单分散SiO_2胶体光子晶体的自组装制备与表征(英文)

使用Stber法化学合成了粒径在200-350nm之间的单分散SiO2,采用垂直沉积技术自组装制备了胶体晶体薄膜。通过扫描电镜与分光光度计对样品的微观结构与透过光谱进行了表征,结果表明,组成胶体晶体的SiO2微球呈面心立方结构,膜层的厚度可以通过胶体溶液的浓度加以控制,胶体膜层透射光谱中出现的峰值位置取决于SiO2微球的大小,并且与布拉格定律理论计算的结果相一致,透射光谱中光学阻带的深度可以通过改变胶体悬浮液中SiO2颗粒的体积分数来调控。     

羧基化聚苯乙烯微球的制备及其自组装行为研究

采用分散聚合法,以乙醇、水为分散介质,苯乙烯为共聚单体,聚乙烯吡咯烷酮（PVP）为稳定剂,AIBN为引发剂,丙烯酸（AA）为功能共聚单体,制备了粒径为100—1000nm羧基化聚苯乙烯微球,研究醇水比、分散剂、引发剂用量对微球粒径及分布的影响,分析微球表面形貌、粒径分布、表面羧基含量,结果表明,胶体晶体是面心立方密排结构,微球单分散性好,表面光滑,球形度好,表面羧基含量最高可达到0．206mmol／g。同时,用垂直沉积法制备出较大范围内呈现高度有序的密排结构聚苯乙烯胶体晶体。     

CdSe-SiO2光子晶体的垂直沉积及近红外变频特性

在氧化铟锡玻璃上电化学合成了CdSe薄膜,采用垂直沉积法首次在CdSe薄膜上制备了SiO2胶体晶体, 实现了CdSe表面介电常数的调节.扫描电镜观察表明,500nm微球在CdSe薄膜上呈面心立方密堆结构排列,在微米尺度上胶体晶体显示出一定的多晶序.与SiO2胶体晶体相比,CdSe-SiO2光子晶体的UV-vis-NIR透射谱只有一个较宽的光子带隙,带隙在近红外波段随入射角减小向短波方向移动.所得CdSe-SiO2光子晶体样品可作为地面目标针对红外卫星成像的伪装材料.     

单分散聚苯乙烯微球的制备及其模板表面形貌分析

以丙烯酸为分散剂、过硫酸铵为引发剂、水为分散介质进行了聚苯乙烯微球的制备,讨论了丙烯酸浓度、引发剂浓度、pH值、反应时间与温度等因素对微球制备的影响规律并确定了最佳的制备工艺参数。采用旋涂法制备聚苯乙烯微球模板,并发现其表面排布存在两种排列方式:(1)呈现面心立方〈100〉面的排列方式;(2)呈现面心立方〈111〉面的排列方式。     

薄膜厚度对胶体晶体薄膜光学特性的影响

通过控制温度和湿度,用垂直沉积法快速制备出了不同厚度的高质量二氧化硅和聚苯乙烯胶体晶体薄膜。用透射光谱和反射光谱对制备的样品的光学特性进行了表征,并与理论计算结果进行了对比分析;用衍射光谱中的布拉格衍射峰两侧的波纹测量了薄膜厚度,并对薄膜厚度对其光学特性的影响进行了分析,为用厚度调制胶体晶体薄膜光学特性和实际应用创造了条件。     

聚苯乙烯微球表面合成CdSe纳米晶

以聚苯乙烯(PS)单分散微球为模板, 利用表面化学沉积, 在PS微球表面合成了CdSe纳米晶. 透射电子显微镜(TEM)观察发现, CdSe纳米晶以岛状形貌分布在PS微球表面, X射线衍射(XRD)分 析显示合成CdSe纳米晶具有立方相结构. 通过对产物形貌的演变过程进行观察分析表明, PS球周围的双电层结构对该形貌的形成起决定作用.     

单分散聚苯乙烯颗粒的制备及其胶体晶体微球的组装

采用无皂乳液聚合技术,以过硫酸钾(KPS)为引发剂、碳酸氢钠(NaHCO3)为缓冲剂、丙烯酸(AA)为共聚单体制备了表面含羧基的单分散聚苯乙烯(PS)颗粒。用悬浮液滴蒸发自组装技术制备了三维有序胶体晶体微球。采用傅立叶变换红外光谱(FT-IR)和扫描电子显微镜(SEM)对样品结构和形貌进行表征。结果表明,聚苯乙烯颗粒粒径分布均匀,单分散性好且具有良好的球形度,丙烯酸的共聚使颗粒带有羧基而实现功能化改性。离子强度、引发剂浓度和共聚单体浓度是影响聚苯乙烯颗粒尺寸大小的重要因素。胶体晶体呈规则球形,聚苯乙烯颗粒紧密排列,形成面心立方(fcc)结构,表面表现为六方紧密有序排列。     

