Synthesis and properties of block copolymers composed of norbornene/higher α-olefin gradient segments using ansa-fluorenylamidodimethyltitanium-[Ph3C][B(C6F5)4] catalyst system

Abstract

A series of di- and triblock copolymers composed of gradient norbornene (NB)/higher α-olefin (1-octene (O) or 1-dodecene (Do)) segments (NB/α-olefin-gradient segments) were synthesized with (t-BuNSiMe₂Flu)TiMe₂ (1) – [Ph₃C][B(C₆F₅)₄] using 2,6-bis(1,1-dimethylethyl)-4-methylphenol (BHT)-treated tri-n-octylaluminium (Oct₃Al) as a scavenger. The copolymers were molded to form transparent films using a melt-pressing procedure. The strain at break behaviors of the block copolymer films were significantly improved by controlling the block length, NB mol fraction, and/or the type of α-olefin, without a corresponding loss of strength compared to the corresponding gradient copolymer films. This improvement in the mechanical properties of NB/α-olefin copolymers is expected to broaden their potential applications in optical and medical fields.