Abstract: This work investigated the effects of different phosphorus-nitrogen compounds on the polymerization of 1,3-butadiene and isoprene catalyzed by Fe(acac)3/AlR3. The results showed that the use of isocyanoimino-triphenylphosphorane (IITP) as an electron donor can synthesize syndiotactic 1,2-polybutadiene and 3,4-polyisoprene with high activity in hexane, and the highest catalytic activity can achieve 1.52×106 g·PBd /mol·Fe and 1.47×106 g·PIp /mol·Fe. The obtained polybutadiene displays a low melting point (Tm: 64.0-115 ℃), and the1,2-unit content can reach up to 80.2%. The 3,4-incorporation content of polyisoprene is between 48.8-52.4%, and the Tg is kept from -18.5 to -15.8 ℃. The unimodal distribution GPC curve indicates that the catalytic system has a single active center. Moreover, the quasi living polymerization characteristics of the catalytic system are verified through kinetics and seeding polymerization experiments of isoprene.

Key words: Coordination polymerization, Conjugated diene, Fe-based catalyst, Electron donor