CARBOHYDRATE POLYMERS
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2019
·
IF 6.044
Xinyue Liu,Xiaojun Qi,Yupeng Guan,Yingying He,Shuai Li,Hongxia Liu,Li Zhou,Chun Wei,Chuanbai Yu,Yunhua Chen
We report here the development of transparent and strong polymer composites reinforced by unmodified cellulose nanofibrils (CNFs) with a Pickering emulsion gelation strategy. The CNFs entangle and firmly stabilize on the surface of emulsion droplets containing polymethyl methacrylate (PMMA) solution, leading to the gelation of the emulsions. CNFs/PMMA composites were generated via vacuum filtration and solvent washing of the gel and a subsequent two-step hot pressing. The composites contained a unique self-assembled two-tier hierarchy of CNFs networks and demonstrate promising transparency, tensile strength, flexibility, and an extremely low thermal expansion. Remarkably, these properties are highly tunable with varying the concentration of CNFs and the volume ratio of the water to oil phase. This work offers a facile route to realize the well dispersion of unmodified CNFs in hydrophobic polymer matrix and achieve high performance of polymeric materials reinforced by CNFs.
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高影响因子
CARBOHYDRATE POLYMERS
·
2019
·
IF 6.044
Wenjiao Ge,Shan Cao,Feng Shen,Yuyuan Wang,Junli Ren,Xiaohui Wang
Here, we designed a self-healing composite hydrogel with antioxidant and antibacterial activities by using cellulose nanofibrils (CNF) and tannic acid (TA) as functional additives. Excellent mechanical stability, moldability, stretchability and rapid self-healing ability without any external intervention were realized in one system due to the combined dynamic borate ester bonding between polyvinyl alcohol-borax (PB) and multi-hydrogen bonding between different components. The rheological measurements indicated the incorporation of CNF and TA to PB system substantially affected the viscoelasticity of hydrogels. The unique antioxidant and antibacterial properties were achieved due to the complexation of TA. These high performance multifunctional hydrogels opens a window for a broad application in the field of smart devices and surface engineering.
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JOURNAL OF MATERIALS SCIENCE
·
2019
·Vol. 54
·期 17
·11713-11725
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IF 3.442
Zhang Xinfang,Shao Ziqiang,Zhou Yi,Wei Jie,He Weidong,Wang Shuo,Dai Xiaofu,Ren Jiaying
Because of irreversible agglomeration in the dehydrating process, the wet storage and transport of cellulose nanofibres (CNF) are the serious issues that need to be resolved in the commercialization and application of CNF. In this study, silanized cellulose nanofibres (Si-CNF) were prepared by modifying CNF with phenyltrimethoxysilane (PTS). Moreover, a mixture of redispersed Si-CNF and mineral oil was treated by combining ultrasound and high-pressure homogenizer to prepare Pickering emulsions. Different ratios of CNF/PTS were prepared and redispersed, and their morphological characteristics, thermal performance, rheological properties, zeta potential, and size distribution were analysed to evaluate the changes occurring during modification. The results show that the obtained Si-CNF demonstrates excellent redispersibility in water. The viscosity of the redispersed product exhibits the best suspension stability with the particle distribution uniform at the nanoscale when the addition amount of PTS is 0.18 mmol/g. Rheological and dynamic light scattering results have shown that the Pickering emulsion maintains the best dispersion stability at a concentration of 0.02% and remains stable after 7 days of storage. PTS modified the hydrophobicity of the CNF and provided alternative routes for application of CNF and Pickering emulsions.
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JOURNAL OF NANOSCIENCE AND NANOTECHNOLOGY
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2019
·Vol. 19
·期 8
·4535-4542
·
IF 1.093
Zang Haoliang,Li Yanhui,Li Yali,Chen Long,Du Qiuju,Zhou Kaixuan,Li Hong,Wang Yuqi,Ci Lijie
The application of graphene oxide in water treatment is facing a rigorous challenge of how to separate nanoadsorbents from aqueous solution using conventional methods after adsorption. Herein, a new type of easily separated composite was fabricated using cellulose acetate (CA) crosslinked
with graphene oxide (CAGO) and a simple vacuum freeze-drying method. The CAGO composites were subject to SEM, FTIR, TGA, and BET characterizations. The adsorption performance of the adsorbent for the removal of methylene blue (MB) was evaluated through investigating the experimental parameters
such as initial dye concentration, temperature, adsorbent dose, contact time, and solution pH. The Langmuir and Freundlich isotherm models were applied to fit the equilibrium data. The maximum adsorption capacity of methylene blue onto the CAGO-4 composite was 374.53 mg/g at 323 K. The kinetic
data showed a good determination with pseudo-second-order equation. Thermodynamic analysis indicated that the adsorption was an endothermic and spontaneous process.
