Tailoring the Topological Dynamics of Polyethylene Vitrimer Through Stoichiometric and Catalytic Synergy

ABSTRACT Designing polymer networks that allow independent control of room‐temperature rigidity and high‐temperature rheological behavior is essential for material recycling. To address physical constraints within semi‐crystalline polyolefins, we constructed polyethylene‐based vitrimers with varying crosslinker ratios and catalyst concentrations via in situ reactive melt blending. Results reveal that large physical spacing in loosely crosslinked networks restricts topological rearrangement. However, combining an equimolar crosslinker ratio with 15 mol% catalyst overcomes these constraints, achieving the lowest activation energy of 94.53 kJ/mol. While increasing the catalyst to 20 mol% plateaus the activation energy at 95.44 kJ/mol, it continues driving the initial static network's densification. Moreover, networks deviating from the equimolar ratio release enhanced local segmental mobility via single‐ended dangling chains, endowing the material with exceptional mechanical recovery. This work provides deep insight into the synergistic regulation between crosslinker and catalyst. It achieves a high degree of decoupling between structural rigidity and rheological activity, offering a core design paradigm for tailored, recyclable polyolefin networks.