水滑石在多相催化中应用的研究进展

叙述了水滑石类化合物作为固体酸碱催化剂、氧化还原反应催化剂、催化剂载体等方面的应用情况,提出了水滑石类化合物作为一类新型的环境友好的固体催化剂,在醇醛缩合、腈类水解、环氧化物的开环反应、芳烃类化合物的氧化、醇类氧化、硝基化合物的还原等许多重要的有机合成反应具有重要的应用前景,并且与传统催化剂相比具有污染小、易分离、反应活性高等优点。     

LDHs功能材料在建筑领域的应用研究进展

层状双（或复合）金属氢氧化物（Layered Double Hydroxides,LDHs）是一类具有特殊结构与功能的新型层状材料,因其独特的组成结构可调变性及记忆效应等特性使其在诸多领域获得广泛的研究和应用。综述了LDHs材料的组成、结构和性质以及近年来LDHs功能材料在混凝土、涂料、保温材料及其他建材中的应用进展。讨论了LDHs材料的特点和应用机理,并分析了当前LDHs材料存在的制备成本高、制备工艺条件苛刻、剥离困难及插层组装定位取向和机理分析不够成熟、用途较单一等问题。最后对LDHs在超分子功能材料及剥离重组等方面的开发使用进行了展望。     

水滑石类插层材料的制备技术及应用

水滑石类插层材料(LDHs)具有特殊的层状结构,其组成、离子种类和数量、晶粒尺寸等参量都可以进行调控,使其具有特殊的性能,成为当前研究的热点.主要介绍了LDHs的基本结构、诸多性质、制备技术及应用领域,有助于更全面地认识LDHs以及对其研究的重要性.     

MoO4^2-插层Mg／Al／Ti—LDHs的结构及其催化性能研究

用共沉淀法制备层板含钛的镁铝钛三元层状双金属氢氧化物（LDHs）,将其作为前驱体,利用离子交换法制备MoO4^2-阴离子插层结构的MoO4^2--LDHs型超分子材料,通过X射线衍射（XRD）、红外光谱（FT-IR）和热重及差热分析（TG—DTA）等对插层化合物及其焙烧产物的结构进行了分析,结果表明,通过共沉淀和离子交换法成功得到晶体结构较为理想的层板含Ti^4＋的三元LDHs以及具有超分子结构的MoO4^2-插层LDH化合物。研究发现,MoO4^2--LDHs在500℃焙烧,产物在丙烯环氧化反应中具有较高的催化活性,这与形成一定结合形式和组成的多元复合金属氧化物有关、     

层状双金属氢氧化物的合成与应用

层状双金属氢氧化物（LDHs）是近来受到广泛关注的一类新型固体催化材料，具有碱性、氧化还原性和层间阴离子可交换性。本文综述了近年来层状双金属氢氧化物合成与应用方面的研究进展。主要包括LDHs及柱撑LDHs的合成方法，LDHs及其焙烧产物在碱催化、氧化还原催化和催化剂载体、功能材料、医药等领域的应用。     

LDHs及其复合材料处理重金属废水的研究进展

面对水体中威胁人类健康的重金属污染,研制吸附效率高、成本低、绿色无污染且对多种重金属离子具有吸附效果的吸附剂是国内外学者共同努力的一个重要方向.层状双氢氧化物(LDHs)是一类具有较大比表面积和较高阴离子交换容量的层状结构化合物,在重金属废水处理方面具有潜在吸附优势.基于前人的研究,分别综述了部分层状双氢氧化物及其复合材料在处理废水中重金属阳离子、重金属阴离子及类金属离子方面的研究进展;在此基础上,总结了层状双氢氧化物及其复合材料在处理重金属废水过程中的作用机理.对开发研制高效、经济、可再生的用于处理含多种重金属离子废水的层状双氢氧化物类吸附剂具有参考价值.     

层状双金属氢氧化物用于催化水氧化的研究进展

通过太阳能光解水制取能源(如氢气)是开发清洁能源的重要途径之一,而水分解的半反应--水氧化过程是整体水分解的重要环节与限速步。发展高效、稳定、易获取的水氧化催化剂是实现有效水分解的关键。层状双金属氢氧化物(layered double hydroxides, LDHs)由于其独特的二维层状结构与灵活调变的化学组成,近年来作为水氧化反应催化剂受到研究者越来越多的关注。除用于电化学水氧化的催化剂外,LDHs在光(电)催化水氧化方面也表现出独特的优势。研究者正致力于LDHs基高效水氧化催化剂的研究,取得了很好的进展。主要综述了LDHs及其复合结构在催化水氧化方面的最新研究进展,以期为水氧化催化剂的结构设计与性能增强提供新的思路。     

LDHs的改性及其阻燃应用研究进展

概述了水滑石类化合物(LDHs)的性能特点、阻燃作用机理,重点介绍了LDHs改性的应用研究进展,指出了其今后的发展方向。     

纳米层状双金属氢氧化物的制备及结构表征

采用恒定pH 12±0.2,按n(Mg2+)∶n(Al3+)∶n(OH-)∶n(CO2-3)=6∶2∶16∶1配制溶液,采用一步反应液相法,制备纳米层状双金属氢氧化物(LDH)粉体.为了获得无团聚、分散均匀的纳米粉体,探讨了溶剂置换干燥、真空干燥、常压干燥对纳米LDH粉体形成团聚的影响;用X射线衍射仪、透射电镜、红外光谱仪和元素分析仪对样品的物相、形貌、粒径和组成进行了表征.结果表明,溶剂置换干燥能够有效防止纳米粉体形成硬团聚,样品分散性好,呈针状形态,长50 nm,宽5 nm.     