聚苯乙烯微球的制备及其在光子晶体中的应用

亚微米级聚苯乙烯微球是一类常见的制备光子晶体的材料。综述了分散聚合法和乳液聚合法制备光子晶体用单分散聚苯乙烯微球的研究进展;介绍了聚苯乙烯胶体球在蛋白石结构、反蛋白石结构和可调制光子晶体中的应用进展;并提出了今后的研究方向。     

SiO2胶体晶体的自组装结构及其带隙特征

光子晶体是一种具有光子带隙的新型功能材料.利用垂直沉积自组装法制成SiO2胶体晶体,并利用扫描电子显微镜和紫外分光度计对胶体晶体的显微形貌和光学特征进行了研究.结果表明,利用垂直沉积法自组装得到的SiO2胶体晶体具有面心立方结构;在可见光波段,胶体晶体在＜111＞面方向存在光子带隙.     

聚苯乙烯磁性微球化学镀法制备研究

在聚苯乙烯微球表面进行化学镀镍可以制备磁性微球,其结合了聚苯乙烯轻质的优点和镍的磁性.采用扫描电镜(SEM)表征了微球的表面形貌,研究了前处理(活化)工艺对磁性微球产率及形貌的影响.结果表明,磁性微球的产率、分散性及表面形貌均由活化效果决定;采用优化的活化工艺进行化学镀镍反应,可以得到包覆完整、形状规则的镍包覆聚苯乙烯微球,其有效密度(平均值为2.7g/cm3)明显低于传统磁性颗粒的密度(一般为7～8g/cm3);用X射线衍射分析(XRD)表征了镀层的晶体结构,发现镀层的晶体结构与单质镍十分相似,为面心立方结构.     

Optical properties of three-dimensional P(St-MAA) photonic crystals on polyester fabrics

The three-dimensional (3D) photonic crystals with face-centered cubic (fcc) structure was fabricated on polyester fabrics, a kind of soft textile materials quite different from the conventional solid substrates, by gravitational sedimentation self-assembly of monodisperse P(St-MAA) colloidal microspheres. The optical properties of structural colors on polyester fabrics were investigated and the position of photonic band gap was characterized. The results showed that the color-tuning ways of the structural colors from photonic crystals were in accordance with Bragg’s law and could be modulated by the size of P(St-MAA) colloidal microspheres and the viewing angles. The L¹a¹b¹ values of the structural colors generated from the assembled polyester fabrics were in agreement with their reflectance spectra. The photonic band gap position of photonic crystals on polyester fabrics could be consistently confirmed by reflectance and transmittance spectra.     

Solvothermal preparation of cobalt nanorods

Cobalt nanorods have been prepared through solvothermal process with hydrazine hydrate and dimethylglyoxime (DMG) as reducing and morphology directing agents. The phase structure, morphology and magnetic properties of the as-prepared product were extensively characterized by X-ray diffraction, transmission electron microscopy and superconducting quantum interference device magnetometer. X-ray diffraction pattern revealed that the as-synthesized product was cobalt with face-centered cubic structure. Transmission electron microscopy observation showed that the as-prepared product composed of rod-like shape with size around 10 nm. The presence of DMG molecules on the surface of Co nanostructures was confirmed by the FTIR spectra. Magnetic measurements revealed that the nanorod exhibit ferromagnetic behavior at 300 K. The coercive force value of cobalt nanorods is 340 Oe at 300 K. Compared with bulk cobalt, the nanorods exhibit significant increase in coercive force as a reflection of shape anisotropy. The saturation magnetization value of Co nano rod is 150 emu/g at room temperature.     

Development of an intelligent polymerized crystalline colloidal array colorimetric reagent.

We have developed a novel colorimetric reagent for the determination of Pb2+, pH, and temperature. This colorimetric reagent consists of a dispersion of approximately 100-microm particles composed of an intelligent polymerized crystalline colloidal array (IPCCA). The IPCCA particles are composed of a hydrogel polymerized around a face-centered cubic (fcc) array of monodisperse, highly charged polystyrene colloidal particles. These IPCCA particles diffract visible light because the (111) planes of the fcc polystyrene colloidal particle array have an approximately 200-nm lattice constant. The IPCCA particles also contain a molecular recognition agent that actuates array volume changes as a result of changes in analyte concentration or temperature. This results in changes in the IPCCA lattice constants, which shifts the wavelength of light diffracted. We report here the use of these sensing materials in a liquid dispersion that can be poured into a sample solution. This diffraction measurement method is analogous to X-ray powder diffraction measurements. The diffraction wavelength is monitored at a defined angle relative to the incident light.     

