Rapid Syndiospecific (Co)Polymerization of Fluorostyrene with High Monomer Conversion.

Abstract

Fluoromonomers are difficult to polymerize through a coordination mechanism owing to the strong chelation between fluorine and catalysts and the electron-deficient double-bond. We report herein the unprecedented polymerization of para-fluorostyrene (pFS) with excellent activity (1.12×107 g molLn-1 h-1 ), distinguished syndioselectivity (rrrr >99 %) and high conversion (98.4 %) using rare-earth-metal catalysts bearing a pyridyl methylene fluorenyl ligand. DFT calculations reveal polar fluorine loses overwhelming coordination priority to the active central metal ion due to the sterically bulky and electron-donating CGC-ligand, thus its power of poisoning the active species is dramatically weakened. Based on this, copolymerization of pFS and styrene (St) has been successfully achieved with high activity and controllable pFS insertion. Conversely, the unlinked half-sandwich rare-earth-metal system shows relatively lower activity, because both the transition-states and intermediates incorporate a μ1 -F chelated pFS.