ENZYMATIC CATALYSIS FOR POLYCONDENSATION:
POTENTIAL IMPACT AND TECHNOLOGICAL BARRIERS
Alessandro Pellis1, Livia Corici2, Valerio Ferrario1, Cynthia Ebert1 and Lucia Gardossi1*
1Dipartimento di Scienze Chimiche e Farmaceutiche, Università degli Studi di Trieste, Piazzale Europa 1, 34127 Trieste, Italy
2SPRIN S.p.A., via Flavia 23/1, 34148 Trieste, Italy
e-mail: gardossi@units.it
1.Introduction
The extraordinary catalytic potential of enzymes and lipases in particular in polyesters synthesis has been reported in the last two decades.[1] Enzymes are selective bio-catalysts that enable the minimization of protection/deprotection strategies so that monomers with functionalities can be used while avoiding branching. The benefits coming from the use of enzymes in polycondensation reactions are also related to their sustainability and high efficiency at mild conditions: toxic metal catalysts can be avoided and processes can be carried out at temperatures below 80°C. Although the Mn of products attainable by enzymatic polycondensation is in most cases below 10.000, the technology can be used in the production of pre-polymers or in combination with chemical or thermal polymerization. Thanks to the mild reaction conditions, the enzymatic approach to polycondensation is complementary to the chemical synthesis providing a route for the introduction of functional groups inside the polymeric chain with the aim of production of “reactive” polyesters. However, the wide array of enzymatic polyester synthesis described in the scientific literature at laboratory scale are currently not exploited at industrial scale, especially because of low biocatalyst efficiency under process conditions. Recyclability, stability in the viscous conditions of polymerization process and under stirring are the main problems investigated by the “Laboratory of Applied and Computational Biocatalysis” of the University of Trieste. Results achieved in our recent studies will be presented, along with specific enzymatic and synthetic methodologies that can be now used in the enzymatic polycondensation of bio-based polyols and diacids.
2.Results and discussion
The reactions were performed using a robust immobilized enzymes suspended in the monomers, without addition of solvent. A specific immobilization method has been developed for preventing the release of the enzyme during the polycondensation into the polymeric product.[2] Lipase B from Candida antarctica (CALB) was used as biocatalyst.