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CARBOHYDRATE POLYMERS
·
2019
·
IF 6.044
Chenghao Huang,Hui Ji,Yuan Yang,Bin Guo,Lei Luo,Zhenghua Meng,Lingling Fan,Jie Xu
In this paper, 2, 2, 6, 6-tetramethylpiperidine-1-oxyl (TEMPO)-oxidized bacterial cellulose (TOBC) nanofiber membranes as separators of lithium-ion batteries were successfully prepared from a water dispersion of TOBC nanofibers via a vacuum filtration approach. The TOBC membranes had adequate porosity and desirable affinity with the liquid electrolyte and lithium electrode, giving rise to superior electrolyte uptake and small interfacial resistance. Among the TOBC nanofiber samples, the TOBC1.0 membrane exhibited the best properties, including high electrolyte uptake (339 %), superior electrochemical stability window (>6.0 V), outstanding ionic conductivity (13.45 mS cm −1 ) and small interfacial resistance (96 Ω). The half cells obtained using the TOBC1.0 membrane achieved a discharge capacity of 166 mA h g −1 (0.2 C), corresponding to 97.6 % of the theoretical value of LiFePO 4 (170 mA h g −1 ), excellent cycle stability (with capacity retention of 94 % after 100 cycles) at 0.2 C and good C-rate performance. Thus, the TOBC nanofiber membranes could be considered as a promising high-performance separator used in lithium-ion batteries.
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Polymers
·
2019
·Vol. 11
·期 11
·1846
·
IF 3.164
Yuanfeng Pan,Xiao Zhao,Xiaoning Li,Pingxiong Cai
Developing the ideal biomaterials for wound dressing still remains challenging nowadays due to the non-biodegradable features and the lack of antimicrobial activity of conventional synthetic polymer-based dressing materials. To tackle those problems, a novel and green-based antimicrobial hydrogel dressing was synthesized in this work via modifying sugarcane bagasse cellulose with guanidine-based polymer, followed by crosslinking antimicrobial-modified cellulose with unmodified one at various ratios. The resulting hydrogels were comprehensively characterized with swelling measurements, compression test, Fourier transform infrared spectroscopy, and scanning electron microscopy. The results indicated that the dressing possessed the degree of swelling up to 2000% and the compress strength as high as 31.39 Kpa, at 8:2 ratio of pristine cellulose to modified cellulose. The antibacterial activities of the dressing againstE. coliwere assessed using both shaking flask and ring diffusion methods. The results demonstrated that the dressings were highly effective in deactivating bacterium without leaching effect. Moreover, these hydrogels are biocompatible with live cell viability responses of (NIH3T3) cells above 76% and are very promising as wound dressing.Keywords:cellulose;guanidine-based polymer;hydrogel dressing;antimicrobial activity
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INTERNATIONAL JOURNAL OF BIOLOGICAL MACROMOLECULES
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2019
·
IF 4.784
Zuwu Tang,Mengchan Zhao,Yu Wang,Wenling Zhang,Min Zhang,He Xiao,Liulian Huang,Lihui Chen,Xinhua Ouyang,Hongbo Zeng,Hui Wu
Inspired by marine mussel, catechol-containing materials, such as adhesives, self-healing hydrogels, and antifouling coatings, have been developed with wide applications in chemical, biomedical, and electronics industries. Conventionally, petrochemicals or organic solvents are widely used for preparation and dissolution of adhesives, which makes the adhesives are not eco-friendly and biocompatible. To develop environmentally friendly and biocompatible adhesives with desired properties, here we report catechol-containing cellulose-based tissue adhesives, synthesized by incorporating catechol groups onto cellulose. The structures of the adhesives with different catechol contents were analyzed by UV–vis spectroscopy, Fourier transform infrared spectroscopy (FTIR) and nuclear magnetic resonance ( 1 H NMR) spectroscopy. The adhesion strengths were examined using porcine skin by lap shear tensile tests. The adhesion strength of the as-prepared adhesive with catechol content of 16.5 mol% was 20.0 kPa. Fe 3+ was used as crosslinker to enhance the adhesion strength and accelerate the solidification of adhesives. Through the Fe 3+ -catechol coordination, the adhesion strength of adhesive was increased to 88.0 kPa, showing strong mechanical strength compared to the fibrin adhesive. NIH 3T3 cells test demonstrates that the adhesive is favorable for cell attachment and proliferation, possessing excellent biocompatibility. The catechol-containing cellulose-based adhesive has promising application in bioengineering field.
