JOURNAL OF POLYMER SCIENCE
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2021
·Vol. 59
·期 4
·329-339
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IF 0
Mengjie Hu,Haiquan Chen,Mengxia Wang,Gang Liu,Chunhai Chen,Guangtao Qian,Youhai Yu
Polyimides (PI's) with low-dielectric constant and excellent organic solubility have broad application prospects in the electronic field. Herein, this study designed a series of novel, low dielectric, organic soluble PI films by creatively introducing fluorene and pyridine ring into diamine monomers. Because of the noncoplanar structure of fluorenyl and the polarization of pyridine ring, PI films achieved a low-dielectric constant (2.22–3.09 at 10 MHz) and excellent organic solubility. Even in some organic solvents with low-boiling points, these PI films still exhibited outstanding solubility. In addition, all the films possessed high-tensile strength (≈120 MPa) and excellent optical transparency (>70%, 450 nm). It was worth noting that the glass transition temperature of films was all above 280°C and 5% weight loss temperature ( T 5% ) was at 486–553°C. In general, the novel high-performance low-dielectric PI films are expected to be used in the field of microelectronics. Graphical A series of novel, low dielectric, organic soluble PI films are synthesized by creatively introducing fluorene and pyridine ring into diamine monomers. Compared with traditional Kapton film, these new polyimides containing fluorenyl and pyridine heterocycles in the main chain have low-dielectric constants.
研究领域:
材料科学
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电子工程
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DOI
JOURNAL OF HAZARDOUS MATERIALS
·
2020
·
IF 9.038
Xuerui Yang,Xue Cao,Li Zhang,Yanlin Wu,Lei Zhou,Guangli Xiu,Corinne Ferronato,Jean-Marc Chovelon
The widespread utilization of pesticides has attracted increasing attention to their environmental impacts and effective removal strategies. In the present study, the degradation of herbicides picloram (PCLO) and aminopyralid (AMP) with similar structures were investigated systematically by thermo activated persulfate. Overweight SO 4 •− was determined to be the predominant oxidizing species by quenching experiment. Obtained by laser-flash photolysis (LFP), reaction rate constants of SO 4 •− towards AMP and PCLO were determined at 1.56 × 10 9 M −1 s −1 and 1.21 × 10 9 M −1 s −1 , respectively. Product analysis revealed that both substances underwent similar oxidation paths, namely, successive oxidation on pyridine ring and formation of coupling-products as well as further hydroxylation and decarboxylation . Amino group on the pyridine ring was identified as the main reactive site, which was further confirmed by DFT calculation. It was susceptible attacked by SO 4 •− to form deamination, nitration , and self-coupling products. These couples could be further oxidatively dehydrated to form azo and a series of azo derivatives . EOCSAR program predicted significant hazards on aquatic species during the formation of these couplings and azo derivatives. Our work emphasized the potential ability and toxicity of contaminates to produce azo substances in the presence of amino groups on the pyridine ring.
研究领域:
环境科学
·
化学工程
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产品关联
DOI
PubMed
高影响因子
LANGMUIR
·
2023
·
IF 3.9
Wei Yang,Yanhua Gao,Mingli Cao
The enhanced photocatalytic properties of Z-Scheme Bi@BiOCl/C3N4-DPY heterojunction materials were successfully prepared by the ultrasonic-assisted coprecipitation method. The Bi@BiOCl/C3N4-DPY heterojunction exhibited remarkable photocatalytic activity under visible light irradiation, and the degradation rate of methyl orange (MO) was about 90.6% in 180 min. This impressive efficiency is mainly due to the Z-Scheme charge transfer mechanism in Bi@BiOCl/C3N4-DPY, resulting in the efficient separation of charge carriers and an increase in the REDOX potential of photogenerated electrons and holes. C3N4 was modified with a π-deficient conjugated pyridine ring, which caused the light absorption redshift, promoted the formation of oxidizing •O2–, and improved the photocatalytic activity. At the same time, a well-aligned heterojunction is formed at the interface between C3N4-DPY and BiOCl, facilitating the seamless transfer of light-induced electrons from the LUMO of C3N4-DPY to the CB of BiOCl. In addition, the addition of Bi introduces a unique band gap reduction effect, resulting in a change in the density of the band states, which further promotes charge transfer and separation. It is worth noting that the introduction of metallic bismuth (Bi) brings about a unique band gap reduction effect, resulting in a change in the density of states within the band, which ultimately promotes charge transfer and separation. The Z-scheme charge migration inside Bi@BiOCl/C3N4-DPY further promotes the efficient separation of photogenerated electron–hole pairs, greatly improving the overall efficiency of the material. The Z-structured photocatalyst developed in this study has great application potential in various fields of photocatalysis.
