Nitroxide radical-containing polynorbornenes by ring-opening metathesis polymerization as stabilizing agents for polyolefins
Résumé
A series of original 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO)-containing dicarboximide norbornene monomers have been synthesized and polymerized via ring-opening metathesis polymerization (ROMP) using the Grubbs 3 rd generation catalyst. First-order kinetics and linear evolutions of the molar mass with monomer conversion were obtained together with decreasing dispersity (Đ) down to 1.05-1.15. The rate of polymerization decreased with increasing alkyl chain length and an amide anchor group bound to the TEMPO functionality. Well-controlled TEMPO-containing polynorbornenes were prepared with a monomer to initiator ratio up to 1000, resulting in polymers with a high density in radical sites uniformly distributed along the backbone. These TEMPO-containing polynorbornenes have shown to be efficient as stabilizing agents in polypropylene, through onset oxidation temperature (OOT) measurements.