ACS Applied Polymer Materials
·
2019
·
IF 0
Arun Saini,Chandravati Yadav,Bai-Liang Xue,Nan Wang,Lei Dai,Xinping Li
In this study, a mixed-acid-assisted system utilizing a combination of a weak acid (citric acid, CA) and strong acid (H2SO4, SA) under hydrothermal reaction conditions was proposed for simultaneous preparation and modification (carboxylation) of cellulose nanocrystals (CNCs). Bleached bamboo pulp was used as the cellulose source, and the optimized reaction conditions were further used to produce carboxylated CNCs (cCNCs) from microcrystalline cellulose and Whatman 1 filter paper. Different concentrations of CA and SA (namely, 40 wt % CA (optimized concentration) and 5, 10, 20, and 30 wt % SA) were used for the hydrolytic processing of raw cellulosic material under hydrothermal conditions. The effect of various concentrations of CA and SA on the yield, carboxylate content, microstructure, crystallinity, thermal, and rheological characteristics of cCNCs were methodically investigated and contrasted. The optimized hydrothermal reaction conditions performed for 4 h at 100 °C using a mixture of 40 wt % CA and only 20 wt % SA yielded needle-shaped cCNCs with a yield higher than 70%. The carboxyl functionalization of CNCs was affirmed through Fourier transform infrared spectroscopy and conductometric titrimetric method. The results revealed the carboxylate content of 1.18 mmol/g corresponding to an average degree of oxidation of ∼0.20. The length of nanocrystals lies in the range of 280–420 nm with diameter ranging from 10 to 20 nm, as was perceived through microstructural analytical tools like field emission scanning electron microscopy, transmission electron microscopy, and atomic force microscopy. Dynamic light scattering analysis gives an average size of ∼200 nm. The visual inspection revealed high colloidal stability of cCNCs dispersions, which was further supported through its appreciable Zeta potential value of ca. −49.5 mV. Further, the rheological characterizations revealed typical features reminiscent of critical gels showing elastic behavior of cCNCs. Nanocomposite films of hydroxypropyl methylcellulose (HPMC) with different loadings of cCNCs were fabricated using a simple solvent casting method. The incorporation of very small amounts of cCNCs (0.1 wt %) in HPMC resulted in ∼58% increment in tensile strength, ∼10% increment in modulus, and ∼82% increment in elongation. Moreover, the composite films exhibited high transparency and appreciable water barrier properties that allow their potential application as barrier and transparent films for various applications.
研究领域:
材料科学
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化学工程
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DOI
Analytical Methods
·
2019
·Vol. 11
·期 22
·2868-2874
·
IF 2.378
Lifei Ji,Xian Zhou,Jian Zhang,Xin Zhang,Weidong Kang,Fengchun Yang
Organic dye detection requires high sensitivity, low-cost equipment, simplified procedures, and real-time capabilities; thus, electrochemical methods are gradually emerging in this field instead of chromatography. However, much attention has been paid to toxic and complex metal or noble-metal hybrid materials for constructing electrochemical sensors, which is extremely limiting for practical applications. In this study, a metal-free electrocatalyst, MWNTs with carboxylic groups (MWNTs–COOH), was prepared through surface oxidation in a piranha solution and a simple hydrothermal treatment. The obtained MWNTs–COOH possessed superior hydrophilicity, increased conductivity and substantial active carbon or carboxylic group sites, as determined by characterization using Raman spectroscopy, contact angle measurements, electrochemical surface area analysis, and X-ray photoelectron spectroscopy. The above advantages enabled MWNTs–COOH to exhibit excellent electrochemical activities, with a satisfactory utilization for determining trace Rhodamine B (RhB), showing a lower calculated detection limitation of 2.66 nM and a wider linear range from 0.05 to 850 μM with outstanding specificity and reproducibility. Furthermore, it was found that the carboxyl group on the MWNTs would probably have triggered the electron redistribution and exposed more adjacent active carbon sites, which facilitate the electrocatalytic function to CN on the RhB directly.
