Bingtao Tang

Fe3O4-functionalized graphene nanosheet embedded phase change material composites: efficient magnetic- and sunlight-driven energy conversion and storage

As an important energy utilization mode, thermal energy is closely related to human life and social production. Phase change materials have been widely adopted to store thermal energy to improve its utilization efficiency. However, the inherent low energy conversion ability of these materials is one of the key problems to be resolved urgently. In this paper, we report novel magnetic- and sunlight-driven energy conversion and storage nanocomposites based on Fe3O4-functionalized graphene nanosheet (Fe3O4–GNS) embedded form-stable polymer phase change materials. Owing to the excellent magnetocaloric performance of Fe3O4 and the universal photoabsorption and photothermal conversion of graphene, the nanocomposites can effectively convert magnetic or light energy into thermal energy under an alternating magnetic field or solar illumination. The energy is stored by phase change materials during the phase transition process. The obtained hybrid nanocomposites exhibit excellent thermal stability with high melting–freezing enthalpy and excellent reversibility. Furthermore, the novel nanocomposites show the characteristics of form-stable phase transformation. The Fe3O4–GNS embedded phase change material composites for energy conversion and storage are expected to open up a rich field of energy materials.

Novel organic solar thermal energy storage materials: efficient visible light-driven reversible solid–liquid phase transition

Solar-thermal energy conversion and storage are one promising solution to directly and efficiently harvest energy from solar radiation. We reported novel organic photothermal conversion-thermal storage materials (OPTCMs) displaying a rapid visible light-harvesting, light-thermal conversion and solid–liquid phase transition thermal energy storage characteristic for solar energy, which is promoted by a dye as an effective “photon capturer and molecular heater” for direct and efficient use of solar radiation.

Visible light-driven organic form-stable phase change materials for solar energy storage

A novel visible light-driven organic form-stable phase change material (VLDOPCM) exhibited excellent performances of light-harvesting, light-thermal conversion, thermal energy storage and form-stable effect, which is promoted by the dye as an effective “photon capture and molecular heater” for direct and efficient use of solar radiation.

Facile Synthesis of Monodispersed Polysulfide Spheres for Building Structural Colors with High Color Visibility and Broad Viewing Angle

The synthesis and assembly of monodispersed colloidal spheres are currently the subject of extensive investigation to fabricate artificial structural color materials. However, artificial structural colors from general colloidal crystals still suffer from the low color visibility and strong viewing angle dependence which seriously hinder their practical application in paints, colorimetric sensors, and color displays. Herein, monodispersed polysulfide (PSF) spheres with intrinsic high refractive index (as high as 1.858) and light-absorbing characteristics are designed, synthesized through a facile polycondensation and crosslinking process between sodium disulfide and 1,2,3-trichloropropane. Owing to their high monodispersity, sufficient surface charge, and good dispersion stability, the PSF spheres can be assembled into large-scale and high-quality 3D photonic crystals. More importantly, high structural color visibility and broad viewing angle are easily achieved because the unique features of PSF can remarkably enhance the relative reflectivity and eliminate the disturbance of scattering and background light. The results of this study provide a simple and efficient strategy to create structural colors with high color visibility, which is very important for their practical application.

Size-controlled synthesis of water-dispersible superparamagnetic Fe3O4 nanoclusters and their magnetic responsiveness

Highly water dispersible and size-controllable superparamagnetic Fe3O4 nanoclusters were synthesized by a simple solvothermal route with sodium citrate as a surface modifier in a mixed-solvent system with diethylene glycol (DEG) and ethylene glycol (EG). The Fe3O4 nanoclusters are small-molecule grafted and the size of the Fe3O4 nanoclusters can be effectively controlled by varying the volume ratio of DEG/EG from tens to hundreds of nanometers. Sodium citrate did not only act as a functional ligand anchor on the particle surface to enhance the dispersibility of the magnetite nanoclusters but also controlled the size of the clusters in the reaction. Magnetic measurements revealed the superparamagnetic nature of the magnetic nanoclusters with no coercivity and remanence but with a magnetization saturation of up to 68.0 emu g−1 at room temperature. These monodisperse Fe3O4 nanoclusters can be used for color display and hyperthermia in biomedical applications because of strong magnetic responsiveness. The diffraction color in the visible light can be modulated under the induction of varied external magnetic fields. Furthermore, the temperature of 20 mg mL−1 Fe3O4 (168 nm) water dispersions can be increased by 46.7 °C within 242 s under an alternating current magnetic field.

