ENZYMATIC CATALYSIS FOR THE SYNTHESIS OF FUNCTIONAL POLYESTERS

The extraordinary catalytic potential of enzymes and lipases in particular in polyesters synthesis has been reported in the last two decades. 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.