Synthesis and characterization of microencapsulated paraffin with melamine-urea-formaldehyde shell modified with lignin.

The study aims to fabricate MUF/paraffin microcapsules with lignin nanoparticles (LNPs)/ melamine-urea-formaldehyde (MUF) resin as hybrid shell material with different LNPs addition were synthesized in oil-in-water emulsion stabilized synergistically by styrene/maleic anhydride (SMA) and LNPs. The morphological characterization of LNPs was observed by transmission electron microscopy (TEM). The particle size of LNPs, the mean particle size and ξ potentials of SMA/LNPs mixture at pH =4.5 were investigated by zeta potential measurement. Field emission scanning electron microscopy (FE-SEM), Fourier-transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), thermogravimetric analyzer (TGA), and differential scanning calorimetry (DSC) were characterized the morphologies, crystallography, chemical component, thermal stability and phase change properties of MUF/paraffin microcapsules with different LNPs addition. The results showed that MUF/paraffin microcapsules were spherical. The LNPs did not influence the chemical structure or crystal type of MUF/paraffin microcapsules. When the LNPs addition was 0.15 g, the melting enthalpy and crystallization enthalpy is respectively 130.03 and 121.92 J/g and the encapsulation efficiency of MicroC-15 is 61.04 %.

Effects of Processing Conditions on the Properties of Monoammonium Phosphate Microcapsules with Melamine-Formaldehyde Resin Shell.

To develop monoammonium phosphate (MAP) as a novel acid source for durable intumescent fire retardants (IFR), MAP microcapsules (MCMAPs) containing MAP as the internal core and melamine-formaldehyde (MF) as the external shell were prepared by in situ polymerization in this study. The influences of synthesis conditions (including reaction temperature, polymerization time, and reaction pH value) on the properties of obtained MCMAPs (MAP content, yield, morphologies, and thermal properties) were then investigated systematically. The morphologies, chemical structures, and thermal properties were characterized by optical microscopy, scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), Fourier transform infrared (FTIR) spectroscopy, and thermogravimetry analyzer (TGA). The results show that MAP was well encapsulated by MF resin. No microcapsules are obtained at <55 °C or with polymerization times <1 h. Optimal preparation conditions of reaction temperature, polymerization time, and reaction pH value are 75 °C, 3 h, and 5.5, respectively. Those results provide process reference and theoretical basis for preparing MCMAPs and could promote the application of MAP microcapsules in wood flame-retardant materials.

Combined stabilizers prepared from cellulose nanocrystals and styrene-maleic anhydride to microencapsulate phase change materials.

Cellulose nanocrystals (CNCs) combined with styrene-maleic anhydride (SMA) as stabilizers were used to stabilize paraffin droplets for fabricating paraffin/melamine-urea-formaldehyde (MUF) microcapsules. Effects of mixed emulsifier of CNCs and SMA on the morphologies, chemical structures, and properties of paraffin/MUF microcapsules were characterized by Field emission scanning electron microscopy (FE-SEM), Fourier-transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), thermogravimetric analyzer (TGA), differential scanning calorimetry (DSC), and paraffin leakage rate test. The results showed that using CNCs alone as emulsifier did not work in manufacturing paraffin/MUF microcapsules, but mixed emulsifier of CNCs and SMA was suitable. When CNCs and SMA each account for 50 % of the mixed stabilizer, the phase change latent heat values of melting and crystallization of MicroC5S5 were about 123.6 J/g and 118.4 J/g, respectively. This demonstrates that CNCs can be mixed with SMA to stabilize paraffin droplets in situ polymerization and reduce the need for surfactants.

Nanocellulose supported hierarchical structured polyaniline/nanocarbon nanocomposite electrode via layer-by-layer assembly for green flexible supercapacitors.

The development of a hierarchical structured multicomponent nanocomposite electrode is a promising strategy for utilizing the high efficiency of an electroactive material and improving the electrochemical performance. We propose cellulose nanofibril (CNF) aerogels with a nanoscale fiber-entangled network as the skeleton (via layer-by-layer (LbL) assembly) of electroactive materials polyaniline (PANi), carboxylic multiwalled carbon nanotubes (CMWCNTs), and graphene oxide (GO) to obtain structurally ordered polymer-inorganic hybrid nanocomposite electrodes for high-capacity flexible supercapacitors. The uniformly distributed multilayer nanoarchitecture, interconnected network, and hydrophilicity of the electrode provide a high specific surface area, excellent ion diffusion channels, and large effective contact area, thereby improving the electrochemical performance of the supercapacitor electrode. The specific capacitance of the CNF-[PANi/CMWCNT]10 (CPC10) and CNF-[PANi/RGO]10 (CPR10) electrodes reaches 965.80 and 780.64 F g-1 in 1 M aqueous H2SO4 electrolyte, respectively; the corresponding values in PVA/H3PO4 electrolyte are 1.59 and 1.46 F cm-2. In addition, the assembled symmetric supercapacitors show good energy densities of 147.23 and 112.32 mW h cm-2, as well as excellent durability and flexibility. Our approach offers a simple and effective method for fabricating an ideal well-structured nanocomposite electrode for green and flexible energy storage devices via LbL assembly.

