APPLIED SURFACE SCIENCE
·
2022
·
IF 7.392
Yuan Li,Chen Lei,Jian Yang,Xiang Liu,Kui Zhang
Nitrogen-doped carbon nano dots (N-doped CDs) caught extensive interests since they usually own higher fluorescent quantum yield (QY) with red-shift emission compared with CDs. However, how was nitrogen element doped into CDs? Which groups in N-doped CDs were responsible for the fluorescent emission? Why did the doping cause red shift? These questions were the keys for understanding the origin of photoluminescence of N-doped CDs, which was obscure until today according to recent publications. Herein, CDs derived from poly(ethylene glycol) were prepared in the first step (emission wavelength = 452 nm; QY = 2.3%). Nitrogen doping was realized conveniently by just reflux heating on CDs and m -phenylenediamine at 70 °C for 3 h. Interestingly, such a facile treatment on CDs aroused significant improvement of the fluorescence (emission wavelength = 516 nm; QY = 36.7%). These N-doped CDs performed very well in cellular imaging of MCF-7. Experimental facts demonstrated the C=C bond and the aldehyde in both CDs and N-doped CDs were the fluorophore that was identical with the CDs prepared with carbohydrates reported in our previous work. Additionally, computations revealed that the partly conjugation of the amide and aromatic ring with fluorescent skeleton of CDs caused the red shift of the emission.
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RSC Advances
·
2022
·Vol. 12
·期 36
·23183-23192
·
IF 4.036
Xiaoyan Cao,Lingxin Kong,Zhenggui Gu,Xiao Xu
The application of recyclable heterogeneous catalysts in the production of polypropylene glycol monomethyl ether (MPPG) is of great significance to the green chemical industry. In this study, the CeO2/MgAl-LDH(P123) composite was prepared using a nucleation/crystallization isolation method and aqueous reconstruction method, and CeO2/MgAl-LDO(P123) solid base catalyst was prepared by calcination with it as precursor. Thereafter, the morphology, crystal structure, functional group, and thermal stability of the catalyst were characterized using scanning electron microscopy, X-ray diffraction, Fourier-transform infrared spectroscopy, Brunauer–Emmett–Teller analysis, temperature-programmed desorption of carbon dioxide, thermogravimetry, and X-ray photoelectron spectroscopy. The results showed that the catalyst had a larger specific surface area, pore size and pore volume and more basic sites, providing sufficient catalytic activity for the polymerization process. The experimental results for the fabrication of MPPG using CeO2/MgAl-LDO(P123) as catalyst and methanol and propylene oxide as reaction raw materials showed that the conversion of propylene oxide reached 92.04% and the molecular weight of MPPG was 405 under the optimal reaction conditions. Moreover, the conversion of propylene oxide was maintained above 83.69% after the catalyst was reused six times. This study offers a new prospect for the green synthesis of MPPG products.
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APPLIED SURFACE SCIENCE
·
2022
·
IF 7.392
Shuqian Xie,Hui Huang,Lu Deng,Junhong Li,Ruirui Yue,Jingkun Xu
Exploration of suitable support materials for noble metal nanocatalysts to reduce the mass loading and optimize the electrocatalytic performance for ethylene glycol oxidation reaction (EGOR) remains a key challenge. Herein the crinkly polypyrrole (PPy)-modified reduced graphene oxide (rGO) was prepared through a facile and efficient in-situ polymerization approach and utilized as the support for Pd nanoparticles . PPy as “spacers” coating on the surface of rGO nanosheets, inhibiting the aggregation and restacking, which greatly increased the available surface area of rGO. Furthermore, this interface-rich structure can offer an efficient pathway for electron conduction, which helps to improve the electrochemical properties of the catalyst. More impressively, the optimized Pd-PPy-rGO 1 nanocomposite outperforms the Pd-PPy and commercial Pd-C with the higher mass activity/specific activity (5550.2 mA mg Pd -1 /30.0 mA cm −2 ), the improved intrinsic activity (TOF value of 6.5 s −1 ) and the enhanced stability toward electrocatalytic EGOR. The superior electrocatalytic performance benefits from the increased specific surface area of the crinkly and interface-rich PPy-rGO and the high utilization efficiency of Pd active sites during the EGOR. This work is expected to give a rational avenue to design interface-rich conducting polymer-rGO nanocomposite support for fuel cells anode catalysts.
