Cost-effective synthesis of polyricinoleate: Investigation of coating characteristics, in vitro degradation, and antibacterial activity

Abstract

Ricinoleic acid (RA) is a component of various bio-based copolymers. However, high-molecular weight polyricinoleate homopolymers are not widely investigated due to high cost of commercial monomer and catalysts. In this work, we present low-cost approach for the synthesis of high-molecular-weight polyricinoleate by preparing large amount of pure monomer and use of lipozyme TL IM as catalyst. First, polymerization conditions were optimized and comparative studies of medium-molecular-weight polyricinoleate (PRA-M) of M-w = 30 000 gmol(-1) and high-molecular-weight polyricinoleate (PRA-H) of M-w = 72 000 gmol(-1) were conducted. Polyricinoleates were characterized by common spectroscopic, chromatographic, and thermal methods. Solvent casting of polyricinoleates resulted in thin and continuous coating with perfectly smooth surface under SEM observation. AFM analysis of PRA films showed that surface roughness decreased with increasing molecular weight of polyricinoleate (roughness PRA-M = 68.39 nm and PRA-H = 57.36 nm). Degradation studies under in vitro conditions showed that both PRA-M and PRA-H showed good stability with only ~2% of mass loss after 6 months, possibly due to its hydrophobic nature and relatively high-molecular weight. In contrast to RA, PRA-M and PRA-H do not have significant antibacterial effect on Staphylococcus aureus and Escherichia coli. (c) 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 48172.