Thermally Reversible and Recyclable Polyethylene Networks via Furan–Maleimide Diels–Alder Dynamic Covalent Chemistry

TL;DR

Scientists developed a recyclable and self-healing polyethylene material using a reversible chemical bond that can be processed without solvents.

Contribution

A solvent-free, scalable method for creating recyclable polyethylene networks using furan–maleimide Diels–Alder dynamic covalent chemistry.

Findings

The polyethylene network can be reversibly crosslinked and retains 93% of its strength after one reprocessing cycle.

The material exhibits thermal self-healing behavior at 120°C, observed via scanning electron microscopy.

Crosslink density is controllable and correlates with mechanical properties like tensile strength and ductility.

Abstract

The formation of recyclable polyethylene materials is significantly limited by traditional crosslinking methods, which involve solvent-heavy processes and permanent chemical bonds that cannot be undone. Herein, we report an environmentally friendly and scalable approach to construct a thermo-reversible polyethylene network (PE-g-DA) via solvent-free, one-step melt processing based on furan–maleimide Diels–Alder (D–A) dynamic covalent chemistry. Furan-functionalized polyethylene was dynamically crosslinked with bismaleimide during melt mixing, fully compatible with conventional polyolefin processing techniques. FTIR spectroscopy, temperature-dependent solubility, and differential scanning calorimetry collectively confirm the reversible formation and dissociation of D–A adducts, enabling thermal switching of the network structure. Equilibrium swelling experiments based on the Flory–Rehner model indicate that the crosslink density can be precisely controlled by varying the bismaleimide content. As a result, PE-g-DA exhibits significantly enhanced tensile strength while maintaining high ductility at moderate crosslink densities. Notably, the dynamic network allows efficient thermal reprocessing, with recycled samples retaining approximately 93% and 80% of their original tensile strength after the first and second reprocessing cycles, respectively. Moreover, intrinsic thermal self-healing behavior is directly visualized by scanning electron microscopy at 120 °C. This work demonstrates that combining dynamic Diels–Alder chemistry with solvent-free melt processing offers a practical and sustainable route to recyclable, reprocessable, and self-healable polyethylene materials with clear potential for large-scale industrial production.

Figures