Role of nitrogen–oxygen plasma functionalization of carbon nanotubes in epoxy nanocomposites

Abstract

Carbon nanotubes (CNTs) functionalization was carried out with radio frequency plasma in different working gas Ar/O2 and Ar/O2/N2 at different plasma powers to synthesize epoxy nanocomposites. After the CNT's had been treated, the Fourier transform infrared (FTIR) spectroscopy showed an additional peak at 1,740 cm−1, attributed to carboxylic groups, corroborating the X‐ray photoelectron spectroscopy that shows attachment of oxygen groups, which indicates CNTs' functionalization. Raman shows an increase in the ID/IG ratio, attributed to an increased number of defects, in agreement with transmission electron microscope images that show a nanocoating on CNTs' surfaces. Functionalization carried out with low power plasma makes also some C‐N bonds possible, preserving the aromatic carbons of the CNTs' structure. Nanocomposites showed better dispersion and distribution for samples with CNTs treated by Ar/O2/N2 plasma. Furthermore, there was a decrease in Tg when compared with neat epoxy, especially for samples with more nitrogen atoms attached to the CNTs. Mechanical properties presented an improvement, which is specially related to a better phase interaction led by the nitrogen presence on the CNTs' surface. POLYM. COMPOS., 40:E1162–E1171, 2019. © 2018 Society of Plastics Engineers

Inverse Nacre-like Epoxy-Graphene Layered Nanocomposites with Integration of High Toughness and Self-Monitoring

“…6 To improve the fracture toughness of epoxy, various nano-reinforcements have been investigated. 7 For example, typical nano-reinforcements involve zero-dimensional nanoparticles, such as titanium dioxide (TiO 2 ) and silica (SiO 2 ), 8,9 one-dimensional nanofibers, such as carbon nanotubes (CNTs), 10 and two-dimensional nanoplatelets, such as nanoclay and graphene. [6][7][8][9][10][11][12][13] Although these nanofillers can improve the fracture toughness of epoxy, many processing problems remain unsolved.…”

“…7 For example, typical nano-reinforcements involve zero-dimensional nanoparticles, such as titanium dioxide (TiO 2 ) and silica (SiO 2 ), 8,9 one-dimensional nanofibers, such as carbon nanotubes (CNTs), 10 and two-dimensional nanoplatelets, such as nanoclay and graphene. [6][7][8][9][10][11][12][13] Although these nanofillers can improve the fracture toughness of epoxy, many processing problems remain unsolved. 14,15 For example, a small amount of TiO 2 improves the fracture toughness of epoxy by crack deflection and crack pinning, yet agglomeration of the TiO 2 nanoparticles limits further improvement of the fracture toughness.…”

Trends on Synthesis of Polymeric Nanocomposites Based on Green Chemistry

“…These gases are ionized into a plasma reactor, forming highly reactive species that depending on the conditions of the plasma are grafted to a greater or lesser extent changing the surface chemistry of the NPs. As in the surface modification of polymers, oxygen plasma is also used to graft polar groups onto the surface of the NPs (e.g., hydroxyl, carbonyl, carboxyl) and improve their wettability [105][106][107], although noble gases such as Ar can also be used to activate the surface of the particles or generate vacancies or defects and then at a later stage (or combination of gases) chemical groups are grafted either by plasma or by traditional wet chemistry methods [108]. NPs that have been modified by plasma include carbon nanotubes (CNTs), carbon nanofibers (CNFs), graphite [109], graphite oxide, nanoclays [110], and metallic and non-metallic NPs [111,112].…”

“…These authors found that the plasma treatment formed carboxylic acids and also C-N bonds. As a result of this treatment, a better dispersion and distribution of CNTs was observed, resulting in an improvement of the PNCs mechanical properties [107]. In another work, the CNTs were functionalized in a plasma reactor with a cylindrical chamber of 40 cm in diameter and 30 cm in length, gap of 5 cm, using a RF source of 13.56 MHz and 200 watts (W) of power, during 60 min using air as working gas.…”

Investigation of Plasma-Assisted Functionalization of Graphitic Materials for Epoxy Composites

“…Up to now, many studies have been devoted to the analysis of surface plasma treated fiber-based [31] and carbon nanotubes [32][33][34] based composites but little has been devoted to the study of particulate polymeric composite containing plasma functionalized graphite/graphene.…”