等离子体增强化学气相沉积技术制备锗反蛋白石三维光子晶体

采用溶剂蒸发对流自组装法将单分散二氧化硅(SiO2)微球组装形成三维有序胶体晶体模板,以锗烷(GeH4)为先驱体气用等离子增强化学气相沉积法在350℃填充高折射率材料锗.获得了锗反蛋白石光子晶体.通过扫描电镜、X射线衍射仪对锗反蛋白石的形貌、成分、结构进行了表征.结果表明:锗在SiO2微球空隙内填充均匀,得到的锗为多晶态.锗反蛋白石光子晶体为三维有序多孔结构.等离子体增强化学气相沉积的潜在优势在于可实现材料的低温填充,从而以高分子材料为模板进行复型,得到多种结构的三维光子晶体.     

油性介质中组装二氧化硅胶体晶体薄膜

报道厂一种由粒径大于700nm的SiO2微球组装胶体晶体薄膜的方法。以一种密度较大的疏水性有机物替代水或醇类为分散剂,通过对SiO2微球表面进行疏水性处理改善其在油性介质中的分散性,采用改进的垂直沉积法在油性分散剂中制备SiO2胶体晶体。用扫描电子显微镜、红外光谱仪和紫外－可见光谱仪对SiO2胶体晶体薄膜的形貌、结构和光学性能进行了观察测试。结果表明;较大密度的分散剂能有效降低SiO2微球的沉降速度,组装成直径在700～2000nm范围的SiO2微球的胶体晶体。获得的SiO2光子晶体具有长程有序结构,并在近红外区具有显著的光子频率带隙。     

单分散胶体颗粒的有序组装及其应用研究进展

本文综述了近1～2年来课题组在单分散胶体微球有序组装及其应用方面的研究进展.其中包括250～1300 nm宽尺寸范围单分散二氧化硅胶体微球的重力沉降自组织;旨在提高光子晶体折射率反差的TiO2/SiO2复合胶体微球的有序组装;硬模板与催化材料一步复合的二元胶体体系颗粒的有序自组装;一种高效的聚苯乙烯胶体颗粒的批量组装技术;低体积分数聚苯乙烯胶体晶体的制备;以及聚苯乙烯胶粒晶体作为可调谐三维非线性光子晶体在高开关对比的光子晶体光开关方面的应用,和作为制备有序大孔材料硬模板在大分子催化方面的应用等.     

光子晶体及SiO2光子晶体的制备技术

光子晶体是一种具有光子带隙的周期性电介质结构,落在光子带隙中的光将不能传播。由于其独特的调节光子传播状态的功能,成为实现光通讯和光子计算机的基础。SiO2胶体球作为胶体光子晶体的组成基元,具有广阔的应用前景。本文介绍了光子晶体的概念、特征与应用领域,以及SiO2光子晶体的制备技术。     

单分散SiO2/Ag/SiO2核壳结构微球制备及自组装光子晶体

应用湿化学方法,在SiO2微球表面先后包覆5 nm银层、20 nm SiO2介质膜,制备了直径约300 nm的单分散SiO2/Ag/SiO2核壳结构微球.用提拉技术实现微球的自组装,获得了长程有序的面心立方结构排列的光子晶体,并研究了其光学性能.结果表明:在可见至近红外波段存在非完全光子带隙;SiO2/Ag/SiO2球体自组装成的光子晶体并非完全密堆排列.     

SiO2光子晶体的垂直沉积制备与光学性能研究

采用改进的St(o)ber法合成了不同粒径的单分散SiO2微球颗粒,用种子液法制备了平均粒径约为550 nm的单分散SiO2微球颗粒,在可见光波段垂直沉积制备了SiO2光子晶体薄膜.采用紫外-可见分光光度计测试了不同反应物浓度配比所得微球制备的光子晶体薄膜的光学性能,并分析了退火对光反射性能的影响.     

