Dynamically Cross-Linked Polyolefin Elastomers with Highly Improved Mechanical and Thermal Performance

The controllable introduction of dynamical chemical cross-linking into polymers permits the development of recyclable polymer products with high performance. However, challenges lie in chemically inert polyolefins, which are the largest polymer product in the world to date. Here, we demonstrate the preparation of polyolefin elastomers (POEs) with tunable dynamic chemical cross-linking, compatible with their industrial production. Boronic ester bond cross-linked POEs (BPOEs) present high mechanical performances with tensile strength (σ) up to 23.8 MPa, Young's modulus (E) up to 29.0 MPa, and toughness (UT) up to 69.6 MJ·m–3, far superior to those reported elastomers. BPOEs also demonstrate good thermal stability maintaining a steady storage modulus plateau of 2.9 MPa above 100 °C, instead of 0.2 MPa for pristine POEs. After reprocessing three times, BPOEs show a good reprocessability with a σ recovery of 85.6%, an E of 108.5%, a UT of 95.7%, and an elongation at break (ε) of 97.1%, even higher than that of commercial POEs such as POE-8150 of Dow Company. Our method thus permits the future development of higher-performance POEs and other polyolefins with good reprocessability and recyclability.