Lucile Cluzeau1,2, Daniel Taton2, Yannick Landais1
1. ISM UMR-5255 - Université de Bordeaux – CNRS - Bâtiment A12, 351 cours de la libération 33405 Talence Cedex, France
2. LCPO UMR-5629 – Université de Bordeaux - CNRS - Bordeaux INP ENSCPB ,16 avenue Pey Berland, 33607 Pessac Cedex, France
Polyethylene (PE), a prominent member of the polyolefin family and one of the most widely used polymers in our daily lives, is produced annually in staggering amounts, reaching 150 million tons across various grades. The absence of functional groups greatly restricts polyethylene's compatibility with other polymers and limits its use in certain applications. PE is also recalcitrant to chemical recycling or upcycling due to its robustness and the inherently inert nature of its constitutive C-C and C-H bonds. Therefore, the development of general methodologies that could install functional groups into PE’s remains a challenge in Polymer Science.
This project aims to address this significant task, by developing a metal-free route involving activation of PE C-H bonds through hydrogen atom transfer (HAT) by photochemistry. To this end, agents, hereinafter referred to as A-FG agents, are employed to undergo homolytic cleavage, releasing both a transient radical A• that activates the PE C-H bond and a persistent radical FG• that enables selective chain functionalization. The incorporation of polar functional groups along the PE backbone is a key step for various post-functionalization. Notably, this strategy provides an entry to PE derivatives exhibiting different thermomechanical properties than the parent PE, thereby enabling the production of high-value PE-based materials through post-functionalization. Ultimately, it also allowed a handle for further insertion of cleavable C-X bonds within the polymer backbone, for further PE deconstruction.