Thesis (M.S., Materials Science)--University of Idaho, June 2014 | 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.
