Amido-trihydroquinoline ligated rare-earth metal complexes for polymerization of isoprene

Abstract

Amido-trihydroquinoline ligated rare-earth metal complexes have been synthesized, and in combination with a borate, all these complexes (except 2-Sc) showed moderate catalytic activities for isoprene polymerization to generate 1,4-enriched polyisoprene. In particular, the 2-Y-based catalytic system promoted the isoprene polymerization in a well-controlled manner. The alkylaluminium (AlR₃, R = Me, Et, ⁱBu) exerted a different influence on the polymerization, and AlMe₃ enhanced not only the catalytic reactivity but also the 1,4-selectivity significantly. Considering the influence of the polar sequence on improving the surface property of the non-polar polymer, we further successfully realized the polymerization of ε-caprolactone and its block copolymerization with isoprene by utilizing the active yttrium-polyisoprene species as the marcointiator. The fact that the higher content of the hydrophilic PCL sequence in the copolymer gave a lower WAC, proved the tunable modification of the copolymer's surface hydrophilicity.