Mechanically Robust, Heat-Resistant, and Reprocessable Polyethylene Vitrimers Cross-Linked by β-Hydroxy Ester Bonds via Reactive Processing

Abstract

The development of vitrimers, dynamic covalent bonds cross-liked polymers via the associative exchange mechanism, offers a feasible way to address the recycling issue of traditional chemically cross-linked polyethylene (PE). However, it is still a great challenge to simultaneously achieve recyclability and high performance through a route that is environmentally friendly and easy to scale up. In this work, low-density (LD) PE vitrimers cross-linked by β-hydroxy ester bonds were successfully obtained via reactive processing between polyethylene-co-glycidyl methacrylate (PE-GMA) and decanedioic acid (DA). The high reaction efficiency of epoxy and carboxy groups leads to a high gel content of 84.51%. The activation energy (E a) of the transesterification reaction is calculated to be 111.33 kJ·mol–1. Thanks to the high E a and cross-link density, the obtained (LD) PE vitrimer exhibits a superior tensile strength of 20.41 MPa and an elongation at break of 800.16%, which is one of the highest values among the currently reported PE vitrimers fabricated by reactive processing. Moreover, the (LD) PE vitrimers have good creep resistance, heat resistance, and electrical insulation, thus showing a great potential to be used in the field of cable insulation.

Self-Healing, Recyclable Syndiotactic 1,2-Polybutadiene-Based Thermadapt Shape Memory Polymers with Cold-Programmed Shape Memory Effect

“…According to literature reports, materials containing β-hydroxy ester bonds internally can undergo topological rearrangement of their three-dimensional network at high temperatures, providing them with the characteristic of being recyclable. − Therefore, we envision that the prepared EC-χ materials can rearrange their topological structures through ester exchange reactions. To confirm this assumption, we repeatedly shredded, milled, and hot-pressed the EC-30.…”

Does the Varying Reactivity in the Transient Polymer Network through Dynamic Exchange Regulate the Closed-Loop Circularity in Polyolefin Vitrimers?

“…The Arrhenius activation equation can quantitatively describe temperature ( T ) dependence of relaxation: − where τ 0 is the pre-exponential factor representing the inverse rate of attempts of the reaction, R is the universal gas constant (8.314 J/(K·mol)), T is the temperature, and E a is the activation energy which is calculated from the slope of the fitted lines, as in Figure b and d.…”

Full-life-cycle eco-friendly polymeric insulating materials: research progress and future prospects

“…In addition to the epoxy system vitrimer, researchers also studied the insulating properties of other systems vitrimer [117]. Zhao et al [118] successfully obtained LDPE vitrimers cross-linked by β-hydroxy ester bonds via reactive processing between polyethylene-co-glycidyl methacrylate (PE-GMA) and decanedioic acid. The PE vitrimer they reported exhibits an excellent tensile strength of 20.41 MPa and an elongation at break of 800.16%; however, the mechanical properties of the recycled PE were reduced by more than 50%.…”