反应物的变化对吸附相反应技术制备NiO/SiO2的影响

以SiO2为载体,研究反应物种类和浓度对吸附相反应技术制备NiO粒子的影响。首先采用滴定法测定了各个反应物在载体表面的吸附过程,利用TEM、XRD分析,对比了不同反应物制备得到的NiO粒子的形貌。在确定了反应物的基础上,进一步设计了2种水量下制备实验,研究反应物浓度对粒子形貌的影响。XRD结果表明,1.0mL水量下NiO粒子的晶粒粒径随着反应物浓度增加先缓慢减少后增大。而随反应物浓度增加,5.0mL水量得到的粒子晶粒粒径则一直变大。2种吸附层中不同的反应速率使得相同条件下,高水量(5.0mL)得到的NiO粒子粒径要小于1.0mL水量下得到的粒子。物理吸附层中形成的粒子与载体结合力较弱,使得焙烧后5.0mL水量下得到的粒子在SiO2上分布不均匀。     

Synthesis of a red iron oxide/montmorillonite pigment in a CO2-rich brine solution

The homoionic calcium-montmorillonite was used to synthesize a red iron oxide/clay pigment in a CO2-rich brine solution (0.5 M of NaCl) by using an agitated batch-reactor (engineer autoclave). The operating conditions were 15 days of reaction, 200 bars of pressure and 150 degrees C of temperature. SEM/EDS, STEM/EDS, XRD and Infrared Spectrometry were performed to characterize before and after reaction the solid phase. The results showed the precipitation of spherical nanoparticles (50-500 nm) of iron oxide (Fe2O3) dispersed and/or coagulated in the clay-matrix. Evidently, this oxide produced red coloration in the final product. For this case, the Fe3+ cation was provided to the aqueous solution by the dissolution of Ca-montmorillonite, particularly, the dissolution of most fine particles contained in the starting clay material. The cation exchange process and precipitation of polymorph silica were also observed.     

MoO3 /SiO2复合正极材料的制备及电化学性能研究

本文通过化学沉淀-热处理方法制备了MoO3正极材料,并通过正硅酸乙酯(TEOS)的水解在MoO3的表面包覆SiO2得到MoO3/SiO2复合正极材料[wSiO2/wMoO3=8%],对制备材料的结构和电化学性能进行了表征。结果表明,得到的MoO3为纯的正交相结构,片状MoO3的粒径大小约200～500 nm,厚度约50 nm。片状颗粒倾向于堆积在一起形成层状结构。在MoO3的表面包覆了一层无定形的SiO2。在电压范围1.5～4.0 V的条件下,以0.1C倍率进行恒电流充放电测试,MoO3/SiO2样品的首次放电容量为332.7 mAh.g-1,库仑效率87.6%。循环20次后,放电容量降为277.7 mAh.g-1。SiO2的包覆降低了MoO3正极材料的初始容量,但循环性能得到了提高。     

Dispersion of SiO2-based nanocomposites with high performance liquid chromatography

Core-shell structured Ag/SiO2 nanocomposite has been synthesized by a cyclohexane/Igepal/water reverse micelle system. The spherical nanocomposite particles were washed and concentrated with high performance liquid chromatography (HPLC) to remove the surfactant added during synthesis. Spherical SiO2 micrometer-scale particles were packed in the HPLC column as a stationary phase for the washing and dispersing of Ag/SiO2 nanocomposite particles. Surface modification of Ag/SiO2 nanocomposite particles and SiO2 microspheres with silane coupling agent enhanced the surface charge of the particles and improved the efficiency of washing with HPLC. Well-dispersed Ag/SiO2 stable suspensions were successfully attained in ethanol/water mixed solvents after HPLC washing. The state of dispersion for the Ag/SiO2 nanocomposite suspension was systematically assessed using dynamic light scattering (DLS) and transmission electron microscope (TEM) and spin coat/atomic force microscope (AFM) analyses. The mechanism of the enabling HPLC washing protocol for SiO2-based nanoparticles is discussed.     

