NaCl改性SiO_2微球的制备及其自组装光子晶体研究

为提高SiO2微球的表面电荷密度,通过改进Stober法,引入电解质NaCl合成SiO2微球,并采用垂直沉积法制备出光子晶体.通过Zeta电位粒度仪、带EDS能谱仪的场发射扫描电子显微镜(SEM)和紫外-可见-近红外光谱仪对其电学性能、显微形貌和光学性能进行测试分析.Zeta电位测试结果显示改性SiO2:微球的Zeta电位平均提高11.39mV;EDS能谱分析表明微球中含有钠元素;SEM照片表明样品平均粒径为334 nm,平均标准偏差小于5%,所得光子晶体为面心立方密排结构;吸收光谱表明在725nm处具有光子晶体带隙.     

光子晶体用二氧化硅胶体球的改性制备及其自组装

采用一步法制备了表面接枝甲基丙烯酰氧基三甲氧基硅烷(MPS)的单分散SiO2胶体球,并通过垂直沉积法在40℃、60%相对湿度下组装出有序性较好的密排结构的SiO2光子晶体.傅立叶红外光谱(FT-IR)和X射线光电子能谱(XPS)结果证明SiO2胶体球表面接枝上了MPS;扫描电子显微镜(SEM)结果表明改性后SiO2胶体球平均粒径为284nm,单分散性较高,平均标准偏差＜5%;制备出的光子晶体是面心立方(fcc)紧密堆积结构;吸收光谱表明,所制备的光子晶体在(111)方向具有光子晶体的带隙特性,带隙中心波长为646nm.     

二氧化硅胶体球的制备、改性及其胶体晶体的组装

采用改进的St(O)ber法制备了单分散性较好、表面光滑的SiO2球形颗粒,将丁二酸化学键合于SiO2胶体球表面以提高其Zeta电势,再采用垂直沉积法在水溶液中制备出SiO2胶体晶体.通过X射线衍射仪、场发射扫描电子显微镜(SEM)和Zeta电位粒度仪对颗粒和胶体晶体的晶型、显微形貌、电学性能进行测试分析.结果表明:所...     

双基片垂直沉降法自组装二氧化硅胶体晶体

采用St(o)ber法制备了适于自组装的单分散性的SiO2球体颗粒,再采用双基片垂直沉积法在无水乙醇中制备出SiO2胶体晶体.通过X射线衍射仪和场发射扫描电子显微镜(SEM)对胶体晶体的晶型和显微形貌进行测试分析.结果表明:所得SiO2球体颗粒为无定形态,粒径为70～380nm,粒径随着氨水浓度的增大而增大;随着双基片间距增大,胶体晶体周期性排列越紧密有序,相同基片间距下,双尺寸胶体晶体更难以获得.     

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。     

单分散SiO2微球的合成及胶体晶体的生长

对传统的"Stober-Fink"合成SiO2微球的工艺进行了改进,运用"籽晶生长法"合成了单分散SiO2微球,该法可以准确地控制微球尺寸,提高微球的球形度.采用垂直沉积法制备了胶体晶体,并对样品的结构和光学性能进行了表征.研究了微球尺寸对垂直沉积SiO2胶体晶体光子带隙的影响,结果表明,通过控制微球粒径,可调节光子晶体的带隙位置.     

氘代聚苯乙烯胶体晶体的制备及光学性质研究

以水作为介质合成了高度单分散的氘代聚苯乙烯微球,并利用垂直沉积法制备了高质量的氘代聚苯乙烯胶体晶体.傅立叶变换红外光谱清楚地表明氘代苯乙烯单体发生了聚合反应;扫描电镜表面分析展示出胶体微球的高度有序排列,断面分析表明氘代聚苯乙烯胶体晶体为面心立方结构;光学透射谱显示出氘代聚苯乙烯胶体晶体的高次布拉格衍射特征,通过和理论计算的能带结构对比,进一步证实了氘代聚苯乙烯胶体晶体为面心立方结构;变角度光学透射谱测量显示,随着入射角的增大,(111)面的衍射峰蓝移,而(200)和(220)面的衍射峰发生红移.     

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.     

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.     

离心法制备高质量三维胶体晶体的研究

采用无皂乳液聚合合成了单分散的聚甲基丙烯酸甲酯(PMMA)球形颗粒,运用离心法制备出高度有序的三维胶体晶体。实验分别考察了粒子种类和转速等因素对胶体晶体结构的影响,并利用扫描电子显微镜(SEM)进行形貌表征分析。结果表明:离心法能制备出大尺寸三维胶体晶体(约1.5cm2×0.4cm),颗粒呈现面心立方堆积,周期短,制备的晶体硬度大。在相同实验条件下,SiO2组装耗时较PMMA短。制备高质量胶体晶体存在最佳转速,对于230nm的PMMA胶体悬浮液,在2000r/min时,得到的胶体晶体质量最高。     

