Transforming Waste Cooking Oil into Linear and Branched Polyethylene Mimics

The growing burden of plastics on the environment represents an urgent global challenge. We report a robust strategy to convert waste cooking oil (WCO), an abundant biomass waste, into chemically recyclable polyesters that mimic polyethylene in performance but offer degradability and excellent adhesion. Through catalytical transformation, both the fatty acid and glycerol components of WCO are valorized into monomers, which are then polymerized into long-chain linear and branched aliphatic polyesters with tunable crystallinity and mechanical properties. These materials, especially branched polyesters with long aliphatic side chains, rival low-density polyethylene (LDPE) in flexibility and strength and notably outperform commercial adhesives in shear strength by creating robust yet temporary bonds with multiple substrates, offering safety, ease of handling, and removability. These mimics can be depolymerized and repolymerized under mild conditions, even in mixed plastic streams. Simulations and experiments reveal that the strikingly increased crystallinity in polyesters with longer side chains is driven by side-chain alignment, offering new molecular insights for materials design. This work illustrates a powerful waste-to-materials approach that aligns with circular economy principles and elevates the potential of biomass in sustainable plastics' innovation.