CELLULOSE
·
2021
·Vol. 28
·期 3
·1469-1488
·
IF 5.044
Lu Ya,Han Jingquan,Ding Qinqin,Yue Yiying,Xia Changlei,Ge Shengbo,Van Le Quyet,Dou Xiaomin,Sonne Christian,Lam Su Shiung
Abstract Shape memory hydrogels attract increasing attention due to their promising applications as intelligent biomaterials for actuators, biomedicine and sensory applications. Nonetheless, the integration of synergistic characteristics providing good mechanical properties and ideal self-recovery rate still remains a challenge. To tackle this, we develop a novel nanocomposite hydrogel by radical polymerization. TEMPO-oxidized cellulose nanofibers (TOCNs) with high strength and ultra-high aspect ratio were introduced to improve the energy dissipation mechanism and enhance the fatigue resistance of polyacrylamide (PAAM) hydrogel. Interestingly, the nanocomposite hydrogel displays unprecedented shape memory properties through coordination with Fe 3+ . The resulting TOCN/PAAM hydrogel achieves excellent energy dissipation capability (9.68 MJ m −3 at 60% strain), satisfactory viscoelasticity (51.1 kPa) and good self-recovery rate (about 93.2% after 30 min recovery). In particular, the 3% TOCN/PAAM-Fe 3+ hydrogel exhibits better tensile performance. This nanocomposite hydrogel with good shape memory properties and excellent mechanical strength has broad application prospects in soft actuators and sensory research. Graphic abstract
研究领域:
材料科学
·
生物医学工程
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产品关联
DOI
高影响因子
CARBOHYDRATE POLYMERS
·
2012
·
IF 3.628
Jun Huang,Wan-wen Chen,Sheng Hu,Jing-Yan Gong,Hong-Wu Lai,Peng Liu,Le-he Mei,Jian-wei Mao
TEMPO (2,2,6,6-tetramethylpiperidine-1-oxyl radical)-mediated 6-carboxy β-chitin derivatives (T-chitin) with different carboxylate content were successfully synthesized by controlling the addition level of NaClO as the primary oxidant. The structural and biochemical properties of the derivatives were investigated. The carboxylate contents of the derivatives calculated by electrical conductivity titration were 1.33, 1.68, 1.80, and 2.08 mmol/g, respectively. The yield of T-chitin with carboxylate content of 2.08 mmol/g reached 74.55%. T-chitin exhibited stronger bile acid binding capacities than that of β-chitin. The scavenging ability of T-chitin against hydroxyl radicals improved with increasing concentration, and EC 50 values were below 1.2 mg/mL. All T-chitin exhibited a strong ferrous ion chelating effect. At 8 mg/mL, the chelating effects of T-chitin with carboxylate content of 0.81 mmol/g reached 80.15%. These results showed that T-chitin had good bile acid binding capacity and antioxidant activities and it may be a potential antioxidant in vitro .
研究领域:
生物化学
·
材料科学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
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.
研究领域:
材料科学
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生物化学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
BIOMACROMOLECULES
·
2025
·
IF 5.4
Huangjingyi Chen,Yue Ma,Tian Huang,Liang Liu,Juan Yu,Ruoxian Jia,Meijuan Chen,Lin Lin,Xin Li,Zhiguo Wang,Yimin Fan
Nanomaterial-based hydrogels derived from natural silk have garnered significant attention in advanced applications. However, preparation of silk fibroin nanofibers by directly disintegrating natural silk fibers remains challenging. We initiated the process by employing various pretreatment methods to loosen the intricate structure of the natural silk fibers. Subsequently, carboxyl groups were introduced to the silk fibroin surface using a sequential TEMPO/Laccase/O2 (TLO) oxidation approach, whereby the fabrication of silk nanofibers (TLO-SNFs) or nanocrystals (TLO-SNCs) was achieved with a high carboxyl content (ranging from 0.795 to 0.935 mmol/g) and nanofiber lengths of up to 1843 ± 659 nm. Furthermore, TLO-SNFs were further incorporated with poly(N-isopropylacrylamide) (PNIPAm) through acetic acid coagulation, whereby a reinforced TLO-SNF@PNIPAm hydrogel was constructed with an interpenetrating network. It exhibited excellent mechanical performance and demonstrated shape-retaining shrinkage–expansion capabilities, significantly extending the release time of curcumin to 2 weeks. This makes TLO-SNF@PNIPAm an ideal carrier for the long-term in vitro release of curcumin, offering potential applications in responsive transdermal patches.
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产品关联
DOI
PubMed
高影响因子
SYNTHESIS-STUTTGART
·
2013
·Vol. 45
·期 24
·3387-3391
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IF 2.5
Congyan Chen,Bo Liu,Wanzhi Chen
Various imidazolium salts bearing hydrophilic groups were prepared that reacted with copper powder to afford water-soluble copper complexes of N-heterocyclic carbenes. These copper complexes can catalyze the selective oxidation of benzyl alcohols to the corresponding aldehydes in water at room temperature without the need for a base.
