Zhihang Long

Two step hydrothermal synthesis of flowerbud-like magnetite/graphene oxide hybrid with high-performance microwave absorption

A novel flowerbud-like magnetite/graphene oxide (GO) hybrid was synthesized from facile two-step hydrothermal process by using FeCl3 as iron source, ethylene glycol as the reducing agent, and graphene oxide as template. The magnetite nanoparticles with the diameters of 70–80 nm were attached onto the surface of graphene oxide through the two-step self-assembly process which enhanced the magnetic properties of the hybrids. The final flowerbud-like magnetite/graphene oxide hybrid emerged with the saturated magnetization of ~84.5 emu g–1. More importantly, owing to the combined contribution of enhanced dielectric and magnetic properties, the maximum microwave absorption of as-prepared magnetite/GO hybrid reached 30 dB with a thickness of 4 mm. Besides, the absorption bandwidth with a reflection loss above 23 dB ranged from 6.0 to 11.5 GHz.

Novel amino-functionalized Fe3O4/carboxylic multi-walled carbon nanotubes: One-pot synthesis, characterization and removal for Cu(II)

A novel amino functionalized Fe3O4/multi-walled carbon nanotubes hybrid was synthesized by a facile and efficient one-pot solvothermal process. The 3-aminophenoxyphthalonitrile which was regarded as phthalonitrile monomer was introduced into the solvothermal process and promoted the phthalocyanine cyclization reaction, finally forming the amino functionalized hybrid. The structure, composition, and morphology were characterized by FTIR, XRD, XPS, SEM, and TEM. It was found that the monodispersed amino functionalized Fe3O4 spheres with diameters of 180–220 nm were uniformly attached on the surface of multi-walled carbon nanotubes. Owing to the synergistic effect between the amino groups and magnetic carbon nanotubes, the asprepared hybrid exhibited the high separation efficiency when used to remove Cu(II) from aqueous solutions. The adsorption isotherms of the as-prepared hybrid for Cu(II) removal fitted the Langmuir model, the maximum adsorption capacity of our amino-functionalized Fe3O4/MWCNTs hybrid calculated from the isotherm model is 30.49 mg g–1. This work demonstrated that the amino functionalized Fe3O4/multi-walled carbon nanotubes hybrid was promising as efficient adsorbent for heavy metal ions removal from wastewater in low concentration.

Hydrothermal synthesis of graphene oxide/multiwalled carbon nanotube/Fe3O4 ternary nanocomposite for removal of Cu (II) and methylene blue

In this work, highly activated graphene oxide/multiwalled carbon nanotube/Fe3O4 ternary nanocomposite adsorbent was prepared from a simple hydrothermal route by using ferrous sulfate as precursor. For this purpose, the graphene oxide/multiwalled carbon nanotube architectures were formed through the π-π attractions between them, followed by attaching Fe3O4 nanoparticles onto their surface. The structure and composition of as-prepared ternary nanocomposite were characterized by XRD, FTIR, XPS, SEM, TEM, Raman, TGA, and BET. It was found that the resultant porous graphene oxide/multiwalled carbon nanotube/Fe3O4 ternary nanocomposite with large surface area could effectively prevent the π-π stacking interactions between graphene oxide nanosheets and greatly improve sorption sites on the surfaces. Thus, owing to the unique ternary nanocomposite architecture and synergistic effect among various components, as-prepared ternary nanocomposite exhibited high separation efficiency when they were used to remove the Cu (II) and methylene blue from aqueous solutions. Furthermore, the adsorption isotherms of ternary nanocomposite structures for Cu (II) and methylene blue removal fitted the Langmuir isotherm model. This work demonstrated that the graphene oxide/multiwalled carbon nanotube/Fe3O4 ternary nanocomposite was promising as an efficient adsorbent for heavy metal ions and organic dye removal from wastewater in low concentration.

Improving the properties of poly(arylene ether nitrile) composites reinforced by covalently modified multi-walled carbon nanotubes

To develop high-performance carbon nanotube (CNT)-based polymer nanocomposites, both the interface control and the dispersion of CNTs within the polymer hosts need to be considered. In this study, we show an effective way to modify the surface of multi-walled CNTs (MWCNTs) by applying a cyclization reaction between nitrile-modified MWCNTs and bis-phthalonitrile. Fourier transform infrared spectroscopy, ultraviolet–visible spectroscopy, Raman spectroscopy, scanning electron microscopy, and transmission electron microscopy were used to examine the structure and morphology of as-prepared functional CNTs. Phthalocyanines (Pcs) were found to be evenly coated on the surface of MWCNTs, resulting in good dispersion and strong interfacial adhesion between MWNCTs and the poly(arylene ether nitrile) (PEN) matrix. Compared with neat PEN, the tensile strength and tensile modulus of PEN nanocomposites with 2 wt% MWCNTs–Pc increased from 85.6 MPa to 108 MPa and from 2300 MPa to 3350 MPa, respectively. Furthermore, surface-functionalized CNTs can also form the physical MWCNT network within the PEN matrix, as confirmed by rheological and thermal stability tests. Additionally, a low rheological percolation threshold of 0.69 wt% was obtained, and the dielectric constant of PEN nanocomposites was increased from 3.3 for neat PEN to 16.6 with 5 wt% MWCNTs–Pc.

Exfoliated graphite nanoplatelets/poly(arylene ether nitrile) nanocomposites In situ synthesis, characterization, and enhanced properties

In this work, we demonstrate a method for synthesis of exfoliated graphite nanoplatelets (xGnPs)/poly(arylene ether nitrile) (PEN) nanocomposites via an efficient in situ polymerization. The GnPs were treated by the ultrasonic bath to reduce the layers of the GnPs, where the PEN were intercalated subsequently. Therefore, the dispersion of xGnP in the PEN resin was enhanced through in situ polymerization, which was characterized and confirmed by scanning electron microscopy, transmission electron microscopy, and Fourier transform infrared spectroscopy. It was found that the tensile strength and modulus were greatly enhanced with the addition of xGnP. For 2.5 wt% of xGnP-reinforced PEN, the tensile strength and modulus were increased to 115 MPa and 3121 MPa, respectively. Owing to the well dispersion of xGnP, the low rheological percolation of 2.5 wt% for PEN nanocomposites was obtained. Besides, with 1 wt% of xGnP, the corresponding initial decomposition temperature (Tin) increased from 451°C in pure PEN to 470°C. The addition of xGnP showed enhanced thermal stability of PEN nanocomposites, which demonstrated a promising method for preparing advanced polymer-based nanocomposites.