Dispositivos microfluídicos: uma nova ferramenta para preparação de fibras de grafeno e derivados
Tipo
Dissertação
Data de publicação
2020-07-15
Periódico
Citações (Scopus)
Autores
Rocha, Jaqueline Falchi da
Orientador
Castro e Silva, Cecilia de Carvalho
Título da Revista
ISSN da Revista
Título de Volume
Membros da banca
Maroneze, Camila Marchetti
Guimarães, Kleber Lanigra
Guimarães, Kleber Lanigra
Programa
Engenharia de Materiais e Nanotecnologia
Resumo
Due to the distinctive mechanical, optic, thermal and electric properties of graphene, it
has been gaining global attention from a lot of researchers for the development of
nanofibers, which present superior properties with respect to the carbon fibers, with
the higher values reported of tensile strength and Young modulus, 130 GPa and
1,1 TPa, respectively. However, the biggest challenge resides in preparing the
graphene fibers in a scalable way, in a continuous manner and maintaining its unique
properties. In this regard, it is crucial the development of new technologies to surpass
these difficulties. In this way, the present work shows the employment of 3D flow
focalization of microfluidic devices, based on ceramics, using LTCC (Low Temperature
Cofired Ceramics) technology for the development of graphene oxide fibers. The GO
was synthesized by the modified Hummers method and characterized by the Raman
spectroscopy technique. The wet spinning technique was used for preliminary studies
of the formation of fibers, to optimize parameters such as ideal concentration of GO
dispersion, flow rate of GO dispersion and coagulating agents. The optimized condition
for the formation of GO fibers with appropriate mechanical stability was achieved for a
GO dispersion of 5 mg mL-1, with an inlet flow of 2.5 mL min-1 using a
hexadecyltrimethylammonium bromide coagulant bath (CTAB ) (0.5 mg mL-1). The
fibers formed by the conventional wet spinning method showed satisfactory electrical
conductivity after reduction with two-stage heat treatment (annealing at 300oC in an
Ar / H2 atmosphere for 30 minutes, followed by microwave treatment, 100 W of power
for 2 seconds), reaching electrical conductivity values of 1.19x104 ± 2.38 S m-1. The
tests for obtaining GO fibers using the 3D ceramic-based microfluidic device with
channel dimensions 43.63 mm long and 1.43 mm wide, showed great effectiveness for
making long fibers (50 cm). In addition, the device was able to modulate the diameter
of the fibers due to the ratio between the flow of GO dispersion by the flow of CTAB
solution, making it possible to obtain fibers from 89 to 22 μm of diameter. The
microfibers of GO, with an average size of 7 cm in length and 90 μm in diameter,
presented to support weight of 6.02 ± 0.81 g before breaking. The 3D hydrodynamic
microfluidic focusing device showed potential for the development of microfibers from
other two-dimensional materials.
Descrição
Palavras-chave
fibras de grafeno , óxido de grafeno , microfluídica
Assuntos Scopus
Citação
ROCHA , Jaqueline Falchi da. Dispositivos microfluídicos: uma nova ferramenta para preparação de fibras de grafeno e derivados. 2020. 3? f.. Dissertação (Engenharia de Materiais e Nanotecnologia) - Universidade Presbiteriana Mackenzie, São Paulo.