Polyolefins Vitrimers: Design Principles and Applications

Less than 10% of plastics are recycled worldwide, among which polyolefins, which form two-thirds of all produced polymers, are the most discarded ones. This stems from the nonpolar nature of polyolefins, which limits their degradation and recycling. As such, any approach that may promote the recycling of polyolefins can significantly shift the statistics of polymer recycling toward a more sustainable future. To account for that, the vitrimer concept proposes a unique solution that not only increases the polarity of polyolefins, and as such promotes their degradation, but also expands the utility of polyolefin elastomers and compensates for the significant loss of mechanical properties upon sequential mechanical recycling in thermoplastic polyolefins. Vitrimers are polymer networks formed by reversible covalent cross-links that undergo percolation-conserving exchange reactions at high temperatures. Therefore, while they form a solid network at the service conditions, they can be reprocessed and recycled above a temperature threshold. Thanks to this, they have applications at the interface of thermoplastics and thermosets ranging from recyclable, self-healing, and adhesive materials to creep-resistant and shape-memory networks. This Review aims to classify cross-linking chemistries employed for the production of polyolefin-derived vitrimers and highlight subsequent changes in material properties and applications to promote further development of novel polyolefin vitrimers.