Ionic liquid coated lipase: Green synthesis of high molecular weight poly(1,4-dioxan-2-one)

The ring-opening polymerization (ROP) of 1,4-dioxan-2-one (PDO) catalyzed by ionic liquid 1-butyl-3-methylimidazolium hexafluorophosphate ([BMIM][PF6]) coated lipase was investigated for the first time. By coating Novozym 435 with 10 wt% ionic liquid [BMIM][PF6] (based on PDO) for 6 h, poly(1,4-dioxan-2-one) (PPDO) with a maximum molecular weight (Mw) of 182,100 g mol−1 was obtained. In order to demonstrate the efficiency of this method, [BMIM][PF6] was also employed as a solvent for Novozym 435 catalyzed ROP of PDO. The results achieved using ionic liquid coated Novozym 435 were much superior to that with ionic liquid as a solvent. The probable mechanism of ionic liquid-coated Novozym 435 catalyzed the ROP of PDO was investigated by SEM, FT-IR, GPC and MALDI-TOF. All the results showed that ionic liquid coated lipase was an efficient and green catalyst for the ROP of PDO.