C(膜)/Si(SiO2 )(纳米微粒)/C(膜)热处理的形态及结构分析

用直流辉光溅射+真空镀膜法制备了一种新型结构的硅基纳米发光材料- C(膜)/Si(SiO2)(纳米微粒)/C(膜)夹层膜,并对其进行了退火处理.用TEM、 SEM、 XRD和XPS对其进行了形态结构分析.TEM观察表明: Si(SiO2)纳米微粒基本呈球形,粒径在30 nm左右.SEM观察表明: 夹层膜样品总厚度约为50 μm,膜表面比较平整、致密.400℃退火后,样品表面变得凹凸不平,出现孔状结构; 650℃退火后,样品表面最平整、致密且颗粒均匀.XRD分析表明:制备出的夹层膜主要由SiO2和Si组成,在C原子的还原作用和氧气的氧化作用的共同作用下, SiO2和Si的含量随加热温度的升高而呈现交替变化: 400℃时, C的还原作用占主导地位, SiO2几乎全部被还原成了Si,此时Si含量最高; 400～650℃时,氧化作用占主导地位, Si又被氧化成SiO2, Si含量降低, SiO2含量逐渐上升,在650℃达到最高.XPS分析表明: 在加热过程中, C原子逐渐扩散进入Si(SiO2)微粒层,在650℃与Si反应生成了新的SiC.     

微乳法制备纳米TiO2 /SiO2的结构及光催化研究

Nanosized TiO₂ and TiO₂/SiO₂ particles were prepared by hydrolysis of tetrabutyl titanate (TBOT) and tetraethyl orthosilicate (TEOS) in the TX-100 reverse microemulsion. These particles were characterized by TG-DSC, XRD, FTIR, TEM，N₂ adsorption-desorption. Their photocatalytic activity was tested by degradation of methyl orange. The result shows that TiO₂/SiO₂ nanoparticles are with a monodispersed spherical phase and a uniform size distribution，and TiO₂ particles are dispersed on the surface of SiO₂. The band for Ti-O-Si vibration in FTIR was observed, the Ti-O-Si bond increased the stability of anatase TiO₂, suppressed the phase transformation of titania from anatase to rutile. And due to the addition of SiO₂, the average size of titania decreased from 38 nm in pure TiO₂ to 5 nm in TiO₂/SiO₂. It was found, under UV light irradiation, TiO₂/SiO₂ particles showed higher activity than pure TiO₂, and TiO₂/SiO₂(1/1) particles showed the highest photocatalytic activity on the photocatalytic decomposition of methyl orange, which was influenced by crystal structure, particle size, crystallinity and Surface area Characteristics.     

Surface modifications of bioglass immersed in TRIS-buffered solution. A multitechnical spectroscopic study

Bioglass 45S5 is used in the medical field as a bone regenerative material. In fact, when immersed in body fluid, a layer of hydroxy carbonate apatite (HCA), an analogue to the mineral phase that bones are made of, is deposited on its surface. A mechanism that would explain this process has been hypothesized and includes cation leaching from the glass to the solution and formation of both a silica-rich layer and a Ca/P-rich surface layer, prior to the actual crystallization of HCA. The present paper analyzes the dissolution of 2-mum-size particles of Bioglass in TRIS-buffered solution, focusing on the modifications occurring at the surface of the particles. Results from Transmission FT-IR, Raman, and X-ray Photoelectron Spectroscopy were compared in order to obtain this information. In all cases, precise spectral band assignments were obtained by comparing Bioglass spectra, before and after reaction, with the spectra registered on some selected reference samples. The results confirm the hypothesized mechanism of Bioglass reactivity and yield new insights on the surface modifications of the samples. In particular, the following is shown: the strength of the surface H-bonding system and of water coordination decreases during the reaction; surface carbonates, initially mainly bound to Na, are substituted by an increasing amount of Ca-bound carbonates; and the final calcium phosphate layer obtained is very similar, but not identical, to carbonated hydroxyapatite.     

聚醚型氨酯酰亚胺/二氧化硅杂化材料的合成与性能研究

利用Sol Gel共聚合反应制备出聚醚型氨酯酰亚胺 (PUI) /二氧化硅 (SiO2 )杂化材料 .利用NMR、FTIR、TG、DSC及SEM等测试手段对性能进行了基本表征 .FTIR研究结果发现在 10 0℃下能同时完成有机相PUI的亚胺化和无机相SiO2 凝胶网络的Sol Gel转变 .TG及SEM发现SiO2 含量为 9wt%时SiO2 聚集相粒径在 0 2～1 0 μm之间 ,耐热性明显提高并达到最佳 ;发现SiO2 含量的增加其颗粒粒径不断增大 ,并不断聚集成大粒径SiO2 相 ,有机和无机相分离明显 .DSC研究显示 ,SiO2 相的引入 ,对杂化材料聚醚软段富集相的Tg 不产生明显影响 .     

