Fabrication of Large-area 3-D Ordered Silvercoated Colloidal Crystals and Macroporous Silver Films Using Polystyrene Templates

The highly ordered silver-coated colloidal crystals arrays and macroporous silver films were derived through an electrostatics-induced adsorption effect using polystyrene(PS) as templates. Carboxyl-modified PS microspheres were prepared by emulsifier-free emulsion polymerization using methacrylic acid(MAA) as the functional monomer. PS microspheres were self-assembled into close packing colloidal crystals of facecentered cubic arrays to the substrate with vertical deposition method. These colloidal crystals were modified using dopamine(DA) to form poly-dopamine(PDA) during its oxidative polymerization. Through electrostatic interaction, the silver nanoparticles were deposited and adsorbed onto the surfaces of colloidal crystals templates by exposing [Ag(NH_3)_2]^+solution to infrared irradiation. Removal of the polymeric template by etching with methylbenzene solvent resulted in 3D ordered macroporous silver films. The structural and properties of the ordered silver-coated arrays and macroporous silver films were characterized by field emission scanning electron microscopy(FE-SEM), X-ray diffraction(XRD), UV-vis spectroscopy and surface-enhanced Raman spectroscopy(SERS). The results indicate that the prepared silver-coated arrays and macroporous silver films possess the features of ordered multilayer arrangement, uniformity and repeatability as well as an ideal SERS effect.

Facile Fabrication of Large Area Polystyrene Colloidal Crystal Monolayer via Surfactant-free Langmuir-Blodgett Technique

A facile and novel method for the production of a large area of well-ordered polystyrene （PS） colloidal crystal monolayer was established using the surfactant-free Langmuir-Blodgett （LB） technique. The hydrophobic property （film-forming ability） of PS spheres was improved by a thermo-rheology treatment before LB assembly, and a large film was obtained. In contrast to the traditional LB technique, no surfactant was needed in this method, which could eliminate the additional contamination of surfactants in the preparation process and provided the products with versa- tile applications in nanosphere lithography （NSL） for biosensor, surface plasmon resonance, and surface enhanced Raman spectroscopy .

INVERSE OPALINE STRUCTURE TITANIA PHOTONIC CRYSTALS BY FUNCTIONALLY MODIFIED COLLOIDAL CRYSTALS TEMPLATING

Ordered macroporous titania photonic crystals （PCs） and photonic balls were fabricated by functional modified polymer colloidal crystals. The TiO2 PCs and balls formed through this method exhibit no cracks and lacunae in large areas on their surface and their inner structures.

Improving self-assembly quality of colloidal crystal guided by statistical design of experiments

A versatile and reliable approach is created to fabricate wafer-scale colloidal crystal that consists of a monolayer of hexagonally close-packed polystyrene （PS） spheres. Making wafer-scale colloidal crystal is usually challenging, and it lacks a general theoretical guidance for experimental approaches. To obtain the optimal conditions for self-assembly, a systematic statistical design and analysis method is utilized here, which applies the pick-the-winner rule. This new method combines spin-coating and thermal treatment, and introduces a mixture of glycol and ethanol as a dispersion system to assist self-assembly. By controlling the parameters of self-assembly, we improve the quality of colloidal crystal and reduce the effect of noise on the experiment. To our best knowledge, we are first to pave this path to harvest colloidal crystals. Importantly, a theoretical analysis using an energy landscape base on our process is also developed to provide insights into the PS spheres＇ self-assembly.

Modification of the spontaneous emission of quantum dots near the surface of a three-dimensional colloidal photonic crystal

This paper demonstrates experimentally and numerically that a significant modification of spontaneous emission rate can be achieved near the surface of a three-dimensional photonic crystal. In experiments, semiconductor coreshell quantum dots are intentionally confined in a thin polymer film on which a three-dimensional colloidal photonic crystal is fabricated. The spontaneous emission rate of quantum dots is characterised by conventional and time-resolved photoluminescence （PL） measurements. The modification of the spontaneous emission rate, which is reflected in the change of spectral shape and PL lifetime, is clearly observed. While an obvious increase in the PL lifetime is found at most wavelengths in the band gap, a significant reduction in the PL lifetime by one order of magnitude is observed at the short-wavelength band edge. Numerical simulation reveals a periodic modulation of spontaneous emission rate with decreasing modulation strength when an emitter is moved away from the surface of the photonic crystal. It is supported by the fact that the modification of spontaneous emission rate is not pronounced for quantum dots distributed in a thick polymer film where both enhancement and suppression are present simultaneously. This finding provides a simple and effective way for improving the performance of light emitting devices.

