Direct synthesis of poly(α-olefin) thermoplastic elastomers via nickel catalyzed chain walking polymerization

Abstract This study presents the direct synthesis of poly(α-olefin) thermoplastic elastomers (PTEs) via nickel-catalyzed chain walking polymerization of linear α-olefins (LAOs) such as 1-hexene, 1-octene, and 1-decene. A series of axially flexible α-diimine nickel(II) catalysts with bulky cycloalkyl substituents were employed to investigate the effects of polymerization conditions – including temperature, monomer concentration, reaction time, and catalyst structure – on the activity, molecular weight, branching density, and thermal properties of the resulting polymers. The catalysts exhibited moderate to high activity and produced high-molecular-weight ( M n up to 683 kg/mol) polymers with tunable branching densities and melting points. Mechanical testing revealed that the resulting PTEs possess excellent elastomeric properties, including high strain at break (strain up to 1487 %) and moderate stress at break (stress up to 18.2 MPa), along with good elastic recovery (SR up to 76 %). This work demonstrates an efficient one-step route to tailor-made PTEs using single LAO monomers, offering a promising alternative to traditional multi-monomer copolymerization systems.