多孔球形羟基磷灰石生物材料的制备

研究了一种作为药物载体的多孔球形羟基磷灰石生物材料的制备工艺。采用微乳液法先制得多孔球形碳酸钙,并以此为模板与磷酸氢二钠在一定条件下反应制备出直径约10μm的多孔球形羟基磷灰石。通过X射线衍射,扫描电子显微镜等手段对制备的羟基磷灰石的结构、组成和形貌进行表征,考察了不同反应温度、表面活性剂浓度、反应时间对多孔球形貌的影响,并对反应机理进行了初步探讨。结果表明,当制备多孔球形碳酸钙模板的温度为25℃、吐温-80浓度为3％且碳酸钙与磷酸氢二钠反应时间为30h时,得到的羟基磷灰石为5-10μm、分散性好的球形晶体。     

溶胶–凝胶法制备纳米羟基磷灰石粉体

以四水合硝酸钙和五氧化二磷为原料，无水乙醇为溶剂，采用溶胶一凝胶法制备了含co}的羟基磷灰石（hydroxy印atite，HAP）粉体。采用热重-差热分析、X射线衍射、透射电子显微镜、Fourier变换红外光谱等研究了反应体系pH值、反应温度及前驱体热处理温度等因素对产物结构与性能的影响规律，结果表明：采用溶胶-凝胶工艺，调控反应体系的pH、反应温度及前驱体的热处理温度是获得纯度高、分散性较好的纳米HAP粉体的关键。pH值为8．0、反应温度为30℃，经600℃热处理可获得到粒径为40~50nm的HAP纳米粉体。     

双亲嵌段共聚物PSt-b-P(St-alt-MA)-b-PAA的自组装行为

以三硫代碳酸二(α, α'-二甲基-α-乙酸)酯(BDATC)为链转移剂, 以苯乙烯、马来酸酐、丙烯酸为原料, 通过可逆加成-断裂链转移(RAFT)合成了双亲嵌段共聚物PSt-b-P(St-alt-MA)-b-PAA。通过选择性溶剂N, N-二甲基甲酰胺(DMF)诱导聚合物进行自组装, 利用紫外-可见光光度仪、纳米激光粒度仪详细研究了共聚物中亲疏水嵌段长度、初始浓度、体系pH值对聚合物自组装行为的影响。通过化学交联的方法制备得到了聚合物交联胶束, 利用透射电镜表征了形貌与尺寸, 研究明确了其形状和尺寸的稳定性。结果表明, 上述因素均会影响共聚物的自组装行为和自组装胶束的形态, 经乙二胺交联得到的交联自组装胶束平均粒径为145.4nm, 并具有良好的形状和尺寸稳定性。     

Synthesis of Pure Hydroxyapatite and the Effect of Synthesis Conditions on its Yield,Crystallinity, Morphology and Mean Particle Size

Abstract

Hydroxyapatite (HAP) is a calcium phosphate compound with the chemical formula Ca₅(PO₄)₃OH. This compound is especially significant in biomedical applications since it resembles the mineral constituents of the hard tissue in the human body. Its biocompatibility, castability, and sinterability make it a very attractive material for simulating bones and therefore for implantations. The objective of this study was to produce HAP with a high purity and to determine quantitatively the exact percentage of HAP in the synthesized powder. Hydrothermal methods have been used to produce HAP. In the present work, Hydroxyapatite powder was produced using the chemical precipitation method in a batch and semi‐batch modes of operation. The effect of temperature, pH, and reactant addition rates on the mean particle size was studied. Results showed a maximum in the mean particle size at pH 9, while a minimum was observed at around 45°C. As the reactant addition rate increased the mean particle size increased as well. The purity of the obtained powder was characterized using both quantitative and qualitative techniques. The quantitative results were performed using the powerful Rietveld refinement method. The quantitative results were obtained for three samples. Results showed that pure HAP was produced at a temperature of 85°C, pH 9 and reactant addition rate of 1.3 mL/min.     

