Investigação de diferentes organossilanos na funcionalização e grau de dispersão do óxido de grafeno reduzido (rGO) em nanocompósitos poliméricos

Abstract

Graphene is gaining more and more attention due to its unique properties, and is increasingly being applied in various sectors, including its application as a nanofiller in polymeric matrices. However, this nanomaterial finds challenges in this application due to factors that contribute to low dispersion in the matrix and, consequently, lower than desired properties. Thus, chemical modification of its surface can be a key alternative for enhancing different applications. This work aims to evaluate the degree of dispersion of reduced graphene oxide (rGO) functionalized with different organosilanes in an epoxy matrix. To this end, graphene oxide (GO) was first synthesized in the laboratory, functionalized with 3-aminopropyltriethoxysilane (APTES), 3- aminopropyltrimethoxysilane (APTMS), 3-glycidoxypropyltrimethoxysilane (GPTMS) and triethoxymethylsilane (MTES), and then thermally reduced to produce functionalized reduced graphene oxides. Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), Raman spectroscopy, thermogravimetry (TGA), solvent dispersion stability and scanning electron microscopy (SEM) analyses were carried out to prove the success of the synthesis of these materials and to help evaluate the functionalization efficiency. The results obtained confirmed the success of covalent functionalization with all the silanes used on the surface of GO, as well as the permanence of their molecules in the basal plane of reduced graphene oxide (rGO) carbons. To check the degree of dispersion in the polymer matrix, polymer nanocomposites were prepared with 0.5% by mass of each functionalized rGO. Analysis of the fracture surfaces of these materials by SEM showed that better distribution, dispersion and interfacial bonding were obtained for nanocomposites containing functionalized rGO rather than pure rGO. It was possible to observe that the dispersion of the nanoparticles improved for the nanocomposites containing rGO functionalized with the different organosilanes, and the most satisfactory results were obtained for the nanocomposites containing rGO/APTES.