DEFORMATION OF SOFT COLLOIDAL CRYSTALLINE STRUCTURE-THEORETICAL CONSIDERATIONS AND EXPERIMENTAL EVIDENCES BY SYNCHROTRON SMALL-ANGLE X-RAY SCATTERING ON TENSILE STRETCHED POLYMERIC LATEX FILM

Films obtained via drying a polymeric latex dispersion are normally colloidal crystalline where latex particles are packed into a face centered cubic (fcc) structure.Different from conventional atomic crystallites or hard sphere colloidal crystallites,the crystalline structure of these films is normally deformable due to the low glass transition temperature of the latex particles.Upon tensile deformation,depending on the drawing direction with respect to the normal of specific crystallographic plane,one obs...

Applied electric field to fabricate colloidal crystals with the photonic band-gap in communication waveband

The macropore silica colloidal crystal templates were assembled orderly in a capillary glass tube by an applied electric field method to control silica deposition. In order to achieve the photonic band gap （PBG） of colloidal crystal in optical communication waveband, the diameter of silica microspheres is selected by Bragg diffraction formula. An experiment was designed to test the bandgap of the silica crystal templates. This paper discusses the formation process and the close-packed fashion of the silica colloidal crystal templates was discussed. The surface morphology of the templates was also analyzed. The results showed that the close-packed fashion of silica array templates was face-centered cubic （FCC） structure： The agreement is very good between the experimental data and the theoretical calculation.

Influence of colloidal particle transfer on the quality of self-assembling colloidal photonic crystal under confined condition

The relationship between colloidal particle transfer and the quality of colloidal photonic crystal（CPC） is investigated by comparing colloidal particle self-assembling under the vertical channel（VC） and horizontal channel（HC） conditions.Both the theoretical analyses and the experimental measurements indicate that crystal quality depends on the stability of mass transfer.For the VC,colloidal particle transfer takes place in a stable laminar flow,which is conducive to forming high-quality crystal.In contrast,it happens in an unstable turbulent flow for the HC.Crystals with cracks and an uneven surface formed under the HC condition can be seen from the images of a field emission scanning electron microscope（SEM） and a three-dimensional（3D） laser scanning microscope（LSM）,respectively.

A colloidal crystal double-heterostructure fabricated with the angle controlled inclined deposition method

A self-assembly method, named the angle controlled inclined deposition method, is developed for fabricating well- ordered silica and polystyrene colloidal crystals. A high-quality colloidal crystal with a flat and uniform surface over a large area can be produced rapidly using a minute quantity of suspension and without any additional equipment. By controlling the inclined angle, we can fabricate colloidal crystals with diverse numbers of layers. A colloidal crystal double-heterostructure （composed of three different colloidal photonic crystals） can be rapidly fabricated with this method. Both experimental and simulation results show that the photonic band gap of the double-heterostructure is not a simple superposition of that of the compositional colloidal crystals along the stacking direction.

Influence of Sedimentation on Crystallization of Charged Colloidal Particles

密度在固体和液体阶段之间匹配的方法经常被采用有效地在一个胶体的系统的动态行为上消除暂停的沉积的效果。有在匹配密度、无敌的媒介(在合适的比例的 H2O 和 D2O 的混合物) 驱散的 98 nm 的直径的控告的胶体的 microspheres 的结晶化的实验与相比检验沉积的影响。胶体的暂停的思考系列被用来监视结晶化进程。结果证明水晶缩放密度无敌(也就是，面对沉积) 样品变得比的快匹配密度(当沉积不在时) 在结晶化的起始的阶段的大小写，然后后者追上并且超过前者。解释这些观察，我们假设在安定晶体，沉积在进入水晶结构的更多的粒子便于结果。当晶体增加到改变尺寸，安定速度不管多么变得大并且水动力学磨擦从精细的水晶结构剥去一些粒子。总的来说，沉积看起来开始加速水晶尺寸生长然后延迟生长。另外，在 microgravity 下面形成的水晶结构更仔细在正常严肃比那被包装。