Dyeability of Polylactide Fabric with Hydrophobic Anthraquinone Dyes

The dyeability of polylactide fabric has been investigated with the substituted aminoanthraquinone hydrophobic dyes. Their application to the polylactide fabric led to good exhaustion values and good wash fastness between 4 and 5. Microscopic assessment of cross-sections of the dyed polylactide fibres confirmed that these dyes could penetrate into the fibres. The nature of the substituted amino groups showed little influence on the wash fastness, but clearly influenced the exhaustion and light fastness.

Easy approach to assembling a biomimetic color film with tunable structural colors.

The self-assembly of silica microspheres into a close-packed array is a simple method of fabricating three-dimensional photonic crystal structural color films. However, the color is very dull because of the interferences of scattering and background light. In this study, we added a small quantity of surface-modified carbon black (CB) to the system of colloidal silica in n-propanol. The use of n-propanol as a dispersant is beneficial to the rapid development of photonic crystal films during the process of dip-coating. The doping of CB into silica microspheres can absorb background and scattering light, resulting in vivid structural colors.

Light–thermal conversion organic shape-stabilized phase-change materials with broadband harvesting for visible light of solar radiation

To achieve highly efficient utilization of sunlight, organic shape-stabilized phase change materials (OSPCMs) with light–thermal conversion and visible light (solar radiation) harvesting abilities were designed and synthesized through color matching (yellow, red, and blue) according to the solar irradiation energy density. These materials exhibited excellent rapid and broadband visible light-harvesting, light–thermal conversion, thermal energy storage, and form-stable (remained in the same state upon transition) effects. The chemical structures of OSPCMs were verified using Fourier transform infrared and proton nuclear magnetic resonance techniques. Differential scanning calorimetry results indicated that the melting temperatures and latent heats of the synthesized OSPCMs ranged from 48 °C to 64 °C and from 107.1 J g−1 to 138.5 J g−1, respectively. The novel materials show a reversible (more than 200 cycles) phase transition (crystalline state change) via ON/OFF switching of visible light irradiation. Colour matching showed that the light-to-heat conversion and thermal energy storage efficiency (η) of the OSPCMs significantly improved upon solar irradiation.

Multiple Colors Output on Voile through 3D Colloidal Crystals with Robust Mechanical Properties

Distinguished from the chromatic mechanism of dyes and pigments, structural color is derived from physical interactions of visible light with structures that are periodic at the scale of the wavelength of light. Using colloidal crystals with coloring functions for fabrics has resulted in significant improvements compared with chemical colors because the structural color from colloidal crystals bears many unique and fascinating optical properties, such as vivid iridescence and nonphotobleaching. However, the poor mechanical performance of the structural color films cannot meet actual requirements because of the weak point contact of colloidal crystal particles. Herein, we demonstrate in this study the patterning on voile fabrics with high mechanical strength on account of the periodic array lock effect of polymers, and multiple structural color output was simultaneously achieved by a simple two-phase self-assembly method for printing voile fabrics with 3D colloidal crystals. The colored voile fabrics exhibit high color saturation, good mechanical stability, and multiple-color patterns printable. In addition, colloidal crystals are promising potential substitutes for organic dyes and pigments because colloidal crystals are environmentally friendly.

Hydrophilic Modification of Multi-Walled Carbon Nanotube for Building Photonic Crystals with Enhanced Color Visibility and Mechanical Strength.

Low color visibility and poor mechanical strength of polystyrene (PS) photonic crystal films have been the main shortcomings for the potential applications in paints or displays. This paper presents a simple method to fabricate PS/MWCNTs (multi-walled carbon nanotubes) composite photonic crystal films with enhanced color visibility and mechanical strength. First, MWCNTs was modified through radical addition reaction by aniline 2,5-double sulfonic acid diazonium salt to generate hydrophilic surface and good water dispersity. Then the MWCNTs dispersion was blended with PS emulsion to form homogeneous PS/MWCNTs emulsion mixtures and fabricate composite films through thermal-assisted method. The obtained films exhibit high color visibility under natural light and improved mechanical strength owing to the light-adsorption property and crosslinking effect of MWCNTs. The utilization of MWCNTs in improving the properties of photonic crystals is significant for various applications, such as in paints and displays.