研究领域:
材料科学
·
环境科学
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产品关联
DOI
PubMed
高影响因子
Small
·
2024
·
IF 13
Xiang Zhong,Yuxiang Zhu,Yan Wang,Zhengtao Jia,Meng Jiang,Qiufan Sun,Jianfeng Yao
In this work, an intramolecular carbon nitride (CN)-based quaternary homojunction functionalized with pyridine rings is prepared via an in situ alkali-assisted copolymerization strategy of bulk CN and 2-aminopyridine for efficient visible light hydrogen generation. In the obtained structure, triazine-based CN (TCN), heptazine-based CN (HCN), pyridine unit incorporated TCN, and pyridine ring inserted HCN constitute a special multicomponent system and form a built-in electric field between the crystalline semiconductors by the arrangement of energy band levels. The electron-withdrawing function of the conjugated heterocycle can trigger the skeleton delocalization and edge induction effect. Highly accelerated photoelectron-hole transfer rates via multi-stepwise charge migration pathways are achieved by the synergistic effect of the functional group modification and molecular quaternary homojunction. Under the addition of 5 mg 2-aminopyridine, the resulting homojunction framework exhibits a significantly improved hydrogen evolution rate of 6.64 mmol g −1 h −1 with an apparent quantum efficiency of 12.27% at 420 nm. Further, the catalyst verifies its potential commercial value since it can produce hydrogen from various real water environments. This study provides a reliable way for the rational design and fabrication of intramolecular multi-homojunction to obtain high-efficient photocatalytic reactions.
研究领域:
材料科学
·
光催化
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产品关联
DOI
PubMed
高影响因子
HIGH PERFORMANCE POLYMERS
·
2014
·
IF 1.09
Yewei Xu,Yi Sun,Yonglin Lei,Jichuan Huo,Lin Zhang
Poly(N-arylenebenzimidazole ketone ketone pyridine)s have been prepared via N–C coupling reaction that removed the N–H sites from the novel bis(benzimidazoyl) derivatives with activated aromatic difluorides in sulfolane. The reaction was carried out at 210°C in the presence of anhydrous potassium carbonate. The structures of the polymers were characterized by means of Fourier transform infrared and proton nuclear magnetic resonance spectroscopies and elemental analysis. All resulting polymers showed essentially amorphous patterns. Differential scanning calorimetry and thermogravimetric measurements showed that the polymers had high glass transition temperatures (>179°C), good thermostability, and high decomposition temperatures (>401°C). These novel polymers also showed easy solubility.
研究领域:
高分子化学
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材料科学
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产品关联
DOI
高影响因子
NEW JOURNAL OF CHEMISTRY
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2021
·Vol. 45
·期 21
·9382-9393
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IF 3.591
Xiangzhi Feng,Yuanyuan Li,Yuanyuan Yang,Yulong Ma,Wenxin Ji,Yonggang Sun,Tong Chen,Yang Chen
In order to achieve rapid and effective analysis of praziquantel and pymetrozine residues in food, a new magnetic solid phase extraction (m-SPE) material based on GO and ZIF-67 was synthesized. Because the release of ZIF and GO materials may lead to secondary environmental pollution and their separation from solutions is difficult, ZIF-67 loaded on sheet-like MGO@PDA, a magnetic porous nano-composite, was fabricated by a convenient method at room temperature. The poly-dopamine (PDA) layer can improve the hydrophilicity of the material. The resultant MGO@PDA@ZIF-67 preserved the properties of ZIF-67 and MGO. The adsorbent material was characterized by XRD, VSM, TEM, SEM, TGA, XPS and FTIR experiments. An m-SPE technique was developed to selectively enrich two pyridine ring insecticides (praziquantel and pymetrozine) using high performance liquid chromatography (HPLC). The adsorption mechanism was investigated. Results showed that the maximum adsorption capacities of the new material for praziquantel and pymetrozine are 22.68 and 24.27 mg g−1, respectively. The method was successfully applied to the analysis of praziquantel and pymetrozine in vegetable samples with satisfactory recoveries (92.3%–102.8%) and precisions. Due to the advantages of easy preparation, high efficiency, and renewability, the prepared hydrophilic magnetic porous nano-composite is an excellent candidate for adsorption and separation and provides a promising magnetic ZIF-67 material for multi-component system separation.
