Upcycling of Polypropylene Wastes via Catalytically C−H Modification with Polar Olefins

Graphical Abstract

Experiment to Application: We have developed an efficient strategy to introduce the polar groups into polypropylene materials via visible light-induced Fe-catalyzed C−H functionalization. Various polar polypropylene could be obtained in good level of functionalization to modify the mechanical properties. The practical applications in upcycling of plastic wastes, hydrophilicity enhancement, and the miscibility with other polymers were also studied.

Abstract

While polypropylene (PP) is one of the most widely used polyolefin materials, its post-functionalization has been a continuously researched topic in the polymer field since it could significantly improve physical and chemical properties by introducing polar groups, beneficial for development of the next generation of polyolefin materials. In this work, we describe the development of a visible-light promoted, environmentally friendly iron-catalyzed strategy and establishing of the reaction scope for C−H alkylated modification of polypropylene. Under our conditions, various polypropylenes could be functionalized with diverse polar alkenes with good levels of functionalization (LOF). The properties of the resulting polymers were investigated by thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), and tensile testing. Polypropylene wastes could also be upcycled. While the incorporation of the polyglycol groups enhanced hydrophilicity, the installation of the ester groups increased the miscibility with other polymers by acting as a compatibilizer for polystyrene and polyethylene.