Direct synthesis of poly(α-olefin) thermoplastic elastomers via controlled chain straightening using bulky α-diimine palladium complexes

Abstract

Thermoplastic elastomers (TPEs) are considered as the third generation of rubber. How to generate TPEs using one-step homopolymerization of α-olefin is important for polymer synthesis. In this study, a series of chain-walking α-diimine palladium(II) complexes were utilized for the highly active (TOF up to 558 h⁻¹) homopolymerization of α-olefin. The polymerization system including activity and polymer properties can be significantly modulated by the steric and electronic effects of catalysts. The generated poly(α-olefin)s exhibited high molecular weights (M_n up to 200 kg mol⁻¹) and various branching densities (39–131/1000C). The rational catalyst structure selection enables direct catalysis of α-olefin chain walking polymerization with a suitable ratio of chain straightening for the preparation of thermoplastic elastomers. The resulting poly(α-olefin)s exhibited high strain values (up to 3002%) at break, with strain recovery values of up to 64%.