The terpolymerization of ethylene and propylene with isoprene via THF-containing half-sandwich scandium catalysts: a new kind of ethylene–propylene–diene rubber and its functionalization

The terpolymerization of ethylene and propylene with isoprene was performed catalyzed by half-sandwich scandium complexes (C5Me4SiMe3)Sc(CH2SiMe3)2(THF) (1) and [1,3-(Me2Si)2C9H5]Sc(CH2SiMe3)2 (THF) (2) in combination with 1 equiv. of [Ph3C][B(C6F5)4]. The terpolymers with ethylene contents of 60–84 mol% and isoprene contents of 5–26 mol% (1,4/3,4 ≈ 50/50) were obtained in the presence of complex 1. In comparison, the terpolymers with ethylene contents of 38–75 mol% and isoprene contents of 4–43 mol% (1,4/3,4 ≈ 70/30) were obtained in the presence of complex 2. Subsequently, a functionalized ethylene–propylene–isoprene terpolymer was prepared by the epoxidation of the 1,4-isoprene units in the terpolymer backbone and further hydroxylation/chlorination through ring-opening reaction of the epoxy groups.