双介孔SiO2的制备及表征

以正硅酸乙酯(TEOS)为硅源,十六烷基三甲基溴化铵(CTAB)为模板剂,采用溶胶-凝胶法制备了具有双介孔独立分布的SiO2,并用FT-IR、HRTEM、BET等方法对SiO2进行了表征.结果表明,双介孔SiO2中存在大量无序排列的2～3nm的小介孔和18nm左右的大介孔,具有高比表面积(716.4～968.6m2/g)和大孔(1.03～1.63mL/g):通过改变氨水及模板剂的用量可以实现对孔分布的调控.     

沉淀纳米SiO2的聚硅氧烷原位改性及应用研究

以聚醚改性羟基官能聚二甲基硅氧烷为改性剂,采用化学沉淀-原位改性法合成纳米SiO2.研究了聚硅氧烷原位改性对纳米SiO2特性的影响,并考察了其作为消光剂在醇酸清漆中的应用效果.结果表明,原位改性制得了粒径分布均匀、分散稳定性高的纳米SiO2,其在醇酸清漆中具有高的消光效率,同时能改善漆的透光度.     

原位生成纳米SiO2/橡胶复合材料的制备及性能研究

采用原位生成技术制备了纳米SiO2/橡胶复合材料,研究了生胶的结构、反应时间、催化剂、偶联剂种类及用量对SiO2生成量及其增强橡胶硫化胶性能的影响.结果表明:生胶的结构对SiO2的生成量有较大的影响,不同生胶中生成SiO2量的顺序为NR＞IIR＞SBR＞BR＞NBR.随着反应时间的增加,SiO2的生成量增加,72h后基本达到恒定值,偶联剂的种类对SiO2生成量影响不大.当Si-69的用量为2g/100gNR、催化剂为乙二胺、反应时间为72h时,效果最佳.原位生成纳米SiO2填充橡胶硫化胶的性能优于机械共混法填充橡胶硫化胶的性能.     

室温下介孔分子筛MCM-41的合成与表征

在室温下 ,以十六烷基三甲基溴化铵 (CTABr)为模板剂 ,正硅酸乙酯和水玻璃为硅源 ,通过水热法分别合成出了性能优良的介孔分子筛MCM 4 1,并采用XRD、N2 吸附脱附、FTIR、SEM、热重等手段对合成的样品进行了分析表征。其结果表明 ,合成的固体产物具有MCM 4 1特有的六方排列的孔道结构 ,并且具有较高的有序度、比表面积、孔容和热稳定性     

TiAl/Al_2O_3复合材料的原位合成与表征

采取铝热原位合成的方法,以钛白粉和铝粉为原料原位合成制备TiAl/Al2O3复合材料。通过XRD分析了不同温度下反应过程及烧结样品的物相形成规律。分析结果表明:在750℃条件下反应时,原料中心部分变成了黑色,反应生成了钛的低价氧化物。随着温度的升高逐渐形成了部分TiAl金属间化合物和Al2O3。当温度达到1250℃时,反应比较充分,主要生成了TiAl金属间化合物和Al2O3,原位合成了TiAl/Al2O3复合材料。     

球形SiO2颗粒的合成及反应机理

利用Stober方法合成了球形SiO2颗粒.在乙醇和水的混合溶剂中,以正硅酸乙酯(TEOS)为硅源、氨水作催化剂,在40℃水浴下制备SiO2球形颗粒.通过改变反应物TEOS以及催化剂氨水的加入量,制备了不同粒径的球形SiO2颗粒.利用扫描电镜(SEM)可以看出,随着TEOS和氨水加入量的增加,SiO2颗粒的粒径增大,并探讨了其变化机理.     

SiO2空心微球的制备与表征

以自制的微米级碳酸钙颗粒为模板,正硅酸乙酯为硅源,通过溶胶-凝胶方法合成出CaCO3/SiO2核壳结构;随后通过高温煅烧、酸浸和干燥处理,制备出圆形度高、分散性好、结构完整的微米级SiO2空心球。并利用SEM、XRD、FTIR、TG和压缩实验等方法对空心微球的形貌、结构和抗压强度进行了分析和测定。SiO2空心微球的粒径为2-5μm,壳层厚度为0.42-0.85μm,比表面积为554.01m^2/g,最可几孔径为1.7nm,抗压强度在20~30MPa之间。     

室温条件下-(CH2)3NH2修饰的介孔分子筛MCM-41的合成与表征

在室温条件下,以3-氨丙基三乙氧基硅烷为前驱体,使有机官能团-CH2CH2CH2NH2修饰了硅铝介孔分子筛MCM-41(Si/Al=35),制备了无机-有机复合材料MCM-(CH2)3NH2.并通过XRD,DTA-TGA,FTIR,N2吸附-脱附对复合材料MCM-(CH2)3NH2进行了表征.     

