Scalable enzymatic polymerization and low-temperature post-polymerization of poly(butylene succinate): Process parameters and application

Abstract

Poly(butylene succinate) is a semicrystalline bio-based and biodegradable polymer with good processability. However, using metal-based transesterification catalysts during chemical synthesis can be a drawback, especially for the biomedical and food packaging sector. An alternative approach was herein employed, using immobilized Candida antarctica Lipase B as a biocatalyst in a solvent-free process to synthesize PBS in line with green chemistry. The key process parameters (reaction temperature, pressure, time) were studied regarding the prepolymer’s molecular weight, thermal properties, and morphology. Thanks to the process's simplicity, scaling up followed, and a quantity of 20 g of PBS (Mn¯ 1700 g·mol−1) was received, thus filling the relevant gap in the open literature. The scaled-up grade was subsequently submitted to different sustainable post-polymerization methods (SSP, melt post-polymerization) to increase the molecular weight while maintaining the green character of the final product. The post-polymerized PBS (Mn¯ 3000 g·mol−1) was used as a carrier for the naturally occurring antioxidant flavonoid naringin. The release profile of naringin from the PBS nanocarrier was assessed, proving the enzymatically synthesized and upgraded PBS an effective matrix for high-purity encapsulation systems for the first time.