Dongzhi Chen

Preparation and characterization of novel hydrophobic cellulose fabrics with polyvinylsilsesquioxane functional coatings

A series of novel hydrophobic cotton fabrics with polyvinylsilsesquioxane (PVS) polymer functional coatings were successfully prepared by solution immersion. The influence of the added amount of PVS polymer on the morphology, resistance to thermal and thermooxidative degradation, and hydrophobic properties of the treated cotton fabrics was studied by attenuated total reflection infrared spectroscopy, scanning electron microscopy, thermogravimetric analysis, and water contact angle measurements, respectively. The experimental results show that the PVS polymer formed a protective film on the surface of the cotton fibers; the resistance to thermal and thermooxidative degradation, and the water-repellent properties of the novel cotton fabrics were also improved with increasing added amount of PVS polymer, compared with that of reference material. The enhancement in the thermal properties of the treated cotton fabrics can likely be attributed to synergistic carbonization between the PVS protective layer and the cellulose fibers during thermal degradation. Meanwhile, it was also found that, with increasing added amount of PVS polymer, the hydrophobicity of the treated cotton fabrics was greatly improved. The noticeable improvement in the hydrophobicity of the treated cotton fabrics is ascribed to the combination of low-surface-energy PVS film and the intrinsically rough surface of the woven cotton fabrics. This strategy for fabricating novel cellulose fabrics provides a guide for the development of high-performance functional cellulose fabrics with tunable properties in the textile industry.

Fabrication of hydrophobic cotton fabrics inspired by polyphenol chemistry

Highly hydrophobic cotton fabrics were fabricated via coordination assembly of tannic acid (TA) and Fe(III) followed by treatment with 1-octadecylamine. Scanning electron microscopy analysis showed that this novel Fe(III)/TA metalorganic system coated the cotton fabrics and affected the surface roughness, making the textiles hydrophobic. This approach is facile and low cost without substrate limitation or addition of fluorinated chemicals. Wettability tests showed that the highly hydrophobic textiles were robustly resistant to acid, alkaline, and salt corrosion and long-term laundering. In addition, the obtained highly hydrophobic surface could effectively separate oil–water mixtures by simple filtration. The simplicity and versatility of this direct approach inspired by polyphenol chemistry may facilitate fast development of functional textiles for many applications.

Photopolymerized maleilated chitosan/methacrylated silk fibroin micro/nanocomposite hydrogels as potential scaffolds for cartilage tissue engineering

Hydrogels composed of natural materials exhibit great application potential in artificial scaffolds for cartilage repair as they can resemble the extracellular matrices of cartilage tissues comprised of various glycosaminoglycan and collagen. Herein, the natural polymers with vinyl groups, i.e. maleilated chitosan (MCS) and methacrylated silk fibroin (MSF) micro/nanoparticles, were firstly synthesized. The chemical structures of MCS and MSF micro/nanoparticles were investigated using Fourier transform infrared (FTIR) spectroscopy, proton nuclear magnetic resonance (1H NMR) spectroscopy, and X-ray photoelectron spectroscopy (XPS). Then MCS/MSF micro/nanocomposite hydrogels were prepared by the photocrosslinking of MCS and MSF micro/nanoparticles in aqueous solutions in the presence of the photoinitiator Darocur 2959 under UV light irradiation. A series of properties of the MCS/MSF micro/nanocomposite hydrogels including rheological property, equilibrium swelling, sol content, compressive modulus, and morphology were examined. The results showed that these behaviors could be tunable via the control of MSF content. When the MSF content was 0.1%, the hydrogel had the compressive modulus of 0.32±0.07MPa, which was in the range of that of articular cartilage. The in vitro cytotoxic evaluation and cell culture of the micro/nanocomposite hydrogels in combination with mouse articular chondrocytes were also investigated. The results demonstrated that the micro/nanocomposite hydrogels with TGF-β1 was biocompatible to mouse articular chondrocytes and could support cells attachment well, indicating their potential as tissue engineering scaffolds for cartilage repair.

