Fei-Peng Du

Water-soluble graphene grafted by poly(sodium 4-styrenesulfonate) for enhancement of electric capacitance

Water-soluble poly(sodium 4-styrenesulfonate) modified graphene (PSSS-GR) was successfully synthesized via covalently grafting poly(sodium 4-styrenesulfonate) (PSSS) on the surfaces of graphene (GR) nanosheets. The structure of PSSS-GR was investigated with Fourier transform infrared, x-ray photoelectron and Raman spectroscopy, thermogravimetric analysis, transmission and scanning electron microscopy and atomic force microscopy. The PSSS chains made the GR nanosheets fully exfoliate into a single-layer structure, and the PSSS layer on GR reached 90 wt%. PSSS chains displayed mutually repulsive effects on promoting GR sheets that were more stable in water. The performances of supercapacitors made of PSSS-GR and unmodified GR electrodes were compared using cyclic voltammetry and galvanostatic charge/discharge techniques. The results showed that PSSS is an effective binder for graphene sheets and can increase the specific capacitance of PSSS-GR based supercapacitors and improve their rate capability. The maximum specific capacitance of the PSSS-GR based supercapacitor was 210 F g(-1) at 5 A g(-1), which was 166% higher than for one made of unmodified graphene electrodes. Electrochemical impedance spectroscopy demonstrated fast ion diffusion in the PSSS-GR electrode structure. PSSS-GR based supercapacitors can fulfil one of the essential requirements for potential electric energy storage applications.

Enhancing the Heat Transfer Efficiency in Graphene–Epoxy Nanocomposites Using a Magnesium Oxide–Graphene Hybrid Structure

Composite materials, such as organic matrices doped with inorganic fillers, can generate new properties that exhibit multiple functionalities. In this paper, an epoxy-based nanocomposite that has a high thermal conductivity and a low electrical conductivity, which are required for the use of a material as electronic packaging and insulation, was prepared. The performance of the epoxy was improved by incorporating a magnesium oxide-coated graphene (MgO@GR) nanomaterial into the epoxy matrix. We found that the addition of a MgO coating not only improved the dispersion of the graphene in the matrix and the interfacial bonding between the graphene and epoxy but also enhanced the thermal conductivity of the epoxy while preserving the electrical insulation. By adding 7 wt % MgO@GR, the thermal conductivity of the epoxy nanocomposites was enhanced by 76% compared with that of the neat epoxy, and the electrical resistivity was maintained at 8.66 × 10(14) Ω m.

Fabrication of an ionic polymer--carbon nanotube composite for a new configurative actuator

In this study, an ionic polymer—carbon nanotube composite (IPNTC) was developed to function as a new configurative actuator. The IPNTC was fabricated with carbon nanotube-reinforced ionic polymer as electroactive middle layer and functional multi-walled carbon nanotube (MWNT) diaphragm as electrode layers coated on the two sides of the membrane. Scanning electron microscopy images show that the interface between functional MWNT-diaphragms and polymer membrane has strong adhesion. Furthermore, the MWNT-diaphragm has a uniform dense porous structure, and MWNTs entangle and interpenetrate each other. The IPNTC actuator has remarkable displacement output under low-voltage stimulation and it can last for 3000 cycles with only 10% reduction in the displacement output.

25 – Carbon nanotube nanocomposites for biomedical actuators

: Ionic polymer–metal composites (IPMCs) have great prospects in electromechanical devices used for artificial muscles and other biomedical applications. But their low output force and the required service conditions in humid or water environments are the main challenges to their applications. This chapter focuses on recent advances made in IPMC actuators modified by carbon nanotubes (CNTs). CNT actuators and actuators based on ionic liquid as electrolyte are also discussed. Finally, a new multiple-mechanism driven actuator is introduced.

Chapter 9:Polymer–Magnesium Hydroxide Nanocomposites by Emulsion Polymerization

With ever increasing awareness of environmental sustainability and tighter legislation, in-situ emulsion polymerization process has been widely adopted to prepare halogen-free flame retardant polymer/MH (magnesium hydroxide) nanocomposites with homogenous dispersion. Such composites possess excellent thermal stability, low flammability, good rheological properties and superb mechanical properties. They can be beneficially used as flame retardant adhesives and coatings, elastomers and plastics.We believe in-situ emulsion polymerization is an efficient method to modify the surface of nano-MHs. We can adjust the thickness of the polymer shell covered on the nano-MH surface by controlling the ratio of monomer to nano-MHs; we can easily adjust the solubility parameter of polymers or copolymers covered on the nano-MHs, and disperse the modified nano-MHs in any polymer matrix uniformly, and hence enhance the interfacial interaction between nano-MHs and polymer. Hence, we have the tools to fabricate high-performance polymer/MH nanocomposites. Finally, to overcome the formation of homopolymer during in-situ monomer/nano-MH emulsion polymerization or copolymerization, surface-initiated in-situ emulsion polymerization seems to be a promising method not yet explored to-date.