CARBOHYDRATE POLYMERS
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2017
·
IF 4.811
Xue Yang,Hui Liu,Fuyi Han,Shuai Jiang,Lifang Liu,Zhaopeng Xia
Cellulose nanocrystal (CNC) was extracted from Carex meyeriana Kunth (CMK) by a combination of TEMPO oxidation and mechanical homogenization method, and used to remove methylene blue (MB) from aqueous solution. After alkali-oxygen treatment, the aqueous biphasic system (polyethylene glycol/inorganic salt) was applied to further remove lignin from CMK. The characteriazation of CNC, and the effects of H 2 O 2 dosage, CNC dosage, adsorption time, and initial MB concentration on the MB removal capacity of CNC were investigated. The results showed that the removal percentage of MB by CNC was raised with the increase of H 2 O 2 and CNC dosage. The adsorption kinetics of prepared CNC followed the pseudo-second-order model, and the adsorption isotherms fitted well to the Langmuir model with a calculated maximum adsoption capacity of 217.4 mg/g, which was higher than those of CNC extracted by acid hydrolysis method, indicating CNC extracted from CMK had promising potentials in the field of MB adsorption.
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高影响因子
TEXTILE RESEARCH JOURNAL
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2017
·
IF 1.443
Liu Liu,Yeping Xiang,Ruiyun Zhang,Bei Li,Jianyong Yu
In this study, different dosages of NaClO were used in the 2,2,6,6-tetramethyl-1-piperidinyloxy (TEMPO)-laccase degumming system to remove non-cellulosic materials, and their effects on the structure of hemp fibers were analyzed and discussed. A scanning electron microscope was used to depict the surface morphology of fibers after oxidative degumming under various dosages of NaClO in the TEMPO-laccase degumming system. Chemical composition analysis was used to determine the content changes of the different components. Meanwhile, the content of functional groups was also discussed. Fourier transfer infrared spectroscopy, nuclear magnetic resonance spectroscopy, and X-ray diffraction were employed to evaluate the microstructural changes of degummed hemp fibers obtained from the degumming processes with different dosages of NaClO. The results showed that after the TEMPO-laccase system degumming process with a NaClO dosage of 16%, the cleanest and smoothest surface of degummed fibers could be observed and the non-cellulosic materials were significantly removed without any crystalline transformation or damage in the cellulose. This research could shed light on determining favorable operation parameters for hemp oxidation degumming and increasing the degumming efficiency, as well as in the oxidation control and quality assurance of hemp fibers for textile downstream end uses.
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CARBOHYDRATE POLYMERS
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2016
·
IF 4.219
Qijun Meng,Shiyu Fu,Lucian A. Lucia
A fundamental study was undertaken to determine the general role of heteropolysaccharides during the production of TEMPO-oxidized cellulose nanofibrils (TOCNs). Four major fiber resources, viz. , fully bleached kraft pulps of softwood and hardwood varieties (pine, eucalyptus) and non-woods (bamboo, bagasse) were used because of their substantial morphological differences and relative abundance. The effect of heteropolysaccharides during TEMPO-mediated oxidation and high-pressure homogenization for TOCNs production was investigated under constant conditions. Most galactoglucomannans were removed during oxidation, whereas the majority of xylans were retained. The galactoglucomannans, however, non-beneficially consumed NaClO, the terminal TEMPO oxidant, while xylans adversely affected carboxylate group formation by limiting chemical accessibility to cellulose. However, lower xylans content led to more transparent and processable suspensions, while during mechanical processing, heteropolysaccharides supported nanofibrillation. The average length of the final TOCNs from eucalyptus, bamboo, bagasse, and pine were 290, 350, 360 and 370 nm, respectively, with average widths of ∼4 nm.
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FIBERS AND POLYMERS
·
2016
·Vol. 17
·期 11
·1820-1828
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IF 1.022
Yang Xue,Liu Hui,Zhao Yanjiao,Liu Lifang
Cellulose nanocrystals (CNCs) extracted from corn husks were used as additive to modify the hydrophilicity and anti-fouling properties of polysulfone (PSf) membrane. The PSf/CNCs blend membranes were prepared via an immersion phase inversion method. The influence of CNCs content on the morphology, structure, and performances of PSf membrane were carefully investigated by SEM, TG, DTG, DSC, break strength, elongation-at-break, Young modulus, contact angle and filtration experiment. The results showed that the isolated CNCs from corn husks were a promising additive for modifying the properties of PSf membrane. CNCs can improve mechanical property, thermal stability, hydrophilicity and anti-fouling performance of the pure PSf membrane. The PSf/CNCs blend membrane reached optimal properties at 2 wt% CNCs content, which was 2.76 and 1.57 times in pure water flux and FRR values respectively as compared to pure PSf membrane. Meanwhile, PSf-2 also can maintain a relatively high BSA rejection.
