The effect of catalyst concentration in poly lactic acid synthesis from L-lactide using Candida rugosa lipase and DMA (dimethylacetamide) solvent through ring-opening polymerization (ROP)

Abstract

Poly Lactic Acid (PLA) is a polymer that can be used as an alternative to fossil-based plastics. PLA is the right solution because of its biodegradability, biocompatibility, mechanical strength, and processability. PLA synthesis process is more often carried out using the Ring-Opening Polymerization (ROP) pathway since it allows to produce a high molecular weight PLA. This study used Candida rugosa lipase as a green catalyst and DMA (Dimethylacetamide) as the solvent in the ROP of L-lactide. The observations were made by varying the catalyst ratio at 2, 5, and 10% w/w. The obtained PLA was characterized using H-NMR (H Nuclear Magnetic Resonance) to estimate the average number molecular weight (Mn) and monomer conversion, and GPC (Gel Permeation Chromatography) was also used to determine the number average and weight average molecular weight (Mn and Mw) of the PLA. It was found that the optimal catalyst ratio when the polymerization was performed at 80℃ for 3 days was 5%w/w.