Preparation and characterization of monodisperse solvent-free silica nanofluids

ABSTRACT A series of solvent-free ionic silica (SiO2) nanofluids of 12.3–17.3 nm in diameter were synthesized by surface functionalizing nanoscale SiO2 with a charged corona and ionically tethering with oligomeric chains as canopy. The structure and properties of the nanofluids were systematically characterized by Fourier transform infrared (FTIR), differential scanning calorimeter (DSC), transmission electron microscopy (TEM), thermogravimetric analysis (TGA), and rheology tests. The resultant nanofluids with low-molecular-weight oligomeric as canopy are homogeneous, stable yellow-like fluids with no evidence of phase separation at room temperature, while other nanofluids containing high-molecular-weight as canopy behave like a soft glassy, and they exhibit fluidity with still high modulus and viscosity above 60°C. For deeper understanding of the nature of SiO2 nanofluids, the rheological behavior, thermal stability, as well as morphology of SiO2 nanofluids were investigated in details. The flow properties of nanofluids could be easily regulated from soft glassy to free flowing liquids by varying the molecule weight of canopy. Most importantly, the thermal stability, rheological behavior, as well as morphology can be also regulated through varying molecule weight and thickness of canopy, which will guide our future work on synthesis of nanofluids with controllable physical properties. GRAPHICAL ABSTRACT

Enhanced wettability and moisture retention of cotton fabrics coated with self-suspended chitosan derivative

From the industrial viewpoint, it would be desirable to use neutral aqueous solution when applying chitosan coatings for textile treatment. However, in most cases, chitosan only dissolves in acid solvents. In this work, a self-suspended chitosan derivative with liquid-like behavior was prepared by decorating chitosan with a quaternary ammonium salt followed by ion exchange with nonylphenol polyoxyethylene ether sodium sulfate (NPES). The chitosan derivative with higher NPES content dissolved in neutral aqueous solution, and even exhibited liquid-like viscous behavior without water at room temperature. The morphology, structure, composition, and rheological behavior of the chitosan derivative were systematically characterized using various methods. It was found that incorporation of NPES into the chitosan structure could greatly enhance its dispersion, while the modulus and viscosity of the derivative gradually decreased with increasing temperature. Moreover, the novel chitosan derivative not only directly coated cotton fabric via hydrogen-bonding interaction without removing water but also improved the long-term wettability and moisture retention because of the dual-layer ion structure of the chitosan derivative. The results showed that cotton fabrics coated with such chitosan derivatives could be developed as wound dressing materials in future work.

Functionalized magnesium hydroxide fluids/acrylate-coated hybrid cotton fabric with enhanced mechanical, flame retardant and shape-memory properties

AbstractFunctionalized magnesium hydroxide fluids (MHFs) with both grafting reactive acrylate groups and organic long chain ion are successfully fabricated and then incorporated in poly(ethylene glycol) diacrylate (PEGDA) to produce flexible MHFs/PPEGDA coated hybrid cotton fabric via UV photo-polymerization. The morphology, composition, transparency, rheological behavior, mechanical and flamexa0retardantxa0properties of MHFs/PPEGDA coating are systematically characterized by various techniques. It is found that tensile strength and young’s modulus of MHFs/PPEGDA/cotton composite are as high as 46 and 556xa0MPa at MHFs loading amount of 40xa0wt%, respectively, an enhancement of 58.6 and 66.4% in comparison with PPEGDA/cotton composite. What’s more, the addition of MHFs not only reduces the surface energy of PEGDA to improve its film-forming property during polymerization process, but also maintains high transparency over 90%. Besides the above mentioned advantages, MHFs/PPEGDA coating as thermal induced shape memory material could be fixed their shape at −xa04xa0°C and rapidly recover their original shape at 60xa0°C, which is related to the melting transition temperature of MHFs. More importantly, with the synergistic effect of magnesium hydroxide and surface grafted organic long chain ion molecules, the flamexa0retardantxa0property of MHFs/PPEGDA/cotton is also significantly improved. These functionalized organic/inorganic fluids provide a simple approach to fabricate high performance cellulose fabrics with tunable properties in the textile industry.n

Photopolymerized water-soluble maleilated chitosan/methacrylated poly (vinyl alcohol) hydrogels as potential tissue engineering scaffolds