二氧化硅胶体晶体制备方法进展

SiO2 胶体晶体制备过程的研究是许多新型功能材料发展的基础 ,对人们进一步了解物质在纳米、微米尺度的许多特殊性质也将具有指导意义。本文综述了SiO2 胶体晶体制备方法的进展。     

Vertical cell assembly of colloidal crystal films with controllable thickness

Formation of colloidal crystal films (CCFs) is the first step in the fabrication of inverse colloidal crystals, a class of three-dimensionally ordered, macroporous materials. A new vertical cell assembly method is described that yields CCFs with thicknesses up to 100 µm. The cell consists of two microscope cover glasses separated by a thin polymeric spacer. The lower edge of the cell is placed in a colloidal dispersion. Particles are transported to the top of the cell by capillary force and self-assemble into a CCF as the solvent evaporates. This novel vertical cell assembly method is well suited for fabrication of large area CCFs with controllable thickness that could be further processed into ICC filters for size-based separations of molecules and particles.     

二氧化硅胶体晶体的制备及其光子带隙特性

利用胶体颗粒悬浊液的自组织生长技术制备了两种二氧化硅胶体晶体．透射光谱表明：所制备的胶体晶体的光子带隙位于近红外波段,带隙的位置随胶体晶体中胶粒的尺寸而变化;且放置时间延长,带隙将发生蓝移．     

Photonic Microcapsules Containing Single‐Crystal Colloidal Arrays with Optical Anisotropy

Colloidal particles with a repulsive interparticle potential spontaneously form crystalline lattices, which are used as a motif for photonic materials. It is difficult to predict the crystal arrangement in spherical volume as lattices are incompatible with a spherical surface. Here, the optimum arrangement of charged colloids is experimentally investigated by encapsulating them in double‐emulsion drops. Under conditions of strong interparticle repulsion, the colloidal crystal rapidly grows from the surface toward the center of the microcapsule, forming an onion‐like arrangement. By contrast, for weak repulsion, crystallites slowly grow and fuse through rearrangement to form a single‐crystal phase. Single‐crystal structure is energetically favorable even for strong repulsion. Nevertheless, a high energy barrier to colloidal rearrangement kinetically arrests the onion‐like structure formed by heterogeneous nucleation. Unlike the isotropic onion‐shaped product, the anisotropic single‐crystal‐containing microcapsules selectively display—at certain orientations but not others—one of the distinct colors from the various crystal planes.     

Long-term colloidal stability of graphene oxide aqueous nanofluids

Abstract

The use of nanofluids for industrial applications depends on its stability during transport and use. In this work, we demonstrate that graphene oxide (GO)-based aqueous nanofluids can remaining stable for as many as 90?days. The structural and morphological analyses showed that the GO samples have an average thickness of two graphitic layers with interlayer spacing of 1?nm. The long-term colloidal stability of the nanofluids was monitored for 90?days using three different techniques: UV-vis, zeta potential (ζ) and DLS, which confirmed this stability. The observed ζ value (average of ?64.8?±?1.81?mV) at 200?ppm of GO is the highest negative value reported at pH = 4. The particle size distribution after 90?days of storage presented a major population with diameter of (530?±?40) nm that represented 98% of the scattered light intensity.     

Electrophoretic deposition of colloidal crystals assisted by hydrodynamic flows

Latex-based colloidal crystals have been grown by electrophoretic deposition. The deposition has been assisted by hydrodynamic von Kármán-like flows, which lead to quantitative improvements. It has been studied the influence of applied voltage, deposition time and flow rate on the number of deposited layers and on the mean domain size. The samples were studied with microscopy and precision weight measurement. It has been found that there is a critical time after which the deposition mechanism changes, and the behavior of the system before and after this critical time is considered. The mean domain size and the deposition time were reduced to non-dimensional forms which show the collapse of the data for different applied voltages and flow rates into one curve.     

胶体阵列及三维光子晶体制备的研究进展

单分散的胶体颗粒能自发排列成胶体阵列,其长程有序结构能获得许多特殊的性质.胶体阵列被用作制备可见光及近红外波长范围的光子晶体的基础.以其为模板制备的反蛋白石结构可拥有全光子禁带,为新一代光子器件开发和应用带来了希望.介绍了单分散胶体颗粒的主流制备方法,归纳总结了胶体阵列制备的几种方法和国内外最新的相关报道,简述了其在制备三维光子晶体领域的最新进展以及该领域国内外的研究进展.     

挥发速率对胶体悬浮液干燥花样的影响

研究了不同挥发速率下厚度较薄的凹液层胶体悬浮液的干燥花样。Panasonic照相机用于拍摄宏观干燥花样。结果表明,随着挥发速率的减小,马兰哥尼对流强度下降,胶体悬浮液的干燥花样更为平整均匀。在较低的挥发速率下可避免宽环花样形成,制备得到表面平整的薄膜,反射光谱证明其可作为三维光子晶体材料。