水热法制备ZnS微球及其生长机理研究

以硝酸锌和硫脲为原料,乙二胺四乙酸二钠(Na2EDTA)为螯合剂,用水热法制备了ZnS微球。用扫描电子显微镜(SEM)对产物的形貌进行了表征,结果表明反应温度以及反应pH对产物粒径大小、表面形貌有很大影响。当反应温度为180℃、pH值为9,反应时间为12h时,所制备的产物约为500nm的球状颗粒。     

基于热重分析的氢气还原氧化铜粉体动力学研究纸箱厂锅炉冷凝水开闭式回收分析

采用激光粒度仪测定氧化铜粉体试样的粒度分布,利用透射电镜（TEM）观察表征其形貌。在含氢25％的氢氮混合气流中,在不同的升温速率（2．5、5、10、12．5、17．5、25K／min）下,利用微机差热天平进行非等温的热重分析实验,测定样品的TG—DTA曲线。研究结果表明,氧化铜粉体样品结构不规则,粒径分布较宽,粒径约为9．4gm：TG曲线的起始反应温度和DTA曲线的峰值温度均随着升温速率的增大而增大;氢气还原氧化铜粉体为单质铜的表观活化能为59．42kJ／mol,指前因子为6．75×10^5min-1,反应级数为1．08。     

Polymerization of liquid propylene with a fourth‐generation Ziegler–Natta catalyst: Influence of temperature,hydrogen, monomer concentration,and prepolymerization method on powder morphology

Liquid propylene was polymerized in a 5‐L autoclave batch reactor using a commercially available TiCl₄/MgCl₂/Al(ethyl)₃/DCPDMS Ziegler–Natta catalyst, with a phthalate ester as internal electron donor. The powders from these polymerizations were characterized using laser diffraction particle size distribution (PSD) analysis, scanning electron microscopy (SEM), and bulk density measurements. These characteristics were analyzed as a function of the process conditions, including hydrogen and monomer concentration, polymerization temperature, and the prepolymerization method. It was shown that polymerization temperature influences the powder morphology to a large extent. At low temperatures, high‐density particles were obtained, showing regular shaped particle surfaces and low porosities. With increasing temperature, the morphology gradually was transferred into a more open structure, with irregular surfaces and poor replication of the shape of the catalyst particle. When using a prepolymerization step at a relatively low temperature, the morphology obtained was determined by this prepolymerization step and was independent from conditions in main polymerization. The morphology obtained was the same as that observed after a full polymerization at temperature. Even when using a short polymerization at an increasing temperature, the morphology was strongly influenced by the initial conditions. The effect of variation in hydrogen concentration supported the conclusion that the initial polymerization rate determines the powder morphology. In the absence of hydrogen, high bulk densities, and regularly shaped particles were obtained, even at high temperatures. With increasing hydrogen concentration, the reaction rates increased rapidly, and with that changed the morphology. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 87: 1421–1435, 2003     

微通道反应-水热晶化法制备羟基磷灰石纳米粉体

采用微通道反应与水热晶化相结合的工艺路线,制备HAP纳米粉体。结果表明,增大反应物流量比或减小微通道高度会导致HAP粉体的颗粒粒径变小,增加水热温度或时间会提高HAP的结晶性和热稳定性,反应物流量比和水热温度是影响HAP纳米粉体制备的主要因素。当反应物流量比为5∶1,微通道高度为250μm,220℃下水热4 h时,实验可以制得平均粒径约为80 nm、粒度分布均匀、结晶度高的短棒状HAP纳米粉体。     

水热法制备BaF2粉体材料

以销酸钡和氟化铵为原料,以柠檬酸为络合剂,采用水热法合成了BaF2粉体。用扫描电子显微镜(SEM)和X射线衍射仪(XRD)对产物的形貌和结构进行了表征,结果表明反应温度及pH值对产物的形状和尺寸有很大影响,可以通过改变温度和pH值调控产物的形貌。     

Mechanical properties of hydroxyapatite‐filled ethylene vinyl acetate copolymer composites: Effect of particle size and morphology

Pliable and bioactive composites made of hydroxyapatite (HAP) and ethylene vinyl acetate (EVA) copolymer were developed for the repair of defective cranium. This article describes the mechanical properties of HAP–EVA composites. The effects of HAP particle size and morphology of HAP on the properties of resultant composites were investigated using various techniques. It was found that the composites containing smaller HAP particles had higher values of tensile modulus, flexural modulus, and impact strength. Examination of the fracture surfaces revealed that only a mechanical bond existed between the filler and the matrix. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Preparation and property of porous hydroxyapatite as an inorganic dispersant used in suspension polymerization

