Nanocompósito polimérico a base de poliuretano e óxido de grafeno para aplicação em dispositivo de assistência ventricular (DAV)

• Autor(a) principal: Maestrelli, Lícia Maria D'Arezzo
• Data de Publicação: 2021
• Tipo de documento: Tese
• Idioma: por
• Título da fonte: Biblioteca Digital de Teses e Dissertações do Mackenzie
• Texto Completo: https://dspace.mackenzie.br/handle/10899/28432
• topic: óxido de grafeno; policarbonato-uretano; nanocompósitos; dispositivo de assistência ventricular; coração artificial; biomateriais; engenharia de tecidos cardíacos; CNPQ::ENGENHARIAS::ENGENHARIA DE MATERIAIS E METALURGICA::MATERIAIS NAO METALICOS

A new generation of graphitic structure nanomaterials such as graphene and its derivatives (graphene oxide - GO and reduced graphene oxide - rGO) has been exponentially studied due to their potential for use in several areas, including biomaterials. The objective of this research is to produce nanoparticles in the form of GO with appropriate characteristics (lateral dimension, number of sheets stacked and oxidation level) for use as a reinforcing filler for a diaphragm made with polycarbonate-urethane (PCU) showing high mechanical performance for use in a ventricular assist device (DAV) pediatric size. Initially two types of GO were produced with different levels of oxidation following a methodology based on the oxidation of graphite via the modified Hummers Method. The characterization of these materials was performed by gravimetric thermal analysis (TGA), x ray diffraction (XRD), Raman and infrared spectroscopy (FTIR), atomic force microscopy (AFM) and x ray photoelectronic spectroscopy (XPS). These materials presented different oxidation levels and they also have different structures in terms of lateral sizes and number of stacked sheets. PCU-GO nanocomposites were produced by mixing in an aprotic solvent when using the two types of GO in concentrations by weight of 0.2%, 0.4%, and 2.0%. Polymeric films were obtained by solvent evaporation, characterized by exploratory differential calorimetry (DSC), dynamic-mechanical analysis (DMA), contact angle measurements, mechanical tensile strength, and transmission electron microscopy (MET). The results obtained by DMA and DSC clearly indicated that the action of GO particles occurs mainly along the rigid segments of the PCU structure, largely due to the polar chemical similarity of these structures. The GO particles oxidized for two hours (GO-II) and inserted in the PCU matrix were better distributed and dispersed (mainly at lower concentrations, 0.2wt%), consequently, better mechanical responses for the PCU-GO-II nanocomposites were obtained when compared to the composites produced with the GO oxidized for 4 hours. This result is a consequence of the lower number of stacked layers and higher degree of oxidation for the GO-II produced which led to a better and larger polymer-particle interaction area. The biological behavior of the nanocomposite when applied to the VAD diaphragm manufacturing was evaluated for cytotoxicity and cell viability, cell proliferation and adhesion. The response time to the pressure pulse and the resistance to fatigue for VAD assembly was also measured. The results suggest that the mechanical performance of the new diaphragms is adequate for their use in ventricular assist devices.