In this paper, we present a highly efficient, cost-effective, and widely applicable functionalized SiO2/TiO2-polymer based coating to fabricate a translucent, fluorine-free, chemically stable, photocatalytic active, self-healable superhydrophobic coating, which consisted of two mixed functionalized particles (MFP) and polydimethylsiloxane (PDMS) in a proper ratio. Both SiO2 and TiO2 powders were functionalized with PDMS brushes to achieve superhydrophobicity. To maximally optimize its properties, including superhydrophobicity, transparency, and photocatalytic activity, the ratios between MFP with PDMS were carefully studied and optimized. Glass slides coated with this mixed coating (MC) showed translucence with a transparency of 75%. It also presented superior photocatalytic activity and strong UV resistance that could repeatedly degrade organic oil pollutants as many as 50 times, while still maintaining superhydrophobicity even upon exposure to UV light with a high intensity of 80 mW/cm2 for as long as 36 h. When low-surface-tension oils such as dodecane wetted the MC surface, it showed excellent slippery performance and could quickly repel strong acid/alkali/hot water and even very corrosive liquids such as aqua regia. MC achieved extremely stable underoil superhydrophobicity (toward liquids including water, strong acid and base, hot water, etc.) and self-cleaning properties, not only in oils at room temperature but also in a scalded oil environment. Moreover, MC showed self-healable performance after recycled plasma treatment. The stainless steel mesh coated with MC was also used to highly efficiently separate oil–water mixtures. Moreover, harsher liquids including strong acid/alkali solutions/hot water/ice water–oil mixtures could also be successfully separated by the coated mesh. This coating was believed to largely broaden both indoor and outdoor applications for superhydrophobic surfaces.
The superfine fiber synthetic leather base (SFSLB) is composed of the two components of nylon fibers and polyurethane. SFSLB has excellent performance, especially in terms of mechanical properties. However, compared with native leather, SFSLB has a hot feeling due to its poor moisture absorbent and transfer abilities. So our study proposed a method of grafting collagen-chrome tannins (C-CrT) on nylon fiber in the SFSLB for improving the moisture absorbent and transfer abilities. A three-step surface modification was developed, involving washing pretreatment, sulfuric acid hydrolysis and grafting of C-CrT on SFSLB. The dosage of sulfuric acid and chrome tannins, bath ratio, reaction temperature and the time for collagen permeation and chrome tannin cross-linking were optimized via single-factor experiments. Their efficiency was determined by measuring static water-vapor transmission rate (SWVT) and liquid wicking rate. The results showed that the dosage of sulfuric acid was 15% and chrome tannins was 5%, the bath ratio was 1500%, the reaction temperature was 60℃ and the time for collagen permeation and chrome tannin cross-linking was 3 hours. Under this condition, the SWVT of modified SFSLB was 986 g/m2 · 24 h, and the liquid wicking rate was 1.323 mm/s. Compared with untreated SFSLB, the SWVT and liquid wicking rate of modified SFSLB were improved by 90.35% and 344%, respectively. The static state contact angle, scanning electron microscopy and X-ray photoelectron spectroscopy were used for the determination of sample surface performance, morphology and chemical composition, and states before and after treatment, respectively.
Using waste leather collagen, collagen microspheres with “–CHCH2” (CMAs) were prepared using the emulsification cross-linking method and then incorporated into a nonwoven polyamide fiber material with the “thiol–ene” click chemistry method to obtain modified nonwoven polyamide fibers (PA-CMAs). Experiments showed that for a CMA concentration of 6 wt %, initiator concentration of 0.008 wt %, and irradiation time of 5 h, the grafting rate can reach 25.83%. Scanning electron microscope (SEM) and X-ray photoelectron spectrometer (XPS) are used to confirm the successful grafting of CMAs onto nonwoven PA materials. The stability and fastness test was used to show that PA-CMAs have good stability with acid, alkali, organic solvent resistance, and rubbing resistance. The contrast test indicated that the moisture absorption and permeability of PA-CMAs were better than those of nonwoven polyamide/polyurethane (PA/PU), which is a synthetic leather-based material considered as one of the mainstream products. In addition, PA-CMAs maintained the original softness and elastoplasticity of PA.
Superfine fiber synthetic leather is a high‐grade artificial leather product with numerous characteristics and advantages. However, compared with natural leather, it shows poor moisture absorption and moisture permeability, and it gives people a hot and tacky feeling; thus, the improvement of these properties has become a popular topic in the industry. In this paper, the “click” chemistry method was employed to modify the nylon fiber of the superfine fiber synthetic leather base with waste collagen to improve the moisture absorption and permeability of the superfine fiber synthetic leather base, thus enhancing the hygienic performance and wearing comfort of the end products, realizing waste recycling. This study obtained the optimal reaction conditions for the “click” modification of unfigured sea‐island superfine fiber synthetic leather base with collagen methacrylamide. The characterizations by static contact angle measurements, attenuated total reflection infrared spectroscopy, and X‐ray photoelectron spectroscopy analysis confirmed that collagen was successfully grafted onto the surface of the nylon fiber. Compared with the original base, the moisture absorption, and permeability of the base were improved by 602.4% and 43%, respectively. This study shows the theoretical research significance and excellent practical value for the resource utilization of skin collagen waste.
