Controlled ring‐opening homo‐ and copolymerization of ɛ‐caprolactone and <scp>d,l</scp>‐lactide by iminophenolate aluminum complexes: An efficient approach toward well‐defined macromonomers

Abstract

ABSTRACT The aluminum complexes containing two iminophenolate ligands of the type ( p ‐XC 6 H 4 NCHC 6 H 4 O‐ o ) 2 AlR' (R′=Me ( 3, 4 ) or R′=O(CH 2 ) 4 OCH=CH 2 ( 5, 6 ), X=H ( 3, 5 ), F( 4, 6 )) were synthesized and characterized by 1 H, 13 C NMR spectroscopy, and X‐ray crystallography. The reaction of AlMe 3 with two equivalents of substituted iminophenols gave five‐coordinated {ONR} 2 AlMe ( 3, 4 ) complexes. Subsequent reaction of these methyl complexes with unsaturated alcohol, HO(CH 2 ) 4 OCH=CH 2 , resulted in target compounds 5 and 6 in a good yield. It was shown that the complexes ( 3 ‐ 6 ) are monomeric in solution (NMR) and in solid state (X‐ray analysis). The catalytic activity of the complexes 5 and 6 towards ring‐opening polymerization (ROP) of ɛ‐caprolactone and d,l ‐lactide was assessed. Complex 5 showed higher activity as compared with 6 , while both of these catalysts induced controlled homo‐ and copolymerization to afford the macromonomers with high content of vinyl ether end groups ( F n &gt; 80%) in a broad range of molecular weights ( M n = 4000–30,000 g mol −1 ) with relatively narrow MWD ( M w / M n = 1.1–1.5). © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014 , 52 , 1237–1250