A highly efficient catalyst for the "living" and "immortal" polymerizationof epsilon-caprolactone and L-lactide

A novel ligand, 2,2'-methylenebis(4,6-di(1-methyl-1-phenylethyl)phenol) (MM PEP-H-2) (1), has been prepared by the reaction of 2,4-bis(alpha,alpha -dim ethylbenzyl)phenol with formaldehyde in the presence of a catalytic amount of benzenesulfonic acid. Further reaction of compound I with Me3Al in dieth yl ether produces a four-coordinated monomeric aluminum complex [(MMPEP)AlM e(OEt2)] (2). [(MMPEP)-Al(mu -OBn)](2) (3) can then be synthesized from the reaction of 2 with 1 molar equiv of benzyl alcohol at ambient temperature. 3 has demonstrated highly efficient catalytic activities in the ROP of eps ilon -caprolactone and the ROP Of L-lactide. The "living" character of comp lex 3 enable us to prepare PCL-b-PLA copolymer, and the "immortal" characte r of 3 has paved a way to synthesize as much as 160-fold polymer chains of poly(caprolactone) with very narrow PDI in the presence of a small amount o f initiator.