Microstructure of brushite crystals prepared via high internal phase emulsion

For the first time, various microstructures of calcium phosphates were successfully synthesized using a high internal phase emulsion process. The crystals were possessed in the brushite crystalline phase. The morphology of the crystals was influenced by the variables related to the emulsion process route, which consisted of flakes, dendrites and particulates structures.     

Unique crystal morphologies of glycine grown from octanoic acid-in-water emulsions

We have obtained both porous and dendritic, intricate morphology crystals of beta-glycine by the novel and simple method of emulsion droplet adhesion and encapsulation. By using octanoic acid emulsified with nonionic surfactants, the adhesion of the emulsion droplets can be so strong that, remarkably, crystal growth often proceeds around the droplets, leading to their inclusion within the single crystals. Consequently, porous single crystals can be produced with the pore diameters ( approximately 10-25 mum) corresponding to the emulsion droplet sizes. Highly intricate, dendritic morphologies for glycine were obtained by increasing the surfactant concentration in the emulsions to 50%. In this case, partial droplet encapsulation results in crystal dendrites growing on either side of adsorbed droplets, with the complex morphologies developing due to the high density of dendritic branches that can occur. These intricate morphologies are in stark contrast to the facetted crystals that normally develop at these low supersaturations in the absence of octanoic acid droplets. This study demonstrates that complex architectures can be attained by using simple emulsion systems and tuning the degree of droplet adhesion.     

Three-Component Olive Oil-In-Water High Internal Phase Emulsions Stabilized by Palm Surfactant and Their Moisturizing Properties

In the present study, olive oil was used for the preparation of three-component high internal phase emulsions with oil volume fraction of more than 0.77 stabilized by palm-based polyoxyethylene lauryl ether for the first time. These emulsions were investigated on their morphology, structural properties, stability, and hydration efficacy. Droplet size distribution observed from the optical micrographs was in agreement with the light scattering results, which suggested that droplet size was influenced by oil phase and surfactant concentrations. Rheological results exhibiting flow curves cross-over implied structural build-up that gave rise to high stability which was supported by stable three-month storage at an elevated temperature. The hydration efficacy of the emulsion was examined in vivo using a corneometer.     

Emulsion stability and potassium leakage in emulsion liquid membrane systems

Potassium leakage was studied in liquid membrane systems containing various emulsifiers and compared with emulsion, stability in the storage test. The effects of various parameters upon emulsion stability and the leakage of standard traces are discussed. The transfer of cations can be caused by emulsion breaking, by transport with the specific carrier and/or with surfactants used as emulsifiers. The latter case becomes especially important when hydrophilic surfactants, e.g. ones containing polyoxyethylene chains, are present in liquid membranes. In systems containing hydrophobic emulsifiers the transfer of potassium is relatively low. In each case considered the effect of emulsifiers upon the transfer of the standard tracer should be checked prior to using the leakage test to characterize emulsion stability.     

Controlled synthesis of calcium carbonate in a mixed aqueous solution of PSMA and CTAB

A mixed system of poly (styrene-alt-maleic acid) (PSMA) and cetyltrimethylammonium bromide (CTAB) was used as a very effective crystal growth modifier to direct the controlled synthesis of CaCO₃ crystals with various morphologies and polymorphs. The as-prepared products were characterized with scanning electron microscopy and X-ray diffraction. It was found that the concentrations and relative ratios of PSMA and CTAB in the mixed aqueous solution were turned out to be important parameters for the morphology and polymorph of CaCO₃ crystals. Various morphologies of CaCO₃ crystals, such as hollow microsphere, peanut and so on, were produced depending on the concentrations and relative ratios of PSMA and CTAB. Moreover, the formation mechanisms of CaCO₃ crystals with different morphologies were discussed.     

SOLUTION CRYSTALLIZATION OF METALLOCENE SHORT CHAIN BRANCHED POLYETHYLENE:MORPHOLOGY AND MECHANISM*

Solution crystallization of metallocene short chain branched polyethylene (SCBPE) was carried out and very nicesingle crystals were obtained. Compared with single crystals grown from linear polyethylene, SCBPE single crystals are dirtydue to intermolecular heterogeneity The crystal morphology changes with crystallization temperatures. Lozenge, truncatedlozenge, hexagonal, rounded and elongated crystal morphologies have been found at much lower crystallization temperaturethan in linear polyethylene. The electron diffraction shows there is a possibility that the single crystals may have hexagonalpacking in a crystallization temperature range. The lateral habits of single crystal are discussed based on roughening theories.     