Effect of Particle Inhomogeneity on Band-gap of Silica Colloidal Crystals in Vertical Deposition Method

The effect of inhomogeneity of particles on the band-gap of silica colloidal crystals(SCCs) fabricated by vertical deposition method was studied.The optical properties of the crystals were examined.The SEM images and transmission spectrum of the crystals showed that the inhomogeneity of particles not only affected the ordering,but also their mid-gap position.When the volume ratio of S particles(VS) to L particles(VL) in suspension was 1:1,the band-gap of silica colloidal crystals changed with the growth of particles.When the ratio was 2:1,the quality of SCCs on substrate was obviously improved simultaneously with the number decreasing of L particles.Especially,the quality of SCCs at the bottom of substrate was the best and its mid-gap(634 nm) was very close to that of theoretic value of S particles(636 nm).When the ratio was 3:1,the effect of L particles became smaller with the number decreasing of L particles in suspension.The mid-gap position(638 nm) of whole SCCs on substrate were all close to that of theoretic value of S particles(636 nm).

Preparation and properties of polymeric colloidal crystals containing rare earth complexes

稀土元素器官的建筑群被介绍进聚合系统，并且包含稀土元素建筑群的聚合胶体的 nanospheres 被乳剂 copolymerization 准备。描述结果显示聚合范围在纳米尺寸是小的，直径是 monodisperse，特别地， nanospheres 拥有了好荧光灯性质。而且，聚合 nanospheres 是自我装配的制作胶体的晶体，它是三维的常规多层的电影。聚合胶体的水晶电影展出了优秀光、新奇的光性质。

Influence of Gravity on Structure of Colloidal Crystal Using Simulated Microgravity

水和重氢氧化物的液体混合物作为液体分阶段执行，被用来匹配控告的胶体的粒子的密度。Kossel 衍射方法被用来检测水晶结构。实验在下面匹配密度(g = 0 ) 并且无敌(g= 1 ) 条件与相比在结构形成了由的水晶上检验严肃的影响 110 nm 自己组装(在直径) 聚苯乙烯微范围。结果证明严肃趋于在更低的位置使胶体的晶体的格子常数更小，它显示严肃的效果应该在胶体的晶体的学习被考虑。

High-quality SiO_2 Colloidal Crystal Fabricated by Controllable Vertical Deposition Method

Monodispersed silica microspheres with diameter of 353nm were assembled into photonic crystal in ethanol colloidal suspensions of varied silica volume fraction at different temperature and humidity by means of controllable vertical deposition method. The surface morphology and optical properties were studied by SEM and UV-Vis-NIR. It was found that the high-quality silica colloidal photonic crystals were obtained from ethanol solutions with environment temperature between 45℃ and 55℃, humidity between 66% and 76%, the volume fraction of microspheres is between 0.8% and 1.5%. The ordered close-packed photonic crystal fabricated by controllable vertical deposition method had the two photonic bandgaps in the visible light band and near infrared band.

Real-time quantitative optical method to study temperature dependence of crack propagation process in colloidal photonic crystal film

A real-time quantitative optical method to characterize crack propagation in colloidal photonic crystal film（CPCF）is developed based on particle deformation models and previous real-time crack observations. The crack propagation process and temperature dependence of the crack propagation rate in CPCF are investigated. By this method, the crack propagation rate is found to slow down gradually to zero when cracks become more numerous and dense. Meanwhile, with the temperature increasing, the crack propagation rate constant decreases. The negative temperature dependence of the crack propagation rate is due to the increase of van der Waals attraction, which finally results in the decrease of resultant force. The findings provide new insight into the crack propagation process in CPCF.

Tunable negative-index photonic crystals using colloidal magnetic fluids

The model of using colloidal magnetic fluid to build tunable negative-index photonic crystal is established. The effective permittivity εe and permeability μe of the two-dimensional photonic crystal are investigated in detail. For transverse magnetic polarization, both εe and μe exhibit a Lorentz-type anomalous dispersion, leading to a region where εe and μe are simultaneously negative. Then, considering a practical case, in which the thickness of photonic crystal is finite, the band structures for odd modes are calculated by the plane wave expansion method and the finite-difference time-domain method. The results suggest that reducing the external magnetic field strength or slab thickness will weaken the periodic modulation strength of the photonic crystal. Simulation results prove that the negative-index can be tuned by varying the external magnetic field strength or the slab thickness. The work presented in this paper gives a guideline for realizing the flat photonic crystal lens with tunable properties at optical frequencies, which may have potential applications in tunable near-field imaging systems.