Photocrosslinkable water-soluble maleilated chitosan and methacrylated poly (vinyl alcohol) were synthesized and therefore maleilated chitosan/methacrylated poly (vinyl alcohol) (MCS/MPVA) hydrogels were prepared under UV radiation. Series of properties of the hydrogels including rheological property, swelling behavior, morphology and mechanical test were investigated. The main results showed that the MCS/MPVA hydrogels had fast gel-forming rate (complete transformation to gel within 150s), improved compressive strength at 0.169±0.011MPa and rapid absorbent capacity. These behaviors could be tunable via the control of weight ratio of MCS to MPVA. The indirect cytotoxicity assessments demonstrated the photocrosslinked hydrogels was compatible to mouse fibroblasts (L929 cells), indicating their potential as tissue engineering scaffolds.

Multifunctionalization of cotton fabrics with polyvinylsilsesquioxane/ZnO composite coatings

Ultraviolet (UV) shielding, superhydrophobic and antimicrobial cotton fabrics were fabricated using functional coatings combined with advantages of polyvinylsilsesquioxane and ZnO nanoparticles by solution immersion. The influence of composite coatings on surface morphology, water-repellence, UV shielding property, mechanical property, thermal degradation behavior and antibacterial property of the cotton fabrics was investigated respectively. It is evidently found that the cotton fabrics functionalized by composite coatings exhibited excellent UV shielding, durable superhydrophobic and antimicrobial properties as compared to the reference materials. Most notably, the mechanical properties of cotton fabrics was significantly improved by surface treatment of the composite coatings without compromising their thermal stability as compared to the pristine cotton fabric. This strategy for fabricating UV shielding and superhydrophobic cotton fabrics will guide for developing advanced functional textile in the future work, which will likely be found in many applications such as advanced protective textiles, oil/water separation, water-proof, antibacterial and self-cleaning fields.

Photocrosslinked methacrylated chitosan-based nanofibrous scaffolds as potential skin substitute

AbstractNanofibers based on natural polymers have recently been attracting research interest as promising materials for use as skin substitutes. Here, we prepared photocrosslinked nanofibrous scaffolds based on methacrylated chitosan (MACS) by photocrosslinking electrospun methacrylated chitosan/poly (vinyl alcohol) (PVA) mats and subsequently removing PVA from the nanofibers. We comprehensively investigated the solution properties of MACS/PVA precursors, the intermolecular action between MACS and PVA components, and the morphology of MACS/PVA nanofibers. Results indicated that the fiber diameter and morphology of the photocrosslinked methacrylated chitosan-based nanofibrous scaffolds were controlled by the MACS/PVA mass ratio and showed highly micro-porous structures with many fibrils. In vitro cytotoxicity evaluation and cell culture experiments confirmed that MACS-based mats with micro-pore structure were biocompatible with L929 cells and facilitated cellular migration into the 3D matrix, demonstrating their potential application as skin replacements for wound repair.n

UV-blocking, superhydrophobic and robust cotton fabrics fabricated using polyvinylsilsesquioxane and nano-TiO 2

UV-blocking, superhydrophobic and robust cotton fabrics were successfully developed by combination of polyvinylsilsesquioxane (PVS) and nano-TiO2 for the first time. The influence of the add-on amount on morphologies, ultraviolet (UV) protection, hydrophobicity, mechanical properties, rigidity and thermal degradation of the treated cotton fabrics was studied. The nano-TiO2 particles were found to be embedded in the PVS film layer on the surface of cotton fibers by covalent Ti–O–Si bonds after curing. The UV blocking and hydrophobic properties of the functionalized cotton fabrics were also improved with increases in the amount of add-on, compared to the reference materials. The improvements on the UV blocking, water repellency and rigidity of the treated cotton fabrics are likely attributed to synergism between the PVS polymer and nano-TiO2. The mechanical properties of the finished cotton fabrics are significantly enhanced by treatment of composite coatings. However, the resistance to thermal degradation evidently did not change despite changes in the add-on amount. Hence this strategy for developing the composite coatings can guide in constructing the advanced functional surface, and the discovery of this new class of UV-blocking, superhydrophobic and robust cotton fabrics has many potential applications such as advanced UV-blocking textiles, stretchable electronic devices and self-cleaning fields.