APPLIED ORGANOMETALLIC CHEMISTRY
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2020
·Vol. 34
·期 5
·e5619
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IF 3.14
Yijun Du,Sailong Wei,Minchao Tang,Miaoting Ye,Hongyu Tao,Chenze Qi,Linjun Shao
Palladium chloride doped chitosan composite nanofibers were prepared by electrospinning with sodium polyacrylate (PAAS) as the co-spinning agent. The composite nanofibers are subsequently treated at elevated temperature to improve their solvent resistance. The Pd (II) cations inside the composite nanofibers were reduced into uniform palladium nanoparticles (Pd NPs) with mean diameter of ~4.93 nm. These Pd NPs inside the chitosan composite nanofibers exhibited excellent catalytic activity for Heck reactions of aromatic iodides with alkenes with yields over 85%. Moreover, due to the fibrous structure, this novel fibrous palladium catalyst could be readily recovered by simple filtration and reused for 18 times without loss of initial catalytic activity. It was found that the reactants could readily diffuse from the reaction solution to the active Pd NPs inside the nanofibers and the products could departure from composite fibers into the reaction solution, while the Pd NPs were tightly restricted inside the chitosan composite nanofibers.
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COLLOIDS AND SURFACES A-PHYSICOCHEMICAL AND ENGINEERING ASPECTS
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2020
·
IF 3.99
Yanqing Wang,Qianqian Han,Ying Wang,Dan Qin,Qiang Luo,Hongmei Zhang
In this study, aromatic amino acid-conjugated chitosan are designed and developed, as viewed by multi-spectral methods. The results from 1H NMR , FTIR, and UV–vis indicated the successful grafting of tryptophan (Trp) or phenylalanine (Phe) onto chitosan (CS) to form Trp-CS and Phe-CS nano-conjugates with 4.7 % and 6.8 % grafting ratio. The grafting induced some influences on the chiral structure and the symmetry and backbone structure of CS. The thermal stability of Trp-CS and Phe-CS nano-conjugates is less than that of CS. Trp-CS and Phe-CS conjugates were formed as spherical nanoparticles . The rheological studies show that Trp-CS and Phe-CS exhibit characteristic of an elastic material. In addition, Trp-CS and Phe-CS present well antioxidant activities and good biocompatibility.
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PROGRESS IN ORGANIC COATINGS
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2020
·
IF 4.469
Zhidong Ma,Min Sun,Anhang Li,Guiyu Zhu,Yue Zhang
A novel environment-friendly composite coating (P/P'-Ch-P/P') was prepared by layer-by-layer assembly of polyvinyl butyral (PVB), polymethylhydrosiloxane (PMHS) and chitosan (Ch) on AA 2024 substrate to improve the corrosion resistance of AA 2024 sample. The properties of the coatings were characterized by Fourier transform infrared spectroscopy (FT-IR), scanning electron microscope (SEM) and laser confocal microscope. The results showed that the addition of PMHS increased the hydrophobicity of composite coating；as the intermediate layer, Ch also crosslinked other components while forming the film. At the same time, the corrosion resistance of the coating in 3.5 wt.% NaCl solution was characterized by electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization. Compared with the bare aluminum substrates, the impedance modulus of the composite coating was increased by 3 orders of magnitude; the corrosion current density (Icorr) of the composite coating was reduced by 5 orders of magnitude. The results of long-term immersion test showed that the composite coating still had good anticorrosion ability after 60 days. This study provides a simple and environment-friendly method for corrosion protection of aluminum alloy in marine environment.
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APPLIED SURFACE SCIENCE
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2020
·
IF 6.182
Jiayi Zhao,Feng Wei,Weili Xu,Xiaojun Han
The high demand for food safety and quality has stimulated the investigation of antibacterial packaging films based on natural biomaterials. Capsaicin, an effective extract of red chili, is thought to be a favorable antibacterial candidate in food packaging. Herein, Fe III doped hollow metal-organic frameworks (Fe III -HMOF-5) were prepared as promising nanocarriers for capsaicin and incorporated into gelatin/chitosan matrix to fabricate antibacterial packaging films. Fe III -HMOF-5 regulated the hydrophobicity of capsaicin and effectively solved the phase separation problem. The addition of capsaicin loaded Fe III -HMOF-5 into gelatin/chitosan film significantly improved the tensile strength, water vapor permeability and UV barrier properties. Moreover, Cap-Fe III -HMOF-5 endowed efficient antimicrobial activity against E. coli to gelatin/chitosan films by practical application on fresh apple cubes . The strategy proposed here provides an effective way to develop promising antibacterial biomaterials for food packaging.