The porous hydroxyapatite (HAP) for suspension polymerization dispersant was prepared using calcium carbonate and phosphoric acid as raw materials. The samples were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD) and BET nitrogen adsorption. The results show that the prepared HAP has a porous structure, low particle density, large specific surface area, uniform particle size and does not agglomerate easily between the particles. The preparation conditions for the HAP were optimized as follows: solid content of calcium carbonate aqueous suspension 90 g/L, concentration of phosphoric acid 1.0 mol/L, reaction/aging temperature 50°C, and aging time 3 h. The HAP prepared under optimal preparation conditions has 106.8 m²·g^-1 of specific surface area, which is about 1.5–1.8 times as much as that of Japanese HAP or commercial HAP. Its application result in the suspension polymerization of styrene show that the porous HAP dispersant has high surface activity, excellent suspension dispersibility and stability and can markedly improve the quality of polystyrene beads.     

Collagen modulating crystallization of apatite in a biomimetic gel system

Apatite crystals were formed at 37 °C in a biomimetic gel system with the presence and absence of collagen under pH 6.5, 7.0 and 7.5 respectively. X-ray diffraction, transmission electron microscope and selected area electron diffraction pattern were applied to characterize the crystals. The results indicated that collagen modulate crystallization of apatite both in composition and morphology. With the absence of collagen, the obtained crystals were ribbon-shaped octacalcium phosphate (OCP) at pH 6.5, the mixture of OCP and nanosize rod-shaped hydroxyapatite (HAP) at pH 7.0 and 7.5 respectively. OCP would be a precursor of HAP with the absence of collagen. With the presence of collagen, collagen acted more effectively in controlling crystallization of HAP than pH did in the system. Ribbon-shaped HAP was the main phase at pH 6.5, kept a very thin structure at pH 7.0 while the needle-shaped HAP with several nanometers in diameter was obtained at pH 7.5. It was discussed amorphous calcium phosphate would be an intermediate phase of HAP with the presence of collagen. Such understanding of collagen and pH control on biomineralization gives new insights on the controlled synthesis of apatite.     

Storage Stability of Alpha-Lipoic Acid-loaded Lipid Nanoparticles

Alpha-lipoic acid-loaded lipid nanoparticles(ALA-LNs) were prepared by high pressure homogenization method.The influences of storage conditions such as time and temperature on the physical and chemical storage stability of ALA-LNs were studied in details.The stability was evaluated by particle size and polydispersity index,morphology of ALA-LNs,and capacity of ALA loading.The dilution and pH stability of ALA-LNs suspensions were also studied.After three months storage,the mean size of ALA-LNs at 4 and 40 ℃ was increased by 2.68% and 3.62% compared with the original size,respectively.ALA-LNs stored at 40 ℃ had ellipsoid shape and the mean size was about 152 nm(SD=23.6).The loading capacity of ALA at 40 ℃ was much higher than those stored at other two temperatures.The good dilution and pH stability were also demonstrated.The sample had good fluidity even at 4 ℃.     

羟基磷酸钙的制备及其对甲基丙烯酸甲酯悬浮聚合的影响

利用Ca(OH)2和H3PO4中和反应制备悬浮聚合分散剂超细羟基磷酸钙(HAP). 通过正交实验法,研究了反应温度、Ca(OH)2浓度、H3PO4滴加速度、表面活性剂十二烷基苯磺酸钠(SDBS)的加入量等各因素对反应产物羟基磷酸钙结晶形态与尺寸的影响. 分别将不同条件下制备的HAP与聚乙烯醇(PVA)组成复合分散体系,通过甲基丙烯酸甲酯(MMA)的悬浮聚合反应,比较了各组的聚合效果. 应用红外光谱及透射电镜对HAP进行了表征,分析了HAP的结晶形态及尺寸对聚甲基丙烯酸甲酯(PMMA)的粒径及其分布的影响. 结果表明,本实验制备的长′宽为140 nm×35 nm的针状结晶HAP与PVA的复合分散体系对MMA悬浮聚合效果最好,可制备出综合性能较好、粒径d32达1.41 mm的PMMA光学小球.     

