An Overview of Functionalized Graphene Nanomaterials for Advanced Applications

Interest in the development of graphene-based materials for advanced applications is growing, because of the unique features of such nanomaterials and, above all, of their outstanding versatility, which enables several functionalization pathways that lead to materials with extremely tunable properties and architectures. This review is focused on the careful examination of relationships between synthetic approaches currently used to derivatize graphene, main properties achieved, and target applications proposed. Use of functionalized graphene nanomaterials in six engineering areas (materials with enhanced mechanical and thermal performance, energy, sensors, biomedical, water treatment, and catalysis) was critically reviewed, pointing out the latest advances and potential challenges associated with the application of such materials, with a major focus on the effect that the physicochemical features imparted by functionalization routes exert on the achievement of ultimate properties capable of satisfying or even improving the current demand in each field. Finally, current limitations in terms of basic scientific knowledge and nanotechnology were highlighted, along with the potential future directions towards the full exploitation of such fascinating nanomaterials.

Tunable Mechanical, Electrical, and Thermal Properties of Polymer Nanocomposites through GMA Bridging at Interface

Polymer nanocomposites (PNCs) have become an exciting field of current research and have attracted a huge interest among both academia and industry during the last few decades. However, the multifunctional single-nanocomposite film exhibiting the combination of desired structure and properties still remains a big challenge. Herein, we report a novel strategy to address these problems by using versatile polymer glycidyl methacrylate (GMA) as a bridging medium between the filler and the polymer matrix, resulting in high density of interfaces as well as strong interactions, which lead to generation of tunable thermal, mechanical, and electrical properties in the materials. The nanocomposites prepared by GMA bridging exhibit the remarkable combination of thermal (T _d = 342.2 °C, T _g = 150.1 °C ), mechanical (E = 7.6 Gpa and H = 0.45 Gpa ) and electrical (σ = 3.15 × 10^-5 S/cm) properties. Hence, the conjugation approaches related to GMA bridging facilitate a new paradigm for producing multifunctional polymer nanocomposites having a unique combination of multifunctional properties, which can be potentially used in next-generation polymer-based advanced functional devices.

Preparation of self-healing polyurethane/functionalized graphene nanocomposites as electro-conductive one part adhesives

We report the synthesis and investigation of the electrical conductivity and self-healing properties of moisture curable polyurethane (PU) adhesives filled with functionalized graphene nanosheets and isophorone diisocyanate (IPDI) loaded poly(methyl methacrylate) (PMMA) nanocapsules. For this purpose, chemically functionalized graphene was prepared by covalently grafting 4-(4,5-diphenyl-1H-imidazol-2-yl)phenol (DIP) on the surface of graphene oxide and synthesized PMMA nanocapsules were loaded with IPDI. Both nanofillers were then dispersed in a polyurethane matrix and the effects on the adhesion properties of the adhesives in aluminum–aluminum metal joints were studied. The results showed that by surface modification and better exfoliation of graphene nanosheets, the electrical conductivity was increased from 2.2 × 10⁻⁹ S m⁻¹ to 4.1 S m⁻¹ for pure PU and 10 wt% graphene based nanofiller loaded PU, respectively. The thermal stability, electrical conductivity, shear strength and self-healing process of the ECAs were also studied. The results provide evidence that the prepared adhesives have the potential for applications in electronic device packaging.

One part moisture curable adhesives based on polyurethane/functionalized graphene nanocomposites were synthesized and showed good electrical conductivity, thermal stability, shear strength and self-healing properties.

One-step approach for the synthesis of CoFe2O4@rGO core-shell nanocomposites as efficient adsorbent for removal of organic pollutants

CoFe₂O₄-reduced graphene oxide nanocomposites (CFG) have been successfully synthesized via one-step solvothermal method. The prepared CFG are characterized by X-ray diffraction, Raman spectroscopy, Fourier transform infrared spectroscopy, field emission scanning electron microscopy (FESEM), vibrating sample magnetometer and so on. The FESEM results show that CFG have uniform core-shell structure with an average diameter of about 75 nm and the thickness of the outer graphene shell is about 15-20 nm. The mass ratio of CoFe₂O₄ to graphene oxide is a key factor affecting the formation of core-shell hybrids. CFG display much higher adsorption capacity for anionic dyes than cationic dyes owing to the favorable electrostatic interaction. The adsorption capacity for methyl orange is observed as high as 263 mg g^-1 at 298 K, and the adsorption isotherms follow the Langmuir model. Furthermore, the specific saturation magnetization (Ms) of CFG is 32.8 emu g^-1, and the as-synthesized nanocomposites can be easily separated by external magnetic field after adsorption. The results suggest that CFG have great potential for the practical industrial wastewater treatment.

Alginic acid/graphene oxide hydrogel film coated functional cotton fabric for controlled release of matrine and oxymatrine

The present study describes the fabrication of a functional cotton fabric and investigated the drug release capability of the functional cotton fabric.

Interfacial Synthesis of Gold-Polyaniline Nanocomposite and Its Electrocatalytic Application

Gold-polyaniline (Au-PANI) nanocomposite was prepared using a simple interfacial polymerization method, performed in an immiscible water/toluene biphasic system using tetrachloroaurate, AuCl4(-) as an oxidant. The formation of Au nanoparticles (AuNPs) or Au-PANI nanocomposite can be controlled to a certain degree by varying the ratio of initial Au(+) and aniline concentrations. Under optimal condition (HAuCl4/aniline ratio is 1:2), green dispersion of Au-PANI nanocomposite is produced in aqueous phase, whose morphology, structure and physicochemical properties are investigated in details. The nanocomposite shows granular morphology with mostly rodlike AuNPs embedded in polymer. It was found that polyaniline in the composite is in the conducting emeraldine salt form, containing high amount of Au (28.85 wt %). Furthermore, the electrical conductivity of the nanocomposite was found to be four-fold higher than that of the polymer itself. In addition, the nanocomposite powder, isolated from the as-prepared aqueous dispersion, can later be easily redispersed in water and further used for various applications. Moreover, the obtained Au-PANI nanocomposite showed excellent electrocatalytic performance toward the electrochemical oxygen reduction reaction (ORR), with high ORR onset potential and good selectivity. This makes it a promising candidate for a new class of Pt-free ORR catalyst.

Graphene nanosheets decorated with ZnO nanoparticles: facile synthesis and promising application for enhancing the mechanical and gas barrier properties of rubber nanocomposites

In this study, graphene nanosheets decorated with ZnO nanoparticles (NZG) were prepared from graphene oxide by a facile solvothermal method.