Aliphatic Polyketones from Alternating Copolymerization of CO and Olefins: Phosphinoamidate Nickel Catalyst, Polymerization Study, Mechanical Properties and Degradations

A Ni catalyst has been developed that is highly productive for the alternating CO-ethylene copolymer and capable of incorporating a substantial amount of propylene to produce the alternating CO-ethylene-propylene terpolymer. The tensile properties of the copolymer and terpolymers were studied. The copolymer is brittle, but the terpolymers display ductility and high toughnesses. Young's modulus of the terpolymer decreases with an increase in the propylene content. Both the copolymer and the terpolymer are photodegradable. A decrease of an order of magnitude in molecular weight was observed for both the alternating copolymer and terpolymer when they were irradiated by 275 nm UV light for 4 weeks. While pyrolysis of aliphatic polyketones is known to leave a large amount of carbonaceous residue, complete pyrolysis is achieved here with a small amount of FeCl3 as the catalyst for pyrolysis. The results suggest that alternating CO-ethylene-propylene terpolymers constitute a family of more sustainable polymers as potential replacements for polyethylene and polypropylene.