Development of radioligands for the dopamine transporter

The extraction of Penicillin G (Pen G) and its conversion to 6-aminopenicillin acid (6-APA) and phenylacetic acid (PAA) was performed by means of Penicillin G Amidase immobilised in the emulsion liquid membranes. Using various surfactants as emulsifiers and an appropriate carrier it is possible to obtain different extraction rates of Pen G as well as back transfer rates of the hydrolysis products. The surfactants with polyoxyethylene chain facilitate the back transfer through the membrane phase, whereas the more hydrophobic surfactants, e.g., Paranox 100, tend to accumulate Pen G hydrolysis products in the internal aqueous phase.     

Effect of Butyl α-Hydroxymethyl Acrylate Monomer Structure on the Morphology Produced via Aqueous Emulsion Polymerization-induced Self-assembly

Polymerization-induced self-assembly(PISA) is an efficient and versatile method to afford polymeric nano-objects with polymorphic morphologies. Compared to dispersion PISA syntheses based on soluble monomers, the vast majority of emulsion PISA formulations using insoluble monomers leads to kinetically-trapped spheres. Herein, we present aqueous emulsion PISA formulations generating worms and vesicles besides spheres. Two monomers with different butyl groups, n-butyl(n BHMA) and tert-butyl(t BHMA) α-hydroxymethyl acrylate, and thus possessing different water solubilities were synthesized via Baylis-Hillman reaction. Photoinitiated aqueous emulsion polymerizations of n BHMA and t BHMA employing poly(ethylene glycol) macromolecular chain transfer agents(macro-CTAs, PEG45-CTA, and PEG113-CTA) at 40 °C were systematically investigated to evaluate the effect of monomer structure and solubility on the morphology of the generated block copolymer nano-objects. Higher order morphologies including worms and vesicles were readily accessed for t BHMA, which has a higher water solubility than that of n BHMA. This study proves that plasticization of the core-forming block by water plays a key role in enhancing chain mobility required for morphological transition in emulsion PISA.     

Single-chain single crystals

Single-chain single crystals of isotactic polystyrene and poly(ethylene oxide) were studied by using transmission electron microscopy, high resolution electron microscopy, electron diffraction. Single-chain single crystals were prepared by spreading a dilute solution of polymers on a water surface and collecting the resulting single-chain particles on copper grids, followed by isothermal crystallization. A statistical analysis of the sizes of single-chain crystals was found to match with the known molecular weight distribution of original sample, indicating the particles to be composed of single chain. Observation of the morphology and electron diffraction gave evidence of the single crystal nature. Regular-shaped single-chain crystals were obtained after isothermal crystallization for a longer time. By close observation, several types of morphologies were found for single-chain crystals of isotactic polystyrene and poly(ethylene oxide); in addition to the conventional morphologies observed for multi-chain crystals, new morphologies were observed in both cases. The morphologies of poly(ethylene oxide) were explained according to the crystal structure and twin modes. Tent-like single-chain crystals were often observed. Because of the small size of the crystals, they can avoid collapse on the substrate. The crystalline c-axis of single-chain crystals were found to orient preferably in the direction normal to the substrate. The investigation of electron diffraction and high resolution electron microscopy revealed that the structure of the single-chain crystals of isotactic polystyrene is the same as for multi-chain crystals. A reasonable explanation is given for the unusual resistance to electron irradiation and the missing of lower-index reflections. Regular periodic stripes were found on the top surface of single-chain crystal of isotactic polystyrene with an average periodic length in accordance with (220) spacing. In addition, a statistical thermodynamics theory was developed for single-chain crystal. It is found that the equilibrium dimensions are related to molecular weight and annealing temperature, while the equilibrium melting temperature depends on molecular weight.     

聚氧乙烯醚类表面活性剂表面扩张粘弹性质研究

研究了非离子表面活性剂壬基苯酚聚氧乙烯醚NP-8, NP-10和NP-12水溶液的表面扩张粘弹性质, 考察了氧乙烯数的变化对表面吸附膜特性的影响. 研究结果表明, 三种表面活性剂的扩张弹性随着工作频率的增大而增大, 扩张粘性则在0.1~0.01 Hz范围内通过不明显的极大值; 扩张弹性和粘性随着浓度的增加在同一浓度处通过一个极大值; 氧乙烯数从8增加到12, 表面扩张弹性、粘性和相角的变化不大. 从发生在表面上和表面附近的微观弛豫过程的角度对实验结果进行了讨论.     