有序大孔二氧化硅微球的制备研究

采用乳液聚合法合成了单分散改性聚苯乙烯（PS）乳胶粒,利用PS乳胶粒自组装制得胶体晶体（“蛋白石”）微球,通过溶胶-凝胶模板法制备了有序大孔SiO2（“反蛋白石”）微球,通过SEM对改性PS乳胶粒、胶体晶体微球和有序大孔SiO2微球表面形貌进行了表征。结果表明,改性PS乳胶粒呈单分散性,粒径为317 nm;胶体晶体微球表面PS乳胶粒排列有序;有序大孔SiO2微球表面呈有序多孔,其孔呈六边形,孔径分布均一,约为200 nm。     

响应性光子晶体的研究进展

简要介绍了光子晶体的概念及各种制备方法,详细综述了响应性光子晶体的研究进展,包括:1胶体晶体水凝胶阵列;2反蛋白石结构水凝胶;3反蛋白石状光子晶体微球;4微凝胶胶体晶体;5浸润性控制的光子晶体。     

溶剂萃取法制备SiO_2光子晶体薄膜

以设计的双基片装置作为辅助,利用溶剂萃取法成功制备了SiO_2胶体光子晶体薄膜。SEM和紫外可见光谱表征显示,用溶剂萃取制备的SiO_2胶体光子晶体薄膜具有三维有序结构和明显的光子带隙。此外,考察了SiO_2光子晶体生长高度与萃取时间的关系,发现其生长速率呈现先快后慢的现象,这主要是重力作用造成的,随生长时间增加,它会导致在竖直方向上SiO_2微球存在浓度梯度。     

光子晶体编码微球载体的层层自组装稳定

单分散羧基功能化的交联聚甲基丙烯酸甲酯(PMMA)纳米粒子以液滴为模板自组装成三维胶体光子晶体微球,并层层自组装(LBL)包覆上支化的聚乙烯亚胺(PEI)和聚苯乙烯磺酸钠(PSS)高分子聚电解质对,加以戊二醛(GA)交联。制得的三维胶体光子晶体微球结构有序稳定,可用作性能稳定的编码载体。     

Effects of Thermal Annealing on Formation of Micro Porous Titanium Oxide by the Sol–Gel Method

We investigated the structural and optical properties of microporous titanium oxide (TiO₂) fabricated by the sol–gel method using templates of colloidal crystals with polystyrene spheres when the annealing temperature was changed between 600° and 1000°C. From X-ray diffraction patterns and SEM images, the rutile TiO₂ annealed at a high temperature did not form periodic porous bodies, while the anatase TiO₂ annealed at lower than 800°C formed periodic porous bodies. The porous TiO₂ obtained acts as an air-sphere/TiO₂ photonic crystal with an FCC structure. It is suggested that TiO₂ sol annealed at a lower temperature do not lead to phase transition from the anatase phase to the rutile phase to obtain the air-sphere/TiO₂ photonic crystal by the sol–gel method using templates of colloidal crystals.     

Artificial opals prepared by melt compression

In recent years, colloidal crystals with a refractive index varying periodically on the scale of the light wavelengths have been prepared by various methods. These photonic crystals reflect light and exhibit, at sufficiently strong contrast, even a complete band-gap in which light cannot propagate in any direction. Most studies published so far were aimed at such high-contrast photonic crystals with a complete band-gap or their precursors. Frequently, a face-centered cubic (fcc) lattice was built up from monodisperse polymer or silica spheres with diameters in the submicron range. Methods as sedimentation and drying of dispersions led to usually small and thin specimens. This report deals with films that were produced by a novel technique based on shear flow in the melts of polymer core-shell latex spheres. The process is fast and yields large area films, thin or thick, in which the latex spheres are crystallized in fcc order. The refractive index contrast of these purely polymeric films is too small for a complete band-gap photonic crystal, but the films are attractive color materials showing wavelength and angle dependent reflection colors.     

