Surface modification and microstructure of single-walled carbon nanotubes for dental resin-based composites

In the present study, a novel process has been developed to improve the application of single-walled carbon nanotubes (SWCNTs) in dental resin-based composites (RBCs). Efforts have been made to deposit a thin shell of nano-SiO(2) onto the oxidized surface of SWCNTs by using a thin adlayer of 3-aminopropyltriethoxysilane; this was followed by modification of the nano-SiO(2) layer by using another organosilane with allyl-terminated functional groups to achieve well dispersion and integration in the matrix. Fourier transform infrared spectroscopy (FTIR) and transmission electron microscopy (TEM) are used to analyze the modified SWCNTs. The obtained shell has a sandwich-like structure, with an amino-modified silane layer on the inside, a nano-SiO(2) layer in the middle, and an allyl-terminated silane layer on the outside. Composite resin specimens with modified SWCNTs are prepared and examined using TEM. A three-point-bend test is performed using the MTS Synergie 100 testing machine. Statistical analysis reveals that the addition of modified SWCNTs improves the flexural strength (p < 0.05) of dental RBCs.