Abstract: The chain-end functionalized rubbers play important roles in improving the filler dispersion, increasing the interaction force between rubbers and filler particles, both of which affect the properties of the final products. In this paper, amine-capped trans-1,4-poly (butadiene-co-isoprene) copolymers (F-TBIR) with controllable composition and micro-structure were synthesized through in one-step coordination chain transfer polymerization by using heterogeneous TiCl4/MgCl2 type Ziegler-Natta catalyst with dichyclohexylamine (DCHA) as chain transfer agent. The effects of the amount of DCHA and co-catalyst triethylaluminum (AlEt3) on the the catalytic efficiency, amine-capped efficiency (CE) and chain micro-structure of the F-TBIR were investigated. The results indicated that DCHA did not change the stereo-regularity of the catalytic species. With the increase in DCHA dosage, the catalytic efficiency and molecular weight of the copolymers decreased, while CE increased significantly. With the increase in the amount of AlEt3, the catalytic efficiency initially increased then subsequently decreased, and the molecular weight of polymer and CE gradually decreased. Under the specified experimental conditions, the chain transfer constants of DCHA and AlEt3 were 0.0537 and 0.016, respectively. Combined with Density Functional Theory (DFT) simulation, the chain transfer mechanism of DCHA and AlEt3 in the diene coordination polymerization catalyzed by heterogeneous Ziegler-Natta catalyst was discussed. This work was expected to provide a straightforward and feasible strategy for developing chain-end functionalized synthetic rubber.

Key words: Coordination chain transfer; Chain-end functionalization, Trans-1,4-(butadiene-co-isoprene) copolymer rubber; Ziegler-Natta catalyst