Theses and Dissertations Collection

ABSTRACT

Nanocomposites of bacterial cellulose (BC) nanofibers and paramagnetic iron oxide nanoparticles--magnetite/maghemite (Fe₃O₄ /γ-Fe₂O₃)--were created, and the materials and interactions were analyzed using Fourier transform infrared spectroscopy with attenuated total reflection (ATR-FTIR), X-ray diffraction, field emission scanning electron microscopy, transmission electron microscopy, dynamic light scattering, and energy-dispersive X-ray spectrometry.

To engineer the composites' composition, structure, and morphology, BC was combined with Fe₃O₄ /γ-Fe₂O₃ nanoparticles of various types and concentrations by two methods: (1) the culture medium of Gluconacetobacter hansenii was augmented with Fe3O4 /γ-Fe2O3 nanoparticles, which aggregated, and cellulose biosynthesis was endeavored--in some cases BC production was hindered due to Gluconacetobacter mutation into non-producers or iron oxide toxicity; (2) purified BC was used as a nanofiber matrix on which Fe₃O₄ /γ-Fe₂O₃ nanoparticles were deposited by co-precipitation synthesis--both reverse co-precipitation and NH₃ gas-enhanced co-precipitation.

In method (1), Fe₃O₄ /γ-Fe₂O₃ nanoparticles were physically entangled in the BC nanofibers, with no evidence of hydrogen bonding. In method (2), nanoparticles were coated on the nanofibers, resulting in homogeneous dispersions. ATR-FTIR revealed hydroxyl band broadening indicative of increased hydrogen bonding, which implied the surface hydroxyl groups of the iron oxide nanoparticles synthesized in the BC nanofiber matrix interacted with the hydroxyl groups located along the cellulose molecule. Reverse co-precipitation of Fe₃O₄ /γ-Fe₂O₃ nanoparticles on the BC nanofibers was the best method for creating nanocomposites of bacterial cellulose nanofibers and paramagnetic iron oxide nanoparticles.