A novel 3D composite hydrogel composed of reduced graphene oxide nanosheets and α-Fe₂O₃ nanoparticles (rGO/α-Fe₂O₃) was synthesized via a two-step process in a solution phase technique. The experimental results show the composite has an interconnected 3D porous network with micrometer pores, and the α-Fe₂O₃ nanoparticles with the size of about 50–100 nm are uniformly dispersed onto the thin graphene nanosheets. The rGO/α-Fe₂O₃ composite hydrogel exhibits excellent microwave absorbability. Compared to a pristine reduced graphene oxide (rGO) hydrogel, the reported composite hydrogel has both wider and stronger wave absorption achieved in the frequency range of 1–18 GHz. The composite with a coating layer thickness of 5.0 mm exhibits a maximum absorption of −33.5 dB at 7.12 GHz and in particular, the product with a coating layer thickness of only 3.0 mm shows a bandwidth of 6.4 GHz (from a frequency of 10.8–17.2 GHz) corresponding to reflection loss at −10 dB. The excellent microwave absorption properties are ascribed to the improved impedance matching. Our findings pave a way to design and prepare lightweight and high performance electromagnetic wave absorption materials based on 3D graphene and other nanomaterials.

The effects of polydimethylsiloxane (PDMS) on phase separation, optical transmittance and surface properties including surface composition, morphology and wettability of waterborne polyurethane (WPU) containing PDMS were investigated. After the introduction of PDMS into the WPU backbone by polymerization, the large difference in the solubility parameter of the non-polar PDMS segment and the high-polar urethane segments promoted PDMS enrichment at the air–polymer interface and enhanced phase separation, resulting in rough structures. Accordingly, the combination of PDMS enrichment and the rough structures contributed to the high or superhydrophobic surfaces and the highest contact angle with water achieved was 156.5°. The optical transmittance of the highly hydrophobic coatings reached about 78–87% throughout most of the visible light region. Importantly, the highly hydrophobic and transparent properties will greatly broaden the applications of WPU, showing potential for the environmental protection and industrial applications.

Graphene oxide (GO) nanosheets and polyoxometalate such as H₃PW₁₂O₄₀ (PTA) are prepared into a multilayer film via a layer-by-layer inkjet printing method. The GO/PTA composite thin film shows linear, uniform and regular layer-by-layer growth. Under UV-irradiation, a photoreduction reaction takes place in the film which converts GO to reduced GO (rGO) due to the photoreduction activity of polyoxometalate clusters. According to the cyclic voltammograms measurement, the rGO/PTA composite film displays good electrocatalytic activity for the oxidation of dopamine (DA). The oxidation peak current (I_pa) increases gradually with increasing the dopamine concentration, which may be used in electrochemical biosensors.

As a result of their lightweight properties and high dielectric loss, graphene and their composites have attracted great attention for potential applications in wave absorption. Herein, we report room temperature conditions for the synthesis of a 3D composite hydrogel composed of reduced graphene oxide nanosheets and Fe₃O₄ nanoparticles (RGO–Fe₃O₄). The experimental results show that the composite has an interconnected 3D porous network with micrometer-sized pores, and that the Fe₃O₄ nanoparticles with a small size of about 5–10 nm are uniformly dispersed onto the thin graphene nanosheets. The as-prepared RGO–Fe₃O₄ composite hydrogel shows excellent microwave absorbability compared with previously reported nanocomposites based on graphene and Fe₃O₄. The obtained composite with a coating layer thickness of only 2.5 mm exhibits a maximum absorption of −47.9 dB at 10.1 GHz. In particular, the product with a coating layer thickness of only 2.0 mm shows a bandwidth of 5.3 GHz (from frequency of 11.3–16.6 GHz) corresponding to reflection loss at −10 dB (90% absorption). Additionally, the fabrication method is simple, low cost and easily done on a large scale. This further confirms that nanoscale Fe₃O₄ particles on graphene networks give the composite hydrogel the ability to realize practical applications for wave absorption.

A multifunctional coating composed of polyhexamethylene guanidine phosphate (PHMGP) and potassium alginate-carbon nanotubes (PA-CNTs) was constructed on cotton fabric via a layer-by-layer assembly technique. The growth of the assembly coating was monitored by Fourier transform infrared spectroscopy and the result shows the assembly coating grows approximately linearly with the increase of bilayer number. The electrical conductivity test shows that the assembly coating endows cotton with electrical conductivity, due to the formation of a CNT network on the cotton fabric. The thermo-stability and flame resistance were evaluated by thermo-gravimetric analysis and a vertical flammability test, and the results indicate that the assembly coating promotes char formation, decreases the burning time and eliminates the afterglow during combustion. The antimicrobial assessment suggests that the assembly coating can effectively inhibit the growth of Escherichia coli, and the inhibiting effect increases with the growth of bilayer number. A multifunctional cotton fabric could be produced by the LBL assembly technique, which enlarges its application area.