RSC Advances
·
2014
·Vol. 4
·期 46
·24328-24333
·
IF 3.708
Jinshi Fan,Wan Shao,Guiyun Xu,Xinyan Tracy Cui,Xiliang Luo
Novel conducting polymer nanocomposites of poly(3,4-ethylenedioxythiophene) (PEDOT) doped with nanocrystalline cellulose (NCC) were prepared through both chemical and electrochemical polymerization methods. The prepared nanocomposites were characterized by scanning electron microscopy, Fourier transform infrared spectroscopy, electrochemical impedance spectroscopy and cyclic voltammetry. In both cases, NCC could be effectively incorporated into the polymerized PEDOT to form uniform conducting polymer nanocomposites that exhibit good electrochemical properties. With NCC acting as the only dopant in the electrochemical polymerization process, pure NCC doped PEDOT (PEDOT/NCC) with a unique nanostructure could be synthesized through the simple electrodeposition method. The electrochemically deposited PEDOT/NCC nanocomposite showed very low electrochemical impedance, large charge storage capacity and good electrocatalytic activity. Based on the excellent catalytic activity of the PEDOT/NCC nanocomposite towards the oxidation of dopamine, a sensitive amperometric sensor for the detection of dopamine with a detection limit of 69 nM was developed.
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Nanoscale Research Letters
·
2014
·Vol. 9
·期 1
·1-10
·
IF 2.481
Li Chen,Wang Zhuan-Hua,Yu Deng-Guang,Williams Gareth R
This manuscript reports a new type of drug-loaded core-shell nanofibers that provide tunable biphasic release of quercetin. The nanofibers were fabricated using a modified coaxial electrospinning process, in which a polyvinyl chloride (PVC)-coated concentric spinneret was employed. Poly (vinyl pyrrolidone) (PVP) and ethyl cellulose (EC) were used as the polymer matrices to form the shell and core parts of the nanofibers, respectively. Scanning and transmission electron microscopy demonstrated that the nanofibers had linear morphologies and core-shell structures. The quercetin was found to be present in the nanofibers in the amorphous physical status, on the basis of X-ray diffraction results. In vitro release profiles showed that the PVP shell very rapidly freed its drug cargo into the solution, while the EC core provided the succedent sustained release. Variation of the drug loading permitted the release profiles to be tuned.
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ACS Sustainable Chemistry & Engineering
·
2017
·
IF 5.951
Xiao-ning Ye,Qiang Lu,Xin Wang,Hao-qiang Guo,Min-shu Cui,Chang-qing Dong,Yong-ping Yang
Activated carbon (AC) prepared by chemical activation with H3PO4 (named AC-P) was employed for catalytic fast pyrolysis of cellulose and biomass to selectively produce levoglucosenone (LGO). The catalytic pyrolysis behaviors and product distributions were revealed via both analytical pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS) and lab-scale experiments. Moreover, the performance of AC-P catalyst was compared with previously reported strong acid catalysts and other ACs prepared by different activation methods. In addition, reusability and stability of the AC-P catalyst have been examined via recycling experiments. The results indicated that the AC-P catalyst was effective for selectively preparing LGO from both cellulose and biomass and performed better than other catalysts. Among the three biomass materials (pine wood, poplar wood, and bagasse), pine wood showed the best selectivity for producing LGO. The maximal LGO yields of 18.1 and 9.1 wt % were obtained from cellulose and pine wood, respectively, in Py-GC/MS experiments under a catalyst-to-feedstock ratio of 1:3 at 300 °C, whereas the lab-scale setup obtained the highest LGO yields of 14.7 and 7.8 wt % from cellulose and pine wood with selectivities of 76.3 and 43.0%, respectively, based on organic liquid products. Furthermore, granular AC-P catalyst exhibited good reusability and stability in the recycling experiments. Stable yields of LGO above 12.5 wt % from cellulose were obtained in six consecutive runs without any regeneration of the recycled granular AC-P catalyst.
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CELLULOSE
·
2016
·Vol. 23
·期 2
·1375-1382
·
IF 3.195
Li Qing,Chen Wenshuai,Li Yanna,Guo Xiaoyu,Song Shan,Wang Qingwen,Liu Yixing,Li Jian,Yu Haipeng,Zeng Jie
This article describes the comparative study of the structure, mechanical and thermomechanical properties of cellulose nanopapers with different thicknesses. Cellulose nanopapers were fabricated by vacuum-filtering cellulose nanofiber (CNF) suspensions. The surfaces of the nanopapers consisted of long and entangled CNFs (10–30 nm in width) and their aggregates, while cross-sections exhibited parallel aligned lamellar structures. The nanopaper thickness can be tailored by controlling the amounts of CNF suspensions used for filtration. Owing to the packing density of CNFs, nanopapers with different thicknesses had similar densities of ~1.50 g cm −3 . The thin nanopapers were transparent and flexible. With increasing thickness, the Young’s modulus of the nanopapers slightly decreased, while the ultimate strain and work of fracture increased. The thicker nanopapers displayed higher storage and loss modulus. The nanopapers still kept advantageous mechanical properties even at high temperatures around 260 °C because of the high thermal stability of CNFs and their strong entangled web-like structures.
