Acid‐Catalyzed Alternating Copolymerization of Oxetane With Cyclic Anhydride

Ring‐opening (co)polymerization is a versatile method for the synthesis of aliphatic polyesters. A fundamental challenge in this field lies in devising fresh synthetic methodologies to broaden the scope of aliphatic polyesters. In this study, we have successfully achieved the cationic copolymerization of various oxetanes (OX) and cyclic anhydrides using diverse Lewis/Bronsted acid catalysts. The method yields aliphatic polyesters with various structures and properties. It is proposed that OX firstly self‐polymerized rapidly to form polyether, which then converted into polyester via the chain transfer reaction from polyether to cyclic anhydride. The resulting polyesters exhibit low number‐average molecular weights ( M _n s) of 1.7–4.8 kDa, dispersities ( Ð ) of 1.1–1.6, glass transition temperatures ( T _g s) ranging from −55 to 2 °C, and high decomposition temperatures ( T _d s) of up to 339 °C. This study has introduced a practical approach for synthesizing aliphatic polyesters through cationic copolymerization.