Chusheng Qi

Development of Eco-friendly Soy Protein Isolate Films with High Mechanical Properties through HNTs, PVA, and PTGE Synergism Effect

This study was to develop novel soy protein isolate-based films for packaging using halloysite nanotubes (HNTs), poly-vinyl alcohol (PVA), and 1,2,3-propanetriol-diglycidyl-ether (PTGE). The structural, crystallinity, opacity, micromorphology, and thermal stability of the resultant SPI/HNTs/PVA/PTGE film were analyzed by the Attenuated total reflectance-Fourier transformed infrared (ATR-FTIR) spectroscopy, X-ray diffraction (XRD), UV-Vis spectrophotometry, scanning electron microscopy (SEM), and thermo-gravimetric analysis (TGA). The SPI/HNTs/PVA/PTGE film illustrated that HNTs were uniformly dispersed in the SPI matrix and the thermal stability of the film was enhanced. Furthermore, the tensile strength (TS) of the SPI/HNTs/PVA/PTGE film was increased by 329.3% and the elongation at the break (EB) remained unchanged. The water absorption (WA) and the moisture content (MC) were decreased by 5.1% and 10.4%, respectively, compared to the unmodified film. The results highlighted the synergistic effects of SPI, HNTs, PVA, and PTGE on the mechanical properties, water resistance, and thermal stability of SPI films, which showed excellent strength and flexibility. In short, SPI films prepared from HNTs, PVA, and PTGE showed considerable potential as packaging materials.

A co-production of sugars, lignosulfonates, cellulose, and cellulose nanocrystals from ball-milled woods

This study demonstrated the technical potential for the large-scale co-production of sugars, lignosulfonates, cellulose, and cellulose nanocrystals. Ball-milled woods with two particle sizes were prepared by ball milling for 80min or 120min (BMW80, BMW120) and then enzymatically hydrolyzed. 78.3% cellulose conversion of BMW120 was achieved, which was three times as high as the conversion of BMW80. The hydrolyzed residues (HRs) were neutrally sulfonated cooking. 57.72g/L and 88.16g/L lignosulfonate concentration, respectively, were harvested from HR80 and HR120, and 42.6±0.5% lignin were removed. The subsequent solid residuals were purified to produce cellulose and then this material was acid-hydrolyzed to produce cellulose nanocrystals. The BMW120 maintained smaller particle size and aspect ratio during each step of during the multiple processes, while the average aspect ratio of its cellulose nanocrystals was larger. The crystallinity of both materials increased with each step of wet processing, reaching to 74% for the cellulose.

Preparation of mechanical abrasion and corrosion resistant bulk highly hydrophobic material based on 3-D wood template

Bulk highly hydrophobic wood (BH-wood) was successfully prepared by grafting long-chain alkyl groups onto wood cell walls via the ester linkage. The resulting wood showed lower surface free energy and favorably high hydrophobicity compared to non-treated wood. The microstructure and chemical composition of the control and treated wood were characterized by field emission scanning electron microscopy (FE-SEM), solid state 13C NMR, X-ray diffraction (XRD) analysis, and Fourier transform infrared (FT-IR) spectroscopy. The hydrophobic property of the wood was characterized according to contact angle (CA) measurements. The mechanical and chemical durability of the BH-wood were also evaluated. The results suggested that the BH-wood had low surface free energy microstructures extending throughout its whole volume, and possessed excellent mechanical abrasion and corrosion resistance. The self-cleaning property was also significantly improved in the BH-wood compared to the control.

Highly hydrophobic and self-cleaning bulk wood prepared by grafting long-chain alkyl onto wood cell walls

Highly hydrophobic bulk wood was successfully prepared by grafting long-chain octadecyl isocyanate (OTI) onto wood cell walls via a urethane linkage. The resulting wood was highly hydrophobic and showed significantly reduced surface free energy. The microstructure and chemical composition of the untreated and treated wood were characterized using the scanning electron microscopy, energy-dispersive X-ray spectrometry, and Fourier transform infrared spectroscopy. The hydrophobic property of the wood was characterized using contact angle measurements. The mechanical and physical properties as well as the chemical durability of the highly hydrophobic wood were evaluated. The results suggested that the resultant OTI-treated wood presented fairly low surface free energy, high hydrophobicity even in the wood core, and excellent stability and durability against chemical corrosion and mechanical abrasion. Furthermore, the physical properties, including self-cleaning, dimensional stability, and water uptake, were significantly improved in the treated wood.