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CARBOHYDRATE POLYMERS
·
2017
·
IF 4.811
Ximei Li,Keke Zhang,Ran Shi,Xiaomei Ma,Liwen Tan,Quan Ji,Yanzhi Xia
Magnesium oxide (MgO) microcapsules were synthesized via in-situ emulsion polymerization as confirmed by Fourier transform infrared spectroscopy and scanning electron microscopy. Pure MgO and the MgO microcapsules were separately incorporated into cellulose fibers by blend wet spinning. Inductively coupled plasma-emission spectroscopy results revealed that cellulose fibers modified with the MgO microcapsules contained more Mg 2+ than those modified by pure MgO, indicating more acid resistance. The flammability and thermal degradation of modified cellulose fibers (cellulose-Mg fibers) were studied by calorimeter (CONE), thermogravimetry (TGA), and the determination of the limiting oxygen index (LOI). The minimal LOI value obtained for the cellulose-Mg fibers was 35, being much higher than that of the unmodified cellulose fiber (19). The heat release rate of the cellulose-Mg fibers was significantly lower than that of the non-doped ones. The TGA curves showed that the generated residues increased from 13.79% (cellulose fiber) to 30.26% (cellulose-Mg fiber).
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INTERNATIONAL JOURNAL OF BIOLOGICAL MACROMOLECULES
·
2017
·
IF 3.671
Weijuan Huang,Yingfei Zhan,Xiaowen Shi,Jiajia Chen,Hongbing Deng,Yumin Du
Electrospinning is a facile method to fabricate nanofibers, in terms of their high specific surface area and porous structure. Electrospun nanofibrous mats are excellent candidates for immobilization of enzymes . In this study, a simple route based on electrospinning and layer-by-layer (LBL) self-assembly processes has been developed to prepared naringinase/alginate multilayer coated electrospun cellulose acetate nanofibers. The content of immobilized naringinase could be tuned by adjusting the number of multilayers. XPS results indicated that naringinase was successfully immobilized on cellulose acetate nanofibers. SEM images showed the nanofibers maintain their sharp but became rougher after multilayer coating. Besides, the surface area of electrospun cellulose acetate nanofibers decreased and mesopores reduced. The major bitter components of grapefruit juice are naringin and limonin, naringin could be slightly removed by hydrolysis with naringinase and limonin might be removed by adsorption with cellulose acetate nanofibers.
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ENERGY & FUELS
·
2016
·
IF 2.835
Shurong Wang,Haizhou Lin,Li Zhang,Gongxin Dai,Yuan Zhao,Xiaoliu Wang,Bin Ru
Cellulose and hemicellulose were isolated directly from softwood Pinus armandii Franch by the alkali method for pyrolysis mechanism study. Structural characterization based on FTIR, 1H NMR, and 13C NMR showed that the hemicellulose was mainly composed of galactoglucomannan and arabinoxylan with abundant branches, while the cellulose was mainly composed of β-1,4-glucan with a few residual hemicellulose fragments. Pyrolysis of extracted cellulose showed high char yield due to the lower crystallinity. Hemicellulose pyrolysis showed a shoulder peak at low temperature and high char yield because of its abundant branches. A double-Gaussian distributed activation energy model was introduced for pyrolysis kinetics analysis. The devolatilization process for both cellulose and hemicellulose was dominated by a parallel decomposition reaction pathway. The distributions of their pyrolysis products were analyzed by Py-GC/MS. It is suggested that the utilization of isolated sample as model compound could give a better understanding of the biomass pyrolysis mechanism.
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CARBOHYDRATE POLYMERS
·
2016
·
IF 4.219
Dawei Hua,Zhongche Liu,Fang Wang,Buhong Gao,Fei Chen,Qilu Zhang,Ranhua Xiong,Jingquan Han,Sangram Keshari Samal,Stefaan C. De Smedt,Chaobo Huang
In this study we present the use of co-axial electrospinning to produce core-shell composite micro-/nano- fibers of polyurethane (PU) and cellulose acetate phthalate (CAP). The designed fibers possess enhanced mechanical properties with a tensile strength of 13.27 ± 2.32 MPa, which is a clear improvement over the existing CAP fibers that suffer from a poor mechanical strength (0.2 ± 0.03 MPa). The CAP imparts pH responsiveness to the core-shell structure giving the fibers potential for “semen sensitive” (intravaginal) drug delivery.