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CHEMICAL RESEARCH IN CHINESE UNIVERSITIES
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2016
·Vol. 32
·期 4
·586-593
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IF 1.086
Zhang Guofu,Zhang Guihua,Lei Jie,Li Shasha,Xu Shengjun,Ding Chengrong,Shan Shang
A facile, practical and scalable catalyst system for alcohols ammoxidation into nitriles is developed using amino acid as ligand, oxygen as terminal oxidant and copper iodide(CuI) as catalyst. The catalyst system shows excellent functional groups compatibility for a wide range of testing substrates, even the substrates bearing oxidation-sensitive groups such as MeS—, alkenyl and —NH 2 can also work well. In addition, the protocol is readily scaled up to more than 20 g and the product can be obtained just through filtration or distillation without conventional column chromatography.
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BIOMACROMOLECULES
·
2016
·
IF 5.583
Jing-Xiao Hu,Jia-Bing Ran,Si Chen,Pei Jiang,Xin-Yu Shen,Hua Tong
By in situ combining the dual cross-linking matrices of the carboxylated agarose (CA) and the silk fibroin (SF) with the hydroxyapatite (HA) crystals, the CA-SF/HA composites with optimal physicochemical and biological properties were obtained, which were designed to meet the clinical needs of load-bearing bone repair. With the synergistic modulation of the dual organic matrices, the HA nanoparticles presented sheet and rod morphologies due to the preferred orientation, which successfully simulated the biomineralization in nature. The chemical reactivity of the native agarose (NA) was significantly enhanced via carboxylation, and the CA exhibited higher thermal stability than the NA. In the presence of SF, the composites showed optimal mechanical properties that could meet the standard of bone repair. The degradation of the composites in the presence of CA and SF was significantly delayed such that the degradation rate of the implant could satisfy the growth rate of the newly formed bone tissue. The in vitro tests confirmed that the CA-SF/HA composite scaffolds enabled the MG63 cells to proliferate and differentiate well, and the CA/HA composite presented greater capability of promoting the cell behaviors than the NA/HA composite. After 24 days of implantation, newly formed bone was observed at the tibia defect site and around the implant. Extensive osteogenesis was presented in the rats treated with the CA-SF/HA composites. In general, the CA-SF/HA composites prepared in this work had the great potential to be applied for repairing large bone defects.
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CELLULOSE
·
2016
·Vol. 23
·期 4
·2457-2473
·
IF 3.195
Tian C.,Fu S. Y.,Meng Q. J.,Lucia Lucian A.
Polycaprolactone (PCL) was grafted to TEMPO-oxidized nanocellulose (TONCs) through a classical ring-opening polymerization reaction mediated by the surface TONC hydroxyl and carboxyl groups. The PCL increased the thermal stability and hydrophobicity without compromising the crystallinity. When TONCs and PCL-grafted TONCs (PTONC) were compared with respect to their perfusion within a segmented polyurethane matrix (CLPU), PTONC dispersed far better as evidenced by increased storage modulus and Young’s modulus. The mechanical strength of the PTONC nanocomposites was nearly that of unmodified TONCs while at a low content (<3 wt%). Furthermore, PTONC in CLPU promoted micro-phase separation of the matrix leading to a smaller decrease in loss factor and elongation at break for the nanocomposites, highly superior to unmodified TONCs. Thus, PTONC as a reinforcement agent enhanced the mechanical properties and ductility of CLPU.
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INTERNATIONAL JOURNAL OF BIOLOGICAL MACROMOLECULES
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2016
·
IF 3.138
Hongli Liu,Xiaoli Liu,Lin Yue,Qixing Jiang,Wenshui Xia
N , O -Carbonylated chitosan derivative (NTCS) was synthesized via oxidation and substitution reaction, respectively. The carboxyethylation of the polysaccharide was identified by Fourier transform infrared (FTIR), 1 H nuclear magnetic resonance (NMR), X-ray diffraction analysis (XRD), Zeta potential measurement and Thermogravimetric analysis (TGA). It is revealed that compared with chitosan (CS), NTCS exhibited an excellent solubility in distilled water, high in vitro bile acid binding capacity, as well as a low viscosity. The in vitro bile acid binding capacity reached 17.21 mg/g, which was 4.5-fold higher than that of CS. The results suggest that NTCS may be useful as a potential functional food supplement in food industry or a key ingredient in the pharmaceutical industry. These findings provide important supports for developing new food additive, and expand the scope of application of CS in the food industry.