MCM-41介孔分子筛和纳米TiO2/MCM-41的合成与结构表征

以工业水玻璃为硅源,表面活性剂十六烷基三甲基溴化铵为结构模板剂,利用室温晶化法合成出MCM-41介孔分子筛,并以钛酸丁酯为前驱体,通过溶胶凝胶法及液相沉积法对介孔分子筛MCM-41进行纳米TiO2的组装。运用XRD、FT-IR、N2吸附-脱附等表征手段对其结构特征和氧化钛分散状态进行了研究,结果表明：TiO2与MCM-41端基硅氧键反应形成Ti-O-Si键;纳米TiO2不仅进入孔道,较均匀地修饰了介孔分子筛MCM-41的孔壁,而且使介孔分子筛MCM-41仍保持有序的孔道结构。     

原位复合法制备P(AALi-AN-BA)/LiX/SiO2聚合物电解质及其导电性

共聚单体丙烯酸锂(AAL i)、丙烯腈(AN)、丙烯酸丁酯(BA)聚合的同时前驱体正硅酸乙酯(TEOS)水解缩合,在聚合物基体原位生成S iO2粒子,添加复盐L iX(L iC lO4-L iNO3-L iB r共熔盐)后制备了P(AAL i-AN-BA)/L iX/S iO2复合聚合物电解质,用IR和DTA-TG对其进行了表征,采用交流阻抗法研究了电解质膜的离子导电性能。结果表明,原位复合S iO2后体系的热稳定性提高,锂离子传输表观活化能Ea明显降低,电导率增大,当S iO2添加量为10%,L iX含量为75%时,体系的室温电导率达到最大值6.26×10-4S/cm(20℃)。     

One-step synthesis of hydrophobic mesoporous silica ellipsoidal particles with a bimodal mesopore system

Highly CH₃-functionalized mesoporous silica ellipsoidal particles with bimodal mesopore structure were prepared via a one-step route using polymethylhydrosiloxane (PMHS) and tetraethoxysilane (TEOS) with triblock copolymer P123 as template under acidic conditions. N₂ adsorption–desorption, XRD, HRTEM, SEM and ²⁹Si MAS NMR were used to characterize the obtained material. The introduction of PMHS into the synthetic system led to the formation of a bimodal mesopore system consisting of framework mesopores of ∼7.2 nm and textural mesopores of ∼29.4 nm. The two scale pores were directly observed in HRTEM images and indirectly proved by the two-step increase in N₂ adsorption–desorption isotherm. Also, PMHS played an important role in morphology controlling and organic functionalization, ensuring monodisperse ellipsoidal particle morphology and high CH₃ functionalization degree of the mesoporous silica product. Subjected to removing highly diluted nonylphenol from aqueous solution, the hydrophobic bimodal mesoporous silica ellipsoidal particles showed high adsorption performance.     

Bending strength of silica gel with bimodal pores: Effect of variation in mesopore structure

Silica gels with both macropores and mesopores were prepared from water glass by fixing transitional structure of phase separation, and their strength was investigated. Pore structure of the gels was controlled by changing gel-preparation compositions, aging conditions and calcination temperature. Strength of the gels varies depending on the mesopore volume. At the same time, porosity of the gels decreases with decreasing mesopore volume, and correlation between strength and porosity is recognized like other porous systems. The strength of the bimodal porous silica gel is somewhat larger than that in literature for the silica aerogel with similar porosity.     

In situ synthesis method and damping characterization of magnesium matrix composites

Magnesium matrix composites reinforced with 8 wt% TiC was in situ synthesized using remelting and dilution technique. X-ray diffraction analysis revealed the presence of TiC phase in sintered block and magnesium matrix composites. Uniform distribution of fine TiC particulates in matrix material was obtained through microstructure characterization. The results of damping characterization revealed that damping capacity of materials is independent of frequency, but dependent on strain and temperature. There were damping peak in damping–strain curve, which is due to the foul and tangle of dislocations. There were two damping peaks at damping–temperature curve under respective temperature of 130 °C and 240 °C. The former damping peak of magnesium matrix composites is due to dislocation motion, and the latter is due to interface and grain boundary sliding. Generally, damping capacity of magnesium matrix composites is higher than that of AZ91 magnesium alloy, which is due to the addition of TiC particulates.     

In situ synthesis and characterization of porous polymer-ceramic composites as scaffolds for gene delivery

The use of three-dimensional scaffolds in gene delivery has emerged as a popular and necessary delivery vehicle for obtaining controlled gene delivery. In this report, techniques to synthesize composite scaffolds by combining natural polymers such as agarose and alginate with calcium phosphate (CaP) are described. The incorporation of CaP into the agarose or alginate hydrogels was performed in situ and the presence of CaP was confirmed by X-ray diffraction (XRD). The crystallite size of the CaP particles was determined to be 7.20 nm. Lyophilized, porous composites were examined under scanning electron microscopy (SEM) to estimate the size of the pores, an essential requirement for an ideal scaffold. The swelling properties of the composite samples were also investigated to study the effect of CaP incorporation on the behavior of the hydrogels. By incorporating CaP into the hydrogel, the aim is to synthesize a scaffold that is mechanically strong and chemically suitable for use as a gene delivery vehicle in tissue engineering.     