This study is to introduce waste collagen into an unfigured islands-in-sea microfiber nonwoven material, replacing the polyurethane impregnation section of the traditional manufacturing process with the collagen impregnation process. The modified collagen was first impregnated in polyamide/lowdensity polyethylene (PA/LDPE) fiber nonwoven to form a film. Then the low-density polyethylene component was extracted and dissolved in toluene, resulting in a collagen-based microfiber nonwoven substrate. Waste collagen was first modified to introduce CC into the molecular chain to obtain vinyl collagen (CMA), and then the following film formation conditions for CMA were studied: 73% degree of substitution (DS), 3 h cross-linking time, and 0.005−0.01 wt % initiator concentration. Then, the preparation of CMA-PA/LDPE and toluene extraction processes were investigated. The optimum toluene extraction conditions were obtained as an extraction temperature of 85 °C and an extraction time of 110 min. The properties of the nonwoven materials were compared before (CMA-PA/LDPE) and after (PA-CMA) extraction. It was found that the homogeneity, tensile strength, and static moisture permeability of the PA-CMA materials prepared by CMA with 50 and 73% DS were all superior to those of PA/ LDPE. In particular, the static moisture permeability of PA-CMA (691.6 mg/10 cm 2 •24 h) increased by 36.2% compared to the microfiber synthetic leather substrate currently in the market. Using scanning electron microscopy (SEM), the continuity of a film of PA-CMA with 73% DS was observed to be better and the fibers were differentiated and relatively tighter fiber-to-fiber gap. The studied novel green process can eliminate the large amount of dimethylformamide (DMF) pollution caused by the current solventbased polyurethane impregnation process.
Unfigured sea-island superfine fiber PA/PU non-woven (USFSLB) is used to mimic leather’s microstructure as the base of artificial leather. USFSLB has many characteristics and advantages resembling those of natural leather. However, compared with natural leather, the wearing comfort of artificial leather is inferior due to its poor moisture adsorption and permeability. In this work, a “two-step” method of chemical treatment is proposed, in which collagen/chromium-vegetable tannin (C-CrT) is immobilized on nylon fiber of USFSLB to improve its moisture adsorption and permeability (“breath” property). The two-step surface modification involved sulfuric acid hydrolysis and modifying the C-CrT on nylon fiber. Compared with the pristine USFSLB, the tensile strength, the elongation at break, the anti-static performance, the thickness, and the uniformity of C-CrT-treated USFSLB were improved at different levels. Importantly, the C-CrT-treated USFSLB showed excellent moisture adsorption and permeability, especially the liquid wicking rate (LWR) improved by 344%. The self-assembly mechanism of collagen/chromium-vegetable tannin (C-CrT) modified on nylon fibers was analyzed and discussed.
In this paper, unsaturated collagen microspheres (CMA-Cr/ST) were constructed from vinyl collagen (CMA, which is from leather solid waste) and chromium/synthetic tannins (Cr/ST) through hydrogen and coordination bonds and grafted on polyamide nonwoven fiber by thiol-ene click chemistry to improve the moisture absorption and permeability of nonwoven. The results showed that when the quality ratio of CMA to Cr/ST was 1:1, the magnetic stirring time was 20 min with 250 rpm at room temperature, the surface and particle size distribution of the obtained microspheres were smooth and relatively uniform, and the average particle size was 2–3 μm. When the concentrations of the microspheres and the initiators were 6 and 0.006 wt %, the irradiation time was 4 h and the grafting rate of CMA-Cr/ST on the surface of polyamide fibers would reach 31.3%. The moisture absorption and permeability of the obtained microsphere-modified polyamide nonwoven fiber (CMA-Cr/ST-S-PA) were increased. It was found that the collagen microspheres were firmly modified on the polyamide fibers by moisture and heat resistance, wash resistance, and solvent resistance studies.
Pure lithium iron phosphate and Mo -doped lithium iron phosphate were synthesized via improved coprecipitation, followed by spray dry processing and sintering at a high temperature for crystallization. The synthesis was based on a key step to promote the dissolution of Fe powder by the addition of Cu or CuO powder in phosphoric acid solution. The improved coprecipitation process could achieve homogeneous mixing of the reactants at the molecular level. The crystalline particle size of the LiFePO4 was between 20 and 70 nm. All the samples were pure single-phase indexed with orthorhombic Pnmb space group. The electrochemical performance of LiFe0.96Mo0.04PO4 , including its reversible capacity, cycle number and charge–discharge characteristics, were all better than those of pure LiFePO4 .
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