Utilização de líquidos iônicos na esfoliação em fase líquida do grafite e aplicação na formação de nanocompósitos condutores de polímero-grafeno para impressão 3D

• Autor(a) principal: Godoy, Anna Paula
• Data de Publicação: 2019
• Tipo de documento: Tese
• Idioma: por
• Título da fonte: Biblioteca Digital de Teses e Dissertações do Mackenzie
• Texto Completo: http://dspace.mackenzie.br/handle/10899/24293
• topic: grafeno; esfoliação em fase líquida; sistema bifásico; líquidos iônicos; nanocompósitos poliméricos; impressão 3D; CNPQ::CIENCIAS EXATAS E DA TERRA::QUIMICA::QUIMICA ANALITICA::ELETROANALITICA; CNPQ::CIENCIAS EXATAS E DA TERRA::QUIMICA::QUIMICA ANALITICA::INSTRUMENTACAO ANALITICA; CNPQ::CIENCIAS EXATAS E DA TERRA::QUIMICA; CNPQ::ENGENHARIAS::ENGENHARIA DE MATERIAIS E METALURGICA

This thesis reports on graphene production by graphite liquid phase exfoliation (LPE) in biphasic system containing ionic liquid (IL) and its application in conductive polymeric nanocomposites’ synthesis for 3D printing by Fusion Depostion Molding (FDM) technique. For better understanding, the activities were divided into three steps and performed in parallel or sequentially as specified below. In the first step, a graphite LPE protocol using a water/dichloromethane biphasic liquid system with 1,3-dibenzylimidazolium benzoate and 1,3-dibenzylimidazolium naphthoate ILs is described. The combination of ILs-biphasic system improved the exfoliation efficiency and emulsion stability and decreased the damages by cavitation. Emulsion stability and ILs-graphene interaction were studied by Dynamic Light Scattering (DLS) and Density Functional Theory (DFT), respectively. Raman Spectroscopy, Scanning Electronic (SEM), Transmission (TEM) and Atomic Force (AFM) microscopies, and X-ray Diffraction (XRD) results showed high quality and exfoliation level of produced graphene. In parallel, in step 2, poly(lactic) acid (PLA) nanocomposites with graphene nanoplatelets (GNP) and carbon nanotubes (MWCNTs) as fillers obtained by melt extrusion were studied in terms of filler concentration and presence of bi-fillers effect in electrical and thermal conductivities. The goal was to verify which filler concentration surpasses the electrical percolation threshold while maintaining the processability for FDM. Nanocomposites with 6 wt.% of GNP or MWCNT, or both, showed electrical conductivities values of 6 decades order of magnitude higher than pure PLA and increasing of 181% in thermal conductivity. In step 3, is showed the polyvinyl alcohol (PVOH) nanocomposite production with 6 wt.% of graphene, concentration optimized in step 2, and obtained by graphite LPE described in step 1, using 1-benzyl-3-methylimidazolium chloride (BnzMImCl) and 1,3-dibenzylimidazolium chloride (Bnz)2ImCl. The imidazole-based ILs demonstrated to be valuable to prevent graphene re-aggregation. These were characterized by optical microscopy, SEM, Raman and electrical conductivity, and showed potencial aplicability in FDM, due to the good filler-polymer interaction and electrical conductivity.