Morphology of single-chain single crystals of poly(ethylene oxide)

Single-chain particles of poly(ethylene oxide) (PEO) were prepared by spreading a 10^-4 wt.-% solution of PEO in benzene on a hot water surface. After isothermal crystallization at 317,2 ± 0,1 K for 10 h, regular-shaped single-chain crystals were observed. A variety of typical morphologies were also found, and some of them are discussed on the basis of the habit of PEO crystals and various twin modes.     

Synthesis of polystyrene-block-polyoxyethylene for use as a stabilizer in the emulsion polymerization of styrene

Five well-defined polystyrene-block-polyoxyethylene copolymers were synthesized by anionic polymerization for use as stabilizers in the emulsion polymerization of styrene. The size of the blocks and their relative weight ratios to each other were the main variables. The molecular weights of the blocks varied from M?_n = 1000–7000 for polystyrene, and M?_w = 3000–9000 for polyoxyethylene. The results of the styrene emulsion polymerization with these block copolymers as stabilizers indicate that for efficient anchoring the block length need not be more than 10 monomer units, possibly even less, and that the polyoxyethylene block M?_w = 3000 is just as capable of stabilizing the polystyrene particle as the higher molecular weight blocks. A very important factor was found to be the weight ratio of the two blocks: block copolymers with a polyoxyethylene content between 75 and 90 wt % were effective stabilizers for the emulsion polymerization of styrene © 1992 John Wiley & Sons, Inc.     

Thermal properties of poly(methyl methacrylate) prepared by emulsifier-free emulsion polymerization

Emulsifier-free emulsion polymerization of methyl methacrylate in the presence of potassium persulfate initiator, taken in several different concentrations, at various pH values was studied with the aim to obtain colloidal crystals. The thermal properties of poly(methyl methacrylate) prepared by emulsifier-free emulsion polymerization, as the starting material for fabrication of photonic crystals, were examined in relation to the synthesis conditions.     

磺化聚苯乙烯胶体晶的红外光谱分析

单分散乳胶体系可以通过自组装形成有序的胶体晶结构 ,在窄波段光过滤器[1] 、生物医学传感器[2 ] 、智能化学传感器[3] 等领域具有重要的应用价值 .最近 ,人们以此有序结构作为模板 ,制备了有序孔材料[4～ 7] .另外 ,此有序结构在仿生学如模拟蛋白石等有序结构等方面也具有重要意义[8] .但是 ,一般的单分散体系如聚苯乙烯体系所形成的有序结构都属于硬性材料 ,缺乏对外场的响应特性 .此外 ,微球表面没有功能性基团 ,很难与其它物质兼容 ,这使得其作为模板合成其它复合材料的潜力大大降低 .本实验室通过对聚合物胶体晶进行改性 ,使其成为功…     

叶状Cu(OH)2的合成及其向带有纳米孔的CuO的转化

通过乳液界面反应法, 利用以Span80(sorbitan monooleate)作为稳定剂的乳液体系控制合成了叶状Cu(OH)2单晶. 通过热处理, 可以得到表面有纳米孔的CuO, 且保持了原有的叶状形貌. 通过X射线衍射(XRD)、Fourier红外光谱(FTIR)、扫描电镜(SEM)和透射电镜(TEM)观测了其形貌和结构特征. 实验结果表明, 叶状Cu(OH)2为单晶, 且沿[111]晶面定向生长. 孔的形成是由于相转变过程中Cu(OH)2失去H2O分子所致. 通过观测不同反应时间产物的形貌, 深入探讨了叶状Cu(OH)2纳米结构的组装机理. 整个组装过程是由能量高的颗粒状纳米粒子通过端部取向连接定向生长而得到能量相对较低的叶状结构. 并且得到的CuO的紫外光谱相对于其块体材料发生了蓝移, 显示出比较大的禁带宽度.     

