Stijn Billiet

Chemistry of Crosslinking Processes for Self-Healing Polymers

Recent developments in material design have seen an exponential increase of polymers and polymer composites that can repair themselves in response to damage. In this review, a distinction is made between extrinsic materials, where the self-healing property is obtained by adding healing agents to the material to be repaired, and intrinsic materials, where self-healing is achieved by the material itself through its chemical nature. An overview of the crosslinking chemistries used in self-healing materials will be given, discussing the advantages and drawbacks of each system. The review is not only aiming to enable researchers to compare their ongoing research with the state-of-the-art but also to serve as a guide for the newcomers, which allows for a selection of the most promising self-healing chemistries.

Sustainable thermoplastic elastomers derived from plant oil and their “click-coupling” via TAD chemistry

We report the preparation of plant oil based triblock copolymers based on soybean oil monomers. The monomers were polymerized via atom transfer radical polymerization with subsequent chain extension, resulting in poly(styrene-b-soybean oil acrylate-b-styrene) (PS-b-PSBA-b-PS) and poly(styrene-b-soybean oil methacrylate-b-styrene) (PS-b-PSBMA-b-PS) triblock copolymers. These polymers, ranging from thermoplastics to thermoplastic elastomers (TPEs), were obtained by tuning molecular structures. We employed a “click coupling” strategy using triazolinedione (TAD) chemistry to create chemical junctions between the soft middle blocks of the triblock copolymers, which behave similar to physical chain entanglements. This method helps to overcome the drawbacks of plant oil based polymers, allowing for increase of tensile strength without sacrificing elongation. Cyclic tensile tests show that the “click coupled” triblock copolymers exhibit excellent elastic recovery characteristics.