Thesis (Ph.D.) - Cairo University - Faculty of Science - Department of Organic Chemistry

First, nanocomposites of chitosan grafted with 4-vinyl pyridine (4-VP) as well as N- vinyl-2-pyrrolidone (NVP) in the presence of organophilic montmorillonite (OMMT) in aqueous acetic acid using ammonium persulfate as initiator were prepared. The used OMMT was synthesized by cationic exchange between Na+-MMT and N-octyl-N-vinyl-2-pyrrolidonium bromide. The degree of dispersion and the intercalation spacing of these nanocomposites were investigated using X-ray diffraction. The enhanced thermal stability of nanocomposites was characterized by the differential scanning calorimetry (DSC) and thermogravimetric analysis (TG). Preliminary results of the antibacterial and antifungal activities of the prepared nanocomposites demonstrated a significant antimicrobial activity of the nanocomposites compared with chitosan and graft chitosan. Second, nanocomposites based on biodegradable poly(3-hydroxybutyrate) (PHB) and two types of organically modified layered silicates, Cloisite 30B (C30B) and montmorillonite grafted-poly(f-caprolactone) (MPCL), were prepared through solution intercalation technique. The DSC results showed that the dispersed MPCL enhanced the rate of crystallization of PHB from glassy and molten states, whereas C30B retarded the crystallization of PHB from glassy state and enhanced its crystallization from molten state.

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