Semi-aromatic polyester synthesis via alternating ring-opening copolymerization using a chromium complex based on a pentapyridine ligand

Abstract

The present study examined the use of a Cr(III) complex bearing a pentapyridine ligand as a catalyst in alternating ring-opening copolymerization (ROCOP) to prepare polyesters. Alternating ROCOP of anhydride (phthalic anhydride or 1,8-naphthalic anhydride) and cyclic epoxide (cyclohexene oxide) was performed using a Cr(III) pentapyridine complex (1) and a cocatalyst, DMAP (4-dimethylaminopyridine) or PPNCl ((bis(triphenylphosphine)iminium chloride). After optimizing the monomer ratio and reaction conditions, fully alternating polyesters with narrow polydispersity were synthesized (M-n up to 10.4 kg/mol, D below 1.3). These results demonstrate that Cr(III)-based catalysts bearing pentapyridine ligands can generate fully alternating polyesters.