Structure Determination in Colloidal Crystal Photonic Bandgap Structures

Structure/optical property relationships in photonic bandgap structures are evaluated by a novel combination of sample sectioning, microscopy, and image analysis. Disordered colloidal crystals of solution-derived, monosized SiO₂ particles were sectioned by focused ion beam (FIB) milling and then imaged using field emission scanning electron microscopy (FE-SEM). Pair correlation and radial distribution functions of the particulate arrangement were generated directly from a binary color scale rendering of the FE-SEM images, therein defining the level of order or disorder in the structure. These experimentally obtained spatial correlation functions were used to compute the scattering spectral properties in an analogous, although inverse (i.e., solving the inverse scattering problem), method to that used in X-ray diffraction for structure determination. Using a first-order approximation to the scattering from a disordered structure, the bandwidth and midgap values for the colloidal crystal photonic bandgap materials were within 15% of those measured. This new methodology promises to provide a simple and direct approach for quantifying the structure/optical property relationships in ordered and disordered photonic crystals directly from standard microstructural imaging techniques.     

胶体二氧化硅光子晶体自组装机理及缺陷分析

通过改进Stober方法，严格控制反应条件合成了平均直径为238 nm、分布偏差约为5.7%的球形二氧化硅单分散颗粒. 首次利用乙醇作为沉降介质，在重力场作用下制备了二氧化硅光子晶体. 提出了自组装方法生长光子晶体的机理，并对缺陷形成原因进行了初步分析.     

Microstructures and optical features of polymer‐immobilized non close‐packed colloidal crystalline array

We have investigated to immobilize non close‐packed silica colloidal crystalline arrays in aqueous dispersion with hydrophilic polyethylene glycol acrylate polymer and to examine microstructures of the immobilized colloidal crystalline array by using the angle‐resolved reflection spectroscopy and scanning probe spectroscopy (SPM). Above nine of ethylene glycol chain length and below 10 wt % of monomer concentration in the dispersion, the structure of the three‐dimensional array in the aqueous dispersion is kept with immobilizing process. Angle‐resolved reflection spectra indicate refractive index increase, and interplaner spacing decreases with the increase of the particle volume fraction. The SPM phase images proved the crystal structure of the immobilized colloidal crystalline array of face‐centered cubic (fcc) structure. The interplaner spacings of the crystalline structure derived from angle‐resolved reflection spectra agree with those derived from SPM topographic images. We have demonstrated the microstructure of the polymer‐immobilized colloidal crystalline array directly and open the possibility of tuning the microstructure of colloidal crystalline array for photonic crystal. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 2308–2314, 2006     

Fabrication of high‐quality silica photonic crystals on polyester fabrics by gravitational sedimentation self‐assembly

A series of monodispersed silica microspheres with favourable sphericity and different diameters in the range 180–380 nm were prepared by adjusting the concentrations of tetraethylorthosilicate, ammonia, and deionised water by the Stöber method. In different self‐assembly conditions, the quality of silica photonic crystals on a polyester fabric substrate was investigated by field‐emission scanning electron microscopy for the morphology of the crystal structures and by spectrometry for their stop band intensities. High‐quality silica photonic crystals with a face‐centred cubic (fcc) array on polyester fabrics were produced at a low evaporation rate by adopting a high‐relative‐humidity controlled condition with a medium mass fraction of colloidal silica, and exhibited brilliant and variable structural colours, depending on the photonic band gap regulated by the spherical size of the silica microspheres and the viewing angles.     

垂直排列法组装胶体晶体的最新进展

光子晶体是一种具有光子带隙的新型功能材料．利用胶体粒子自组装三维光子晶体由于其制备过程比较经济、简单，从而为很多人所关注．目前报道的方法已有多种．其中垂直排列法的简便易行使得其受到了广泛的研究，但另一方面这种方法本身的缺点也限制了它的使用范围．针对这种情况，很多研究机构提出了他们的改进方法．本文简要概述了在这一方面的最新进展，并且在本实验室已能够制备任意单分散、均一尺寸二氧化硅粒子的基础上，采用恒温快速蒸发自组装法得到了高质量的胶体晶体排列．