不同晶型纳米二氧化钛的水热合成

水热法合成了不同晶型、形貌和大小的纳米二氧化钛。利用X射线衍射(XRD)和透射电镜(TEM)对所得的样品进行了表征。研究了pH值、水热反应温度和水热反应时间对纳米二氧化钛晶型、形貌和晶粒尺寸的影响。结果表明,前驱体pH值是决定产品晶型、晶粒尺寸和形貌的主要因素。随着水热反应温度的升高,纳米二氧化钛的晶粒尺寸逐渐变大,但pH=3.0时所形成的锐钛矿型纳米二氧化钛的晶粒尺寸却几乎不变;随着水热反应时间的延长,金红石型纳米二氧化钛晶粒的生长速度最快,而锐钛矿型的纳米二氧化钛的晶粒生长速度则最慢。     

包覆SiO2的硬脂酸相变储能材料的低热固相化学合成及其热性能

采用低热固相化学反应法,一步制备了表面包覆SiO2的硬脂酸相变储能纳米粒子.由红外光谱、X射线衍射和差示扫描量热法对表面包覆SiO2的硬脂酸纳米粒子进行了表征.利用动态光散射激光力度仪测定了材料的粒径分布,同时对材料表面包覆前后的接触角进行了测定.结果表明:硬脂酸纳米粒子表面成功包覆了SiO2层.包覆的硬脂酸纳米粒子为球状,粒径大约为110 nm.包覆的硬脂酸纳米粒子相转变温度为61.4℃,相变过程中的焓值为153.1 J/g,具有良好的蓄热能力,可用于太阳能利用等方面的储能蓄热.     

溶胶-凝胶法制备的BaMgAl10O17:Eu前驱体的晶化过程

采用柠檬酸作为螯合物的溶胶-凝胶法制备了BaMgAl10O17：Eu(barium magnesium aluminate,BAM)蓝色荧光粉,并研究了,其晶化过程。通过X射线衍射、扫描电镜和荧光光谱等表征手段,研究了前驱体晶化过程的焙烧条件、结晶动力学、颗粒大小和发光性能等。BAM晶相在1100℃开始产生。温度达1200℃时,前驱体由无定型态完全转变成BAM晶相。在1120～1300℃时晶化反应的表观活化能为233kJ／mol。在室温下测得荧光粉的最大吸收峰和发射峰分别处在334nm和454nm。合成荧光粉的粒径为5μm左右,其形态和粒径取决于前驱体。     

柠檬酸作分散剂制备HAP超细粉的研究

采用沉淀法并用柠檬酸作分散剂合成HAP超细粉体.采用XRD,SEM等实验方法研究了柠檬酸的加入对产物粒径大小、团聚的影响,并对实验中的有关工艺参数进行了研究.结果表明,在用柠檬酸作分散剂的条件下,产品的粒径和分散性能得到改善.     

Hydrothermal synthesis of hierarchical hydroxyapatite: Preparation, growth mechanism and drug release property

Hydroxyapatite (HAP) hierarchical microspheres were synthesized by a facile hydrothermal method using calcium nitrate and ammonium dihydrogen phosphate through controlling complexing agents. The influences of two kinds of complexing agents (potassium sodium tartrate tetrahydrate and trisodium citrate) and reaction time on the morphology of HAP crystals have been investigated. These results indicate that complexing agents have a great influence on the morphology of HAP. When potassium sodium tartrate tetrahydrate was used as complexing agent, HAP flowers were composed of the network of nanosheet building blocks. Well-crystallized HAP dandelions with nanorods radiating from the center can be obtained by the introduction of trisodium citrate. Broader XRD diffraction peaks imply a nanometer scale size. Based on XRD and SEM results, the formation mechanism of HAP crystals has been discussed. The hierarchically structured HAP microspheres were explored as drug carriers. The results indicate that HAP flowers and dandelions showed a favorable sustained release property for ibuprofen; thus, they are very promising for application in drug delivery.     

原子力显微镜在纳米材料表面形貌及粒度的研究

在探测纳米尺寸上、分子水平上的表面形貌,原子力显微镜是最先进的测试工具之一。文章主要是在室温大气条件下,用原子力显微镜分别对液相化学沉淀法制备的羟基磷灰石（HAP）粉体,压片后在马福炉中用不同的温度和时间烧结,得到不同烧结状态的样品表面进行扫描成像,并用原子力显微镜分析软件分析发现羟基磷灰石样品颗粒的平均尺寸随温度升高而增大的变化趋势。并用RISE-2008型激光粒度分析仪测样品颗粒粒度作对比测试印证原子力显微镜测试结果的可靠性。