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Food Packaging and Shelf Life
·
2022
·
IF 8.749
Bing Yang,Shengnan Yin,Xiaofang Bian,Changlin Liu,Xinhong Liu,Yongli Yan,Chunxia Zhang,Hui Zhang,Zhaosheng Hou
The main target of the current exploration is to represent a novel type of edible biomaterial composed of monomethoxyl polyethylene glycol-modified O-carboxymethyl chitosan (MPEG-O-CMC) for fresh-keeping food packaging materials. MPEG-O-CMCs were prepared by a facile method that consists of three steps: the C 6 -hydroxyl group of chitin (CH) was first substituted by chloroacetic acid ; O-carboxymethyl chitosan (O-CMC) was subsequently obtained via a deacetylation reaction; and finally, the NH 2 groups of O-CMC were reacted with isocyanate-terminated methoxypolyethylene glycol (MPEG-NCO) to yield MPEG-O-CMC. The chemical structures of O-CMC, MPEG-NCO, and MPEG-O-CMC were scrutinized through nuclear magnetic resonance spectroscopy (NMR) and Fourier transform–infrared spectroscopy (FT-IR), and the influences of the MPEG content on the physicochemical features of the solution-cast MPEG-O-CMC films was extensively researched. The results showed that the introduction of polyethylene glycol (PEG) could ameliorate the hydrophilicity, thermal stability, flexibility, and tensile features of the film. When the grafting degree of MPEG was approximately 25% (the MPEG content in MPEG-O-CMC was 18.5 wt %), the film possessed a lower T g of −30 °C and higher tensile features (strain at break: 221%; ultimate stress: 4.4 MPa). The water vapor transmission rates (WVTR) of the MPEG-O-CMC films was evaluated by osmosis tests at different humidity, and the results showed that films possessed good WVTR of 25–200 g·mm/(m 2 ∙24 h) at 50% humidity. The WVTR decreased gradually with the increase of MPEG content in the material, which was mainly attributed to the flexible MPEG segments acting as a plasticizer and reducing the dimension of the transient interspaces. Furthermore, the preliminary evaluation of bacteriostatic activity indicated that the films possess a certain bacteriostatic activity against Escherichia coli . Due to its good tensile properties , acceptable WVTR and potential bacteriostatic activity, this nontoxic and even edible biomaterials hold significant promise for application in fresh-keeping food packing materials.
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RENEWABLE ENERGY
·
2022
·
IF 8.634
Yanting Lv,Zhengyu Chen,Huan Wang,Yongcang Xiao,Rongxin Ling,Murong Gong,Weiqi Wei
In this work, an HCl-catalyzed ethylene glycol (EG) pretreatment was exploited for promoting sugar release from sugarcane bagasse (SCB). The results showed that the combination of HCl and EG could remove the xylan (∼100.0%) and lignin (∼61.3%) in SCB together, which finally resulted in the pretreated substrate having a good efficacy for follow-up enzymatic hydrolysis . The maximum glucose yield of this work was 93.9% and obtained after pretreatment at 130 °C for 60 min with 0.5% HCl and 72 h enzymatic digestion. The analysis of various pretreated or un-pretreated SCB indicated that the changes of surface morphology and internal compositions of SCB were the mainly reasons for its hydrolysis efficiency enhancement. The addition of Tween 80 into hydrolysis process could remarkably shorten hydrolysis time and cellulase dosage from 72 h to 36 h and 20 FPU/g substrate to 10 FPU/g substrate, respectively, meanwhile maintaining a relatively high glucose yield (91.4%).
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POLYMER
·
2022
·
IF 4.432
Qisong Lin,Feng Gao,Yongjun Wang,Wangyang Lu,Wenxing Chen
Antimony-free poly(ethylene terephthalate) (PET) has been synthesized through polycondensation of p -phthalic acid and ethylene glycol , and then subjected to a viscosity-increasing process by liquid-state polycondensation (LSP). For both of these processes, a novel environmentally benign ethylene glycol-soluble Ti/Mg bimetal (TM) catalyst has been used. The structure of the TM catalyst has been comprehensively characterized and its catalytic activity in the polycondensation reaction has been evaluated and compared with those of other titanium-based catalysts. The results reveal that the TM catalyst is a chelated complex with high catalytic activity for polycondensation to afford PET without significant side reactions. Indeed, the LSP process catalyzed by TM affords a PET product with high intrinsic viscosity suitable for industrial yarn production (1.08 dL/g) within 60 min, and that exhibits higher thermostability with increasing intrinsic viscosity. Finally, the kinetics of the TM-catalyzed polycondensation has been probed based on the variation of intrinsic viscosity with increasing polycondensation time.
