Synthesis, Characterization and Antimicrobial Properties of Poly(styrene-co-maleic anhydride) Coupled 4-Aminophenol

Abstract

PSMA can be coupled conveniently with an active antimicrobial agent containing amino (-NH2) or hydroxyl (-OH) groups via ring opening reaction of succinic anhydride unit to prepare antimicrobial polymers. In the present experiment free radical polymerization was used to synthesize PSMA using AIBN initiator, from styrene and maleic anhydride monomers in 1:1 ratio at 70 oC in an inert atmosphere. The AP was selected as an antimicrobial agent due to its antibacterial phenolic group and coupled with PSMA and SMA-AP conjugate was obtained using TEA as a catalyst at 90 oC for 12 hours in an inert atmosphere. The PSMA and SMA-AP was characterized by FT-IR which showed complete ring opening of the maleic anhydride unit, new peaks appeared at 1706 cm-1 and 1650 cm-1 and there were complete disappearances of characteristics anhydride peaks at 1855 cm-1 and 1774 cm-1. The content of maleic anhydride in PSMA was estimated by acid-base titration. Two steps loss in weight were observed in the TGA curves of SMA and SMA-AP, as a result of water loss. The Tg of PSMA-AP of was observed at 217 oC which is slightly higher than Tg of PSMA i.e. 197 oC, which may be due to intermolecular hydrogen bonding interaction, there was no melting transition for PSMA and PSMA-AP. The structure’s analysis of copolymer was studied by proton NMR spectroscopy. The viability of SMA-AP was determined by mitochondrial cell viability assay against Huh7 cells, and showed high viability and low cytotoxicity. The antifungal test was done against fungus Aspergillus niger, and proved good antifungal activity. The SMA-AP demonstrated 99.9 % reduction in colonies for bacteria E. coli and S. aureus, by shake flask method.