We introduced a facile method to construct hierarchical nanocomposites by combining one-dimensional (1D) conducting polyaniline (PANI) nanowires with 2D graphene oxide (GO) nanosheets. PANI nanowire arrays are aligned vertically on GO substrate. The morphologies of PANI nanowires can be controlled by adjusting the ratios of aniline to GO, which are attributed to different nucleation processes. The hierarchical nanocomposite structures of PANI-GO were further proved by UV-vis, FTIR, and XRD measurements. The hierarchical nanocomposite possessed higher electrochemical capacitance and better stability than each individual component as supercapacitor electrode materials, showing a synergistic effect of PANI and GO. This study will further guide the preparation of functional nanocomposites by combining different dimensional nanomaterials.
A facile approach to disperse graphene in aqueous solution is described. Triblock copolymers (PEO-b-PPO-b-PEO) were employed as the solubilizing agent for chemically exfoliated graphite oxide, and graphene formed through in situ reduction by hydrazine. The formation of the stable aqueous copolymer-coated graphene solution is due to the noncovalent interaction between the hydrophobic PPO segments of the triblock copolymer and the hydrophobic graphene surface, whereas the hydrophilic PEO chains extend into water. It was characterized by atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS), and Raman spectroscopy. Utilizing the dual roles of Pluronic copolymer in dispersing graphene in aqueous solution and forming supramolecular hydrogel with α-cyclodextrin through the penetration of PEO chains into the cyclodextrin cavities, we further developed a facile and effective method to hybridize the well-dispersed graphene into a supramolecular hydrogel, which was investigated by a variety of techniques, such as X-ray diffraction (XRD), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), scanning electron microscopy (SEM), and rheometer. The supramolecular hybrid hydrogel possessed a cross-linked network and showed shear-thinning properties. The viscosity and strength of the supramolecular hybrid hydrogels decreased significantly as compared to those of the native hydrogel resulting from the lamellar structure of the hybrid hydrogel because of the presence of the graphene sheets. Furthermore, the supramolecular hybrid hydrogel transformed into a sol upon increase in temperature. All these features made our supramolecular hybrid hydrogel a nice candidate in a drug delivery and controlled release system.
High mechanical performances of macroscopic graphene oxide (GO) papers are attracting great interest owing to their merits of lightweight and multiple functionalities. However, the loading role of individual nanosheets and its effect on the mechanical properties of the macroscopic GO papers are not yet well understood. Herein, we effectively tailored the interlayer adhesions of the GO papers by introducing small molecules, that is, glutaraldehyde (GA) and water molecules, into the gallery regions. With the help of in situ Raman spectroscopy, we compared the varied load-reinforcing roles of nanosheets, and further predicted the Young's moduli of the GO papers. Systematic mechanical tests have proven that the enhancement of the tensile modulus and strength of the GA-treated GO paper arose from the improved load-bearing capability of the nanosheets. On the basis of Raman and macroscopic mechanical tests, the influences of interlayer adhesions on the fracture mechanisms of the strained GO papers were inferred.
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