Isospecific (Co)polymerization of Unmasked Polar Styrenes by Neutral Rare‐Earth Metal Catalysts

Abstract

AbstractSyndioselective polymerization of unprotected polar styrenes has achieved great success via specially designed catalysts and the establishment of “self‐assisted” theory. In contrast, isospecific polymerization of polar styrenes has remained less explored. Herein, we present new racemic ansa‐bis(benz[e]indenyl) rare‐earth metal complexes and their high activity and perfect isoselectivity (mmmm>99 %) for the polymerization of unmasked polar styrenes without any activators. Moreover, the copolymerizations of para‐ and meta‐methoxystyrenes with styrene give gradient and random copolymers, respectively. The insertion rate of polar monomers could be readily tuned in the range of 0–100 mol % by changing their loading ratios. The resultant isotactic polar polystyrenes are quantitatively transformed into hydroxyl or methylsulfonyl polystyrenes with high Tgs. DFT calculations reveal the isospecific mechanism.