COMPOSITES PART B-ENGINEERING
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2020
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IF 7.635
Jingkai Liu,Jinyue Dai,Shuaipeng Wang,Yunyan Peng,Lijun Cao,Xiaoqing Liu
With the purpose to obtain an eco-friendly flame retardant for epoxy resin, a facile method for the synthesis of a bio-based epoxy monomer containing DOPO units (DGEBDB) from lignin-derived vanillin and guaiacol, was presented in this work. During the synthesis process, guaiacol acted as both reactant and solvent. And it could be recycled in situ and re-used as the fresh one. In order to evaluate the flame retardancy of DGEBDB, it was mixed with diglycidyl ether of bisphenol A (DGEBA) and cured with 4,4-diaminodiphenylmethane (DDM). Results showed that, DGEBDB demonstrated a good compatibility with DGEBA, and the mechanical properties of cured resins were obviously improved with the addition of DGEBDB. As expected, the limiting oxygen index (LOI) of cured resin reached 30.2% with the content of phosphorus only 0.67 wt%, in which the weight ratio between DGEBDB and DGEBA was 1:9 (B1D9/DDM). When the weight ratio of DGEBDB to DGEBA was further increased to 2:8 for the B2D8/DDM system, the UL-94 V-0 grade was achieved. Meanwhile, the mechanism of DGEBDB in improving the flame retardancy of cured resin was discussed and revealed. This easily available and eco-friendly DGEBDB was proved to be a highly efficient reactive flame retardant for epoxy resin.
研究领域:
材料科学
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化学工程
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DOI
高影响因子
JOURNAL OF APPLIED POLYMER SCIENCE
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2022
·Vol. 139
·期 45
·e53105
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IF 3.057
Xiaohan Li,Ke Zhang,Jiateng Huang,Ziyao Zhou,Kaili Xie,Xiaojie Li,Wei Wei
In order to improve the flame-retardant properties of epoxy resin (EP) without sacrificing the mechanical properties, a high-efficient P/N/S-containing reactive flame retardant (VTZD) was synthesized by a facile one-pot method from vanillin, 2-aminobenzothiazole and 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO), and used in epoxy-amine thermosets. When 5 wt% of VTZD was added with merely 0.31 wt% of phosphorus, the LOI value of cured resins increased to 32.7%, and the thermosets achieved a UL-94 V-0 rating. Furthermore, the peak heat release rate and the total heat release of the VTZD-modified EP decreased by up to 34.66% and 32.49%, respectively, in comparison to those of the original EP. Subsequently, the residual char morphology and structure of epoxy thermosets were investigated, as well as the pyrolysis behavior of VTZD. The flame-retardant mechanism was discussed in detail, and it confirmed that VTZD exhibited a bi-phase flame retardant effect. In addition, the mechanical properties of the cured products were well maintained and even improved. All the results demonstrated that the VTZD was a bio-based high-efficiency flame retardant for EP with a broad prospect in practical applications.
研究领域:
材料科学
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化学工程
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DOI
高影响因子
ACS Catalysis
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2018
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IF 11.384
Cheng Liang,Qiyi Ma,Haoran Yuan,Yongtao Wang,Jianyong Mao,Zhirong Chen,Jia Yao,Haoran Li
An investigation of aerobic oxidation of 2-methoxy-4-methylphenol to vanillin catalyzed by a number of cobalt salts, complexes, oxides, and hydroxides in alkaline solutions is reported. A good yield of vanillin (90%) was obtained when CoCl2 was used as the catalyst, while a poor yield (6%) was obtained with Co3O4. Unexpectedly, however, the Co3O4 catalytic activity was restored after heating in an alcoholic solution of NaOH for 24 h, producing a good yield of vanillin (85%). The recovered catalytic activity of Co3O4 indicated a conversion of inactivated heterogeneous particles to activated particles. In addition, precipitates were generated when “homogeneous” CoCl2 was employed as a catalyst, making us wonder about the true nature of the catalyst in this reaction. A series of experiments are described, including kinetic studies, filtration tests, centrifugation tests, dynamic light scattering, transmission electron microscopy, X-ray photoelectron spectroscopy, and powder X-ray diffraction, for the investigation of the true catalyst under catalytic conditions. The key observations led to the conclusion that the cobalt salts and complexes act as precatalysts that transform to cobalt oxide/hydroxide [CoOx(OH)y] nanoparticles, which is responsible for the benzylic C(sp3)–H oxyfunctionalization of 2-methoxy-4-methylphenol. Additionally, the size of the particles is decisive for catalyst performance. The nature of the active nanoparticles was also studied. With regard to the identification of homogeneous or heterogeneous catalysis, this study provides a complement to existing catalytic reaction types.