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COMPOSITES SCIENCE AND TECHNOLOGY
·
2022
·
IF 9.879
Danian Liu,Jingwen Wang,Wenhai Peng,Houqing Wang,Hua Ren
In order to meet the ever-increasing demand for lightweight and flexibility with the development of aeronautics, astronautics and wearable technology , dielectric ceramics are inappropriate for the polymer-based dielectric materials due to their high density. An organic semiconductor material polyethylene glycol-polyaniline multi-alternating block (more than triblock) copolymer (with a low density ∼ 0.9 g/cm 3 ) was designed. This polymer had a good solubility in polar solvents (e.g. DMF and DMSO) which could provide it with a good processing performance and a good dispersion in PVDF matrix. Its alternating block structure had a special role in the charge transport of PANI segments, providing composites with high dielectric constant and overcoming the poor breakdown strength problem of conductive filler-based dielectric composites, even better than BaTiO 3 . The breakdown strength of PEG-PANI/PVDF composite was 10.74 kV/mm and the dielectric constant was 86.64 (100 Hz) at 20 vol%, better than BaTiO 3 /PVDF (9.89 kV/mm and 45.23).
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ACS Sustainable Chemistry & Engineering
·
2022
·
IF 9.224
Hui Yang,Chaonan Tao,Lincai Peng,Junhua Zhang,Liang He,Huai Liu
It remains a challenging task for the efficient conversion of carbohydrates to value-added chemicals at concentrated feedstock solution. In this contribution, the acid-catalyzed processing of high-concentration C5/C6 sugars (180 g/L) in the ethylene glycol (EG) solvent system was investigated, and prominent discrepancy was noticed between C5 and C6 sugars. A large amount of liquefied products was achieved in the concentrated C6 sugars EG solution, whereas the main products in the case of C5 sugars were found to be solid humins. The reaction mechanism studies revealed that EG can shelter fructose and reaction intermediates (5-hydroxymethylfurfural and levulinic acid) from the cross-polymerization and self-etherification reactions, thereby reducing the generation of solid humins during the fructose liquidation process. However, in the case of xylose, the copolymerization between EG and furfural (FF) generates a solid resin, thus rendering a high solid product yield. Moreover, the produced FF–EG resin was found to be a polymer with high molecular weight formed by connecting the furan ring and the alkyl structure through an ether bond. This finding provides insights into the acid-catalyzed conversion of concentrated C5/C6 sugars in EG, facilitating rationally designed processes for the valorization of concentrated carbohydrates.
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JOURNAL OF ALLOYS AND COMPOUNDS
·
2022
·
IF 6.371
Kang Chen,Mili Liu,Liuzhang Ouyang,Hui Wang,Jiangwen Liu,Min Zhu
Hydrolysis of LiBH 4 (LB in short) is considered as a potential means of releasing the hydrogen stored in the hydride and the water. However, the hydrolysis of LB occurs only above 0 °C and efficient catalysts are required to accelerate the hydrogen kinetics. Here, we demonstrate an efficient non-catalytical hydrogen generation system that enables H 2 production of LB over a wide range of temperatures with methanol (referred to MeOH), ethylene glycol, and MeOH/water mixtures as reaction solvents. The results indicate that the hydrogen kinetics of LB is controllable by MeOH dose, MeOH species, reaction temperature, and solution components. For instance, the hydrogen evolution rate could be accelerated from 266 to 515 mL H2 min −1 g −1 (per unit weight of LB) with a H 2 yield up to 93% by tailoring the dose of methanol at 25 °C. Notably, the glycolysis kinetics is much faster than that for the methanolysis of LB, delivering a hydrogen rate varying from 523 to 10,125 mL H2 min −1 g −1 . By optimizing reaction conditions, a gravimetric hydrogen density of ~4.6 wt% H 2 was realized in the LB-MeOH system. Interestingly, the methanolysis/glycolysis products of LB can spontaneously convert into MeOH and hydrated byproduct (LiBO 2 ‧2H 2 O) by reacting with water, and MeOH may be separated and reused as an intermediate. Here, LiBO 2 ‧2H 2 O can be easily regenerated back to LB by ball milling with Mg under ambient conditions. Thus, a hydrogen cycle combining hydrogen generation and storage in a closed material cycle is achieved, which may lay the foundation for developing practical hydrogen sources for mobile/portable applications.