研究领域:
分析化学
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环境科学
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材料科学
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DOI
高影响因子
RSC Advances
·
2015
·Vol. 5
·期 51
·40588-40594
·
IF 3.84
Dan-Dan Liu,Hua Su,Qian Cao,Xue-Yi Le,Zong-Wan Mao
Carbon nanodots (C-Dots) have recently been proposed as promising alternatives to traditional semiconductor quantum dots and organic fluorophores. However, C-Dots were often prepared and studied as a mixture, and the ignorance of the real composition significantly limits the accurate understanding and control of physical/chemical properties of C-Dots and further practical applications. Herein, we demonstrated and identified for the first time the co-existence of highly-fluorescent carboxylic group-rich C-Dots (CR-C-Dots) and amine group-rich C-Dots (AR-C-Dots) during the one-pot pyrolysis of citric acid and branched polyethylenimine precursors. Transmission electron microscopy demonstrated that the average size of CR-C-Dots was slightly smaller than that of amine group-rich C-Dots (AR-C-Dots), 1.5 nm vs. 1.9 nm. Photophysical characterization indicated that CR-C-Dots had a longer fluorescence lifetime and higher quantum yields (QYs) than the AR-C-Dots, despite the same excitation-independent emission at 445 nm, unlike most previous reports, which stated that amine group passivation enhanced the QYs of C-Dots. Both the C-Dots showed excellent biocompatibility and great potential for cellular imaging. A fluorescence- and electron spin resonance-responsive dual-model probe for ascorbic acid detection was also constructed, further proving the existence of CR-C-Dots. This study facilitates the understanding of the nucleation/surface passivation process during C-Dots formation and the development of a new synthetic and purification strategy for C-Dots.
研究领域:
材料科学
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生物医学工程
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DOI
高影响因子
Molecular Catalysis
·
2017
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IF 0
Li Liu,Ying Shi,Menglu Li,Chaoqun Sun,Yijuan Long,Huzhi Zheng
Recently, an important and intriguing property of fluorescein to function as an artificial peroxidase was found. Although, as a new class of small molecule enzyme mimics, the catalytic activities should be highly associated with the composition and structure, little is known about the mechanism underlying the functional groups mediated enzyme-like activities. Herein, we report for the first time that fluorescein derivatives, i.e. , carboxyfluorescein (CF) and aminofluorescein (AF) possess peroxidase-like activity, and investigate the impact of different functional groups on the catalytic performance. By systematically evaluating absorption intensity, electron spin resonance (ESR) signals, enzyme kinetic parameters and activation energies, we obtain evidence that the carboxyl group can enhance catalytic activity and may serve as substrate-binding sites, but the amino group can even inhibit the catalytic reaction. Correspondingly, the theoretical study further identified these experimental results in molecular-level. These observations pave the way for identifying highly effective functional groups that promote the overall performance of fluorescein-based artificial peroxidase. Meanwhile, this work should facilitate the design and construction of tailor-made small molecule peroxidase mimics.
研究领域:
生物化学
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分子生物学
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DOI
JOURNAL OF WUHAN UNIVERSITY OF TECHNOLOGY-MATERIALS SCIENCE EDITION
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2018
·Vol. 33
·期 1
·226-232
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IF 0.524
Chen Gang,Lei Jiaheng,Du Yong,Chen Xuebing
The dispersion ability of polycarboxylate superplasticizer (PCE) in fresh concrete was much impeded by clay impurities. To improve the dispersion of PCE in the clay-contained concrete, a novel PCE with carboxyl as a specific branched chain terminal group was synthesized, using modified polyether as the raw material which was prepared through esterification between hexahydrophthalic anhydride (HHPA) and isobutenyl polyoxyethylene ether (IPEG) with hydroxy as the terminal group. The esterification product and PCE molecular structure were characterized by infrared spectroscopy and 1HNMR resonance. The results confirmed that the product molecular structure was a comb-type copolymer with long-chain terminal carboxyl group and PEO attached directly to the backbone chain. The as-synthesized PCEs had favorable dispersibility in cement than conventional PCE in the presence of montmorillonite (Mmt) clay. This can be attributed to the introduction of electronegative carboxyl to PCE long-chain terminal group, which reduces the adsorption of PCE on Mmt, and thus improves the tolerance of PCE to the Mmt.
研究领域:
材料科学
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化学工程
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产品关联
DOI
高影响因子
JOURNAL OF MOLECULAR STRUCTURE
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2017
·
IF 1.753
Qi Yao,Chenying Li,Henghui Huang,Hualin Chen,Bailing Liu
A series of carboxyl-terminated hyperbranched oligomer polyester (HBP) with different degree of branching (DB) and number average molar mass ( M ¯ n ) have been prepared. The molecular structure, degree of branching, molecular mass and its distribution of HBP were investigated by FTIR, 1 H NMR, and GPC , respectively. And the coordination number , stability constant and degree of dissociation (α) between HBP and chromium(Ⅲ) were measured via continuous variation method (Job's plot). Experimental results show that the coordination capability between HBP and chromium(Ⅲ) affected by both DB and molecular mass, and the latter plays a decisive role. Moreover HBP outperforms low molecular weight of organic acids (citric acid, acetic acid) and linear polyacrylic acid with similar molecular mass. The coordination number and stability constants of HBP-3 ( M ¯ n = 1713 Da, M ¯ w / M ¯ n (PDI) = 1.11 and DB = 0.72) can reach 4 and 6.55e+008, which demonstrated it can be selected as a good ligand to coordination with chromium(Ⅲ). Therefore HBP can be used as chrome auxiliary in chrome tanning to improve the absorption of chromium.