乙酸苄酯合成中接枝型三相相转移催化剂的活性及催化反应动力学

采用"接出(grafting from)"方式,将苯乙烯(St)接枝聚合在微米级硅胶表面,然后对接枝的聚苯乙烯进行了氯甲基化(CM)反应,制得了氯甲基聚苯乙烯/硅胶微粒(CMPS/SiO2);使三丁胺与三苯基膦分别与CMPS大分子链上的苄氯基团发生季铵化与季鏻化反应,分别制得了固载有季铵盐与季鏻盐的接枝微粒QN-PSt/SiO2与QP-PSt/SiO2,即制得了两种接枝型三相相转移催化剂.将该催化剂用于苄氯与乙酸钠合成乙酸苄酯的相转移催化反应,并重点考察了催化剂的活性与催化动力学.实验结果表明,两种接枝型三相相转移催化剂QN-PSt/SiO2与QP-PSt/SiO2对乙酸苄酯的合成都具有明显的催化活性,在液-固-液之间可有效地实现反应物种乙酸根的转移;两者相比,季鏻盐型的催化剂QP-PSt/SiO2的催化活性更高;当水相中乙酸钠用量大大过量时,在有机相中苄氯与乙酸根的反应属准一级反应;两个相转移反应体系相比,以QP-PSt/SiO2为催化剂时反应的表观活化能更低.     

pH值和前驱体用量对核壳结构PSt/SiO2复合微球结构形态的影响

首先通过无皂乳液聚合法制得表面含羧基、粒径为360 nm的单分散聚苯乙烯(PSt)种子乳液,并在EtOH/H2O混合介质中用γ-氨丙基三乙氧基硅烷(KH-550)对其进行改性,制得表面含有活性硅乙氧基并带有正电荷的改性PSt乳胶粒,然后再加入原硅酸乙酯(TEOS)进行共水解与共缩聚反应,制备出了核壳结构PSt/SiO2...     

Sorption of tartrate ions to lanthanum (III)-modified calcium fluor- and hydroxyapatite

The present article details the formation of lanthanum-modified apatites and the binding process of tartrate ions with these obtained apatites. Chemical analyses, FT-IR and (31)P NMR spectroscopies, XRD powder, TGA, and TEM analyses were employed for studying the reaction between Ca(10)(PO(4))(6)(OH)(2) (HAp) or Ca(10)(PO(4))(6)(F)(2) (FAp) and LaCl(3). The reaction was found to take place mainly through partial dissolution of the apatite followed by precipitation of a new phase containing lanthanum phosphate. When La(3+) was introduced in the presence of L(+)-tartaric acid (TAH(2)), no fundamental changes were observed in the HAp or FAp structures. However, there did occur a formation of a new phase of Ca or/and La tartrate salt.     

原位制备PEI/SiO2复合材料及其改性环氧树脂的研究

在N,N-二甲基乙酰胺/四氢呋喃(DMAc/THF)混合溶剂中,在正硅酸乙酯(TEOS)存在条件下,通过溶胶-凝胶法原位制备了聚醚酰亚胺(PEI)/SiO2复合材料.在该复合材料中,当SiO2含量低于20 wt％时,透射电镜(TEM)和扫描电镜(SEM)的观察表明,SiO2纳米粒子可以均匀分散,粒径可在80～300 n...     

钙磷物质的量比对磷酸钙骨水泥性能的影响

本研究通过在磷酸钙骨水泥(calcium phosphate cement,CPC)固相配方中添加不同量的氯化钙(CaCl2),制备不同钙磷物质的量比的CPC,研究不同钙磷物质的量比对CPC性能的影响。测试CPC的初、终凝时间。将CPC体外模拟浸泡3d和7d,研究模拟生理条件下CPC的性能,分别利用X-射线衍射(XRD)、力学性能实验机、扫描电镜(SEM)等研究CPC相成分、抗压强度和断面微观形貌。通过化学滴定测定浸泡液中氯离子浓度。结果表明:提高钙磷物质的量比不会显著延长CPC凝结时间;模拟浸泡液中的氯离子浓度处于正常生理条件的范围内;随钙磷物质的量比的增加,水化后CPC的抗压强度显著提高,而经过体外模拟浸泡后,钙磷物质的量比为1.67和1.80的CPC的抗压强度明显下降;具有较高钙磷物质的量比的CPC体外模拟浸泡后,形成多孔结构、弱结晶类骨磷灰石的终产物。     

