CARBOHYDRATE POLYMERS
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2015
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IF 4.074
Huan Tan,Bo Wu,Changpeng Li,Changdao Mu,Hongli Li,Wei Lin
We present the use of a natural derivative, dialdehyde carboxymethyl cellulose (DCMC) as the cross-linker for the preparation of spongy collagen cryogels by freezing-thawing method. The DCMC has been characterized by laser light scattering (LLS), showing the molecular weight of 2.38 × 10 5 g/mol. FT-IR studies demonstrate that the cross-linking reaction and the cryogenic treatment do not destroy the triple helix of collagen. SEM images indicate that the cryogel has a heterophase structure with interconnecting macropores. DSC measurements reveal that the incorporation of a very small amount of DCMC can significantly improve the thermal stability of collagen. Moreover, the cryogels exhibit fast swelling rate, and their equilibrium swelling ratio is related to DCMC content and pH-dependent. The in vitro blood-compatibility tests prove that the introduction of DCMC does not cause the reducing performance in hemolysis and blood clotting compared with pure collagen. Hence, the low-cost and non-toxic nature of DCMC confers the cryogel great potential in tissue engineering and other biomedical applications.
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JOURNAL OF CHROMATOGRAPHY A
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2013
·
IF 4.612
Qianying Sheng,Yanxiong Ke,Kuiyong Li,Dongping Yu,Xinmiao Liang
A hydrophilic interaction liquid chromatography (HILIC) stationary phase of cellulose-coated silica was synthesized as a novel saccharide separation material. The material, prepared with a method based on ionic interaction, was demonstrated to be efficient for immobilization of saccharides on silica supports. The method is more efficient than traditional immobilized saccharide stationary phase synthesis methods. It was evolved from a method using anion exchanger microparticles agglomerated onto macroparticles of cation exchangers to produce anion exchangers. Cationic cellulose, which has a large number of hydroxyl groups, was immobilized on sulfonated silica. The cellulose-coated stationary phase we designed used strong hydrogen bonding between cellulose hydroxyl and carbohydrate compounds for HILIC retention and separation. The stationary phase was successfully used to separate the samples of polar compounds and the complex samples of oligosaccharides, and demonstrated good reproducibility and stability. The material exhibited good separation selectivity for carbohydrates and ability to enrich glycosylated peptides. The method described here is easy to achieve, environmentally safe and innovative than other methods. It also has extensive application possibilities to separate other categories polar compounds.
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CARBOHYDRATE POLYMERS
·
2014
·
IF 3.916
Guo-min Wu,Jian Chen,Shu-ping Huo,Gui-feng Liu,Zhen-wu Kong
We prepared thermoset nancomposites from biomass-based two-component waterborne polyurethane (2K-WPU) and cellulose namowhiskers (CNWs). Due to the formation of hydrogen bonds, the viscosity of 2K-WPU dispersion was found to be increased with the addition of CNWs. SEM images showed “sea-island structure” corresponding to the microphase separation between CNWs nano-filler and the 2K-WPU matrix. The α-relaxation temperature ( T α ) and glass transition temperature ( T g ) increased with the increase of CNWs content, which was due to the formation of a rigid CNWs nano-phase acting as crosslinking points in the 2K-WPU matrix. Mechanical properties from tensile test showed Young's modulus and tensile strength of 2K-WPU/CNWs nanocomposites were reinforced by the addition of CNWs. Thermo-stability of 2K-WPU/CNWs nanocomposites decreased slightly with the increase of CNWs content, which could be attributed to the increased thermal conductivity of the material after adding CNWs.
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ACS Sustainable Chemistry & Engineering
·
2014
·
IF 0
Jinxu Xi,Daqian Ding,Yi Shao,Xiaohui Liu,Guanzhong Lu,Yanqin Wang
The efficient usage of lignocellulosic biomass is of great significance for large-scale low-cost biomass conversion to biofuels and other useful chemicals. Here, an interesting catalytic process was reported related to converting cellulose into ethylene glycol (EG) and ethylene glycol monoether (EGME) in methanol over a Ru/NbOPO4 catalyst, with the cleavage of a C–C bond by NbOPO4 and further hydrogenation by supported Ru particles. The influence of reaction temperature, hydrogen pressure, and reaction time was systematically investigated and showed that a 54.5% total yield of EG and EGME could be obtained at 220 °C in 3 M Pa H2, which was an exciting result. Meanwhile, the effect of solvent was also studied in detail. It was shown that methanol played an important role in the production of EG and EGME, especially in the cleavage of the C–C bond. Methanol could protect the C═O bond in glucose produced from cellulose through acetalization, thus prevent its hydrogenation, and led to the production of EG and EGME. Furthermore, the influence of dopants (W, Sn, Ni, Cu) was further investigated, and it was found that only the Ru–Ni/NbOPO4 catalyst was more effective through limiting the further hydrogenolysis of products (EG and EGME) to CO and alkanes, and as high as 64% total yield of EG+EGME was achieved. Moreover, the Ru–Ni/NbOPO4 catalyst showed good reusability, which can be reused at least four times with a little loss in EG and EGME yield.