表面改性及原位还原法制备聚酰亚胺/镍纳米复合薄膜

通过对均苯四甲酸二酐-4,4’-二胺基二苯醚(PMDA-4,4’-ODA)型聚酰亚胺(PI)成品薄膜的表层水解处理、并在硫酸镍水溶液中实施离子交换以及随后的乙二醇热还原的方法,制备了聚酰亚胺/镍纳米复合薄膜。通过X射线衍射仪(XRD)、傅立叶变换红外光谱仪(FT-IR),透射电子显微镜(TEM)等方法研究了复合薄膜结构的变化,结果表明,经乙二醇热还原后,水解后的聚酰亚胺表层又重新形成亚胺环结构,并在其内部形成了均匀分散的具有面心立方晶型(FCC)的金属镍粒子,直径约为100 nm~200 nm。     

Synthesis and characterization of PbSe nanoparticles obtained by a colloidal route using Extran as a surfactant at low temperature

Lead selenide nanoparticles (PbSe NPs) have been obtained through an easy and low cost route using colloidal synthesis in aqueous solution. The synthesis was carried out at room temperature using Extran (Na?P?O??, NaOH and H?O) as surfactant. Hydrochloric acid (HCl) was used to eliminate the generated by-products. The size of PbSe NPs was varied by changing the Pb:Se molar concentration. The PbSe NPs were characterized by powder x-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive x-ray analysis (EDAX), high-resolution transmission electron microscopy (HRTEM) and Raman spectroscopy. The XRD measurements showed that the PbSe NPs have the face-centered cubic phase structure. The crystal size was found to be between 14 and 20 nm as calculated from the XRD patterns and these values were corroborated with SEM and TEM. Additionally, HRTEM micrographs showed crystalline planes at (200), (220) and (111) of the PbSe NPs, in agreement with the XRD results.     

Aqueous synthesis of luminescent magic sized CdSe nanoclusters

Highly stable water-soluble CdSe nanoclusters (NCs) with magic size were successfully synthesized using homocysteine (HCY) as capping ligands. Their sizes were tunable between 1.2 and 2.0 nm depending on reflux time. The final products were characterized by UV-vis absorption, steady and time-resolved photoluminescence (PL) spectra, X-ray powder diffraction (XRD) and high-resolution transmission electron microscopy (HRTEM). XRD analysis showed that the HCY-capped CdSe NCs were of the cubic structure, UV-vis absorption spectra and HRTEM micrograph exhibited that the NCs were nearly monodisperse and relatively uniform. The as-prepared CdSe NCs had a PL quantum yield of up to 1.4%, almost comparable to the CdSe magic sized clusters prepared by an organometallic route.     

Domain structure and optical properties of colloidal photonic crystal

Thin colloidal photonic crystals were grown using shear-flow crystallization of polystyrene colloidal nanoparticles. The arrays consist of two types of domains, which are clearly visible on scanning electron microscopy patterns. Both domains have cubic close packing and are distinguished by their orientation with regards to substrate surface. The positions of the main minima in the visible-near-IR transmittance spectrum of the arrays as well as the dependence of these minima on the angle of the light incidence have been measured and interpreted using photon band structure of the two-component media.     

Green synthesis and characteristic of core-shell structure silver/starch nanoparticles

An eco-friendly method was put forward to synthesize Ag nanoparticles (Ag NPs) by using biodegradable starch as a stabilizing agent. The silver ion from AgNO₃ was reduced by glucose in soluble starch solution. Morphological observation and characterization of Ag NPs were performed by using high-resolution transmission electron microscopy (HRTEM), X-ray diffraction (XRD) and UV–vis absorption spectroscopy. HRTEM showed that Ag NPs were covered by starch layer to form spherical core-shell Ag/starch NPs with diameter ranging from 5 to 20 nm. XRD pattern confirmed the presence of Ag NPs with face-centered cubic (fcc) structure. All these results indicated that starch played an important role in stabilizing Ag NPs.     

Introduction of a planar defect into colloidal photonic-crystal films and their optical properties

A defect mode in the bandgap of photonic crystals is a key factor for potential applications, emission, bandpass filter, sensor, and low throughput laser. A Fabry-Perot type cavity was known as a multilayer film with a planar defect or a one-dimensional colloidal photonic crystal film with a planar defect. In this work, we have developed a simple and easy method by two colloidal crystals, i.e., face center cubic (fcc) structure, films bonded together by hot pressing to form a sandwich structure, and clear defect mode was observed in the photonic bandgap of fcc (1 1 1) direction. We have investigated the effect of the thickness of the defect layer in the sandwich structure on the optical properties. A single or double dips appeared in Bragg's diffraction peak at different planar defect thicknesses. In addition, a simulation of the reflection spectra of multilayer film calculation showed the defect mode is much influenced by the planar defect thickness.