Sustainable Up-cycling of Waste polyethylene to Linear Aliphatic di-Aldehydes (LAAs)

The rapid rise in plastic production, particularly polyolefins like polyethylene, has led to a critical environmental crisis due to their durability, resistance to degradation, and limited recyclability. Addressing this challenge, we have developed a novel chemical recycling method that efficiently converts waste polyethylene into high-value products, offering a sustainable solu-tion for polyolefin upcycling. In this context, we developed a copper-catalyzed dehydrogenation method for polyolefins, followed by oxidative cleavage of the dehydrogenated polyolefin chain into linear aliphatic di-aldehydes (LAAs). We have demonstrated an efficient dehydrogenation strategy utilizing an earth-abundant, cost-effective copper catalyst in combina-tion with a catalytic amount of oxidant, achieving dehydrogenated polyolefins with a 93% yield and an overall double bond content of 2%. The recovered unsaturated polyethylene was subjected to oxidative cleavage using a commercially available 5 wt% Ru@C heterogeneous catalyst, yielding linear aliphatic di-aldehydes (LAA) with 99% double bond conversion and up to 76 wt% LAA. The methodology was further validated on a one-pot gram-scale reaction. The reduction in the polymer molecular weight was confirmed by HT-GPC, DSC, WAXD, and TGA analysis. Mechanistic studies proved that the reaction proceeding via a radical mechanism.