Fabrication of superhydrophobic and conductive surface based on carbon nanotubes

Properties and Fabrication of Waterborne Polyurethane Superhydrophobic Conductive Composites with Coupling Agent-Modified Fillers

The addition of abundant fillers to obtain conductive and superhydrophobic waterborne polyurethane (WPU) composites generally results in increased interfaces in the composites, leading to reduced adhesion and poor corrosion resistance. Fillers such as Polytetrafluoroethylene (PTFE) and multi-walled carbon nanotubes (MWCNTs) were first treated by a coupling agent to reduce the contents of the fillers. Thus, in this work, WPU superhydrophobic conductive composites were prepared using electrostatic spraying (EsS). The polar groups (-OH and -COOH, etc.) on the WPU, PTFE, and MWCNTs were reacted with the coupling agent, making the WPU, PTFE, and MWCNTs become crosslinked together. Thus, the uniformity of the coating was improved and its curing interfaces were reduced, causing enhanced corrosion resistance. The dehydration reaction that occurred between the silane coupling agent and the polar surface of Fe formed -NH2 groups, increasing the adhesion of the coating to the steel substrate and then solving the problems of low adhesion, easy delamination, and exfoliation. With the increased content of the modified fillers, the conductivity and hydrophobic property of the composite were amplified, and its corrosion resistance and adhesion were first strengthened and then declined. The composite with the WPU, PTFE, MWCNTs, and KH-550 at a mass ratio of 7:1.5:0.1:0.032 held excellent properties; its volume resistivity and WCA were 1.5 × 104 Ω·cm and 155°, respectively. Compared with the pure WPU coating, its adhesive and anticorrosive properties were both better. This provides a foundation for the fabrication and application of anticorrosive and conductive waterborne composites.

Effects of multiwalled carbon nanotubes on CH4 hydrate in the presence of tetra-n-butyl ammonium bromide

Hydrate formation is an important technology for gas storage and transportation. In this work, the effect of multiwalled carbon nanotubes (MWCNTs) on CH4 hydrate formation was examined by determining the phase equilibrium conditions and kinetics characteristics of a mixed system of CH4, tetra-n-butyl ammonium bromide (TBAB), and MWCNTs. The phase equilibrium was examined in the temperature range of 286.13-293.04 K and the pressure range of 0.55-6.56 MPa for various mass fractions of MWCNTs (0.004, 0.1, 0.5, and 1.0 wt%). In the CH4 + TBAB system, the presence of MWCNTs was found to shift the phase equilibrium conditions to a lower temperature by about 1 K compared with those in the absence of MWCNTs. However, the concentration of MWCNTs had little effect on the phase equilibrium conditions. When the concentration of MWCNTs was 1.0 wt%, the addition of MWCNTs reduced the induction time of hydrate formation by 79.5%. When the concentration of MWCNTs was 0.1 wt%, the addition of MWCNTs enhanced the hydrate growth rate by 61.5%. Powder X-ray diffraction patterns revealed that hydrates with orthorhombic structures (corresponding to TBAB·38H2O with 3D cages) were formed in the systems with and without MWCNTs. Moreover, peaks corresponding to MWCNTs were not observed in the patterns of the hydrates and the addition of MWCNTs had no influence on the structure and type of hydrate. Thus, MWCNTs were not incorporated into the hydrate cages.

BaFe12O19-chitosan Schiff-base Ag (I) complexes embedded in carbon nanotube networks for high-performance electromagnetic materials

The multiwalled carbon nanotubes/BaFe12O19-chitosan (MCNTs/BF-CS) Schiff base Ag (I) complex composites were synthesized successfully by a chemical bonding method. The morphology and structures of the composites were characterized with electron microscopy, Fourier transform infrared spectroscopy and X-ray diffraction techniques. Their conductive properties were measured using a four-probe conductivity tester at room temperature, and their magnetic properties were tested by a vibrating sample magnetometer. The results show that the BF-CS Schiff base Ag (I) complexes are embedded into MCNT networks. When the mass ratio of MCNTs and BF-CS Schiff base is 0.95:1, the conductivity, Ms (saturation magnetization), Mr (residual magnetization), and Hc (coercivity) of the BF-CS Schiff base composites reach 1.908 S cm(-1), 28.20 emu g(-1), 16.66 emu g(-1) and 3604.79 Oe, respectively. Finally, a possible magnetic mechanism of the composites has also been proposed.