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Polymers
·
2023
·Vol. 15
·期 10
·2363
·
IF 5
Di Wang,Ren Zhang,Jin Liu,Bibi Ji,Wenping Wang,Mengyuan Peng,Chen Huang,Lizhuoran Cheng,Yi Ding
A novel one-dimensional malleable spin-crossover (SCO) complex {[Fe(MPEG-trz)3](BF4)2} has been successfully synthesized by molecular self-assembly between 4-amino-1,2,4-triazoles (MPEG-trz) grafted with a long flexible chain methoxy polyethylene glycol (MPEG) and metallic complex Fe(BF4)2•6H2O. The detailed structure information was illustrated by using FT-IR and1H NMR measurements, while the physical behaviors of the malleable SCO complexes were systematically investigated by using magnetic susceptibility measurements using superconductivity quantum interference device (SQUID) and differential scanning calorimetry (DSC). This new metallopolymer exhibits a remarkable spin crossover transition behavior, between two spin quantum states (Fe2+ions): high spin (HS) state (quintet state) and low spin (LS) state (singlet state), at a specific critical temperature with a slender hysteresis loop of 1 K. DFT computations revealed the partial rules of HOMO-LUMO energy levels and spin density distributions of different four-position substituted [Fe(1,2,4-triazole)3]2+derivatives with different length of repeat units in polymer complexes. This can go a step further to depict the spin and magnetic transition behaviors of SCO polymer complexes. Furthermore, the coordination polymers possess an excellent processability due to an outstanding malleability, which can be easily shaped into a polymer film with spin magnetic switching properties.Keywords:spin crossover (SCO) complex;malleable;magnetic transition polymer;modification;MPEG films
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REACTIVE & FUNCTIONAL POLYMERS
·
2023
·
IF 5.1
Haoran Tian,Zhifei Zhu,Feng Ma,Junying Li,Jian Li,Yingzhou Li,Pengfei Yang
The treatment of dye pollutants in wastewater was a serious environmental issue. In this paper, freezing radical polymerization was used to prepare poly (polyethylene gly co l diacrylate - co - maleic anhydride) (p(PEGDA- co -MA)) cryogels with redox initiators of ammonium persulfate / tetramethylethylene diamine in aqueous solution. The mechanical property and chemical structure of cryogels were characterized compression tests, IR, and XPS. After that, adsorption performance of p(PEGDA- co -MA) cryogels for cationic dyes was measured and the maximum adsorption capacity for methylene blue and crystal violet was 447.7 mg·g −1 and 329.5 mg·g −1 (pH = 7.0), respectively. Adsorption isotherm , adsorption kinetics and adsorption thermodynamics were investigated to reveal adsorption mechanism of cryogel materials, which showed that monolayer chemical adsorption was dominant and the adsorption capacity decreased with the increase of temperature. This p(PEGDA- co -MA) cryogels would not only partly developed the polymerization method of vinyl monomers but also strongly expanded the field of dye adsorption materials.
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MACROMOLECULAR RAPID COMMUNICATIONS
·
2022
·Vol. 44
·期 1
·2200227
·
IF 5.006
Zhao Zheng,Mu Li,Yuyan Lai,Youjin Cao,Panchao Yin
Superionic anhydrous proton conductors can be obtained from the complexation of nanoscale polyoxometalates (POMs) and poly(ethylene glycol) (PEG) in the “polymer in salt” regime. The reduced energy barrier of H + hopping is facilitated from the increased H + concentration and shortened inter-POM distances. POMs with identical structure/size (≈1 nm) but different charge densities are complexed with PEG, respectively, with concentrations ranging from 10 to 60 % wt. Increasing trends of viscosities can be observed with the rising charge densities of POMs due to the increasing confinement strength on PEG substrate from POMs. Fractional Walden rule is further applied to analyze the viscosity and proton conductivity correlations, and microscopic mechanisms of proton conduction for PEG-POM nanocomposites are revealed: 1) ion transport is highly associated with polymer chain dynamic for POMs concentrations ranging from 10 to 30 % wt.; 2) ionic conduction is largely decoupled from chain dynamic of polymer matrix for concentrations ranging from 40 to 60 % wt. with Walden plots shifted to the superionic regime. The decoupling of proton transport from polymer segment dynamics allows the simultaneous enhancements of the nanocomposites’ mechanical properties and proton conductions, providing guidelines for the rational design of anhydrous proton conductors with integrated functionalities.
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