Enzyme-Catalyzed Polymerization of β-alanine Esters, A Sustainable Route Towards the Formation of Poly-β-alanine

The synthesis of poly-β-alanine by a lipase catalyzed polycondensation reaction between β-alanine esters is reported. The effect of different solvents, reaction temperatures and substrate/enzyme concentrations on polymer yield and degree of polymerization (DP) was determined. Also the effect of methyl substituents at the α and β position of β-alanine was studied. Cross-Linked Enzyme Aggregates (CLEA) of Candida antarctica lipase B converted β-alanine esters into polymers in high yield (up to 90%) and with high (DP) (up to 53 units). Optimum results were obtained when methyl esters are used in methyl tert-butyl ether (MTBE) as the solvent, at 50°C for 16 h. Keywords: Biobased, biocatalysis, CLEA, enzymatic catalysis, lipases, Novozyme 435, nylon 3, polyamides.