Synthesis and characterization of bead-like particles based on chitosan and vinyl polymers
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Styrene, methyl methacrylate and glycidyl methacrylate vinyl monomers were grafted onto chitosan by surfactant-free emulsion copolymerization using potassium persulfate as initiator. The grafted compounds were characterized by X-ray diffraction, FTIR spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM), atomic force microscopy (AFM) and zeta potential measurements. X-ray diffraction showed changes in the crystallinity pattern of chitosan after the copolymerization reaction. Evidence of grafting was confirmed by FTIR spectroscopy. From zeta potential measurements it is found that the surfaces of graft copolymers latex particles have positive charges resulting from the cationic chitosan molecules. The morphology evaluated by SEM, TEM and AFM proves that in the absence of chitosan, latexes of vinyl homopolymers contain quasi-monodispersed spheres with average diameter of about 400 nm or 250 nm while the graft copolymers latexes are formed by clustered irregular beads with average diameter around 100 nm.
KeywordsChitosan Surfactant-free emulsion copolymerization Graft vinyl copolymers FTIR spectroscopy Scanning electron microscopy
Authors thank to Dr. Victor Fruth for zeta potential measurements and to Raluca Negrea for TEM investigations. This work was supported by CNCSIS-UEFISCSU, Project number PNII-RU code 59/2010 (Contract no. 18/28.07.2010) and by the Romanian Education and Research Ministry through the Nucleu Project No. 45N.
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