Synthesis, characterization, conductivity and antimicrobial study of a novel thermally stable polyphenol containing azomethine group

Abstract

Poly(4-[[(4-methylphenyl)methylene]amino]phenol) (P(4-MMAP)), which is a Schiff base polymer, was synthesized by an oxidative polycondensation reaction of 4-[[(4-methylphenyl)methylene]amino]phenol (4-MMAP) with the oxidants NaOCl, H2O2 and O2 in an aqueous alkaline medium. The polymerizations were carried out at various temperatures and times, and the highest polymer yield could be obtained when using 37% with NaOCl oxidant. The structures of the monomer and polymer were characterized by UV–Vis, FTIR 1H NMR and X-ray diffraction techniques. The thermal behaviors of the monomer and polymer were identified by the TG and DTG techniques. The thermal degradation of the polymer which was observed thermally stable up to 1000 °C, was also supported by the Thermo-IR spectra recorded in the temperature range of 25–800 °C. The number average molecular weight (Mn), weight average molecular weight (Mw) and polydispersity index (PDI) of the polymer were found to be 16682, 57796 g/mol and 3.4, respectively. The highest electrical conductivity value of P(4-MMAP) doped with iodine vapor at different temperatures and times was measured to be 7.8 × 10−5 Scm−1 after doping for 48 h at 60 °C. The antibacterial and antifungal activities of 4-MMAP and P(4-MMAP) were also assayed against the bacteria Sarcina lutea, Enterobacter aerogenes, Escherichia coli, Enterococcus faecalis, Klebsiella pneumoniae, Bacillus subtilis and the fungi Candida albicans, Saccharomyces cerevisiae, respectively.