研究领域:
化学工程
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催化科学
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材料科学
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DOI
高影响因子
CHINESE JOURNAL OF CHEMICAL ENGINEERING
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2022
·
IF 3.898
Yuandong Cui,Bin He,Yu Lei,Yu Liang,Wanting Zhao,Jian Sun,Xiaomin Liu
High and cost-efficient capture of CO 2 is a prerequisite and an inevitable path of carbon emission reduction. To address the challenges (high cost, low efficiency, less sustainability, etc .) of existing petroleum-based CO 2 absorbents, herein, a class of efficient and sustainable lignin-based absorbents were resoundingly prepared by grafting the active amine group on a lignin derived compound vanillin and alkali lignin. The results demonstrated that vanillin modified by acrylamide achieved the excellent absorption capacity among the three absorbents, whose ability was 0.114 g CO 2 per gram of absorbent under 25 °C and 100 kPa. In addition, the absorbent retained stable absorbability of CO 2 after 6 cycles. The absorbing capacity of the absorbent formed by the coupling of vanillin and acrylamide to CO 2 was much greater than their own ( i.e. 0 g CO 2 ·g −1 vanillin, 0.01 g CO 2 ·g −1 acrylamide, respectively). Detailed information revealed the multi-site synergistic absorption mechanism, in which CO 2 has C and O double interactions with the amide group of the absorbent, and single interaction with the hydroxyl oxygen on the benzene ring of the absorbent. The absorption capacity of modified lignin for CO 2 is as high as 0.12 g CO 2 per gram of absorbent, which is comparable with that of model compound vanillin. This work not only provides a new idea for the design of bio-absorbents for CO 2 capture, but explores the application potential of lignin-based materials.
研究领域:
材料科学
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环境科学
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DOI
高影响因子
ANALYST
·
2025
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IF 3.3
Lu Li,Xiaodi Liu,Shijie Xu,Shiming Zhang,Zhuangzhuang Yang,Debao Xiao
Vanillylmandelic acid (VMA) and homovanillic acid (HVA) are biomarkers for the diagnosis and course-of-disease monitoring of malignant tumor neuroblastomas, which endanger infants and children. Herein, we demonstrated a proof-of-concept visual detection of VMA and HVA on an electrochromic basis, in which the viologen 1,1′-dibenzyl-4,4′-bipyridinium dichloride was used as a coloration chromophore. It was found that VMA and HVA can be used as effective electron mediators to improve the electrochromic performance of devices. It is interesting to note that VMA and HVA reduce the driving voltage of electrochromic devices (ECDs) down to −1.0 V, which is lower than that (−2.1 V) achieved without these additives, and the coloration of ECDs is undoubtedly dependent on the concentration of VMA and HVA from 0.8 to 10−6 mol L−1. Thus, this study presents an ECD platform as a breakthrough strategy for the facile, routine and portable visual detection of the neuroblastoma biomarkers VMA and HVA with obvious advantages over other detection techniques such as HPLC/MS used in clinical diagnosis.
研究领域:
医学诊断
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生物化学
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肿瘤学
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产品关联
DOI
PubMed
高影响因子
LANGMUIR
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2021
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IF 3.882
Bing-Pan Zhang,Hao-Nan Li,Jia-Lu Shen,Di Zhou,Zhi-Kang Xu,Ling-Shu Wan
Mussel-inspired surface modification has received significant interest in recent years because of its simplicity and versatility. The deposition systems are still mainly limited to molecules with catechol chemical structures. In this paper, we report a novel deposition system based on a monophenol, vanillic acid (4-hydroxy-3-methoxybenzoic acid), to fabricate metal–phenolic network coatings on various substrates. The results of the water contact angle and zeta potential reveal that the modified polypropylene microfiltration membrane is underwater superhydrophobic and positively charged, showing applications in oil/water separation and dye removal. Furthermore, the single-face modified Janus membrane is promising in switchable oil/water separation. The results demonstrate a novel example of the metal–monophenolic deposition system, which expands the toolbox of surface coatings and facilitates the understanding of the deposition of phenols.
研究领域:
材料科学
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表面化学
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产品关联
DOI
PubMed
高影响因子
POLYMER DEGRADATION AND STABILITY
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2024
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IF 6.3
Kai Dong,Shasha Tang,Di Zhao,Yang Pang,Chengji Zhao
Incorporating reversible covalent bonds into the crosslinked matrix of bio-based epoxy resins can address the challenges of difficult degradation and sustainable development associated with petroleum-based epoxy resins. However, the dynamic capability conferred by a single dynamic chemical bond proves relatively insufficient in thermosetting polymers. Therefore, we propose a strategy to introduce proportionally adjustable dual dynamic covalent bonds in the bio-based epoxy resin system to leverage the advantages of different dynamic bonds and improve the dynamic properties of the resulting epoxy vitrimers in this study. First, a bio-based epoxy monomer (BVF-EP) derived from vanillin was prepared and cured with a diamine hardener (AFD). Subsequently, vanillin-derived epoxy vitrimers were prepared by varying the stoichiometric ratio of AFD to BVF-EP ( R = 0.5, 1.0, and 1.5) without catalysts. Some of the vitrimers showed good thermal stability and excellent reprocessability and degradability. Notably, BVF-EP/AFD ( R = 1.5) containing both dynamic reversible covalent bonds of S-S and C=N with the highest crosslink density, exhibited the highest thermal decomposition temperature, highest tensile modulus (7175 MPa), and the shortest stress relaxation time (6 s at 200 ℃). Simultaneously, BVF-EP/AFD ( R = 1.5) demonstrated good multiple reprocessing capacity under a pressure of 5 MPa at 140 ℃. It can be completely degraded in two distinct mixed solutions (50 % DMF/50 % β -ME and 50 % 1 M HCl/50 % DMF), offering great potential in recovering high-value carbon fibers from its carbon fiber-reinforced composites. This work advances the development of bio-based epoxy resins with dual dynamic crosslinked networks, providing new insights for the degradation and reprocessing of thermoset polymers.
研究领域:
材料科学
·
化学工程
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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）