吸附相反应技术制备Ag纳米粒子的反应机理

利用吸附相反应技术在SiO2表面制备Ag粒子, 研究了温度变化对载体表面NaOH的吸附、生成Ag的反应过程以及产物Ag粒子形貌的影响. NaOH的吸附率测定结果表明, 吸附平衡时间随着温度升高而增加. 温度升高加快了NaOH与Si—O—Si的反应, 使得NaOH的平衡吸附率不随吸附层的破坏而减少. 采用实时在线UV-Vis光谱研究了Ag粒子的生成过程, 发现温度超过40 ℃时, 反应体系中Ag出现的时间、Ag粒子的浓度和粒径分布范围都发生较大变化. 样品的TEM和XRD分析也表明, 当体系温度超过40 ℃时SiO2表面Ag粒子出现了团聚, 其晶粒粒径也出现了突变. 温度升高导致表面吸附层破坏, 使得Ag的生成场所从吸附层转移到SiO2表面, 最终导致Ag的反应机理和粒子形貌的变化.     

单分散二氧化硅球形颗粒的制备与形成机理

在醇水混合溶剂中以氨作催化剂，正硅酸乙酯为硅源，通过溶胶—凝胶工艺制 备单分散二氧化硅球形颗粒，通过透视电镜进行研究各种反应条件如溶剂类型、氨 和水的浓度、水解温度等对二氧化硅的颗粒大小和形貌的影响．结果显示：以甲醇 和乙醇为溶剂可以形成单分散的二氧化硅球形颗粒，以丙醇和丁醇为溶剂，二氧化 硅球形颗粒容易聚集；在其它条件不变的情况下，球形颗粒的粒径随水和硅源的浓 度增加而增大；而且水解温度的升高，生成的颗粒粒径也逐渐增大，仔细研究和讨 论了二氧化硅颗粒在不同反应条件下的形成机理．     

Characterization of silicate monomer with sodium,calcium and strontium but not with lithium and magnesium ions by fast atom bombardment mass spectrometry

Fast atom bombardment mass spectrometry (FABMS) was applied to the direct detection of silica species dissolved in LiCl, NaCl, MgCl(2), CaCl(2) and SrCl(2) solutions in order to investigate its dissolution process in solution. Several species of dissolved silicate complexes in the solution were directly detected by FABMS. The peak intensities of [SiO(2)(OH)(2)Na](-), [SiO(3)(OH)Ca](-) and [SiO(3)(OH)Sr](-) increased with increasing concentrations of NaCl, CaCl(2) and SrCl(2), whereas the peak intensities of [SiO(2)(OH)(2)Li](-) and [SiO(3)(OH)Mg](-) did not increase with increasing concentrations of LiCl and MgCl(2). These results indicte that silicate and cation bind in the solution not after but before ionization. The isotope pattern of Sr(2+) confirmed the existence of the silicate-Sr complex not only with increase of the concentration of silica but also the mass numbers of Sr. The silicate complexes formed with Na(+), Ca(2+) and Sr(2+) showed high stability in chloride solution. This is in good accordance with the fact that Na(+), Ca(2+) and Sr(2+) accelerate the dissolution of silica to form complexes during solution equilibrium. Considering that the stability constant was examined and reported in other papers, this new findings that Mg(2+) does not form a complex with silicic acid (Si(OH)(4)) is very important.     

