Functional Isotactic Polypropylenes via Efficient Direct Copolymerizations of Propylene with Various Amino-Functionalized α-Olefins

Abstract

A series of novel amino-containing isotactic polypropylenes with high molecular weight and satisfying functional comonomer incorporation were synthesized via direct copolymerization of propylene and α-olefin containing bulky groups protected amino. The highly efficient postmetallocene catalyst system, (pyridylamido)Hf/[Ph3C][B(C6F5)4]/AliBu3, exhibited overwhelmingly favorable reactivity toward α-olefin over amino olefin moieties, effectively promoted the copolymerization of propylene with 5-(N,N-diisopropylamino)-1-pentene, 5-(N,N-diphenylamino)-1-pentene, and 4-(7-octen-1-yl)-N,N-diphenylaniline, respectively, under mild reaction conditions, in which very high catalytic activity (up to 7.44 × 106 gpolymer molCat.–1 h–1) was achieved. The obtained functional copolymers were proved to exhibit high molecular weight (up to 5.90 × 105), amino olefin comonomer incorporation (up to 11.6 mol %) and tacticity ([mmmm] > 99%). Besides, most of the copolymers exhibited high melting points and thermostability (Td around 450 °C). Representative physical properties such as UV–vis absorption and mechanical performances of the newly obtained functional iPPs with different tertiary amine groups have also been explored.