Growing of biomorphic nanomaterials based on calcium carbonate

Master thesis English OPEN
Ritto, Gonçalo Nuno Fernandes (2016)
  • Subject: Chemical synthesis | Calcium carbonate | Nacre | :Engenharia e Tecnologia::Engenharia dos Materiais [Domínio/Área Científica] | dip-coating
    mesheuropmc: technology, industry, and agriculture

Calcium carbonate was produced by precipitation: oil bath and ultra-sounds, being studied several parameters such as: temperature, magnetic stir speed, concentration of the reagents, duration of the reaction and the medium of the reaction. Samples rested for a month before some of the precipitated was removed, washed and dried to get the powder characterized without any secondary product or the solvent of the reaction. Dip-coating technique was also used to produce calcium carbonate with an organic matrix (PVP - Polyvinylpyrrolidone) in an attempt to produce artificial nacre. Several parameters were also modified: number of coating cycles, temperature, dip and dry time; presence/absence of an in-between step and dipping speed. Two anhydrous polymorphs of calcium carbonate were produced from both methods: vaterite and calcite. Some samples were characterized by XRD (X-ray Diffraction), Raman Spectroscopy and were analysed by SEM (Scanning Electron Microscopy). Spectrophotometry was also used to analyse the absorbance/transmittance and reflectance of some dip-coated samples. The samples with an organic matrix showed a very high transmittance in the infra-red region and a very low transmittance in the visible region unlike samples with just inorganic layers indicating the possibility of formation of an organic/inorganic complex.
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