叶状Cu（OH）2的合成及其向带有纳米孔的CuO的转化

通过乳液界面反应法,用以Span80(sorbitan monooleate)作为稳定剂的乳液体系控制合成了叶状Cu(OH)2单晶.通过热处理,可以得到表面有纳米孔的CuO,且保持了原有的叶状形貌.通过X射线衍射(XRD)、Fourier红外光谱(FTIR)、扫描电镜(SEM)和透射电镜(TEM)观测了其形貌和结构特征.实验结果表明,叶状Cu(OH)2为单晶,且沿[111]晶面定向生长.孔的形成是由于相转变过程中Cu(OH)2失去H2O分子所致.通过观测不同反应时间产物的形貌,深入探讨了叶状Cu(OH)2纳米结构的组装机理.整个组装过程是由能量高的颗粒状纳米粒子通过端部取向连接定向生长而得到能量相对较低的叶状结构.并且得到的CuO的紫外光谱相对于其块体材料发生了蓝移,显示出比较大的禁带宽度.     

Synthesis of brushite nanoparticles at different temperatures

Phase pure, stable nanocrystalline brushite particles with average diameter in the range of 23–87 nm were obtained by the reverse microemulsion technique employing a mixture of surfactants (Aliquat 336 & Tween 80) as template directing agents, and calcium nitrate tetrahydrate and biammonium hydrogen phosphate as precursors. Particle sizes and morphologies were tuned by adjusting the reaction parameters, precursor concentration and temperature. FTIR, TEM, and XRD were used to characterize morphological changes of as synthesized nanoparticles. FTIR and XRD analyses confirmed the formation of brushite nanoparticles. Variations in the reaction temperature resulted in changes in the particle morphology and distribution. At high temperatures (60°C), the sample exhibited high monodispersity and spherical morphology with the average grain size of 42 nm. At low temperatures (6°C), nanoflakes were formed. The results suggest that a reverse microemulsion system provides facile media for control of the phase and morphology of nanoscale calcium phosphate biominerals. A mechanism providing an insight into the formation of brushite particles has also been proposed.     

光致变色含氟丙烯酸酯涂层的制备及性能

选取十二烷基硫酸钠(SDS),辛基苯基聚氧乙烯醚(OP-10)为复合乳化剂,过硫酸钾(KPS)为引发剂,将2-(全氟己基)乙基甲基丙烯酸酯(PFM)与丙烯酸酯类单体采用预乳化-半连续种子乳液聚合法进行乳液共聚,再将羟基螺吡喃(SPOH)与乳液进行物理共混,制得光致变色含氟丙烯酸酯乳液。 通过多种表征手段研究丙烯酸正丁酯(n-BA)和甲基丙烯酸甲酯(MMA)软硬单体的质量比,SPOH的用量对聚合反应和乳胶膜性能的影响。 结果表明,加入含氟单体后乳胶膜与水、油的接触角提高,热稳定性提高;加入SPOH的质量分数为1.25%时,乳胶膜具有较好的光致变色性能。     

柠檬酸钠与碳酸钙晶型和形貌的控制

晶体的晶型和形貌是碳酸钙制备中的关键问题之一。 采用尿素水解均匀沉淀法来控制碳酸钙的晶型和形貌。 利用XRD和SEM等技术手段对CaCO₃晶体的结构和形貌进行了表征。 结果表明,高温条件下(90 ℃)水溶液中得到均匀的针状结构的文石晶体。 添加适量柠檬酸钠后,则得到的是特殊形貌的方解石晶体。 在乙醇/水混合溶剂中,柠檬酸钠对CaCO₃晶体的形貌也有重要影响,通过改变乙醇体积分数,得到了中空绒毛球状的球霰石。     

咪唑类离子液体辅助水热法合成棒状微/纳米ZnO晶体

以醋酸锌和氢氧化钠为原料, 以水和含不同长度烷基链的咪唑类氯盐离子液体的混合物作为反应介质, 采用水热法合成出不同形貌的微/纳米ZnO晶体, 用扫描电子显微镜(SEM)和X射线衍射仪(XRD)对合成的ZnO晶体进行表征. 研究了烷基链长度、 离子液体用量、 反应时间以及反应温度对形成棒状ZnO晶体形貌的影响. 实验结果表明, 所制备的棒状ZnO晶体样品均为六方晶系结构. 在棒状ZnO晶体的制备过程中, 控制反应温度, 选择不同的离子液体及其用量十分重要.