Preparation and properties of LDHs/polyimide nanocomposites

Layered double hydroxides/polyimide (LDHs/PI) nanocomposites were prepared from solution of polyamic acid (polyimide precursor) and LDH-amino benzoate using N,N-dimethylacetamide as a solvent. LDH-amino benzoate (LDH-AB) was obtained by coprecipitation method. The amino benzoate, grafted on the surface of the Mg/Al nanolayers, as a connector improved the compatibility between the inorganic Mg/Al nanolayers and the organic polyimide molecules. The dispersion behavior of Mg/Al nanolayers was investigated by transmission electron microscopy and X-ray diffraction, indicating that the Mg/Al nanolayers were exfoliated in PI matrix to form LDH-AB/PI nanocomposites. The maximum tensile strength and elongation of the LDH-AB/PI nanocomposites were found with the LDH-AB content of 5 and 4 wt%, respectively. The initial tensile modulus of these nanocomposites was increased with the LDH-AB content. These nanocomposites exhibited higher storage and loss moduli compared to those of pure PI. T_g of these nanocomposites increased with the LDH-AB content. Coefficients of thermal expansion (CTE, below and above T_g) of these nanocomposites deceased with the LDH-AB content. The thermal properties of these nanocomposites were enhanced by the incorporation of Mg/Al nanolayers in PI matrix.     

Structure and Basicity of Mesoporous Materials from Mg/Al/In Layered Double Hydroxides Prepared by Separate Nucleation and Aging Steps Method

This paper presents the synthesis of mesoporous materials from hydrotalcite-like layered double hydroxides (LDHs) with the Mg^{2 +}/(Al^{3 +} + In^{3 +}) molar ratio of 3.0 on the brucite-like lattice and the interlayer carbonate anions, using a novel separate nucleation and aging steps method developed in our laboratory. The physicochemical properties of as-synthesized LDHs and resulting calcined products at 500C were investigated by powder X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), simultaneous thermogravimetric and differential thermal analysis (TG-DTA), ²⁷Al nuclear magnetic resonance (NMR) and low-temperature nitrogen adsorption-desorption experiments. The results indicate calcination of LDHs with a well-crystallized single phase and nanoscale crystallites leads to the formation of the type MgO-like phase, and the pore size distributions of uncalcined and calcined LDHs are mostly in the range of mesopores. Furthermore, calcined materials have higher surface areas, pore volumes, pore diameters and surface basicities than corresponding precursors. When used as solid base catalysts for the Knoevenagel condensation of ethyl cyanoacetate with benzaldehyde, the material with higher density of base sites on the surface also exhibited a higher catalytic activity. Particularly, calcined MgAlIn-LDH has highest density of base sites resulting in a highest catalytic activity, as points to an important role of indium as a modifier of the surface properties of solid base catalysts.     

Potential for Layered Double Hydroxides-Based,Innovative Drug Delivery Systems

Layered Double Hydroxides (LDHs)-based drug delivery systems have, for many years, shown great promises for the delivery of chemical therapeutics and bioactive molecules to mammalian cells in vitro and in vivo. This system offers high efficiency and drug loading density, as well as excellent protection of loaded molecules from undesired degradation. Toxicological studies have also found LDHs to be biocompatible compared with other widely used nanoparticles, such as iron oxide, silica, and single-walled carbon nanotubes. A plethora of bio-molecules have been reported to either attach to the surface of or intercalate into LDH materials through co-precipitation or anion-exchange reaction, including amino acid and peptides, ATPs, vitamins, and even polysaccharides. Recently, LDHs have been used for gene delivery of small molecular nucleic acids, such as antisense, oligonucleotides, PCR fragments, siRNA molecules or sheared genomic DNA. These nano-medicines have been applied to target cells or organs in gene therapeutic approaches. This review summarizes current progress of the development of LDHs nanoparticle drug carriers for nucleotides, anti-inflammatory, anti-cancer drugs and recent LDH application in medical research. Ground breaking studies will be highlighted and an outlook of the possible future progress proposed. It is hoped that the layered inorganic material will open up new frontier of research, leading to new nano-drugs in clinical applications.     