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CARBOHYDRATE POLYMERS
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2020
·
IF 7.182
Yucheng Zou,Cen Zhang,Peng Wang,Yipeng Zhang,Hui Zhang
The aim of this study was to develop chitosan (CS)/polycaprolactone (PCL) electrospun nanofibers with chlorogenic acid (CGA) loaded halloysite nanotubes (HNTs) as a carrier for CGA to provide a long-term sustained release. Results showed that the addition of [email protected] at the concentrations of 2–6 wt% resulted in continuous nanofibers with an average diameter range of 159–166 nm, with improved thermal stability caused by the formation of hydrogen bonds. The incorporation of [email protected] induced a hydrophilic surface and enhanced water vapor barrier property, but impaired the mechanical properties. However, the 2%, 4%, and 6% [email protected] incorporated fibrous mats exhibited an initial release of 18.3 %, 26.2 %, 33.1 % within 15 h, and 34.7 %, 41.4 %, 51.3 % release after 240 h, respectively, indicating a long-term sustained release with enhanced antioxidant and antimicrobial activities. These results suggested the promising applications of the prepared [email protected] /PCL/CS electrospun fibrous mats for active food packaging.
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PubMed
高影响因子
CHEMICAL ENGINEERING JOURNAL
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2020
·
IF 10.652
Jiayun Chen,Huali Xie,Xuejun Lai,Hongqiang Li,Jiefeng Gao,Xingrong Zeng
High fire-safe aerogel with multi-functionality is urgently desirable due to the frequent fire disasters. However, it is still a challenge to afford both excellent flame retardancy and sensitive fire-warning in combustible aerogels. Herein, we fabricated an ultrasensitive fire-warning and high fire-resistance chitosan/montmorillonite/carbon nanotube composite aerogel (CCA) via freeze-drying. Benefiting from the rapid decrease of the electrical resistance for amino-functionalized carbon nanotube when being burned, CCA achieved a hitherto shortest fire-warning response time (~0.25 s). Importantly, the aerogel exhibited excellent flame retardancy and self-extinguished in the vertical burning test. Besides, owing to the hierarchical porous structure of the aerogel and the excellent barrier effect of the montmorillonite nanosheet, CCA could resist a high-temperature flame up to 1200 °C and effectively prevent the temperature of the nonexposed side from increasing, exhibiting excellent thermal insulation. Furthermore, the mechanical resilience, anti-fatigue performance, electrical conductivity, and unique three-dimensional network endowed the aerogel with good piezoresistivity. This work provides a facile, environmentally-friendly, and cost-effective approach to fabricating multifunctional fire-safe aerogel, showing promising applications in exterior wall insulation, vehicle interior, firefighting, and wearable electronics.
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高影响因子
E-POLYMERS
·
2020
·Vol. 20
·期 1
·303-316
·
IF 1.675
Haihua Yu,Xiuhang Xu,Yunfei Xia,Mingzhen Pan,Nighat Zarshad,Bo Pang,Anis Ur Rahman,Min Wu,Henmei Ni
According to the concept of fire life cycle assessment (LCA), a new type of intumescent flame retardant was designed and synthesized by chemically bonding chitosan, phosphorus pentoxide and melamine. The resultant compound, chitosan ethoxyl melamine phosphate (CEMP), was characterized by FTIR, 1 H NMR, 31 P NMR, XRD and SEM. The performance of CEMP and organic montmorillonite (OMMT) was evaluated in the substrate of epoxy resin (EP) with limited oxygen index (LOI), UL-94, cone calorimetric test (CCT), TGA and TG-IR. As a result, intumescent flame retardant EP (EP3) containing 30.6% LOI and V-0 rating was prepared by adding 3 wt% OMMT and 15 wt% CEMP. The CCT results indicated that CEMP and OMMT reduced the peak of heat release rate (PHRR) to about one fourth that of pure EP and total heat release (THR), 1/2. Decomposition of EP and EP3 was traced from 100 to 600°C by TG-IR.
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Processes
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2020
·Vol. 8
·期 7
·834
·
IF 2.753
Hongxia Su,Chongxing Huang,Ying Liu,Song Kong,Jian Wang,Haohe Huang,Bobo Zhang
In this study, different amounts of cinnamomum essential oil (CEO) were encapsulated in chitosan nanoparticles (NPs) (CS-NPs) through oil-in-water emulsification and ionic gelation. An ultraviolet-visible spectrophotometer, Fourier-transform infrared spectroscopy, synchronous thermal analysis, and X-ray diffraction were employed to analyze the CEO encapsulation. As observed by field-emission scanning electron microscopy, NP size analysis and zeta potential, the prepared CS-NPs, containing CEO (CS-CEO), were spherical with uniformly distributed sizes (diameters: 190–340 nm). The ranges of encapsulation efficiency (EE) and loading capacity (LC) were 4.6–32.9% and 0.9–10.4%, with variations in the starting weight ratio of CEO to CS from 0.11 to 0.53 (w/w). It was also found that the antioxidant activity of the CS-NPs loaded with CEO increased as the EE increased. The active ingredients of the CEO were prevented from being volatilized, significantly improving the chemical stability. The antioxidant activity of CS-CEO was higher than that of the free CEO. These results indicate the promising potential of CS-CEO as an antioxidant for food processing, and packaging applications.Keywords:cinnamomum essential oil;chitosan;encapsulation;antioxidant activity
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CARBOHYDRATE POLYMERS
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2020
·
IF 7.182
Cunli Pan,Junqing Qian,Changyan Zhao,Haiyang Yang,Xiaohua Zhao,Hui Guo
In order to reveal the relationship between the degree of crosslinking and the properties of chitosan nanoparticles, a potassium polyvinyl sulfate (PVSK) titration method was established for the determination of free amino group in chitosan, which showed that there was a window effect in the crosslinking degree and particle size of three kinds of molecular weight chitosan cross-linked by different content of tripolyphosphate (TPP), and the nanoparticles with moderate crosslinking degree were smaller. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) showed the moderate degree of cross-linking nanoparticles had strong antibacterial properties. IR analysis showed that the interaction between chitosan nanoparticles with different crosslinking degree and TPP were different. X-ray diffraction analysis showed that the cross-linked chitosan nanoparticles were amorphous. Above all, the crosslinking degree of TPP cross-linked chitosan nanoparticles was related to the particle size and antibacterial properties.
