Multi-site sulfonation of lignin for the synthesis of a high-performance dye dispersant.

Sulfonated lignin-based dye dispersants have intensively attracted attention due to their low cost, renewability and abundant sources. However, their utilization is limited by the low content of sulfonic groups and high content of hydroxyl groups in their complex lignin structure, which results in various problems such as high reducing rate of dye, severe staining of the fibers and uneven dyeing. Here, the multi-site sulfonated lignin-based dispersants were prepared with high sulfonic group content (2.20 mmol/g) and low hydroxyl content (2.43 mmol/g). When using it as the dispersant, the dye uptake rate was improved from 69.23 % to 98.55 %, the reducing rate was decreased from 20.82 % to 2.03 %, the K/S value was reduced from 0.69 to 0.02, and the particle sizes in dye system before and after high temperature treatment were stabilized below 0.5 µm. Besides, the dispersion effect was significantly improved because no obvious separation between dye and water was observed even if without the assistance of grinding process. In short, the multi-site sulfonation method proposed in this work could remarkably improve the performances of the lignin-based dye dispersants, which would facilitate the development of the dye dispersion and the high value utilization of lignin.

Development of novel paper-based supercapacitor electrode material by combining copper-cellulose fibers with polyaniline.

Along with the developing of flexible electronics, there is a strong interest in high performance flexible energy storage materials. As natural carbohydrate polymer, cellulose fibers have potential applications in the area due to their biodegradability and flexibility. However, their conductive and electrochemical properties are impossible to meet the demands of practical applications. In this study, cellulose fibers were combined with polyaniline to develop novel paper-based supercapacitor electrode material. Cellulose fibers were firstly coordinated to Cu(II) and subsequently involved in polymerization of polyaniline. Not only the mass loading of polyaniline was significantly increased, but also an impressive area specific capacitance (2767 mF/cm2 at 1 mA/cm2) was achieved. The developed strategy is efficient, environmentally friendly, and has implications for the development of cellulosic paper-based advanced functional materials.

Innovative modification of cellulose fibers for paper-based electrode materials using metal-organic coordination polymers.

Cellulosic paper-based electrode materials have attracted increasing attention in the field of flexible supercapacitor. As a conductive polymer, polyaniline exhibits high theoretical pseudocapacitive capacitance and has been applied in paper-based electrode materials along with cellulose fibers. However, the stacking of polyaniline usually leads to poor performance of electrodes. In this study, metal-organic coordination polymers of zirconium-alizarin red S and zirconium-phytic acid are applied to modulate the polyaniline layer to obtain high-performance cellulosic paper-based electrode materials. Zirconium hydroxide is firstly loaded on cellulose fibers while alizarin red S and phytic acid are introduced to regulate the morphology of polyaniline through doping and coordination processes. The results show that the introduction of dual coordination polymers is effective to regulate the morphology of polyaniline on cellulose fibers. The performances of the paper-based electrode materials, including electrical conductivity and electrochemistry, are apparently improved. It provides a promising strategy for the potential development of economical and green electrode materials in the conventional paper-making process.

One-step fabrication of eco-friendly multi-functional amphiphobic coatings for cellulose-based food packaging.

Plastic and fluorine-containing oil and water resistant packaging materials have been gradually replaced by non-toxic and harmless bio-based materials because of their hazard to environment and human health. In this study, chitosan/carnauba wax emulsions (CS/CWs) were firstly prepared by one-step and used as oil and water resistant coating for cellulose-based food packaging paper. The impacts of emulsion components on stability of the emulsions and barrier performance of the coated paper were investigated. The results showed that the viscosity, particle size and polydispersity index of the emulsions were greatly dependent on the concentration of CS and CW, and the coated paper had the best comprehensive performance in water and oil resistance when the concentration of CS was 3 % and the amount of CW was 90 % of the total solid content (CS3/CW90). The particle size of CS3/CW90 was in the range of 0.5-0.7 µm, and the Cobb60 value, water contact angle and the kit ratings of paper coated with CS3/CW90 achieved 7.5 g/m2, 130.9° and 12/12, respectively, and the coated paper also exhibited excellent thermal stability and high antibacterial rate of 99.1 %, demonstrating its great potential for application in multi-functional food packaging.

