Synthesis and characterization of chitosan-g-poly(2-(furan-2-carbonyl)-acrylonitrile): Grafting of chitosan using a novel monomer prepared by a Baylis–Hillman reaction

Abstract

Graft copolymerization of the novel monomer 2-(furan-2-carbonyl) acrylonitrile (FCAN) onto chitosan was carried out under heterogeneous conditions using potassium persulfate and sodium sulfite as a redox system. The monomer, FCAN, was synthesized by iodoxybenzoic acid promoted oxidation of 2-(furan-2-yl(hydroxyl)methyl)acrylonitrile FHMAN, which was prepared by using a Baylis Hillman reaction between acrylonitrile and furfural. The graft copolymers were characterized by using FTIR, 1H NMR, 13C NMR spectroscopy, along with XRD, TGA, SEM. The effects of various parameters on the grafting percentage (G%) and the efficiency of grafting (E%) were determined. The results show that an optimal grafting percentage of 145% results when the process is conducted at 55°C for 3.5h employing a 1:0.5 ratio of K2S2O8 and Na2SO3. The grafted copolymers with varying grafting percentages were found to display a marked increase in swelling in water, as compared to chitosan, and swelling was observed to increase as the acidity of the medium increases. The antifungal and antibacterial activites of chitosan and the grafted copolymers against selected micro-organisms (bacteria; Bacillus subtilis, Escherichia coli and fungi; Aspergillus niger, Penicillium digitatum, Staphylococcus aureus) were determined. The results show that growth inhibition by the copolymers is in the following order: E. Coli>Bacillus>S. Aureus>Aspragillus>Pennicilium, reflective of a higher activity against bacteria than fungi. In addition, a general trend was observed in which increases in biological activities are directly dependent on grafting percentages, presumably a consequence of the presence of more furan moieties in the polymer backbone.