Engineering Sustainable Polymers Through Biology

Polymers from sustainable biobased sources or through green biotransformation routes are of increasing scientific interest.  Among various routes, enzymes immobilized on solid supports are increasingly used for greener, more sustainable chemical transformation processes.  However, process engineering and measurement challenges remain to develop cost-effective products.  In this project we use microreactors to study enzyme-catalyzed ring opening polymerization of ε-caprolactone to polycaprolactone.  The goal is to understand these complex systems by precisely controlling the experimental parameters in microreactors.  Using a novel microreactor design these heterogeneous reactions have been performed in continuous mode, in organic media, and at elevated temperatures.  Faster polymerization rate and higher molecular mass are achieved in microreactors compared to using batch reactors.  To understand the key reaction steps and to provide methods for improving polymerization products a kinetic model has been developed, which successfully predicts molar mass and molar mass distribution as a function of time or conversion.  While this study focused on polymerization reactions, it is evident that similar microreactor based platforms can readily be extended to other enzyme-based systems, for example, precision measurements of new processes where continuous flow mode is preferred.