Effect of AlEt2Cl on the polymerization of isoprene using TiCl4/MgCl2 type Ziegler-Natta catalyst: A DFT study

Alkylaluminium is one of the components of the Ziegler-Natta catalysts, which plays a significant role in the active materials with different regions and stereoselectivity. The polymerization of isoprene with alkylaluminium in TiCl4/MgCl2 type Ziegler-Natta catalysts system is rarely studied by simulation. In this work, density functional theory (DFT) was applied to investigate the mechanism of the polymerization of isoprene with heterogeneous Ziegler-Natta catalyst in the presence and absence of AlEt2Cl on the surface of MgCl2 (110). The interaction between AlEt2Cl and MgCl2 support was studied by the counterpoise corrected approach. Two active models were adopted to analyze the influence of AlEt2Cl on the polymerization of isoprene in the coordination process and the insertion process respectively. The calculations indicated that only one double bond of isoprene was coordinated to the active center, the presence of AlEt2Cl improved the stereoselectivity of the active center, increased the difficulty of cis coordination, and reduced the difficulty of trans coordination. In the insertion process, the cis insertion process was more favorable and the trans product structure was more stable.