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JOURNAL OF ANALYTICAL AND APPLIED PYROLYSIS
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2014
·
IF 3.07
Xinlai Wei,Zhi Wang,Yang Wu,Zhimin Yu,Jie Jin,Ke Wu
Various metal oxides, such as zirconia, titania, and alumina, were screened as solid acid catalysts in the fast pyrolysis of cellulose for levoglucosenone production. The liquid yields were affected by the properties of the catalyst, and an increase in levoglucosenone was observed with the addition of mesoporous metal oxides. Good catalytic properties were observed for anatase titanium oxide with an optimum surface area and pore diameter resulting in a levoglucosenone yield that was as much as 4.98%. The activities of calcined sulfated zirconia increased substantially compared to zirconia-impregnated sulfuric acid without calcination. In the presence of solid super-acid SO 4 2− /ZrO 2 , cellulose produced levoglucosenone in a 7.25% yield.
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INDUSTRIAL CROPS AND PRODUCTS
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2015
·
IF 2.837
Shan Lin,Lihui Chen,Liulian Huang,Shilin Cao,Xiaolin Luo,Kai Liu
Cellulose-based membranes have emerged as an attractive alternative to non-biodegradable petrochemical materials. An important drawback, however, is that cellulose-based membranes are prone to biofouling. Silver nanoparticles (AgNPs) encapped with polyacrylic acid were conjugated with the chitosan/cellulose composite films to enhance the antimicrobial activities. Using the 1-ethyl-3-(3-dimethylaminopropyl) carbodii-mide hydrochloride and N -hydroxysuccinimide as biocoupling agents, AgNPs with an average size of 9 nm were distributed evenly in the film without agglomeration. The presence of AgNPs in the chitosan/cellulose–AgNPs composite films was further confirmed by X-ray diffraction measurements. Fourier transform infrared spectroscopy analysis supported the presence of amide bonds between the primary amino groups of chitosan and the carboxylic residues of coordination to silver nanoparticles. The antimicrobial properties of the chitosan/cellulose and chitosan/cellulose–AgNPs composite films were determined using the disk diffusion tests with Escherichia coli ( E. coli ) and Staphylococcus aureus ( S. aureus ). As compared to the chitosan/cellulose composite films, the chitosan/cellulose–AgNPs composite films showed significantly improved antimicrobial activities.
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BIORESOURCE TECHNOLOGY
·
2014
·
IF 5.039
Jinping Ni,Haining Na,Zhen She,Jinggang Wang,Wenwen Xue,Jin Zhu
This work studied the responsive behavior of regenerated cellulose (RC) in hydrolysis under microwave radiation. Four types of RC with different crystallinity ( Cr ) and degree of polymerization (DP) are produced to evaluate the reactivity of RC by step-by-step hydrolysis. Results show Cr is the key factor to affect the reactivity of RCs. With hydrolysis of amorphous region and the formation of recrystallization, the Cr of RC reaches a high value and thus weakens the reactivity. As a result, the increment of cellulose conversion and sugar yield gradually reduces. Decrease of the DP of RC is helpful to increase the speed at the onset of hydrolysis and produce high sugar yield. But, there is no direct influence with the reactivity of RC to prolong the time of pretreatment. This research provides an accurate understanding to guide the RC preparation for sugar formation with relative high efficiency under mild reaction conditions.
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INTEGRATED FERROELECTRICS
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2017
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IF 0.457
Xin-Feng Zhang,Shu-Jing Yang,Hong-Wei Yao,Xu-Feng Chen,Xiao-Jun Zheng,Ze-Jing Li,Hai-Lin Cong
Fullerene (C60) was successfully grafted on cellulose following with the modification of cellulose by acid chlorination and subsequently azidation. The structures of modified cellulose made by sulfonation, acylating chlorination, Azidation, ionization and fullerenated were determined by infrared spectroscopy. The results show that the raw cellulose can obtain good dissolution property when the methyl imidazole-chloropropylene ionic liquid is used as the solvent system. The choice of intermediates has an important effect on the modification. The better grafting efficiency can be obtained with acyl chlorinated cellulose, and the reactivity and reactivity control of the azided chlorinated cellulose fibers are more easily to obtain. The azided chlorinated cellulose can be grafted by fullerene successfully.