Simultaneously strengthening and toughening soy protein isolate-based films using poly(ethylene glycol)-block-polystyrene (PEG-b-PS) nanoparticles

Well-defined, vesicle-like nanoparticles of poly(ethylene glycol)-block-polystyrene (PEG-b-PS) diblock copolymers, synthesized via a macro-RAFT agent of PEG45-TTC (where “TTC” is the RAFT terminal of trithiocarbonate) mediated dispersion polymerization of styrene, were used to prepare enhanced SPI-based nanocomposite films in this study. The uniform dispersion of the PEG45-b-PS276 nanoparticles into the SPI matrix was confirmed by transmission electron microscopy and field emission scanning electron microscopy. The simultaneously strengthening and toughening mechanism of the SPI-based nanocomposite films was achieved. This was accomplished by discontinuous filling of nanoparticles into the SPI matrix due to the hydrophobic PS core which served as the hard-domains to strengthen the mechanical properties of the resultant films. Concurrently, the hydrophilic PEG block was conjunct with the SPI chains through hydrogen bonding, increasing the compatibility between nanoparticles and the SPI matrix, ultimately transferring interfacial stress and increasing the elongation of the resulting films. Compared to unmodified SPI film, the tensile strength and elongation at break value of the SPI/PEG-b-PS nanocomposite films were improved by 85.3% and 11.5%, respectively. Further, the total soluble matter of the nanocomposite films was reduced by 59.7% compared to the control. The surface hydrophobicity of the films was also elevated due to the hydrophobic PS core surface-aggregation. The diblock copolymer examined here, as opposed to other nanofillers, may be the first to be successfully introduced into the SPI biopolymer matrix to fabricate high-performance bio-nanocomposite films.

Preparation of a Novel Chitosan Based Biopolymer Dye and Application in Wood Dyeing

A novel chitosan-based biopolymer dye possessing antibacterial properties was synthesized by reaction of O-carboxymethyl chitosan and Acid Red GR. The synthesized materials were characterized by Fourier transform infrared spectroscopy (FTIR), degree of substitution (DS), X-ray photoelectron spectroscopy (XPS), thermogravimetric analysis (TG), X-ray diffraction (XRD), water solubility test, antibacterial property test, and dyeing performance, including dye uptake, color difference, and fastness. Results showed that the synthesized dye was combined by –NH3+ of O-carboxymethyl chitosan and the sulfonic group of Acid Red GR. According to the comprehensive analysis of XRD and water solubility, the introduction of the carboxymethyl group and acid dye molecule changed the structure of the chitosan from compact to loose, which improved the synthesized dye’s water solubility. However, the thermal stability of the synthesized dye was decreased. The antibacterial property of the poplar wood dyed with the synthesized dye was enhanced and its antibacterial rate, specifically against Staphylococcus aureus and Escherichia coli, also increased to a rate of more than 99%. However, the dye uptake of the synthesized dye was lower than that of the original dye. Despite this, though, the dyeing effect of the synthesized dye demonstrated better water-fastness, and light-fastness than the original dye. Therefore, the novel chitosan-based biopolymer dye can be a promising product for wood dyeing.

Chitosan/organic rectorite nanocomposites rapidly synthesized by microwave irradiation: effects of chitosan molecular weight

Chitosans with high and low molecular weight (CSH and CSL) were intercalated into organic rectorite (OREC) to prepare chitosan/organic rectorite nanocomposites (CSHOR and CSLOR) via a microwave irradiation method for 75 min, which was found to be much more efficient than the conventional 48 h heating method. The structure and intercalation mechanism of the nanocomposites were investigated by XRD, FT-IR, and zeta potential analysis, and the effects of chitosan (CS) molecular weight on the morphology, crystallization behavior, thermal stability, and antibacterial properties of the nanocomposites were explored. The results indicated that: (1) CSH and CSL were inserted successfully into the silicate layers to form the intercalated nanocomposites, and interlayer spacing could be increased to 5.14 nm and 6.40 nm, respectively. (2) CS and OREC were joined together through hydrogen bonding and electrostatic interaction. (3) Compared to CSH and CSL, the thermal stability and antibacterial properties of both CSHOR and CSLOR were significantly improved. (4) With decreasing CS molecular weight the interlayer distance of OREC increased, which resulted in morphological and crystallization changes to the nanocomposites and enhanced antibacterial activity without impacting thermal stability.