研究领域:
有机化学
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催化化学
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绿色化学
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DOI
高影响因子
Nature Communications
·
2025
·Vol. 16
·期 1
·10578
·
IF 15.7
Li Shiyun,Liu Guangsheng,Liu Chuhao,Fu Yifan,Fu Yixuan,Xu Yifei,Li Chengyu,Zhang Xueqiang,Xu Bingjun,Li Wan-Lu,Li Mufan
Electrocatalysis provides a sustainable alternative route to produce nitrogen-containing molecules. However, poor carbon-nitrogen (C-N) coupling selectivity and limited current density pose challenges to its widespread adoption. Herein, we introduce a carbon-defect enhanced 2,2,6,6-tetramethylpiperidine N-oxyl (TEMPO) mediated tandem process to tackle both problems. Our hetero-homogeneous system achieves a Faraday efficiency of ~99% with industrial-level current density of ~0.6 A·cm −2 for urotropine electrosynthesis. In situ near ambient pressure X-ray photoelectron spectroscopy and quasi in situ electron paramagnetic resonance reveal that the boosted activity originated from the oxidation of TEMPOH on the carbon defective sites, which accelerates the redox cycling of the molecular mediator for urotropine formation. This work highlights the catalytic effect of carbon defects on the redox cycling of TEMPO, improves both the selectivity and the rate of the electrocatalytic C-N coupling reaction, and offers insights for designing efficient electrochemical mediated oxidation processes and C-N coupling reactions.
研究领域:
电化学
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催化
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材料科学
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有机合成
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可持续化学
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产品关联
DOI
PubMed
高影响因子
CELLULOSE
·
2021
·Vol. 28
·期 14
·9309-9321
·
IF 5.044
Zhao Xiaobin,Wang Wenbo,Huang Chenghao,Luo Lei,Deng Zhongmin,Guo Wei,Xu Jie,Meng Zhenghua
Cattail is widely abounding in wetlands and marshes and is usually considered as an abundant and inexpensive biomass lignocellulose resource due to its rapid growth. In this paper, a novel cellulose (named as TOCF) separator for Li-ion batteries (LIBs) is successfully fabricated from cattail fibers by 2, 2, 6, 6-tetramethylpiperidine-1-oxyl (TEMPO) oxidation and vacuum filtration. The proposed TOCF membrane shows good tensile strength (75 MPa), superior thermal dimensional stability, sufficient porosity (64.8%), outstanding liquid electrolyte uptake (323%) as well as large ionic conductivity (2.83 mS cm −1 ). Moreover, the Li/LiFePO 4 cell assembled using the TOCF separator demonstrates better discharge capacity and cycling stability than the cell with a commercial Celgard separator. Thus, the TOCF separator is a promising and low-cost candidate used in high-performance LIBs.
研究领域:
材料科学
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能源技术
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环境科学
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产品关联
DOI
高影响因子
SEPARATION AND PURIFICATION TECHNOLOGY
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2023
·
IF 8.6
Zhaoju Zhang,Lu Liu,Hongyang Ma,Shyam Venkateswaran,Benjamin S. Hsiao
Oxidized cellulose fabrics were fabricated by means of periodate and TEMPO sequential two-step oxidations and were employed as a highly efficient filter for dye adsorption with a multiple and synergistic adsorption mechanism. The mechanical properties, yields, and molecular weights of the oxidized cellulose fabrics depend on the content balance between carboxylate and aldehyde groups distributed either in or on the fiber surface where the oxidized cellulose fabrics with high adsorption sites (e.g., carboxylate and aldehyde groups) and high tensile strength were optimized through TEMPO oxidation that was first enhanced by periodate oxidation. The oxidized cellulose fabrics with both carboxylate and aldehyde groups exhibited remarkable adsorption capability, specifically in the adsorption of amino-containing molecules such as chrysoidine dye and hydrazine. A multiple and synergistic adsorption mechanism based on chemical reaction (e.g., Schiff base reaction between the aldehyde and amino groups) and electrostatic interaction (e.g., carboxyl and amino) was proposed and verified by adsorption kinetics, isotherms, thermodynamics as well as dynamic adsorption, while the maximum adsorption capacities of the oxidized cellulose fabrics against chrysoidine and hydrazine were as high as 118.34 mg/g and 92.76 mg/g, respectively, due to the synergistic adsorption of both carboxylate and aldehyde groups. A spiral wound filtration cartridge (made by 3.6 g of oxidized cellulose fabrics) was fabricated and the removal capability against hydrazine and chrysoidine was investigated. It was impressive that when 18.3 L of hydrazine and 28.8 L of chrysoidine solutions with 3.0 mg/L of concentration were purified separately, the rejection ratios remained as high as 98% and 94%, respectively, with a pressure drop as low as 0.3 kPa. This indicated that the oxidized cellulose fabrics could be employed as highly efficient filters for industrial wastewater treatment through a multiple and synergistic adsorption mechanism.