研究领域:
化学
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材料科学
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DOI
高影响因子
INTEGRATED FERROELECTRICS
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2016
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IF 0.375
Dong-Wei Han,Xiu-Lan Zhang,Bing Yu,Hai-Lin Cong,Chun-Bo Mu,Hua Yuan
Three kinds of carboxyfullerenes, La@C82-COOH, C60-COOH and C70-COOH, were used to modify gold electrodes. The electrochemical behavior of dopamine (DA) at the carboxyfullerenes modified electrodes was studied using the cyclic voltammetry (CV) and differential pulse voltammetry (DPV) methods. The C70-COOH modified electrodes performed the best among them. Under the optimal conditions, linear CV and DPV responses to DA concentration from 1 μmol/L to 13 μmol/L were observed, and the detection limit of DA was 1×10−2 μmol/L in the presence of 10 μmol/L uric acid (UA). The practical analytical utilities of the C70-COOH modified electrodes were demonstrated by the determination of DA HCl in the real samples of dopamine hydrochloride injection (DHI). Moreover, the modified electrodes exhibited good reproducibility and sensitivity, demonstrating its feasibility for analytical purpose.
研究领域:
分析化学
·
神经科学
·
药物分析
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DOI
高影响因子
CELLULOSE
·
2021
·Vol. 29
·期 1
·213-222
·
IF 5.044
Fan Fangwei,Zhu Mengting,Fang Kaiyang,Cao Endi,Yang Yinzhi,Xie Jinpeng,Deng Zhongmin,Chen Yiren,Cao Xinwang
Cellulose nanowhiskers as one kind of renewable and biocompatible nanomaterials evoke much interest because of its versatility in various applications. Herein, the sisal cellulose nanowhiskers with ultrathin diameter of 5–10 nm, high crystallinity of 74% and C6 carboxylate groups converted from C6 primary hydroxyls were prepared via a 2,2,6,6-tetramethylpiperidine-1-oxyl radical (TEMPO)/NaBr/NaClO system selective oxidization combined with mechanical homogenization. The effects of sodium hydroxide concentration in alkali pretreatment on the final sisal cellulose nanowhiskers were explored. It was found that with the increase of sodium hydroxide concentration, the sisal fiber crystalline type would change from cellulose I to cellulose II. The versatile sisal cellulose nanowhiskers would be particularly useful for applications in the nanocomposites as reinforcing phase, as well as in tissue engineering, filtration, pharmaceutical and optical industries as additives.
研究领域:
材料科学
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生物材料学
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产品关联
DOI
高影响因子
CELLULOSE
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2021
·Vol. 28
·期 14
·9489-9504
·
IF 5.044
Zhang Song,Zhang Tingting,He Jinxin,Dong Xia
Silver nanoparticles (AgNPs) loaded on the cotton fiber can endow the fiber with good antibacterial activity, but the AgNPs on the surface of cotton fiber will leach out with the increase of washing times, which will not only greatly reduce the antibacterial properties of cotton fiber, but also cause pollution to the environment. In this paper, carboxyl groups were introduced into cotton fiber by three methods, namely selective oxidation, butane tetracarboxylic acid (BTCA) grafting and polyacrylic acid (PAA) adsorption. The silver ions (Ag + ) were adsorbed on the cotton fibers through electrostatic attraction, and after reduction, the AgNPs were loaded onto the cotton fibers, and the AgNP distribution on the fiber and its effect to the washing resistance of AgNPs were studied. The results showed that the carboxyl groups can be introduced onto the cotton fibers by all the three methods, and the reaction only occurred in the amorphous region of the fibers. The selective oxidation and the BTCA grafting can introduce carboxylic groups into the interior of cotton fibers while the PAA adsorption only imports carboxyl groups on the surface of the fiber. As a consequence, AgNPs were formed inside of the cotton fiber when the selective oxidation and the BTCA grafting were employed, while AgNPs can only be loaded on the surface of the fiber by the PAA adsorption method. AgNPs inside of the fiber have high energetic adherence, resulting in silver-cotton fabric nanocomposites with strong slow-release property and long-term antibacterial ability. The fabric nanocomposites prepared by selective oxidation and BTCA grafting exhibited high AgNP retention rate and excellent antibacterial activity even after 80 washing cycles. Graphic abstract
研究领域:
材料科学
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纺织工程
