Ultrasound assisted lipase catalyzed synthesis of poly-6-hydroxyhexanoate

• Published in: Ultrasonics sonochemistry 2012-05, Vol.19 (3), p.659-667
• Main Authors: Gumel, A.M., Annuar, M.S.M., Chisti, Y., Heidelberg, T.
• Format: Article
• Language: English
• Subjects: Biopolymers; Catalysis - radiation effects; Enzyme Activation - radiation effects; High-Energy Shock Waves; Kinetics; Lipase; Lipase - chemistry; Lipase - radiation effects; Polycaprolactone; Polyesters - chemistry; Polyesters - radiation effects; Polyhydroxyalkanoates; Polymers - chemical synthesis; Polymers - radiation effects; Radiation Dosage; Sonication - methods; Ultrasound
• ISSN: 1350-4177; 1873-2828
• DOI: 10.1016/j.ultsonch.2011.10.016

Ultrasonic irradiation greatly improved the Candida antarctica lipase B mediated ring opening polymerization of ε-caprolactone to poly-6-hydroxyhexanoate in the ionic liquid 1-ethyl-3-methylimidazolium tetraflouroborate. Compared to the conventional nonsonicated reaction, sonication improved the monomer conversion by 63% and afforded a polymer product of a narrower molecular weight distribution and a higher degree of crystallinity. Under sonication, the polydispersity index of the product was ∼1.44 compared to a value of ∼2.55 for the product of the conventional reaction. With sonication, nearly 75% of the monomer was converted to product, but the conversion was only ∼16% for the reaction carried out conventionally. Compared to conventional operation, sonication enhanced the rate of polymer propagation by >2-fold and the turnover number of the lipase by >3-fold.