Ring‐Opening Polymerization of the Cyclic Ester Amide Derived from Adipic Anhydride and 1‐Amino‐6‐hexanol in Melt and in Solution

Abstract The ring‐opening polymerization (ROP) of the cyclic ester amide (cEA) 5 (systematic name, 1‐oxa‐8‐aza‐cyclotetradecane‐9,14‐dione) ‐ prepared from adipic anhydride and 1‐amino‐6‐hexanol ‐ in the melt at 165 °C and in solution at 100 °C and 120 °C with Bu 2 Sn(OMe) 2 or Ti(OBu) 4 as initiator yields the alternating poly(ester amide) (PEA) 4 (systematic name, poly(5‐(6‐oxyhexylcarbamoyl)‐pentanoate) with regular microstructure. Kinetic studies for different monomer‐to‐initiator ratios, different reaction media, initiators and temperatures reveal that the ROP is a first‐order reaction with respect to the monomer. Under suitable polymerization conditions termination and transfer reactions are suppressed. The elementary chain growth reaction proceeds by a coordination insertion mechanism in analogy to the polymerization of lactones. By using monohydroxy‐ and bishydroxy‐functional telechelic poly(ethylene oxide) and Sn(octoate) 2 as the initiating system poly(ethylene oxide)‐ block ‐poly(ester amide)s and poly(ester amide)‐ block ‐poly(ethylene oxide)‐ block ‐poly(ester amide)s are obtained. The poly(ester amide) 4 is a semicrystalline material with a melting point of 140 °C, the block copolymers are phase separated systems showing two melting points characteristic for the respective homopolymers.