PS小球阵列制备及二维激光衍射综合实验设计

为促进本科生科研创新思维和工程实践能力的培养,践行“研教协同”育人理念,以Langmuir-Blodgett技术组装高度有序的聚苯乙烯(PS)小球阵列实验为例,要求学生分析制备样品的形貌特征、有序度和激光衍射现象。该综合实验设计涵盖了自组装原理、结构制备、形貌表征及二维激光衍射等多个知识点,有利于培养学生的科研意识和能力,为培养具有创新科研思维的新型复合人才进行了有益的探索。

pH值对纤维素纳米晶液晶形态及流变性能的影响

为研究纤维素纳米晶(CNC)悬浮液在不同pH值及质量分数下的相变行为,使用偏光显微镜确定CNC液晶相的形态特征,获得了CNC形成向列相、胆甾相和双折射玻璃相的相图。通过稳态剪切和大幅振荡剪切测定了CNC体系的流变学性质,并利用傅里叶流变学分析体系流变行为与其微观结构演变之间的关系。结果表明,添加酸或碱能屏蔽CNC间的静电排斥作用,提高体系的凝胶化作用和非线性黏弹性,从而使向列相与胆甾相区域表现出明显的下降趋势。

Engineering particles towards 3D supraballs-based passive cooling via grafting CDs onto colloidal photonic crystals

Particle engineering has opened the floodgates to material science in both fundamental and application field. However, covalent interactions have not yet been adequately designed in the particle engineering for functional colloidal photonic crystals(CPCs). Herein, we achieved covalent coupling between carboxylrich poly(styrene-acrylic acid)(P(St-AA)) monodispersed colloidal particles and amine-rich carbon dots(CDs) based on an feasible and universal particle engineering strategy. The designed CDs-grafted P(St-AA)monodispersed colloidal particles initiate a hydrogen bond-driven assembly mode and ensure the construction of large-scale crack-free CPCs. Moreover, the CDs equipped with selective broad-band absorption capacity could improve the saturation of structural colors for high-visibility CPCs. Furthermore, an injectable photonic hydrogel(IPH) is developed to design CPC supraball hydrogel via integrating the CDsgrafted P(St-AA) CPC supraballs with supramolecular hydrogel. Combining superior flexibility, sufficient self-healing capacity of supramolecular hydrogel with visual optical information of our CPC supraballs, a cyclically reversible coding and decoding system was developed. Meanwhile, we firstly demonstrated the novel strategy of 3D supraballs-based passive cooling. The designed 3D CPC supraball hydrogel presents nearly full observation angle reflections behavior and excellent water evaporation capacity and achieves3.6 ℃ temperature drops, showing the application advantages in 3D thermal management. This work not only provides a new insight for manipulating optical properties of CPCs, but also demonstrates an easyto-perform platform, as well as indicates the direction for the promising application of CPCs.

三维有序胶晶模板的合成及在3DOM-SiO_(2)碘吸附剂中的应用

为了进一步提高对核工业废气中放射性气态碘的捕集能力,本文采用溶胶凝胶法结合胶晶模板法,将三维有序大孔结构(3DOM)引入二氧化硅气凝胶。系统研究了离心转速和离心时间对单分散聚苯乙烯(PS)微球转化为胶晶模板的影响,以及三维有序胶晶模板在合成三维有序大孔二氧化硅(3DOM-SiO_(2))碘吸附剂中的应用。结果表明,离心组装PS胶晶模板的最佳工艺条件,是以3000r·min^(-1)的转速将单分散的PS微球离心16h。对前驱体/模板复合物进行高温焙烧后,得到了孔道排列整齐有序、孔径尺寸均一、大孔之间有小窗口相互连通、呈三维空间相互交联的3DOM-SiO_(2)碘吸附剂。研究结果可为该材料应用于放射性碘的捕集提供参考。