Towards feasible and scalable solvent-free enzymatic polycondensations: integrating robust biocatalysts with thin film reactions

Abstract

There is an enormous potential for synthesizing novel bio-based functionalized polyesters under environmentally benign conditions by exploiting the catalytic efficiency and selectivity of enzymes. Despite the wide number of studies addressing in vitro enzymatic polycondensation, insufficient progress has been documented in the last two decades towards the preparative and industrial application of this methodology. The present study analyses bottlenecks hampering the practical applicability of enzymatic polycondensation that have been most often neglected in the past, with a specific focus on solvent-free processes. Data here presented elucidate how classical approaches for enzyme immobilization combined\ud with batch reactor configuration translate into insufficient mass transfer as well as limited recyclability of the biocatalyst. In order to overcome such bottlenecks, the present study proposes thin-film processes employing robust covalently immobilized lipases. The strategy was validated experimentally by carrying out the solvent-free polycondensation of esters of adipic and itaconic acids. The results open new perspectives for enlarging the applicability of biocatalysts in other viscous and solvent-free syntheses

Nature Inspired Solutions for Polymers: Will Cutinase Enzymes Make Polyesters and Polyamides Greener?

“…The porosity of carriers seems to play a negligible role in the process design, rather, porosity might induce the risk of undesired occlusion by substrates and products, thus limiting the efficiency of the enzyme. This assumption is also supported by recent data obtained in polycondensation catalyzed by hydrolases immobilized on rice husk [59,66]. Although the enzymes (CaLB and Thc_cut1) were immobilized only on the surface either through adsorption-crosslinking or covalent bonding, the polyester synthesis proceeded with comparable rates and conversion as in the case of the macroporous methacrylic resins.…”

“…In the case of enzymatic polycondensation and more specifically in solvent-free systems, the viscosity of reaction mixtures makes the diffusion of substrates and pre-polymers into the pores highly unlikely [59]. The porosity of carriers seems to play a negligible role in the process design, rather, porosity might induce the risk of undesired occlusion by substrates and products, thus limiting the efficiency of the enzyme.…”

“…Actually, most of the studies related to enzymatic polymerization make use of lipases, and in particular CaLB which is one of the most widely used enzymes in industry and the 'yardstick' for comparison in academia [3,59].…”

Enzymatic Polymerization of Furan-2,5-Dicarboxylic Acid-Based Furanic-Aliphatic Polyamides as Sustainable Alternatives to Polyphthalamides

“…However, the immobilized CALB can be recycled from the enzymatic polymerization and then reused for several cycles. [52][53][54] Moreover, N435…”

Large scale applications of immobilized enzymes call for sustainable and inexpensive solutions: rice husks as renewable alternatives to fossil-based organic resins

“…(tpG) and the invertase from Saccharomyces cerevisiae (ISc) 17 . Overall, lipases have a wide industrial impact in the food, pharma and cosmetic sectors but their catalytic potential is far from being fully exploited for the production of commodities or biodiesel [19][20][21] . CaLB (3.1.1.3) is widely employed in the production of fine chemicals for its selectivity but also in the production of esters for body care sector.…”