Lipase-Catalysed Polymerization of Lactic Acid and the Properties of the Polymer C. Chuensangjun 1,a , C. Pechyen 2,3,b , Y. Chisti 4,c , S. Sirisansaneeyakul 1,5,d * 1 Department of Biotechnology, Kasetsart University, Chatuchak, Bangkok, 10900, Thailand 2 Department of Packaging and Materials Technology, Kasetsart University, Chatuchak, Bangkok 10900, Thailand 3 Center for Advanced Studies for Agriculture and Food, National Research University-Kasetsart University, Kasetsart University, Chatuchak, Bangkok 10900, Thailand (CASAF, NRU-KU, Thailand) 4 School of Engineering, Massey University, Private Bag 11 222, Palmerston North, New Zealand 5 Center for Advanced Studies in Tropical Natural Resources, National Research University-Kasetsart University, Kasetsart University, Chatuchak, Bangkok 10900, Thailand (CASTNAR, NRU-KU, Thailand) a pchaniga@gmail.com, b chiravoot.p@ku.ac.th, c Y.Chisti@massey.ac.nz, d fagissi@ku.ac.th Keywords: Polymerization; Lipase; Polylactic acid Abstract. Lipase-catalysed polymerization is an emerging green alternative method for the synthesis of polylactic acid (PLA) from lactic acid (LA) monomer. Use of the lipase catalyst avoids the need for potentially toxic chemical catalysts. The concentration of the lipase enzyme is one of several factors which influence the polymerization process. This paper reports on the effects of the lipase concentration on the characteristics of the low molecular weight polylactic acid (PLA) formed via lipase-catalyzed polymerization of lactic acid. The polylactic acid products made by this method are characterized by Fourier Transform Infrared Spectroscopy (FTIR). Low molecular weight polylactic acid could be successfully produced from commercial lactic acid by using the commercial lipase Lipozyme TL IM at 50 °C in a 5-hour reaction. Introduction Biodegradable plastics produced from natural monomers are a potential alternative to plastics made from petrochemicals. Polylactic acid or PLA is a biodegradable polymer. Under suitable conditions, PLA can be degraded by the action of microorganisms in the environment [1] . PLA has received increasing attention as a material for packaging, clothing and biomedical products. PLA is biocompatible and bioabsorbable and therefore useful in many biomedical and drug delivery applications. Various methods have been described for producing PLA. Lactic acid or LA may be condensed and converted to lactide, a cyclic diester. Lactide may then be used as the monomer in a ring-opening polymerization process to produce PLA. This process can be carried out under mild reaction conditions to provide a product with a high molecular weight. LA can be polymerized to PLA using chemical catalysts (e.g. oxides of zinc (Zn) and tin (Sn)) [2,3] which leave undesirable residues. In addition, the chemical processes require a high-purity monomer and an elevated temperature for the reaction. In contrast, the lipase-based catalysis does not contaminate the product with potentially toxic residues. Therefore, the product produced through lipase-catalysis is clearly more desirable for biomedical and pharmaceutical applications. This study, reports on lipase-catalyzed synthesis of PLA from commercial lactic acid. Advanced Materials Research Vol. 506 (2012) pp 154-157 © (2012) Trans Tech Publications, Switzerland doi:10.4028/www.scientific.net/AMR.506.154 All rights reserved. No part of contents of this paper may be reproduced or transmitted in any form or by any means without the written permission of TTP, www.ttp.net. (ID: 101.109.224.119-24/04/12,16:03:49)