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高影响因子
CARBOHYDRATE POLYMERS
·
2017
·
IF 4.811
Laifu Song,Yuqi Li,Zhongqiang Xiong,Lulu Pan,Qiyun luo,Xu Xu,Shaorong Lu
A novel water-induced shape memory nanocomposites were prepared by introducing graphene oxide (GO), which was based on microcrystalline cellulose nanofibers (MSF-g-COOH) extracting from sisal fibers. The results showed that the water-induced shape memory properties of MSF-g-COOH were significantly improved by the strong hydrogen bonding interaction between MSF-g-COOH and GO, It leads to some additional physically cross-linked points in MSF-g-COOH. On the other hand, at 0.5 wt% GO loading, tensile strength and Young modulus of the nanocomposite increased from 139 to 184 MPa, and from 5.77 to 8.54 GPa, respectively, compared to those of pure MSF-g-COOH. Furthermore, a water-induced model was proposed to discuss the water-induced shape memory behaviors of the MSF-g-COOH/GO nanocomposites. This study provides a framework for developing a cellulose based shape memory polymers (CSMPs) and better understanding the shape recovery mechanism in water-induced CSMPs.
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ACS Sustainable Chemistry & Engineering
·
2016
·
IF 5.267
Yao Tan,Yongzhuang Liu,Wenshuai Chen,Yixing Liu,Qingwen Wang,Jian Li,Haipeng Yu
Cellulose nanocrystal has been widely used as a reinforcement filler in waterborne coatings, but the application of cellulose nanofiber (CNF) as a filler is difficult because of inhomogeneous dispersion. Herein, a facile and effective strategy to improve the dispersion of CNFs in the polymer matrix by mixing with γ-aminopropyltriethoxysilane (APS) is presented. The APS dosages 0.08–0.48 wt % to 0.3 wt % CNFs were investigated, and the dosage 0.16% was found to achieve a superior stability of CNFs in the aqueous solution. The APS(0.16%)-modified CNFs were then incorporated and demonstrated distributing uniformly in the waterborne acrylic coating. The as-prepared coatings retain high light transmittance around 90%, and display improved mechanical properties. The composite coatings show a maximum 500% improvement in Young’s modulus, two-level improvement in hardness, and 35% reduction in abrasion loss as compared with those of neat coating. These results reveal that APS modification induces the homogeneous dispersion of CNFs in aqueous solution, and turns the CNF into an ideal reinforced filler for waterborne coatings.
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GREEN CHEMISTRY
·
2016
·Vol. 18
·期 17
·4725-4732
·
IF 8.506
Ting Lu,Muge Niu,Yucui Hou,Weize Wu,Shuhang Ren,Fan Yang
The preparation of formic acid (FA) by catalytic oxidation of sustainable biomass is of significant conceptual and practical interest, because FA is an important chemical and is now produced from non-sustainable fossil fuel. In this work, we found that a binary catalyst of Keggin-type heteropoly acid H5PV2Mo10O40 + H2SO4 was efficient in oxidizing biomass cellulose to FA using oxygen as an oxidant in aqueous solution. In the oxidation, the pH of the aqueous solutions plays a key role, and a decrease in pH improves the transformation. Cellulose was transformed to FA with conversions from 60% to 100% and FA yields from 28% to 61% (based on the carbon atoms in the feedstock) after 5 min of reaction at 180 °C, using H2SO4 as an additive to decrease the pH from 1.79 to 0.56. The influences of the pH on both the catalyst and the reaction pathway were discussed. By decreasing the pH, the oxidation potential and electron affinity were increased due to the formation of protonated H5PV2Mo10O40 and VO2+ species, favoring the reduction of the catalyst and oxidation of the substrate. A reaction pathway for the generation of products was proposed, and the influence of the pH on the reaction pathway was also discussed.
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CELLULOSE
·
2017
·Vol. 24
·期 9
·3635-3644
·
IF 3.417
Liu Shaojie,Xing Yubin,Han Jiangze,Tang Erjun
A novel amphiphilic block copolymer of poly(ethylene glycol)-b-poly(2,2,6,6-tetramethylpiperidinyloxy-4-yl-methacrylate) was prepared through activators regenerated by electron transfer atom transfer radical polymerization of 2,2,6,6-tetramethylpiperidine methacrylate monomer, followed by oxidizing it with 3-chloroperoxybenzoic acid. This nitroxide block copolymer was used as a recoverable catalyst instead of free 2,2,6,6-tetramethylpiperidine-1-oxyl for selective catalytic oxidation of cellulose. According to its amphiphilic property, a mixture of acetonitrile and water was used as the reaction medium. The resulting carboxyl content of oxidized cellulose reached 1.07 mmol/g, equivalent to 73.2% of free TEMPO, was satisfactory. Furthermore, the block copolymer was easy to recycle and the activity did not decrease to a noticeable level after 4 cycles.
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危险品化学品经营许可证（带存储）