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Journal of Experimental Nanoscience
·
2016
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IF 0.832
Huan Zhang,Yingying Guo,Jianfeng Yao,Ming He
Microcrystalline cellulose (MCC) grafted with n-octadecyl isocyanate (18C-g-MCC) was introduced as the reinforcing filler in epoxidised soybean oil (ESO) polymer. The wetting characteristics of 18C-g-MCC were evaluated by static contact angle and the results show that the hydrophobicity of MCC was improved by the introduction of nonpolar alkyl groups. The ESO composites were synthesised with different contents of 18C-g-MCC (from 0 to 25 wt%) by a thermally cured method. The reinforcing effects of 18C-g-MCC were evaluated by scanning electron microscopy, mechanical test, dynamic mechanical analysis and thermal stability test. The results show that the tensile strength, the impact strength, Young's modulus, the flexural strength and glass transition temperature of the composites increase gradually with the increase of 18C-g-MCC content, while the elongation at break begins to decrease with 18C-g-MCC content of more than 20 wt%. Contact angle and water absorption analysis of the composites indicate the addition of 18C-g-MCC increases the water absorption of the ESO polymer.
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CELLULOSE
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2016
·Vol. 23
·期 6
·3717-3735
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IF 3.195
Liu Ting,Xue Feng,Ding Enyong
Graft modification is an excellent way to prepare cellulose nanocrystals (CNCs) with various functions. In this work, different water-soluble macro reversible addition fragmentation chain transfer (macroRAFT) agents were used to mediate grafting of polyacrylamide with cellulose nanocrystals. Fourier-transform infrared spectroscopy, 13 C solid-state nuclear magnetic resonance (NMR), X-ray photoelectron spectroscopy, and elemental analysis were used to characterize the presence of polyacrylamide and quantify its content on the modified cellulose nanocrystals. The results show that two amphiphilic macroRAFTs, namely St 5 AA 14 RAFT and St 7 AA 14 RAFT, increased the weight ratio of polyacrylamide on the modified cellulose nanocrystals, whereas a corresponding hydrophilic macroRAFT (AA 14 RAFT) impeded growth of the polymer chains on the cellulose nanocrystals. Examination of the structure of the graft products and the cleaved polyacrylamide chains revealed that the amphiphilic macroRAFTs were involved in the graft reaction through effective chain transfer, thereby increasing the weight ratio of polyacrylamide on the modified CNCs.
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CARBOHYDRATE POLYMERS
·
2017
·
IF 4.811
Yahui Meng,Zhiqiang Pang,Cuihua Dong
It’s challenging to dissolve natural cellulose in most solvents due to its highly ordered crystalline structure. In this paper, we developed an efficient cellulose dissolution system which incorporates solid acid (SA) with 1-butyl-3-methylimidizolium chloride (BmimCl). The results showed that addition of solid acid both Amberlyst ® 15 and Cs x H 3−x PW 12 O 40 could significantly enhance cellulose dissolution in BmimCl, which attributed to the synergistic action of free hydrogen proton from SA and chloride anion in BmimCl on hydroxyl groups of cellulose, and DMF as co-solvent also could facilitate cellulose dissolution in SA/BmimCl. In contrast to BmimCl system, the SA/BmimCl system for cellulose dissolution achieves better efficiency at mild treatment conditions and facile recovery of solvents. In addition, characterization of the regenerated celluloses showed that SA/BmimCl is a non-derivatizing solvent for cellulose, which helps achieve complete dissolution on crystalline cellulose. Attributed to its low cost and environmentally friendliness for biomass processing, SA/BmimCl systems is a promising and effective solvent system.
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JOURNAL OF DISPERSION SCIENCE AND TECHNOLOGY
·
2016
·
IF 1.112
Ming Ma,Bo Fang,Yongjun Lu,Meng Tian,Xiaohui Qiu,Guodong Li,Hao Jin,Yuwei He,Caihe Huang,Yuting Liu,Liwei Wang,Kejing Li
Micro-rheological properties including elasticity index (EI) and solid liquid balance (SLB) of gelation process of hydrophobic amphoteric cellulose solution at different temperatures and crosslinker concentrations were investigated by optical micro-rheometer in this work. During the crosslinking gelation process, EI appears a two-stage rise, and SLB first increases to maximum and then decreases to constant. According to EI curves, the gelation process can be divided into two stages. Intrinsic rheo-kinetics equations were first established to characterize the two-stage crosslinking process. The simulated values by the novel intrinsic rheo-kinetic models were in good agreement with experimental data and the model parameters were well-defined and of reasonable significance.
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