·
纳米技术
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产品关联
DOI
高影响因子
Discover Applied Sciences
·
2024
·Vol. 6
·期 4
·1-16
·
IF 0
Liu Xiaohong,Basta Altaf H.,Liu Rui,Fu Shiyu
This study describes the preparation of cellulose nanofibers (CNFs) with varying amounts of carboxyl groups from rice straw pulp using the TEMPO/NaBr/NaClO oxidation system. The resulting CNFs were found to be in the form of nanofibers with an average diameter of 6 nm and an average length of 160 nm. To further enhance their properties, the CNFs were grafted with polycaprolactone (PCL) to create CNFs-g-PCL, which was then blended with shape memory polyurethane (SMPU) to produce CNFs-g-PCL/SMPU composites. It was observed that as the carboxyl content in CNFs increased from 0.35 to 1.14 mmol/g, the graft ratio of PCL on CNFs decreased from 24.6 to 10.7%. Consequently, the hydrophobicity of the grafted product (CNFs-g-PCL) also decreased. When 10% CNFs-g-PCL was added to the SMPU matrix, the elastic modulus and tensile stress of the resulting composite were both higher than those of the pure SMPU, increasing by up to 54.4% and 67.3%, respectively. Additionally, the shape retention and shape recovery rates of the composite remained stable after addition of CNFs-g-PCL. In conclusion, incorporating CNFs-g-PCL into SMPU can improve its mechanical properties while maintaining its shape memory properties. Graphical abstract
研究领域:
材料科学
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高分子化学
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纳米技术
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DOI
CARBOHYDRATE POLYMERS
·
2025
·
IF 12.5
Junbo Chen,Yuanpeng Xie,Maosong Tian,Jingfu Tian,Zhihao Liang,Haibo Xie,Menglan Lv
Cellulose has drawn much attention in the field of interfacial solar steam generation (ISSG) due to its advantages of renewability, abundant availability, and hydrophilicity. However, the hydroxyl groups of cellulose form weak hydrogen bond interaction with water, resulting in high evaporation enthalpy and thereby low evaporation rate. Herein, carboxylic acid groups possess of strong interaction with water were introduced into cellulose hydrogel to fabricate efficient ISSG. The carboxylated cellulose hydrogels feature excellent hydrophilicity and water supply capacity because of its rich hydroxyl groups, carboxyl groups, and pore structure. More importantly, the carboxyl groups can effectively weaken the hydrogen bond interactions between water molecules, resulting in larger intermediate water contents that reduced water vaporization enthalpy as small as 1198 J g −1 . Consequently, the evaporator shows a remarkable evaporation rate of 3.68 kg m −2 h −1 under one sun irradiation when using bamboo carbon black as the photothermal material. Moreover, the evaporator exhibits superior seawater and sewage purification capabilities, along with outstanding salt resistance. This work presents an advisable strategy of cellulose structure design for interfacial solar evaporation.
研究领域:
材料科学
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能源科学
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产品关联
DOI
PubMed
高影响因子
INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH
·
2024
·
IF 3.8
Huaichang Wang,Xiaobo Wang,Mengran Yu,Jianing Li,Juming Liu
As a classical photocatalyst, nano-TiO2 has been widely investigated globally. However, achieving its photocatalytic activity within the spectral range of 400 to 740 nm through a facile approach remains a challenge. Herein, carboxylated carbon species sensitized nano-TiO2 was successfully synthesized by a low-temperature (300 °C) carbonization method using ethanol as carbon source and modifier and commercially available nano-TiO2 as titanium source. The obtained sensitized TiO2 nanoparticles exhibited excellent full visible-light-driven photocatalytic degradation performance. The synthesized TiO2 samples were comprehensively analyzed using a range of characterization techniques. The results indicate that the sensitization of carboxylated carbon species endows the nano-TiO2 with full-visible light spectral response properties and facilitates the separation of photogenerated electron–hole pairs, which leads to excellent full visible-light-driven photocatalytic degradation performance. This study presents a novel strategy for broadening the spectral response and facilitating the industrial scale-up of commercially available nano-TiO2.
研究领域:
材料科学
·
环境科学
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产品关联
DOI
高影响因子
危险品化学品经营许可证（带存储）