Janus Effect of Lewis Acid Enables One-Step Block Copolymerization of Ethylene Oxide and N-Sulfonyl Aziridine

作者：Song, Qilei; Qiu, Hong; Liu, Lijun; Zhang, Guangzhao; Peruch, Frederic; Carlotti, Stephane^*; Zhao, Junpeng^*

来源：Angewandte Chemie - International Edition, 2023, 62(18).

DOI：10.1002/anie.202300187

• Aziridine
• Block Copolymer
• Epoxide
• Ring-Opening Polymerization

One-step sequence-selective block copolymerization requires stringent catalytic control of monomers relative activity and enchainment order. It has been especially rare for A(n)B(m)-type block copolymers from simple binary monomer mixtures. Here, ethylene oxide (EO) and N-sulfonyl aziridine (Az) compose a valid pair provided with a bicomponent metal-free catalyst. Optimal Lewis acid/base ratio allows the two monomers to strictly block-copolymerize in a reverse order (EO-first) as compared with the conventional anionic route (Az-first). Livingness of the copolymerization facilitates one-pot synthesis of multiblock copolymers by addition of mixed monomers in batches. Calculation results reveal that a Janus effect of Lewis acid on the two monomers is key to enlarge the activity difference and reverse the enchainment order.