Preparation and characterization of poly(ɛ-caprolactone)-b-polyacrylonitrile (PCL-b-PAN) and poly(l-lactide)-b-polyacrylonitrile (PLLA-b-PAN) copolymers by aluminum and lithium alkoxides containing double-headed initiators

Three new metal alkoxides, [(MMPEP)Al(μ-OCH2C6H4CH2Cl)]2 (1), [(MMPEP-H)Li·(BnOH)]2 (2) and [(MMPEP-H)Li·(HOCH2C6H4CH2Cl)]2 (3) (MMPEP-H2: 2,2′-methylene-bis{4,6-di(1-methyl-1-phenylethyl)phenol}) have been synthesized and characterized. Complex 1 was prepared by the reaction of [(MMPEP)Al(CH3)(Et2O)] with p-(chloromethyl)benzyl alcohol. Followed by the reaction of MMPEP-H2 with nBuLi, BnOH or p-(chloromethyl)benzyl alcohol was added to give complexes 2 and 3, respectively. Complex 1 has shown excellent catalytic activity towards ring-opening polymerization (ROP) of ɛ-caprolactone. Both complexes 2 and 3 are active for ROP of l-lactide. Block copolymers of poly(ɛ-caprolactone)-b-polyacrylonitrile (PCL-b-PAN) and poly(l-lactide)-b-polyacrylonitrile can be synthesized by combining a technique of atom transfer radical polymerization (ATRP) and ROP using a double-headed initiator. Microphase-separated morphology of PCL-b-PAN has been observed by transmission electron microscopy, indicating the formation of self-assembled nanostructure.