C–H Insertion Functionalization of Polyolefins for Versatile Polyolefin-Polyester Compatibilization

The effective recycling of commingled plastic waste blends remains a major challenge due to the immiscibility of commonly used polymers like polyethylene terephthalate (PET) with polyolefins, including high- or low-density polyethylene (HDPE, LDPE) and isotactic polypropylene (<i>i</i>PP). This immiscibility causes phase separation of the polymers in the blend, compromising the mechanical properties of these mixtures. Herein, we report a versatile and robust strategy to synthesize polar-group pendant polyolefins via C-H insertion from preexisting polymers, which can subsequently act as compatibilizers for blends of PET with different polyolefins. The addition of 0.5-1.0 wt % of these functionalized polyolefins to blends of PET with HDPE, LDPE, or <i>i</i>PP significantly improved the elongation at break, effectively restoring their material properties. This approach can be applied to prepare a compatibilizer from postconsumer HDPE bottlecaps. The waste derived compatibilizer effectively compatibilized postconsumer PET/HDPE blends, demonstrating the versatility of this method as a low-cost, efficient, and adaptable solution for restoring PET/polyolefin blend properties.