The research on polyolefins focuses on insertion-coordination polymerization catalyzed by molecular transition metal-based catalysts. The major advantage of insertion polymerization is that its mechanism is largely governed by the catalyst structure, which in turn strongly affects the polymer physical and mechanical properties. Amongst the transition metal series, chromium, Group IV and late metal catalysts have been highly reported. [1] Conversely, vanadium complexes have been less investigated as catalyst precursors for olefin polymerization, despite being the catalyst of choice in the production of ethylene-propylene rubber and ethylene-propylene-diene elastomer (EPDM). Herein, we report the synthesis and characterization of a series of imido vanadium(IV) complexes, differing in the ligand substitution, as well as their application in combination with Et2AlCl and Cl3CCO2Et (ETA), in the terpolymerization of ethylene and 5-ethylidene-2-norbornene (ENB) with ?-olefins (e.g. propylene, 1-hexene and 1-octene) (Scheme 1). [2] The resulting polymers have been characterized to study their microstructure, mode of insertion, and thermal properties. Furthermore, the mechanical properties of the obtained EPDMs have been also investigated to evaluate the resistance to strain, the material stiffness and the polymer elasticity. The resulting EPDMs behave as thermoplastic elastomers or soft elastomers, depending on the polymerization conditions and vanadium catalyst employed. Generally, the obtained EPDM thermoplastic elastomers exhibit high elongation at break, strain hardening at large deformation, excellent shape retention properties and remelting processability with no fall in properties for recycle use without the need of polymers blending and reinforcement through the addition of active fillers. Preliminary data about the terpolymerization of ethylene with ENB and ?,?-non conjugated dienes (e.g.1,5-hexadiene and 1,7-octadiene) and subsequent functionalization of the resulting polymers through a radical grafting, will be discussed.
Vanadium-catalyzed olefin terpoymerization: EPDMs with tunable proprieties
Benedetta Palucci;Giorgia Zanchin;Adriano Vignali;Fabio Bertini;Giovanni Ricci;Giuseppe Leone
2021
Abstract
The research on polyolefins focuses on insertion-coordination polymerization catalyzed by molecular transition metal-based catalysts. The major advantage of insertion polymerization is that its mechanism is largely governed by the catalyst structure, which in turn strongly affects the polymer physical and mechanical properties. Amongst the transition metal series, chromium, Group IV and late metal catalysts have been highly reported. [1] Conversely, vanadium complexes have been less investigated as catalyst precursors for olefin polymerization, despite being the catalyst of choice in the production of ethylene-propylene rubber and ethylene-propylene-diene elastomer (EPDM). Herein, we report the synthesis and characterization of a series of imido vanadium(IV) complexes, differing in the ligand substitution, as well as their application in combination with Et2AlCl and Cl3CCO2Et (ETA), in the terpolymerization of ethylene and 5-ethylidene-2-norbornene (ENB) with ?-olefins (e.g. propylene, 1-hexene and 1-octene) (Scheme 1). [2] The resulting polymers have been characterized to study their microstructure, mode of insertion, and thermal properties. Furthermore, the mechanical properties of the obtained EPDMs have been also investigated to evaluate the resistance to strain, the material stiffness and the polymer elasticity. The resulting EPDMs behave as thermoplastic elastomers or soft elastomers, depending on the polymerization conditions and vanadium catalyst employed. Generally, the obtained EPDM thermoplastic elastomers exhibit high elongation at break, strain hardening at large deformation, excellent shape retention properties and remelting processability with no fall in properties for recycle use without the need of polymers blending and reinforcement through the addition of active fillers. Preliminary data about the terpolymerization of ethylene with ENB and ?,?-non conjugated dienes (e.g.1,5-hexadiene and 1,7-octadiene) and subsequent functionalization of the resulting polymers through a radical grafting, will be discussed.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