Preparation and properties of LDHs/epoxy nanocomposites

Layered double hydroxides (LDHs)/epoxy nanocomposites were prepared by mixing the amino laurate intercalated LDHs, EPON 828 resin, and Jeffamine D400 as a curing agent. The organo-modified LDHs with hydrophobic property easily disperse in epoxy resin, and the amino laurate intercalated LDHs with large gallery space allow the epoxy molecules and the curing agents to easily diffuse into the LDHs galleries at elevated temperature. After the thermal curing process, the exfoliated LDHs/epoxy nanocomposites were formed. X-ray diffraction was used to detect the formation process of the exfoliated LDHs/epoxy nanocomposites. TEM was used to observe the dispersed behavior of the LDHs nanolayers, and the LDHs nanolayers were exfoliated and well dispersed in these nanocomposites. Owing to the reaction between the amine groups of the intercalated amino laurate and epoxy groups, the adhesion between the LDHs nanolayers and epoxy molecules makes these LDHs/epoxy nanocomposites more compatible. Consequently, the tensile properties from tensile test and the mechanical properties from DMA were enhanced, and the T_g of these nanocomposites from DMA and TMA were increased. Coefficients of thermal expansion (CTEs, below and above T_g) of these nanocomposites from TMA decreased with the LDHs content. The thermal stability of these nanocomposites was enhanced by the well dispersed LDHs nanolayers.     

水滑石纳米材料特性及其在电化学生物传感器方面的应用

阐述了水滑石纳米材料结构和性能之间的关系及近年来水滑石纳米材料在电化学生物传感器方面应用的最新进展。重点介绍了水滑石纳米材料在吸附生物酶制备电化学传感器、水滑石纳米片固定生物酶制备电化学传感器、水滑石纳米片固定其它活性组分制备电化学传感器、水滑石自构筑电化学传感器等方面的应用。着重对水滑石纳米材料制备电化学传感器的机理和制备方法进行了系统概述。提出了水滑石纳米材料构筑电化学生物传感器应用研究的发展趋势：对水滑石纳米材料进行多层、多组分、微型化和阵列化等多样化设计,指出高选择性和高灵敏度检测是未来新型电化学生物传感器应用研究的主要发展方向。     

水滑石类热稳定剂在聚氯乙烯中的应用研究进展

聚氯乙烯(PVC)全球三大通用树脂之一,广泛应用于国名经济诸多重要领域。但是,因结构的不稳定性,其热加工成型温度远高于其热老化脱氯化氢温度,严重制约其可加工性和应用性能,因此,在其加工过程中必须加入适量的高效热稳定剂以提高其热稳定性。水滑石类(LDHs)热稳定剂作为一种二维阴离子型层状化合物,作为一类新型高效环保型热稳定剂已引起国内外科研界和产业界的广泛关注,有望逐步替代传统有毒有害如铅盐等热稳定剂。本文简要从水滑石热稳定作用机理、主体和客体层板组成及其在PVC复合材料中分散性等方面综述了国内外研究进展,以期有助于对类水滑石热稳定剂结构的可调变性和性能提升的了解。     

纳米双羟基复合金属氧化物(LDHs)对聚氯乙烯(PVC)阻燃抑烟研究

总结了聚氯乙烯(PVC)塑料燃烧时产生烟雾的机理及其阻燃抑烟原理,并且在已开发出的常用无机阻燃抑烟剂的基础上研究了一种新型的无毒环保型无机纳米级阻燃抑烟剂———纳米双羟基复合金属氧化物(LDHs)。分析了其对PVC的阻燃抑烟机理,并且试验证实了它的阻燃抑烟效果。试验结果表明,该阻燃剂只需少量添加就有明显的阻燃抑烟效果,并且克服了以往由于大量添加无机阻燃剂而造成的力学性能下降的缺点,是一种很有发展前景的新型阻燃抑烟剂。     

以煤矸石为铝源制备镁铝层状双金属氢氧化物

以煤矸石为铝源,经机械活化、热活化、酸浸提、制备了一水软铝石,再通过共沉淀法合成Mg-Al层状双金属氢氧化物.采用XRD、FT-IR和SEM等手段对合成样品进行分析和表征.结果表明:煤矸石在热活化温度为700 ℃、浸取温度为100 ℃、浸取时间为150 min、助溶剂/样品质量比为2∶10、硫酸浓度为4 mol/L、液固比为15∶1时,Al2O3浸取率为0.937.共沉淀法制备Mg-Al层状双金属氢氧化物在Mg与Al物质的量比为2∶1,pH值为10,反应温度为60 ℃时,得到层间距d(003)为0.798 nm的镁铝层状双金属氢氧化物.     

水滑石基电极材料的结构调控及电化学储能应用研究进展

水滑石是一种具有层板金属阳离子可搭配、层间客体可替代和高分散性的二维层板状纳米材料,在能量存储与转换应用领域获得广泛的关注和研究.但由于水滑石自身存在容易聚集和电导率差并且在电化学循环过程中易粉化的问题,因此需对水滑石基电极材料进行针对性结构设计,从而提高其电化学性能.系统介绍了水滑石材料的结构与性质特点和当下对其结构...