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ACS Omega
·
2019
·
IF 2.584
Feng Shen,Shuang Sun,Jirui Yang,Mo Qiu,Xinhua Qi
A key problem in the conversion of cellulose into chemicals and fuels is the low product yield from cellulose due to its robust structure. In this work, for the first time, cellulose was pretreated with coupling of liquid nitrogen and ball milling (LN–BM) for cellulose hydrolysis. After the LN–BM treatment, the glucose yield from cellulose by HCl in water increased by almost 2 times and yield of formic acid catalyzed by H2SO4–NaVO3 was more than 3-fold that obtained from untreated cellulose. The yields were also much higher than that from the individually ball-milled cellulose. The structure variation of cellulose indicated that reduction of both crystallinity index and molecular weight contributed to improving the conversion efficiency, but the former was the dominant factor. The combination of liquid nitrogen and ball milling developed in this work is an effective and environment-friendly approach for cellulose pretreatment.
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INDUSTRIAL CROPS AND PRODUCTS
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2019
·
IF 4.191
Zhaoyun Lin,Yuanyuan Xia,Guihua Yang,Jiachuan Chen,Dexian Ji
Cellulose and starch are main chemical components of plant biomass, and can be used to produce value-added materials. Herein, cellulose nanocrystals (CNC) was used along with NaClO to prepare oxidized corn starch. Subsequently, the oxidized starch was blended with PVA/glycerol to prepare oxidized starch-based blends for film formation and coating paper. The properties of oxidized starch and film formability were modified by addition of CNC and PVA/glycerol. The oxidized starch showed the highest oxidizing degree at 1.10% with 0.5 wt% CNC and 8.0 wt% NaClO. Oxidized starch-based blends had lower viscosity and better uniformity than that of corn starch. The oxidized starch-based composite film showed the optimal water resistance, surface free energy and air permeability. Blending with 30 wt% PVA, the oxidized starch-based composite film showed the best tensile strength, and a simple structural model was simulated. The three-dimensional structure of coated paper was visualized using computed tomography scan (CT-Scan), and verified the good penetration of starch-based blends. The coated paper showed a more dense structure compared to the control paper, and had better waterproof performance and physical strength properties with oxidized starch with the highest oxidizing degree.
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NEW JOURNAL OF CHEMISTRY
·
2019
·Vol. 43
·期 37
·14883-14891
·
IF 3.069
Lijie Huang,Hao Xu,Hanyu Zhao,Mingzi Xu,Minghui Qi,Tan Yi,Shuxiang An,Xiaoxiao Zhang,Chunying Li,Chongxing Huang,Shuangfei Wang,Yang Liu
This study investigated the effectiveness of cellulose nanocrystals derived from cassava residues as a reinforcement to starch films. Thermoplastic starch films are biodegradable to a certain extent, but the scope of their applications is limited due to their strong water absorption and poor mechanical properties. Therefore, we used abandoned cassava residues to prepare cellulose nanocrystals quickly and efficiently using a mechanochemical method. Their average diameter and length were 6.281 nm and 437.232 nm, respectively, with an aspect ratio of 70; this average size is smaller than that of CNCs obtained via acid hydrolysis. Cellulose nanocrystals were ester modified using soybean oil to improve their polarity and hydrophobicity. Thermoplastic starch-based composite films were prepared using the film casting method; the mechanical and wettability properties of these films were investigated, by controlling the concentration of modified cellulose nanocrystals in the films. Scanning electron microscopy results showed that M-CNCs were evenly distributed in the composite films; thermal stability analysis showed that composite films exhibited high thermal stability; Fourier transform infrared spectroscopy results showed that the structure of cellulose nanocrystals prepared using a mechanochemical method was stable; water contact angle measurements showed promising hydrophobic effects at a contact angle of 105.7°. Moreover, mechanical tests showed that the tensile strength of the composite film increased by 73%. Therefore, soybean-oil-modified cellulose nanocrystals were excellent reinforcing agents for thermoplastic starch films, effectively improving the overall performance of the films.