Surface free energy and dynamic wettability of wood simultaneously treated with acidic dye and flame retardant

The use of multifunctional wood for decorative purpose has grown increasingly popular in recent years. In this study, fast-growing poplar wood was treated with dye (0.5%) and flame retardant (0, 10, 20, and 30%) simultaneously to enhance its visual characteristic and safety. The dynamic wettability and surface free energy of wood samples were studied using S-D wetting model and van Oss–Chaudhury–Good (vOCG) method, respectively. Dye uptake, drug load, color difference, and combustion performance were determined. The treated wood was also characterized by infrared spectroscopy, scanning electron microscopy, and energy-dispersive X-ray spectroscopy. The results indicated that the proposed treatment yields favorable adhesive spreading and penetration ability at the wood surface. The surface free energy of treated wood was higher than that of untreated wood, and the dye uptake, drug load, color difference, and limited oxygen index all increased after the proposed combination treatment compared to dye-only treated wood. The results also indicated that the flame retardant reacted chemically with the wood as the dye and flame retardant molecules diffused into the cell cavity, wood vessel, and aperture.

In situ green synthesis of antimicrobial carboxymethyl chitosan–nanosilver hybrids with controlled silver release

In order to fabricate antimicrobial carboxymethyl chitosan–nanosilver (CMC-Ag) hybrids with controlled silver release, this study demonstrated comparable formation via three synthetic protocols: 1) carboxymethyl chitosan (CMC) and glucose (adding glucose after AgNO3), 2) CMC and glucose (adding glucose before AgNO3), and 3) CMC only. Under principles of green chemistry, the synthesis was conducted in an aqueous medium exposed to microwave irradiation for 10 minutes with nontoxic chemicals. The structure and formation mechanisms of the three CMC-Ag hybrids were explored using X-ray diffraction, ultraviolet-visible spectroscopy, transmission electron microscopy, and Fourier-transform infrared analyses. Additionally, antimicrobial activity and in vitro silver release of the three synthesized hybrids were investigated in detail. The results revealed that a large number of stable, uniform, and small silver nanoparticles (AgNPs) were synthesized in situ on CMC chains via protocol 1. AgNPs were well dispersed with narrow size distribution in the range of 6–20 nm, with mean diameter only 12.22±2.57 nm. The addition of glucose resulted in greater AgNP synthesis. The order of addition of glucose and AgNO3 significantly affected particle size and size distribution of AgNPs. Compared to CMC alone and commercially available AgNPs, the antimicrobial activities of three hybrids were significantly improved. Of the three hybrids, CMC-Ag1 synthesized via protocol 1 exhibited better antimicrobial activity than CMC-Ag2 and CMC-Ag3, and showed more effective inhibition of Staphylococcus aureus than Escherichia coli. Due to strong coordination and electrostatic interactions between CMC and silver and good steric protection provided by CMC, CMC-Ag1 displayed stable and continuous silver release and better performance in retaining silver for prolonged periods than CMC-Ag2 and CMC-Ag3.

Physical, mechanical properties, and structural characterization of konjac glucomannan-chitosan-polypeptide adhesive blends

Polypeptide was used to improve the water resistance of konjac glucomannan (KGM)-chitosan-based wood adhesives. With identical solid content, the tensile strength in wet state was increased by the addition of polypeptide and a maximum tensile strength of 2.34 MPa was reached. To examine the physical and chemical changes induced by the addition of polypeptide, the structure, viscoelasticity, morphology, and miscibility of the adhesive blends were determined by Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, rheometry, and scanning electron microscopy. Results indicated improvements in mechanical properties were related to the formation of intermolecular hydrogen bonds and covalent bonds between KGM, chitosan, and polypeptide, which was enhanced by increasing the polypeptide concentration. Good miscibility existed between KGM, chitosan and polypeptide, as well as good wettability between the adhesive blends and wood veneer.