Synthesis of Cross-Linked Polyolefin Elastomers with High Performance Yet Good Reprocessability

Abstract

The development of polymer materials with high performance and good reusability is critical to sustainability of the polymer industry. However, the balance of these two aspects in elastomers and rubbers is highly challenging. Here, we report the synthesis of a novel polyolefin elastomer (POE) dynamically cross-linked by an imine-linked boronic ester. It improves the tensile strength at break (σ) of POE by 148.2%, Young’s modulus (E) by 92.6%, and the tensile toughness (U_T) by 49.4%, with a slightly decreased elongation at break. The cross-linked POE also has higher thermal resistance than the pristine one and presents a steady storage modulus plateau of 2.8 MPa above 150 °C. Moreover, it can be reprocessed with an impressive recovery ratio of U_T of 89.7% because of the dynamic exchanges of the boronic ester and imine. Dynamic mechanical analysis shows that the cross-linking of an imine-linked boronic ester has a short characteristic relaxation time of 9.6 min and a low apparent activation energy of 65.1 kJ·mol^–1. Our study on dynamically cross-linked POEs provides a new way for the sustainable development of polymer elastomers.