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CELLULOSE
·
2018
·Vol. 25
·期 6
·3533-3544
·
IF 3.809
Yang Jin,Xia Yunfei,Xu Peng,Chen Beibei
Abstract To overcome the poor mechanical properties of biomass aerogels in oil/water separations, three different freeze-casting methods were used including direct freezing, unidirectional freezing, and bidirectional freezing with sodium alginate (SA) aerogels reinforced with cellulose nanofibrils (CN). After chemical crosslinking and silane modification, compression testing revealed that the SA/CN aerogels with parallel lamellar microstructures prepared by bidirectional freezing exhibited super-elasticity with the minimal energy dissipation of ~ 0.04 in each cycle, a maximum compressive stress of 80.4 kPa, and minimal plastic deformation at ~ 4.15%. Additionally, the water and oil contact angle of the surface of the lamellar SA/CN aerogel was 148.7° and 0°, respectively. By combining the super-elasticity and hydrophobicity/superoleophilicity, the lamella SA/CN aerogels could be reused for the separation of oil/water mixture with oil absorption capacities up to 34 times its weight. Furthermore, the lamellar SA/CN aerogel could continuously separate oil/water mixtures with the assistance of a pump. Therefore, the present study offers a simple and environmentally friendly method for fabrication of super-elastic and hydrophobic/superoleophilic biomass aerogels that are applied to continuous removal of oil from water. Graphical Abstract
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CELLULOSE
·
2018
·Vol. 25
·期 5
·3091-3103
·
IF 3.809
Zhang Yanjuan,Wei Liping,Hu Huayu,Zhao Zengyan,Huang Zuqiang,Huang Aimin,Shen Fang,Liang Jing,Qin Yuben
Abstract Three cellulose esters, cellulose acetate-butyrate, cellulose acetate-octanoate, and cellulose acetate-laurate, were synthesized by both conventional co-reactant reaction (CCR) and mechanical activation-assisted co-reactant reaction (MACR) methods, and the corresponding nano-cellulose esters were prepared by high pressure homogenization to comparatively investigate their tribological properties as lubricant additives in liquid paraffin base oil. MACR method was more effective than CCR method for preparing long chain cellulose esters, and the MACR-prepared cellulose esters were more easily homogenized to smaller nanoparticles. Tribological testing indicated that anti-wear and load-carrying properties of the lubricants were significantly enhanced with nano-cellulose esters as additives compared to those of pure liquid paraffin, especially the MACR-prepared long chain cellulose esters. The wear scar diameter on worn surface of the steel balls reduced with the increase in degree of substitution (DS) and chain length of long chain substituents and the decrease in size dimension of nano-cellulose esters. The polar ester carbonyl groups, unesterified hydroxyl groups, and long hydrocarbon alkyl chains in nano-cellulose esters could lead to the formation of a film layer in the steel/steel contact surfaces for protecting the metals from friction and wear, which gave the lubricants with good anti-wear and load-carrying properties. The nano-cellulose esters with high DS and long chain substituents prepared by MACR technology as ecofriendly additives exhibited better lubricating ability. Graphical abstract Nano-cellulose esters with high DS of long chain substituents prepared by mechanical activation-assisted co-reactant reaction technology used as ecofriendly lubricant additives in base oil showed good anti-wear and load-carrying properties, ascribing to the formation of a film layer in the steel/steel contact surfaces for protecting the metals from friction and wear.
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