Layer-by-layer assembled polyaniline/carbon nanomaterial-coated cellulosic aerogel electrodes for high-capacitance supercapacitor applications.

Traditional layer-by-layer (LbL) assembled electrodes are mostly multilayer composites formed on two-dimensional membrane materials. In this case, the electroactive material cannot enter the interior of the substrate. With porous aerogels as the substrate, the LbL assembly of the electroactive material into the three-dimensional aerogel skeleton can be realised, greatly improving the utilisation and the electrochemical performance of the electroactive material. To create a promising aerogel electrode for high-performance energy storage devices, we herein report an aerogel based on wood pulp fibre (WPF) and cellulose nanocrystals (CNC), for use as a porous substrate for LbL assembly of nanostructural polyaniline (PANI) and graphene oxide (GO) or carboxylic multi-walled carbon nanotubes (CMCNT). Owing to the uniformly distributed multilayer nanoarchitecture, interpenetrating channels, and hydrophilic character of the cellulosic aerogel substrate, the produced electrodes of (PANI/CMCNT)10 and (PANI/CMCNT)10 both display high specific capacitances, favourable capacitance retention, good cycling stabilities, and structural flexibility. In the three-electrode test, their gravimetric specific capacitances are as high as 716.62 and 636.63 F g-1, respectively. In addition, the assembled symmetric supercapacitors show good areal specific capacitances (1.95 and 1.49 F cm-2) in addition to high areal specific energies (168.64 and 113.57 mW h cm-2, respectively). These results demonstrate that the integration of the LbL-assembled electroactive materials and porous cellulosic aerogel substrate can be a promising strategy to design high-efficiency green energy storage devices.

Nanocellulose/polypyrrole aerogel electrodes with higher conductivity via adding vapor grown nano-carbon fibers as conducting networks for supercapacitor application.

Nanocellulose-based conductive materials have been widely used as supercapacitor electrodes. Herein, electrode materials with higher conductivity were prepared by in situ polymerization of polypyrrole (PPy) on cellulose nanofibrils (CNF) and vapor grown carbon fiber (VGCF) hybrid aerogels. With increase in VGCF content, the conductivities of CNF/VGCF aerogel films and CNF/VGCF/PPy aerogel films increased. The CNF/VGCF2/PPy aerogel films exhibited a maximum value of 11.25 S cm-1, which is beneficial for electron transfer and to reduce interior resistance. In addition, the capacitance of the electrode materials was improved because of synergistic effects between the double-layer capacitance of VGCF and pseudocapacitance of PPy in the CNF/VGCF/PPy aerogels. Therefore, the CNF/VGCF/PPy aerogel electrode showed capacitances of 8.61 F cm-2 at 1 mV s-1 (specific area capacitance) and 678.66 F g-1 at 1.875 mA cm-2 (specific gravimetric capacitance) and retained 91.38% of its initial capacitance after 2000 cycles. Furthermore, an all-solid-state supercapacitor fabricated by the above electrode materials exhibited maximum energy and power densities of 15.08 W h Kg-1, respectively. These electrochemical properties provide great potential for supercapacitors or other electronic devices with good electrochemical properties.

Green and facile fabrication of carbon aerogels from cellulose-based waste newspaper for solving organic pollution.

Carbon-based aerogel fabricated from waste biomass is a potential absorbent material for solving organic pollution. Herein, the lightweight, hydrophobic and porous carbon aerogels (CAs) have been synthesized through freezing-drying and post-pyrolysis by using waste newspaper as the only raw materials. The as-prepared CAs exhibited a low density of 18.5 mg cm(-3) and excellent hydrophobicity with a water contact angle of 132° and selective absorption for organic reagents. The absorption capacity of CA for organic compounds can be 29-51 times its own weight. Moreover, three methods (e.g., squeezing, combustion, and distillation) can be employed to recycle CA and harvest organic pollutants. Combined with waste biomass as raw materials, green and facile fabrication process, excellent hydrophobicity and oleophilicity, CA used as an absorbent material has great potential in application of organic pollutant solvents absorption and environmental protection.

Fabrication of cellulose-based aerogels from waste newspaper without any pretreatment and their use for absorbents.

Cellulose-based aerogel (CBA) was prepared from waste newspaper (WNP) without any pretreatment using 1-allyl-3-methyimidazolium chloride (AmImCl) as a solvent via regeneration and an environmentally friendly freeze-drying method. After being treated with trimethylchlorosilane (TMCS) via a simple thermal chemical vapor deposition process, the resulting CBAs were rendered both hydrophobic and oleophilic. Successful silanization on the surface of the porous CBA was verified by a variety of techniques including scanning electron microscopy (SEM), energy-dispersive X-ray analysis (EDX), and water contact angle (WCA) measurements. As a result, the silane-coated, interconnected CBAs not only exhibited good absorption performance for oils (e.g., waste engine oil), but also showed absorption capacity for organic solvents such as chloroform (with a representative weight gain ranging from 11 to 22 times of their own dry weight), making them diversified absorbents for potential applications including sewage purification.