研究领域:
材料科学
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环境科学
✓ 已验证
产品关联
DOI
高影响因子
Gels
·
2024
·Vol. 10
·期 8
·490
·
IF 5
Minjie Hou,Qi Wang,Shunyu Wang,Zeze Yang,Xuefeng Deng,Hailong Zhao
Cellulose nanofibers (NF) were extracted from kapok fibers using TEMPO oxidation, followed by a combination of mechanical grinding and ultrasonic processing. The TEMPO-mediated oxidation significantly impacted the mechanical disintegration behavior of the kapok fibers, resulting in a high NF yield of 98%. This strategy not only improved the fibrillation efficiency but also reduced overall energy consumption during NF preparation. An ultralight and highly porous NF-based aerogel was successfully prepared using a simple ice-templating technique. It had a low density in the range of 3.5–11.2 mg cm−3, high compressional strength (160 kPa), and excellent thermal insulation performance (0.024 W m−1K−1). After silane modification, the aerogel displayed an ultralow density of 7.9 mg cm−3, good hydrophobicity with a water contact angle of 128°, and excellent mechanical compressibility with a high recovery of 92% at 50% strain. Benefiting from the silene support structure, it showed a high oil absorptive capacity (up to 71.4 g/g for vacuum pump oil) and a remarkable oil recovery efficiency of 93% after being reused for 10 cycles. These results demonstrate that our strategy endows nanocellulose-based aerogels with rapid shape recovery and high liquid absorption capabilities.
研究领域:
材料科学
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化学工程
✓ 已验证
产品关联
DOI
PubMed
高影响因子
Polymers
·
2019
·Vol. 11
·期 7
·1130
·
IF 3.164
Dingyuan Zheng,Yangyang Zhang,Yunfeng Guo,Jinquan Yue
Herein, walnut shell (WS) was utilized as the raw material for the production of purified cellulose. The production technique involves multiple treatments, including alkaline treatment and bleaching. Furthermore, two nanocellulose materials were derived from WS by 2,2,6,6-tetramethylpiperidine-1-oxyl radical (TEMPO) oxidation and sulfuric acid hydrolysis, demonstrating the broad applicability and value of walnuts. The micromorphologies, crystalline structures, chemical functional groups, and thermal stabilities of the nanocellulose obtained via TEMPO oxidation and sulfuric acid hydrolysis (TNC and SNC, respectively) were comprehensively characterized. The TNC exhibited an irregular block structure, whereas the SNC was rectangular in shape, with a length of 55–82 nm and a width of 49–81 nm. These observations are expected to provide insight into the potential of utilizing WSs as the raw material for preparing nanocellulose, which could address the problems of the low-valued utilization of walnuts and pollution because of unused WSs.Keywords:Walnut shell;nanocellulose;TEMPO oxidation;sulfuric acid hydrolysis;ultrasonication
研究领域:
材料科学
·
农业废弃物利用
·
化学工程
✓ 已验证
DOI
PubMed
高影响因子
Journal of Materials Research and Technology-JMR&T
·
2022
·
IF 6.267
Xuefeng Zhang,Huanbo Wang,Zhijun Chen,Shiyu Guo,Yuan Fu,Tian Liu
Fast-growing natural poplar wood is not meet with in many requirements such as high strength and flame retardant due to its porous structure and loose materials. In this study, we established a simple and feasible method that includes delignification, ionic bond formation via the crosslinking of carboxyl groups in TEMPO-oxidized wood after delignification with calcium ions , and hot-pressing of stacked veneers to improve the quality, density, strength, toughness, and weather resistance of natural wood (NW). This method has the following advantages: The inner cellulose microfiber is highly aligned, thus closely cross-linking and tightly bonding cellulose microfibers and nanofibers between the interfaces and inner layers of the wood boards via hydrogen bonding and ionic bonding. A laminated densified TEMPO-oxidized ionic wood (IW) showed substantially higher specific strength (∼196.9 MPa cm3 g−1), higher tensile strength (∼246 MPa), higher flexural strength (∼257 MPa), higher flexural modulus (∼36 GPa), higher impact toughness (∼42.34 kJ m−2), and superior fire retardancy, UV resistance, water resistance, and also higher density (∼1.25 g cm−3) than NW. Larger-size laminated densified structural materials with satisfactory thermal stability can also be fabricated using the proposed method.
研究领域:
材料科学
·
林业工程
✓ 已验证
DOI
高影响因子
JOURNAL OF ELECTROANALYTICAL CHEMISTRY
·
2016
·
IF 2.822
Wenbin Zhang,Zhixing Xiong,Yingying Gao,Hang Gao,Ya Zhang
2,2,6,6-Tetramethyl-1-piperidine N -oxyl (TEMPO) and nickel hydroxide (Ni(OH) 2 ) mediated electrooxidation of glycine were performed and roles of bases in these two reactions were investigated by cyclic voltammetry . Trends of 2,4,6-collidine > 2,6-lutidine > 3-picoline > pyridine and KOH > NaOH > LiOH were observed in the studies of bases dependent activities on TEMPO and Ni(OH) 2 mediated glycine electrooxidation, respectively. Base effects can be rationalized by acid neutralization, base assisted deprotonation and the interaction between bases and catalysts.
研究领域:
电化学
·
催化反应
·
分析化学
✓ 已验证
产品关联
DOI
高影响因子
危险品化学品经营许可证（带存储）