ATRP法在纳米SiO2表面接枝PBA及其对POM的改性

本论文研究了原子转移自由基聚合法(ATRP)在纳米二氧化硅(SiO2)表面接枝聚丙烯酸丁酯(PBA)以及其对聚甲醛（POM）进行改性。红外光谱（FTIR）、透射电镜(TEM)及凝胶渗透色谱（GPC）等测试表明：采用ATRP法可制备均匀分散的SiO2-g-PBA纳米复合粒子。力学性能、扫描电子显微镜（SEM）及透射电子显微镜（TEM）等测试表明：纳米SiO2在POM中团聚明显,而SiO2-g-PBA纳米复合粒子POM中分散均匀,导致POM/SiO2-g-PBA纳米复合材料的缺口冲击强度明显高于POM及POM/SiO复合材料,当SiO2-g-PBA纳米复合粒子的质量分数为2%时,POM/SiO2-g-PBA复合材料的冲击强度是POM的8倍多,同时拉伸强度有一定的增加。     

团聚纳米SiO_2在苯乙烯乳液聚合过程中的再分散过程及机理

用二氧化硅 (SiO2 )存在下的乳液聚合法制备了聚苯乙烯 (PSt) 纳米SiO2 复合材料 ,研究了苯乙烯(St)乳液聚合过程中团聚纳米SiO2 的解离与再分散过程及分散的机理 .发现商品纳米SiO2 粒子以团聚体形式存在 ,团聚体大小远超出纳米级范围 .随聚合时间的延长 ,St的转化率逐渐增加 ,而PSt SiO2 复合微胶囊的粒径逐渐减小 ,反应 12 0min后 ,转化率和复合微胶囊粒子的粒径趋于稳定 .透射电镜 (TEM)也显示PSt SiO2 复合微胶囊粒子具有海岛结构 ,而SiO2 粒子的粒径在纳米范围内 ,表明在乳液聚合过程中SiO2 团聚体被逐渐解离 ,并重新分散到纳米尺度 .红外光谱研究发现 ,在乳液聚合过程中 ,除生成PSt均聚物外 ,还在纳米SiO2 表面生成了PSt接枝共聚物 ,改善了无机纳米粒子与聚合物之间的界面相容性 .聚合过程中的反应热和剪切搅拌是团聚体被解离和重新分散的主要原因 ,而生成的聚合物起到隔离作用     

The synthesis, structure, optical and photocatalytic properties of silica-coated cadmium sulfide nanocomposites of different shapes

The CdS nanostructure undergoes photochemical dissolution, and hence, the photocatalytic activity deteriorates with light irradiation time. A thin layer of silica coating over CdS surface may prevent the photocorrosion and coalescence of quantum size CdS particles. Hence, we synthesized SiO(2)@CdS nanocomposites of different shapes and characterized them by XRD, HRTEM, EDX, SAED, BET surface area measurement and absorption and emission study. The dispersion of spherical CdS (Cd-2.62 at% and S-2.33 at%) nanoparticles of cubic crystal structure into thick amorphous SiO(2) (43.79 at%) matrix is demonstrated here. The fabrication of core (CdS)-shell (SiO(2)) structure (SiO(2)@CdS) consisting of CdS nanorod (Cd-19.79 at% and S-22.90 at%) core (length ~126 nm and width ~6 nm) having characteristic lattice fringes of hexagonal crystals and thin SiO(2) (12.81 at%) shell (thickness=1-1.4 nm) is successfully achieved for the first time. The surface area (21.2m(2)/g) of CdS nanorod (aspect ratio=21) is found to increase (42.3m(2)/g) after SiO(2) coating. The photoluminescence of CdS nanosphere (485 nm) and nanorod (501 nm) is highly quenched after SiO(2) layer formation. The superior photocatalytic activity of SiO(2)@CdS composites for the benzaldehyde oxidation under UV irradiation has been displayed.     

Facile preparation method of SiO2/PS/TiO2 multilayer core-shell hybrid microspheres

Organic-inorganic hybrid particles have many potential applications, but almost all of this research was focused on the hybrid particles containing one kind of inorganic nanoparticles. This paper presented a facile preparation method for SiO2/PS/TiO2 multilayer core-shell hybrid microspheres. In this approach, positively charged SiO2/PS core-shell hybrid particles were first synthesized by miniemulsion polymerization using cationic initiator and emulsifier. These positively charged SiO2/PS hybrid particles were mixed with tetra-n-butyl titanate for sol-gel reaction to directly form SiO2/PS/TiO2 multilayer core-shell hybrid microspheres. Some influencing parameters such as surfactant concentration, tetra-n-butyl titanate amount, and glacial acetic acid amount were investigated. TEM, TGA, and EDX analyses indicated that titania layers were successfully coated onto the surfaces of hybrid microspheres.