Lipase-mediated degradation of poly-ε-caprolactone in toluene: Behavior and its action mechanism

Aris, M.H. and Annuar, M.S.M. and Ling, T.C. (2016) Lipase-mediated degradation of poly-ε-caprolactone in toluene: Behavior and its action mechanism. Polymer Degradation and Stability, 133. pp. 182-191. ISSN 0141-3910, DOI

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Lipase-catalyzed hydrolysis of poly(ɛ-caprolactone) (PCL) in toulene was investigated. PCL with number-average molecular weight (Mn) 10,000 g mol−1 was hydrolyzed using immobilized Candida antarctica lipase B (CALB). The increase in PCL concentration led to a decrease in degradation rate. Enhanced rate was observed when reaction temperature was increased from 30 to 50 °C. Enzymatic chain scission of PCL yielded cyclic dicaprolactone, tricaprolactone, tetracaprolactone and oligomers with Mn less than ∼1000 g mol−1. Catalytic formation of cyclic lactones via back-biting mechanism in low water content environment was attributed to CALB. Its hydrolysis of PCL displayed consecutive random- and chain-end scission with time from detailed thermal, molecular weight and structural analyses. Apparent activation energy, Ea for hydrolysis was 45 kJ mol−1 i.e. half of that reverse reaction. Dicaprolactone and oligomers from hydrolysis readily re-polymerized to produce mid-range polymer with Mn 1400 g mol−1 after 36 h in the same reaction medium.

Item Type: Article
Funders: University of Malaya for research funding PG 080-2012B and RG330-15AFR
Uncontrolled Keywords: Poly(ɛ-caprolactone); Lipase; Enzymatic degradation; Organic solvent; Cyclic lactones; Scission mechanism
Subjects: Q Science > QH Natural history > QH301 Biology
Divisions: Faculty of Science > Institute of Biological Sciences
Depositing User: Ms. Juhaida Abd Rahim
Date Deposited: 08 Sep 2017 10:08
Last Modified: 08 Sep 2017 10:08

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