This dataset consists of characterization of telechelic functional polyethylene oligomers, precursors, and resultant step-growth polyethylene with urethane-linkages between segments of different lengths. Polymer characterization data includes nuclear magnetic resonance (NMR) spectra, room-temperature and high-temperature size exclusion chromatography data and associated calibration curves, attenuated total reflection Fourier transform infrared (ATR-FTIR) spectra, transmission FTIR spectra with melting. Several physical measurements were also conducted on the materials in this study and are included in this data asset: differential scanning calorimetry (DSC) measurements, rheological measurements, micro ballistic impact measurements, small angle and wide angle x-ray scattering (SAXS and WAXS, respectively),This is the abstract for the manuscript written using the data provided herein."Over 50% of plastic waste comes from a single class of semi-crystalline polymers called polyolefins. While direct mechanical recycling of these plastics would be highly advantageous, most recycling strategies fail to preserve the broad molecular mass distribution of these polyolefins, from which they derive their unique combination of processability and mechanical strength. Here, we show that the incorporation of reversible interactions into high-density polyethylene (HDPE) can circumvent this issue, by strengthening the amorphous phase through interchain supramolecular interactions, as opposed to traditional entanglements from high molecular mass chains. Critically, we show that many key properties of these dynamic HDPE polymers, including percent crystallinity, melting temperature, bond association, and mechanical properties are determined by the distribution of bond-to-bond spacings along the chain backbone and can be predicted using simple polymer physics theories. Through X-ray scattering experiments, we show that a mixed backbone HDPE dynamic polymer exhibits a unique display of long-range supramolecular order that persists even in the melt state along with mechanical properties that exceed HDPE and approach the strain-hardening behavior seen in ultra-high molecular weight polyethylene. This work demonstrates a promising mechanism for upcycling of polyolefin waste, illuminates key fundamental principles governing how the placement of dynamic bonds in polyolefins can dramatically influence bulk material properties, and provides a framework to design new upcycled polymers based on controlling bond-spacing distributions."