products are separated from plasticizers, different melting points of the resulting PE are observed. PVC dechlorination in the presence of PE waste is also shown. This is the first report of being able to cleanly convert PVC waste to PE in high yields and tune the thermal properties of the PE product, highlighting the remarkable control that silylium ion mediated transformations enables compared to past chemical methods.
以可控方式将聚氯乙烯（PVC）完全脱氯以生产有用的聚合物和氯化产物，对于PVC废料的处理具有重大意义。形成无腐蚀性副产物的聚乙烯（PE）将允许对经常被PVC污染的PE废料进行预处理。在此，通过生成甲硅烷基离子实现了PVC的完全脱氯，以提供PE产物。PVC可在2小时内实现完全脱氯，生成具有与支化PE相似的光谱和热特征且无明显氯的有机聚合物。支化度可在每1000个碳31至57个支链之间调节，熔点范围为51至93°C。该方法不仅适用于纯PVC，也适用于商业PVC产品。根据PVC产品是否与增塑剂分离，观察到所得PE的不同熔点。还展示了在PE废料存在下的PVC脱氯情况。这是第一份关于能够以高收率将PVC废料干净地转化为PE并调节PE产物热性能的报告，突出了与过去化学方法相比甲硅烷基离子介导的转化所实现的显著控制。