研究领域:
食品科学
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环境科学
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分析化学
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产品关联
DOI
高影响因子
JOURNAL OF APPLIED POLYMER SCIENCE
·
2016
·Vol. 133
·期 28
·
IF 1.866
Baoming Li,Zhiyin Wu,Li Lin
A novel organosoluble polyimide (PI) with pyrimidine ring in the main chain was synthesized by chemical and thermal imidization, respectively, from 3,3′,4,4′-benzophenone tetracarboxylic dianhydride and 2,4-diamino-6-chloropyrimidine as raw materials and its molecular structure, solubility, UV–visible absorption characteristic, crystallinity, thermal stability, electrochemical behaviors, and mechanical properties were also studied. It was found that the introduction of pyrimidine ring in the main chain could increase the solubility of PI in polar aprotic solvents at room temperature and 60 °C, respectively, because of its molecular main chain with asymmetric structure and two polar N atoms in pyrimidine ring. Furthermore, PI had strong optical absorption peak intensity, excellent thermal stability, good redox reversibility, especially outstanding mechanical properties, which were conductive to its potential applications in adhesives, polyelectrolyte, separation membrane, and so on. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133 , 43680.
研究领域:
材料科学
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高分子化学
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产品关联
DOI
高影响因子
CHINESE CHEMICAL LETTERS
·
2022
·
IF 8.455
Guoqiang Zhang,Yangsen Xu,Guoshuai Liu,Yongliang Li,Chuanxin He,Xiangzhong Ren,Peixin Zhang,Hongwei Mi
ABSTRACT The strong intrinsic Coulomb interactions of Frenkel excitons in crystalline carbon nitride (CCN) greatly limits their dissociation into electrons and holes, resulting in unsatisfactory charges separation and photocatalytic efficiency. Herein, we propose a strategy to facilitate excitons dissociation by molecular regulation induced built-in electric field (BIEF). The electron-rich pyrimidine-ring into CCN changes the charge density distribution over heptazine-rings to induce BIEF between melon chains. Such BIEF is sufficient to overcome the considerable exciton binding energy (EBE) and reduce it from 38.4 meV to 16.4 meV, increasing the excitons dissociation efficiency (EDE) from 21.5% to 51.9%. Our results establish a strategy to facilitate excitons dissociation through molecular regulation induced BIEF, targeting the intrinsic high EBE and low EDE of polymer photocatalysts.
研究领域:
材料科学
·
光催化化学
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产品关联
DOI
高影响因子
WATER RESEARCH
·
2019
·
IF 7.913
Xuerui Yang,Xi Ding,Lei Zhou,Huan-huan Fan,Xingbao Wang,Corinne Ferronato,Jean-Marc Chovelon,Guangli Xiu
Contamination by herbicides such as clopyralid (CLP) poses a significant threat to human health and ecological systems. In the present study, efficient removal of CLP was achieved by thermo activated persulfate, among which sulfate radical was identified as the predominant oxidizing species responsible for the decontamination . Based on high resolution LC-MS, derivatization method and density functional theory (DFT) computation, the detailed oxidation pathways and mechanisms were proposed. The primary oxidation pathways included dechlorination-hydroxylation, decarboxylation and the formation of quinone-like moieties. Afterwards, numerous intermediate byproducts ranging from high molecular to very small ones were identified, suggesting the pyridine ring was damaged during the thermo activated persulfate process. The detected products containing six and five carbons indicated the pyridine ring cleavage would take place on the quinone-structure intermediate. Further oxidation could continue by breaking each bond on the ring-cleavage product, yielding a series of short-chain carbonyl chemicals, carboxylic acids and inorganic ions. In addition, the presence of dissolved oxygen (DO) was favorable to CLP degradation, indicating DO played an important role in applying such technology . The degradation rate constants of CLP increased appreciably with increasing temperature, and acidic pH facilitated the CLP degradation. The results obtained in this work would increase our understanding on the environmental fates of nitrogen heterocyclic compounds during sulfate radical (SO 4 •− )-based advanced oxidation processes (SR-AOPs).
