Microwave-Assisted Biocatalytic Polymerizations

Enzymatic Ring‐Opening Polymerization of Lactones: Traditional Approaches and Alternative Strategies

“…* The removal of water, which acts as an initiator, from the reaction mixture induces no changes in polymerization rates or monomer conversion, but leads to higher-molecularweight polyesters. [68] The synergistic ROP of lactones using lipase and microwave radiation was applied to the solvent-free polymerization of ɛ-CL [69] and ω-PDL, [70] yielding poly-ɛ-CL with M n of 20,624 g/mol and PDI of 1.2 (four hours reaction at 90 °C and 50 W, with Novozym®435 10 wt%) and poly-ω-PDL 24,997 g/mol M n and 1.93 PDI (four hours reaction at 70 °C and 200 W, with Novozym®435 10 wt%). Compared to using lipase and traditional heating, microwave-assisted lipase-catalyzed ROP of lactones increased the molecular weight of the synthesized Enzyme [a] Enzyme/Monomer ratio [b] T t M n M w PDI [c] C(Y) [d] Ref.…”

On the Effect of Microwave Energy on Lipase-Catalyzed Polycondensation Reactions

“…The most studied and well-characterized enzyme able to catalyze such reactions is Candida antarctica lipase B (CaLB), a thermostable biocatalyst mostly used in its immobilized form [5,6,8]. Despite the biocatalyst’s wide stability towards temperature (up to 90 °C) and organic solvents, several further attempts to improve its performance have also been investigated, involving mainly the immobilization formulation [11,12], ultrasound [13,14] and microwave energy [15,16]. Indeed, microwave energy (MWe) offers several benefits as a greener way of heating chemical reactions [17,18,19,20]: Microwave energy can be introduced remotely without the need for direct contact between the energy source and the chemicals, thus avoiding hot spots and improving product selectivityEnergy input starts and stops immediately when power is turned on or off, thus when hazardous exotherms are encountered the MW irradiation can be instantly removedHeating rates are high as long as one of the components of the reaction can couple strongly with the microwavesEnergy consumption is generally considerably lower for microwave assisted reactions as the reaction media or reagents are heated directly without prior need of heating the reaction vessel and surrounding equipment…”