Rational guidelines for the two-step scalability of enzymatic polycondensation: experimental and computational optimization of the enzymatic synthesis of poly(glycerolazelate)

The lipase catalyzed polycondensation of azelaic acid and glycerol was investigated according to a Design of Experiment approach that allowed to understand the effect of the experimental variables on monomer conversion, M n and regioselectivity of acylation of glycerol. The chemometric analysis showed that after 24h the reaction proceeds regardless of the presence of the enzyme. Accordingly, the biocatalyst was removed after a first step of synthesis and the chain elongation continued at 80°C. That allowed the removal of the biocatalyst and the preservation of its activity: pre-requites for efficient applicability at industrial scale. The experimental study, combined with docking based computational analysis, provided rational guidelines for the optimization of the regioselective acylation of glycerol. Overall, the process was scaled up to 73.5 g of monomer. The novelty of the present study stays in the rigorous control of the reaction conditions and of the integrity of the immobilized biocatalyst, thus avoiding any interference of free enzyme or fines released in the reaction mixture.  The quantitative analysis of the effect of the experimental conditions and the overcoming of the major technical bottlenecks for the scalability of enzymatic polycondensation opens new scenarios for its industrial exploitation.