纳米多孔氧化硅薄膜的制备和表征

以正硅酸乙酯、异丙醇、去离子水为原料,盐酸、氨水为催化剂,采用溶胶-凝胶、旋转涂胶、老化及超临界流体干燥工艺制备纳米多孔氧化硅薄膜.研究了溶胶-凝胶工艺的影响因素,考察了溶胶粘度和匀胶转速对成膜性能的影响,采用扫描电镜表征了薄膜的表面形貌和截面结构,用椭偏仪表征了薄膜的孔隙率、介电常数以及厚度等性能参数,分析了薄膜的结构和红外特性.     

In situ synthesis and characterization of GaN nanorods through thermal decomposition of pre-grown GaN films

Herein we describe a thermal treatment route to synthesize gallium nitride (GaN) nanorods. In this method, GaN nanorods were synthesized by thermal treatment of GaN films at a temperature of 800?°C. The morphology and structure of GaN nanorods were characterized by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The results show that GaN nanorods have a hexagonal wurtzite structure with diameters ranging from 30 to 50?nm. Additionally, GaN nanoplates are also founded in the products. The growth process of GaN nanostructures was investigated and a thermal decomposition mechanism was proposed. Our method provides a cost-effective route to fabricate GaN nanorods, which will benefit the fabrication of one-dimensional nanomaterials and device applications.     

In situ synthesis of ordered mesoporous silica materials embedded in cotton fiber and their CO2 capture properties

Mesoporous silica/cotton fiber composite materials have been prepared in situ by using pluronics P123 (EO20PO70EO20) as template, tetraethyl orthosilicate as silica source and degreasing cotton as supporter. In order to avoid the hydrolysis of cotton fiber in a strong acidic media during the hydrothermal treatment, two kinds of methods were used to control the acidity of the reaction media. One was to adjust the pH to 5 after self-assembly in a strong acidic media; the other was a two-step route containing the pre-hydrolysis of TEOS and self-assembly in a weak acidic media. The resulting shaped composite materials presented the morphology of cotton fiber, and the silica particles mainly covered the surfaces of cotton fibers. These silica particles possessed a slightly ordered pore structure or a well ordered SBA-15 structure according to the difference in the synthetic methods. After modification with tetraethylenepentamine, these shaped composite materials exhibited considerable CO2 adsorption capacity. The use of cotton fiber has the advantages of shaping the powdery materials, dispersing the silica particles and avoiding the formation of moisture and sticky solid surfaces by overloaded tetraethylenepentamine.     

甘氨酸衍生的双介孔掺氮有序介孔炭用于超级电容器和氧气还原

掺氮多孔炭材料在电化学能量储存和转化方面具有良好的应用前景.可控的氮原子掺杂与孔结构设计对提高其性能起着重要作用.本工作利用无溶剂纳米铸造法,以甘氨酸(Gly)为单一前驱体、以SBA-15为硬模板,制备了掺氮有序介孔炭材料(N-OMCs).甘氨酸在SBA-15孔道内的限域热解对提高碳产率、氮掺杂量以及构筑双介孔结构非常...     

Packing of bimodal mixtures of colloidal silica

The aim of this work was to determine the influence of the size distribution of silica powders on the characteristics of the resultant green bodies obtained by colloidal filtration. In order properly to investigate the scientific relationships between the forming parameters and the nature of the particle packing, a model ceramic material was chosen, i.e. monosized (100 and 10 nm) spherical powders of SiO₂ and colloidal filtration under 3.45 MPa was used to cast monomodal and bimodal mixtures of silica sols. The electrophoretic and rheological behaviour of those systems have been investigated. The permeability as well as the pore size distribution was found to decrease as the volume faction of fines increased (to 30%). The evolution of the density as a function of the volume fraction of fines follows the behaviour observed for the packing of bimodal mixtures of hard spheres. The systems with only one size particle were found to pack with densities close to that of random close packing. Two dimensional computer simulations and correlation to the experimental results showed that a model of triangular pores is preferred to a model of square pores.     

In situ biomimetic synthesis,characterization and in vitro investigation of bone-like nanohydroxyapatite in starch matrix

In this work, we report the synthesis of bone-like hydroxyapatite (HAp) nanorods in wheat starch matrix via a biomimetic process. Characterization of the samples was performed by X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FT-IR). Scanning and transmission electron microscopy (SEM and TEM) were used to determine the size, shape and morphology of nano-HAp. The results indicate that, the shape and morphology of nHAp is influenced by the presence of starch as a template agent and rod-like nHAp similar to the inorganic component in the human body is obtained at room temperature. In vitro bioactivity of the synthesized HAp nanocomposites was finally verified by comparison of the HAp's structures and morphology before and after immersion in simulated body fluid (SBF) solution for 3, 7, and 14 days.