研究领域:
环境科学
·
化学
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DOI
高影响因子
JOURNAL OF APPLIED POLYMER SCIENCE
·
2025
·
IF 2.8
Hongbo Xiao,Xin Huang,Wanyu Huang,Yufei Peng
In order to improve the flame retardancy, smoke suppressing, and mechanical properties of epoxy resins (EP), while pursuing low toxicity, environmental protection, and sustainable development, a reactive biobased flame retardant (TVD) containing P/N was synthesized by the one-pot method. The flame retardant, consisting of vanillin, 2,4,6-triaminopyrimidine, and DOPO as reactants, contained reactive groups in its structure and was introduced as a co-curing agent into the DDM-cured EP system. EP/TVD10 (at a phosphorus content of 0.58 wt%) achieved a UL-94 V-0 rating with an increased limit oxygen index (LOI) value of 34.2% (26.5% for pure EP), and the cone calorimetric test (CCT) results showed a decrease in total heat release (THR) values of 33.8% and a decrease in total smoke production rate (TSP) of 21.1% compared to pure EP. In addition, the introduction of TVD improved the mechanical properties of the epoxy resin, with an increase in flexural strength and modulus of 8.7% and 6.5% and a slight increase in impact toughness for EP/TVD10. These results indicate that TVD is a multifunctional and efficient bio-based flame retardant, which provides new ideas for the development of high-performance modified epoxy resin materials.
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
POLYMERS FOR ADVANCED TECHNOLOGIES
·
2022
·Vol. 33
·期 5
·1385-1393
·
IF 3.348
Jinde He,Ye Yuan,Liuyan Tang,Jinqing Qu
In order to prepare multifunctional fluorescent hydrogel (FH), functional Schiff base ligands have been incorporated into polymer networks. We reported here a novel multifunctional Schiff base functionalized FH, P(AM-PEGA-PEPMA), and its corresponding metallohydrogel, Zn 2+ -P(AM-PEGA-PEPMA), which exhibited tunable fluorescence intensity, self-healing ability, stretchability, and shape-memory property. P(AM-PEGA-PEPMA) was obtained by one-pot micellar copolymerization and Zn 2+ -P(AM-PEGA-PEPMA) was formed by metal coordination between Schiff base ligand (PEPMA) and Zn 2+ . Zn 2+ -P(AM-PEGA-PEPMA) hydrogel was obtained after cross-linking by the PEPMA-Zn 2+ metal coordination, whose maximum tensile strain can reach over 900%. The fluorescent intensity of Zn 2+ -P(AM-PEGA-PEPMA) hydrogel gradually increased with the increase of Zn 2+ concentration ([Zn 2+ ]). When [Zn 2+ ] was 0.1 M, it could reach to 400% of the original fluorescence intensity. The reversible fluorescence change of hydrogel can be controlled by Zn 2+ together with pH. What's more, the Zn 2+ -P(AM-PEGA-PEPMA) hydrogel has the ability to self-heal within a minute at room temperature. The shape of the P(AM-PEGA-PEPMA) hydrogel was memorized/restored by the forming/breaking the metal coordination between PEPMA and Fe 3+ . With above properties, P(AM-PEGA-PEPMA) hydrogel and Zn 2+ -P(AM-PEGA-PEPMA) hydrogel are expected to be applied for encryption, flexible sensors and soft wearable devices.
研究领域:
材料科学
·
化学
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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）