Correlation of alkylaluminum cocatalyst in Nd-based ternary catalyst with the polymerization performance of isoprene

- Effect of alkylaluminum cocatalyst in Nd-based ternary catalyst was studied.
- Isoprene polymerization results based on four catalyst systems shown different for the kind of alkylaluminum.
- Local structures around Nd center of the four catalysts were obtained by XAFS technique.
- The structural information is beneficial to elucidate the effect of alkylaluminum to the isoprene polymerization.

Nd-based ternary catalyst systems are widely used for rubber industry. The effect of alkylaluminum cocatalysts has been investigated for decades. However, there is a lack of structural evidence, especially the quantitative result to illustrate the inner reasons. In the present paper, the effect of different alkylaluminum cocatalysts to the polymerization performance of isoprene has been studied. Catalysts adopted in the present paper all show high 1,4-cis selectivity (above 96%) of polyisoprene and kind of alkylaluminum is not the crucial factor to affect the microstructure of polyisoprene. By comparing the polymerization performance of isoprene and the local atomic structure around Nd centers, it can be concluded that the short carbon-chain in the alkylaluminum cocatalyst is helpful to increase the percent conversion of isoprene. While the carbon-chain length and number in each alkylaluminum cocatalyst can be used to modulate the molecular weight of the synthesized polyisoprene. All the results in the present paper provide a clue to improve the Nd-based ternary catalyst for rubber synthesis.

242