Oxidative Upcycling of Polyolefin Wastes into the Dynamically Cross-Linked Elastomer

Oxidative cracking of polyolefins into functionalized molecules or oligomers promises the chemical upcycling of plastic wastes. In this work, we develop a novel approach to polyolefin waste upcycling that utilizes low-temperature oxidative cracking combined with dynamic cross-linking to produce recyclable elastomers. High-density polyethylene is oxidized into functionalized oligomers with end carboxyl groups at 110 degrees C, achieving tunable number-average molecular weights (M n) ranging from 1500 to 5500 Da at distributions (D) between 2.91 and 3.33. These oligomers with high crystallinity directly react with amorphous cis-polybutadiene containing pendant epoxy groups (an oxidized product of cis-polybutadiene) through esterification, forming a dynamically cross-linked elastomer. The elastomer displays a low glass transition temperature (T g) of approximately -100 degrees C while maintaining a melting point (T m) above 80 degrees C; it showcases a Young ' s modulus (E) of 12.0 +/- 0.4 MPa, elongation at break (epsilon) of 600 +/- 28%, tensile strength (sigma) of 16.4 +/- 0.8 MPa, tensile toughness (U T) of 46.0 +/- 3.5 MJ center dot m-3, and a good elasticity with 81.8% elastic recovery in a 10-cycle tensile test, even higher than that of commercial POEs such as POE-8150 of Dow Company. The dynamic ester-bond-based cross-linking enables the elastomer to be reprocessed. Our study introduces an efficient chemical upcycling process for polyolefin wastes, eliminating the need for tedious separation steps of cracking products.