Polyethylene ionomers as thermally reversible and aging resilient adhesives

Abstract

Low-density Polyethylene (LDPE) is a widely used thermoplastic polymer in various industries due to its versatility and cost-effectiveness. However, its inherent limitations, including low strength, poor UV resistance, and poor adhesion properties, have spurred efforts to enhance its applicability. We recently developed a LDPE ionomer based on ion pair comonomers (IPC) that can extend the range of application where traditional LDPE are limited. In this work, we report the effect of the reaction conditions on IPC content and melt flow index (MFI) for the PE ionomer obtained by copolymerizing ethylene with the ion pair dimethyl-amino methacrylate and methacrylic acid. The resulting ionomers exhibited improved mechanical properties, including higher elongation and stress at break, making them superior to conventional LDPE. The developed ionomers display enhanced adhesion properties on aluminum substrates with respect to LDPE. Remarkably, the adhesives exhibit thermal reversibility, making them suitable for applications requiring disassembly. Accelerated aging tests demonstrate the ionomers' durability, with some even showing increased adhesion after exposure to harsh conditions. Overall, this study highlights the potential of PE-based ionomers as advanced materials that combine the benefits of thermosets and thermoplastics, while offering outstanding adhesive properties when the IPC content is higher than 1 mol %.