四种单萜类查尔酮的合成

以2, 4, 6-三羟基苯乙酮和柠檬醛为起始原料经过环化、羟醛缩合和催化加氢合成四种单萜类查尔酮;关键步骤2, 4, 6-三羟基苯乙酮和柠檬醛是在吡啶的催化下经过电子环化、质子迁移及Diels-Alder反应合成天然产物desbenzylidenerubramin (1),中间体1合成一种天然产物产物rubraine (2~5),其结构经~1H NMR和HREIMS表征。     

Decorating surface charge of graphite nanoplate using an electrostatic coupling agent for 3-dimensional polymer nanocomposite

Here, we report a facile approach to electrostatically couple the surface charges of graphite nanoplate (GNP) fillers and poly(methyl methacrylate) (PMMA) polymer particles using ethylene maleic anhydride (EMA) copolymer as an electrostatic coupling agent. Our strategy involved switching the intrinsic repulsive electrostatic interactions between the directly exfoliated GNPs fillers and the PMMA particles to attractive electrostatic surface interactions for preparing core(PMMA)-shell (GNP) precursor in order to optimizing 3-dimensionally dispersed polymer nanocomposite. As a result, the electrical conductivity of the composites dramatically increased by a factor of 16.7 in the EMA-coupled GNP/PMMA composites compared with that of the EMA-free GNP/PMMA composites. In addition, the percolation threshold was also notably reduced from 0.32 to 0.159 vol% after electrostatic coupling of the GNPs fillers and PMMA particles. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48390.     

Magnetic and Electrical Properties of Glass and Glass-Ceramics Based on Weathered Basalt

Silicon - A total of six glass batches (WB100-WB50) based primarily on weathered basalt with successive addition of bypass cement dust (with the weight content 0–50%) were melted at...     

分块大小对BCS框架下移动机器人图像重构影响

将分块压缩感知应用到移动机器人图像成像中时,图像分块的大小对图像重构有一定的影响。重点在基于BCS和SPL-DCT-DDDCWTT重构模型基础上,研究了分块大小对重构效果的影响。实验结果表明,随着分块增大,图像重构精度呈上升趋势,但重构时间都呈先下降后上升的趋势,综合分析,在分块大小为附近时,图像的重构效果达到最佳。     

铝电解废槽衬处理技术现状

废槽衬是铝电解过程中产生的危险废弃物,对生态环境危害极大。如何经济、安全、环保地实现废槽衬的无害化处置及资源化利用已成为铝行业关注的热点。阐述了废槽衬的主要来源、组成及对环境的影响,并对废槽衬的处理方法做了综述,重点介绍了已经产业化的处置技术,并对其未来的发展趋势进行了分析,旨在为中国废槽衬的处理提供参考和借鉴。     

Preparation and flocculation properties of biodegradable konjac glucomannan-grafted poly(trimethyl allyl ammonium chloride)

Polymer Bulletin - Preparation of konjac glucomannan-grafted poly(trimethyl allyl ammonium chloride) (KGM-g-PTMAAC) was carried out using KGM as polysaccharide matrix and TMAAC as cationic...     

Efficient preparation of DHMF and HMFA from biomass-derived HMF via a Cannizzaro reaction in ionic liquids

2,5-Dihydroxymethylfuran (DHMF) and 5-hydroxymethylfuranoic acid (HMFA) are the versatile intermediate chemicals of high industrial potential. An efficient preparation of both DHMF and HMFA is reported from biomass-derived HMF via a Cannizzaro reaction using ionic liquids as a reusable reaction solvent under the water-free conditions. The operationally simple and environment-friendly process produces both DHMF and HMFA from HMF consistently in good to high yields up to five runs with the recycled ionic liquid.     

Photopolymerization of hyperbranched aliphatic acrylated poly(amide ester). I. Synthesis and properties

The hyperbranched aliphatic poly(amide ester) (HAPAE) was synthesized based on 4‐N,N‐di(2‐hydroxy ethyl)‐4‐ketobutyric acid prepared by the reaction of succinic anhydride with diethanol amine, as an AB₂ monomer (repeating unit), and with 2‐ethyl‐2‐(hydroxymethyl)‐1,3‐propanediol, as a core molecule, using acid catalysis. The second generation of the product was characterized by measuring dynamic viscosity, which decreased sharply with the increase in frequency. The product exhibits relative thermal stability as analyzed by thermogravimetry in a nitrogen atmosphere. The glass transition temperature, determined by differential scanning calorimetry, is ?27 °C. The molar mass was measured by vapor pressure osmometry. The polydispersity, measured by size exclusion chromatography, is 2.16. Dynamic mechanical thermal analyses were performed to characterize the thermal properties of the ultraviolet‐cured films of the acrylate‐modified HAPAE. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 1630–1636, 2001     

Phase‐separation prevention and performance improvement of poly(vinyl acetate)/TEOS hybrid using modified sol‐gel process

The formation of covalent bonds between silanols in copolymer and those in silica prevents organic–inorganic phase separation. Two series of hybrid composite materials, poly(vinyl acetate‐co‐vinyl trimethoxysilane)/TEOS and poly[vinyl acetate‐co‐3‐(trimethoxysilyl)propyl methacrylate]/TEOS, were fabricated using a modified sol‐gel process. The hybrids were transparent. Two kinds of silane coupling agents, vinyl trimethoxysilane (VTS) and 3‐(trimethoxysilyl)propyl methacrylate (γ‐MPS), were used to prevent macrophase separation through formation of covalent bonds. Thermal analysis showed that γ‐MPS was more effective than VTS for the formation of covalent bonds. Enhancement of thermal stability of the hybrids was investigated by thermogravimetric analysis. Photomicrographs of scanning electron microscopy and images of atomic force microscopy indicated that inorganic silica particles were homogeneously dispersed in less than 50 nm in organic matrix. The morphological properties of hybrids were strongly dependent on the organic–inorganic composition. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 2310–2318, 2001