Chitosan-graft-poly(lactic acid)/CD-MOFs degradable composite microspheres for sustained release of curcumin.

The solubility of cyclodextrin metal-organic frameworks (CD-MOFs) in aqueous media making it not suitable as sustained-release drug carrier. Here, curcumin-loaded CD-MOFs (CD-MOFs-Cur) was embedded in chitosan-graft-poly(lactic acid) (CS-LA) via a solid-in-oil-in-oil (s/o/o) emulsifying solvent evaporation method forming the sustained-release composite microspheres. At CS-LA concentration of 20 mg/mL, the composite microspheres showed good sphericity. The average particle size of CS-LA/CD-MOFs-Cur (2:1), CS-LA/CD-MOFs-Cur (4:1) and CS-LA/CD-MOFs-Cur (6:1) composite microspheres was about 9.3, 12.3 and 13.5 µm, respectively. The above composite microspheres exhibited various degradation rates and curcumin release rates. Treating in HCl solution (pH 1.2) for 120 min, the average particle size of above microspheres reduced 28.19 %, 24.34 % and 6.19 %, and curcumin released 86.23 %, 78.37 % and 52.57 %, respectively. Treating in PBS (pH 7.4) for 12 h, the average particle size of above microspheres reduced 30.56 %, 26.56 % and 10.66 %, and curcumin released 68.54 %, 54.32 % and 31.25 %, respectively. Moreover, the composite microspheres had a favorable cytocompatibility, with cell viability of higher than 90 %. These composite microspheres open novel opportunity for sustained drug release of CD-MOFs.

High mass loading paper-based electrode material with cellulose fibers under coordination of zirconium oxyhydroxide nanoparticles and sulfosalicylic acid.

With the rapid expansion of the flexible electronics market, it is critical to develop high-performance flexible energy storage electrode materials. Cellulose fibers, which are sustainable, low cost, and flexible, fully meet the requirements of flexible electrode materials, but they are electrically insulating and cause a decrease in energy density. In this study, high-performance paper-based flexible electrode materials (PANI:SSA/Zr-CFs) were prepared with cellulose fibers and polyaniline. A high mass loading of polyaniline was wrapped on zirconia hydroxide-modified cellulose fibers under metal-organic acid coordination through a facile in situ chemical polymerization process. The increase in mass loading of PANI on cellulose fibers not only improves the electrical conductivity but also enhances the area-specific capacitance of the flexible electrodes. The results of electrochemical tests show that the area specific capacitance of the PANI:SSA/Zr-CFs electrode is 4181 mF/cm2 at 1 mA/cm2, which is more than two times higher than that of the electrode with PANI on pristine CFs. This work provides a new strategy for the design and manufacture of high-performance flexible electronic electrodes based on cellulose fibers.

Multiphasic lignocellulose-based suspension for oil-water interfacial stabilization: Synergistic adsorption and phase behavior.

This study described the multiphasic and multi-sized lignocellulose-based suspension (LBS) prepared by green method and its adsorption and phase behavior at O/W interface. The LBS consisting of lignin containing microfibrils (LMFs), lignin containing cellulose nanofibers (LCNFs), and lignin nanoparticles (LNPs), was obtained by mechanical fibrillation and high-shear treatments. They had different functions in emulsion stabilization: (1) synergistic irreversible adsorption of LCNFs and LNPs limited the coalescence of droplets and formed micro-sized droplets; (2) droplets filled in the LMFs network creating a strong fiber-droplet network structure. The fluorescent micrographs confirmed the synergistic irreversible adsorption of LCNFs and LNPs on the surface of the droplets, which was conductive to the high interfacial stability. The droplets were deformed rather than being destroyed under the high flow speed. The increasing viscosity, improving gel-like behavior, decreasing creep compliance and increasing yield stress demonstrated that the internal droplets can support the fiber network to delay the destruction under shear force. And the fiber-droplet network can automatically regenerate in situ after completed destruction.