Biocatalytic Approach for Novel Functional Oligoesters of ε-Caprolactone and Malic Acid

Abstract

Biocatalysis has developed in the last decades as a major tool for green polymer synthesis. The particular ability of lipases to catalyze the synthesis of novel polymeric materials has been demonstrated for a large range of substrates. In this work, novel functional oligoesters were synthesized from ε-caprolactone and D,L/L-malic acid by a green and sustainable route, using two commercially available immobilized lipases as catalysts. The reactions were carried out at different molar ratios of the comonomers in organic solvents, but the best results were obtained in solvent-free systems. Linear and cyclic oligomeric products with average molecular weights of about 1500 Da were synthesized, and the formed oligoesters were identified by matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS) analysis. The oligoester synthesis was not enantioselective in the studied reaction conditions. The operational stability of both biocatalysts (Novozyme 435 and GF-CalB-IM) was excellent after reutilization in 13 batch reaction cycles. The thermal properties of the reaction products were investigated by thermogravimetric (TG) and differential scanning calorimetry (DSC) analysis. The presence of polar pendant groups in the structure of these oligomers could widen the possible applications compared to the oligomers of ε-caprolactone or allow the conversion to other functional materials.

Special Issue on “Enzymatic Synthesis and Characterization of Polymers”

“…The same CALB lipase (available in immobilized form as Novozyme 435 or GF-CALB-IM) was efficient for the biocatalytic synthesis of new oligoesters of D,L-and D-malic acids and ε-caprolactone, as reported by Dreavă et al [6]. The solventless reaction system proved again to have the best performance, and the operational stability of both investigated biocatalysts was excellent during more than 10 batch reaction cycles.…”

Monomers and Macromolecular Materials from Renewable Resources: State of the Art and Perspectives

“…Malic acid is a natural hydroxy acid that can be found in many natural resources (such as grapes and apples) but has so far been mainly produced by chemical synthesis from fossil resources as racemic d , l -malic acid. However, the biotechnological production of malic acid has been proved viable, thanks to the ability of some fungal species of Aspergillus , Ustilago , and Aureobasidium , to synthesize L-malic acid from different carbon sources [ 170 ]. Therefore, the exploitation of malic acid as a building block for polymer synthesis is sought to gain increasing attention in the field of polymers from renewable resources.…”

“…This was the case of a recent contribution of Yang and coworkers [ 171 ], who synthesized polyols from 1,6-hexanediol, malic acid, and citric acid, and then prepared water-blown rigid polyurethane foams with polyisocyanates by a catalyst-free method. Malic acid was also considered for the synthesis of oligoesters via reaction with ε-caprolactone and enzymatic catalysis [ 170 ].…”