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PubMed
高影响因子
ADSORPTION SCIENCE & TECHNOLOGY
·
2020
·
IF 2.425
Qiaoling Xie,Gaojie Liang,Tao Lin,Fuming Chen,Dandan Wang,Bo Yang
A study on selective chelating precipitation of palladium metal from real electroplating wastewater using chitosan and its water-soluble derivative was conducted. The pH parameter, the concentrations of chitosan and its water-soluble derivative and the chelating precipitation time were experimentally investigated, and the optimum conditions were determined. The results revealed that both chitosan and its water-soluble derivative acted as chelating precipitation agents. Rapid chelating precipitation occurred when chitosan was added to real electroplating wastewater containing the chitosan derivative, thereby improving removal efficiency of palladium in different forms up to 95% under the optimum condition of 0.2 g/L chitosan and 0.16 mg/L derivative at pH 2.5. Then, dissolution experiments showed that chelating precipitation products could be dissolved in aqua regia. Additionally, selective chelating precipitation of palladium by chitosan and its derivative was characterized using X-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy. Thus, it can be concluded that the combined utilization of chitosan and its water-soluble derivative is a promising approach method for the removal of different forms of palladium from real electroplating wastewater.
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CARBOHYDRATE POLYMERS
·
2019
·
IF 6.044
Pengfei Zou,Wen-Hui Lee,Zhiqin Gao,Di Qin,Yuxia Wang,Jiao Liu,Tongyi Sun,Yuanyuan Gao
Novel nanomaterials have been developed for antimicrobial and wound healing applications. Here, we report the preparation of a polyvinyl alcohol/chitosan (PVA/CS) nanofiber with carboxymethyl chitosan nanoparticles (CMCS-OH30 NPs) encapsulating the antibacterial peptide OH-CATH30 (OH-30). The PVA/CS nanofibers containing OH-30 NPs (NP-30-NFs) obtained via electrospinning could achieve a secondary embedded OH-30. The effect of NP-30-NFs on the release of OH-30 was investigated through high-performance liquid chromatography. The antibacterial activities of NP-30-NFs against Escherichia coli and Staphylococcus aureus were studied by bacterial plate counting. NP-30-NFs containing different concentrations of NPs were applied to mouse skin wounds to determine their effectiveness in promoting wound healing. Results showed that NP-30-NFs exhibited antibacterial properties and promoted skin wound healing.
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高影响因子
NANO
·
2019
·
IF 1.293
Mengmeng Zhang,Yamin Cheng,Zhiwei Li,Xiaohong Li,Laigui Yu,Zhijun Zhang
An inorganic–organic nanohybrid flame retardant, HNT@CS@Fe 3 O 4 , is prepared by Halloysite nanotubes (HNT) as nanotemplate, chitosan (CS) as char-forming agent and ferroferric oxide (Fe 3 O 4 ) playing in a catalytic role, aiming to endow enhanced flame-retardant performance of its nanohybrid. Results show that HNT@CS@Fe 3 O 4 nanohybrids have a corn-like structure and can significantly improve the flame retardancy and thermal stability of epoxy resin (EP). Especially, the initial thermal degradation temperature of EP/HNT@CS@Fe 3 O 4 is significantly improved by 2 4 ∘ C relative to pure EP, and the residual carbon yield under air atmosphere is 8.8 wt.%, which is significantly higher than other EP composites, indicating a higher thermal stability is offered by the as-prepared nanohybrid. The limiting oxygen index of EP/10HNT@CS@Fe 3 O 4 is 31.3%, which is 10.2% higher than that of pure EP. Meanwhile, the HNT@CS@Fe 3 O 4 nanofiller reduces the peak heat release rate, CO production and peak smoke production release of EP nanocomposite by 32.0%, 44.0% and 33.0% in a cone calorimeter test, respectively. This is because the HNT-based composite can form a three-dimensional network structure into the EP matrix to inhibit heat release and diffusion of flammable moieties upon burning of EP. In the meantime, the incorporated Fe 3 O 4 nanoparticle can in situ catalyze the charring of CS and EP matrix on the surface of HNT during the combustion process, which also contributes to the significantly increased fire safety of EP.
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