o-Benzenedisulfonimide as a recyclable cationic organocatalyst for the controlled/living ring-opening polymerization of δ-valerolactone and ε-caprolactone

o-Benzenedisulfonimide (OBS) was demonstrated for the first time to be a safe, recyclable, and water-tolerant Brønsted acidic catalyst for the ring-opening polymerization (ROP) of δ-valerolactone and ε-caprolactone using benzyl alcohol as the initiator. The polymerizations proceeded to afford poly(δ-valerolactone) and poly(ε-caprolactone) with controlled molecular weights and narrow polydispersities. The kinetics and chain extension experiments were carried out to confirm the controlled/living fashion of the polymerizations. In addition, 1H NMR and MALDI-TOF MS measurements strongly indicated that the initiator residue was incorporated into the obtained polymers. Furthermore, well-defined poly(δ-valerolactone)-block-poly(ε-caprolactone) has been successfully synthesized via OBS-catalyzed ROP.