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ACS Sustainable Chemistry & Engineering
·
2017
·
IF 5.951
Guo Jiang,Mengdi Zhang,Jian Feng,Shuidong Zhang,Xiaohui Wang
Bionanocomposites of poly(propylene carbonate) (PPC) enhanced by cellulose nanocrytals (CNCs) are prepared via a two-step process using polyethylene glycol (PEG) as a carrier. Interfacial interaction among PPC, PEG, and CNCs, dispersion of CNCs in bionanocomposites, thermal properties, mechanical behavior, oxygen barrier property, and rheological responses are investigated. The obtained PPC/PEG/CNC nanocomposites display obvious improvement of barrier properties by adding an extremely low loading of CNCs. O2 permeability is decreased by more than 76% at CNC loading of 0.3 wt %. The Cussler model works better to predict gas barrier for nanocomposites. TEM results show that CNC is well dispersed in the matrix, and the introduction of CNC remarkably increases the tensile strength and storage modulus of PPC. Interestingly, elongation at break of the PPC/PEG/CNC nanocomposite remains above 580%. Moreover, the inclusion of CNCs increases the thermal stability and initial decomposition temperature (T–5%) of nanocomposites. The T–5% for the PPC/PEG/0.7CNC nanocomposite is approximately 246.5 °C, which is increased by 17.1% compared with that of pure PPC (210.5 °C). This makes PPC/PEG/CNC nanocomposites a very promising degradable material for food packaging applications.
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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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CARBOHYDRATE POLYMERS
·
2016
·
IF 4.219
Jie Hao,Shuyi Xu,Naiyu Xu,Duxin Li,Robert J. Linhardt,Zhenqing Zhang
Microcrystalline cellulose, a major component of cell wall of plants, is one of the most abundant natural materials, but the poor solubility of cellulose limits its applications. Cellulose is a linear glucan with exclusive β 1 ⿿ 4 linkage. Oxidation carried out with TEMPO⿿NaBr⿿NaClO system can selectively oxidize the C6 of glucose residues in cellulose. This modification improves polysaccharide solubility and other physicochemical properties. In this work, the impact of degree of oxidation on solubility, degree of crystallization, thermostability, molecular weight and the structures of the resulting oligosaccharide products of selectively oxidized cellulose were investigated using x-ray diffraction, thermogravimetric analysis, gel permeation chromatography⿿multiple angle laser light scattering and ultrahigh performance liquid chromatography⿿electrospray⿿quadrupole/time of flight⿿mass spectrometry, respectively. The physicochemical properties of selectively oxidized cellulose having different degrees of oxidation were carefully characterized providing a theoretical foundation for the more accurate selection of applications of oxidized celluloses.
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JOURNAL OF APPLIED POLYMER SCIENCE
·
2016
·Vol. 134
·期 1
·
IF 1.866
Shaojie Liu,Huali Wang,Xiaomeng Chu
2,2,6,6-Tetramethylpiperidinyloxyl (TEMPO)-containing polymer brushes were grafted onto crosslinked polystyrene microspheres via surface-initiated activators regenerated by electron transfer atom transfer radical polymerization (ARGET ATRP) of 2,2,6,6-tetramethyl-4-piperidyl methacrylate, followed by an oxidation process with 3-chloroperoxybenzoic acid as oxidant. The synthesized nitroxide polymer brushes included homopolymer brushes, block copolymer brushes, and random copolymer brushes with various TEMPO contents and molecular weights. They were characterized by Fourier transform infrared spectroscopy, scanning electron microscopy, transmission electron microscopy, nuclear magnetic resonance spectroscopy, and gel permeation chromatography. These nitroxide brushes bearing high TEMPO contents were used as recoverable catalysts for the hypochlorite and aerobic oxidation of primary alcohols to aldehydes. The effects of polymer brush structure on the catalytic properties were studied and discussed. The results showed that these nitroxide polymer brushes had excellent catalytic properties and good recycling performances. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133 , 44365.
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