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．     

硅槽内自组装二氧化硅光子晶体

采用溶剂蒸发法在硅片上微槽内对不同粒径的SiO2微球进行组装,尝试利用刻有微槽的硅片与平坦衬底间形成的毛细管池限制胶体晶体的生长厚度,获得了具有显著光子带隙特征的光子晶体线形阵列,并在此基础上比较了不同实验条件如微球直径、毛细管池物理限制作用等对微球排列方式及规整度的影响.     

Bioinspired Photonic Pigments from Colloidal Self‐Assembly

The natural world is a colorful environment. Stunning displays of coloration have evolved throughout nature to optimize camouflage, warning, and communication. The resulting flamboyant visual effects and remarkable dynamic properties, often caused by an intricate structural design at the nano‐ and microscale, continue to inspire scientists to unravel the underlying physics and to recreate the observed effects. Here, the methodologies to create bioinspired photonic pigments using colloidal self‐assembly approaches are considered. The physics governing the interaction of light with structural features and natural examples of structural coloration are briefly introduced. It is then outlined how the self‐assembly of colloidal particles, acting as wavelength‐scale building blocks, can be particularly useful to replicate coloration from nature. Different coloration effects that result from the defined structure of the self‐assembled colloids are introduced and it is highlighted how these optical properties can be translated into photonic pigments by modifications of the assembly processes. The importance of absorbing elements, as well as the role of surface chemistry and wettability to control structural coloration is discussed. Finally, approaches to integrate dynamic control of coloration into such self‐assembled photonic pigments are outlined.     

Colloidal Self‐Assembly Meets Nanofabrication: From Two‐Dimensional Colloidal Crystals to Nanostructure Arrays

Self‐assembly of colloidal microspheres or nanospheres is an effective strategy for fabrication of ordered nanostructures. By combination of colloidal self‐assembly with nanofabrication techniques, two‐dimensional (2D) colloidal crystals have been employed as masks or templates for evaporation, deposition, etching, and imprinting, etc. These methods are defined as “colloidal lithography”, which is now recognized as a facile, inexpensive, and repeatable nanofabrication technique. This paper presents an overview of 2D colloidal crystals and nanostructure arrays fabricated by colloidal lithography. First, different methods for fabricating self‐assembled 2D colloidal crystals and complex 2D colloidal crystal structures are summarized. After that, according to the nanofabrication strategy employed in colloidal lithography, related works are reviewed as colloidal‐crystal‐assisted evaporation, deposition, etching, imprinting, and dewetting, respectively.     

Self‐Assembled Photonic Structures

Photonic crystals have proven their potential and are nowadays a familiar concept. They have been approached from many scientific and technological flanks. Among the many techniques devised to implement this technology self‐assembly has always been one of great popularity surely due to its ease of access and the richness of results offered. Self‐assembly is also probably the approach entailing more materials aspects owing to the fact that they lend themselves to be fabricated by a great many, very different methods on a vast variety of materials and to multiple purposes. To these well‐known material systems a new sibling has been born (photonic glass) expanding the paradigm of optical materials inspired by solid state physics crystal concept. It is expected that they may become an important player in the near future not only because they complement the properties of photonic crystals but because they entice the researchers’ curiosity. In this review a panorama is presented of the state of the art in this field with the view to serve a broad community concerned with materials aspects of photonic structures and more so those interested in self‐assembly.     

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.     

Transition from split streamlines to dip-coating during Langmuir–Blodgett film deposition

Mono-molecular films of arachidic acid were deposited on glass slides using the Langmuir–Blodgett (LB) technique. The liquid subphases were dilute solutions of ZnSO₄ at different pH. Glass slides were treated to create contact angles (θ) ranging from approximately 15° for clean glass slides, to contact angles greater than 120° for slides treated with ferric stearate. Intermediate contact angles were created by immersing slides in solutions of Sigmacote^® of varying concentration. Very small contact angles, θ≈0° were obtained with clean glass slides at high pH values. LB deposition data and transfer ratios (TR) were recorded for up-stroke and down-stroke operation. During upstroke, TR increase with decreasing contact angles reaching a maximum TR close to 100% when the receding contact angle is approximately 15–20°. This is typical of the split-ejection flow pattern found during up-stroke. For very small contact angles, i.e. less than 10°, TR suddenly become zero indicating a transition to a dip-coating flow pattern. During down-stroke operation, TR is zero or negative for small contact angles, reaching a maximum TR approximately 100% for contact angles larger than 120°.