Benzhi Ju

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.

Viscosity properties of acetylated carboxymethyl starch.

The viscosity properties of acetylated carboxymethyl starch (ACMS) aqueous solution with different DS (degree of substitution) at concentration of 2.0% (w/w) were investigated using Brookfield R/S+ Portable rheometer. All flow curves of ACMS are well fitted to Power law model. Arrhenius model was used to describe temperature sensitivity. Furthermore, the parameters, which influenced the viscosity properties of the solutions, including temperature, DS of carboxymethyl group (DScm), DS of acetyl group (DSac), presence of salt (NaCl) and shear rate were discussed in detail. Specifically, the viscosity-stability, salt-tolerance and shear-resistance of ACMS with DScm (0.76) and DSac (0.34) were compared with that of sodium alginate as thickener in food or non-food applications. The results indicate that the viscosity properties of ACMS (DScm=0.76, DSac=0.34) were similar to that of sodium alginate and ACMS with DScm (0.76) and DSac (0.34) may be considered as a substitute for sodium alginate in certain application.

Thermoresponsive cellulose ether and its flocculation behavior for organic dye removal

A thermoresponsive polymer, 2-hydroxy-3-butoxypropyl hydroxyethyl cellulose (HBPEC), was prepared by grafting butyl glycidyl ether (BGE) onto hydroxyethyl cellulose (HEC). The lower critical solution temperature (LCST) and critical flocculation temperature (CFT) of HBPEC were varied by changing the molar substitution (MS) and salt concentrations. Transmission electron microscopy (TEM) images and fluorescence spectroscopy showed that HBPEC can assemble into micelles. Additionally, using Nile Red as a model dye, the performance of HBPEC for the removing Nile Red from aqueous solutions via cloud point extraction procedures was investigated in detail. The encapsulation behavior of dye in the aqueous solution of HBPEC was studied by fluorescence spectroscopy and fluorescence microscope. The experimental results indicated that 99.4% of dye was removed from the aqueous solutions, and the HBPEC was recycled and reused easily, Furthermore, the recycle efficiency (RE) and maximum loading capacity portrayed little loss with the number of cycles.

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.

Novel pH- and temperature-responsive polymer: Tertiary amine starch ether

A novel double pH- and temperature-responsive tertiary amine starch ether (TAS) has been developed. Synthesis was performed by grafting dipropyl or dibutyl epoxypropylamine onto hydroxyethyl starch. The cloud point temperatures (TC) of TAS could be tuned to a wide range from 26 to 72.8°C by changing the alkyl chain length, their average molar substitution (MS), and pH value of the solution. The TC of TAS increases with decreasing the alkyl chain length, MS, and pH value of the solution. A linear relationship occurs between the TC and the pH, indicating well-tunable TC. These TAS also showed single pH-sensitive property due to the existence of tertiary amino and hydrophobic alkyl groups. The synthetic strategy presented here could be employed in the preparation of other novel biomaterials with dual pH- and temperature-responsive properties from a variety of polysaccharides.

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.

Thermoresponsive starch derivates with widely tuned LCSTs by introducing short oligo(ethylene glycol) spacers.

Water soluble, thermoresponsive 3-[2-butoxy(ethoxy)m]-2-hydroxypropyl starch ethers (BEmS) (m=0, 1, or 2) were prepared by reacting degraded waxy maize starch with n-butyl glycidyl ether, 3-(2-n-butoxyethyl) glycidyl ether, and 3-[2-(2-n-butoxyethoxy)ethyl] glycidyl ether, respectively. The lower critical solution temperatures (LCSTs) of BEmS could be tuned to a wide range from 17.5°C to 55.0°C by changing the side chain lengths of oligo(ethylene glycol) groups and their average molar substitution (MS). The LCSTs of BEmS increase with increasing side chain length of oligo(ethylene glycol) groups when BS, BES, and BE2S have similar MS values. By contrast, an increase in BEmS concentration and addition of NaCl to the BEmS solutions could lead to a decrease in the LCSTs of BEmS. In addition, the effects of NaCl and BEmS concentrations on the LCSTs become weaker when the side chain length of oligo(ethylene glycol) groups increase.

Biomimetic Structural Color Films with a Bilayer Inverse Heterostructure for Anticounterfeiting Applications

The unique brilliant and angle-independent structural colors of morpho butterfly wings were derived from the multilayer interference, diffraction, and scattering of light with a composite structure including ordered and quasiamorphous arrays. Inspired by the biological heterostructure of ordered and quasiamorphous arrays in the wings, a bilayer inverse heterostructure (BLIHS) containing ordered array layers inverse structure (OALIS) and quasiamorphous array layers inverse structure (Q-AALIS) of polyvinylidene fluoride were successfully prepared through the template method. The BLIHS films selectively displayed iridescent structural color derived from Bragg diffraction of OALIS, whereas the color states transform to noniridescent color because of Q-AALIS just by rotating the sample. Furthermore, the patterning process could be realized by using the spray-coating method on the BILIS films as quasiamorphous array layers. By virtue of this novel photonic structure, the switch between hiding and displaying patterns could be easily realized by changing the viewing angles, and the as-prepared films exhibited inherent excellent durability, which is crucial to their potential for practical applications as anticounterfeiting materials.

Flocculation Behavior of Starch Betainate

Starch betainate was applied in flocculation of kaolin suspension. The flocculation efficiency of starch betainate increased with the increase of both DS and molecular weight of starch betainate, which demonstrated that the flocculation was realized mainly by charge neutralization and bridging of the particles. When the dose of crosslinked starch betainate with DS of 0.33 was 3ppm, the removal ratio of turbidity could reach 90.5%, which was similar to the effect of traditional etherified cationic starch. The flocculation efficiency of starch betainate decreased with the increasing amount of salt in the kaolin suspension. Besides, pH of 5-7 was shown reasonable for starch betainate in the application.