Self-assembling of submicrometer three-dimensional photonic crystals in concave microzones etched on silicon substrates

By vertical sedimentation and oblique titration, silica microspheres were grown in different shapes of concave microzones that were etched on a (100) p-silicon substrate. Through scanning electron microscope observation and optical reflective spectra measurement, sedimentation of microspheres in those microzones was compared. An index was introduced to judge the efficiency of sedimentation. The comparison demonstrates that regular hexagons and triangles facilitate the growth of photonic crystals the most. (c) 2006 Optical Society of America

Micro-mould method for self-assembling three-dimensional opal photonic crystals

By vertical sedimentation, silica micro-spheres were grown in different shapes of concave micro-zones which were etched on a (100) p-silicon substrate. The following were found: this method can effectively raise the quality of films by avoiding cracks; the geometry of the micro-zones affects the sediment of the film; regular hexagons and triangles best facilitate the growth of photonic crystals. This method is practical for its ability to fabricate self-assembly photonic crystals in previously designed small areas.

Transformation from ordered islands to holes in phase-separating P2VP/PS blend films by adding triton X-100

Our previous investigation showed that the ordered hexagonal island pattern in the phase-separating polymeric blend films of polystyrene and poly(2-vinylpyridine) (PS/P2VP) formed due to the convection effect by proper control of PS molecular weight, solvent evaporation rate, and the weight ratio of PS to P2VP. In this paper, we further illustrate that, by adding a proper amount of the surfactant Triton X-100 to the PS/P2VP toluene solution, the ordered hexagonal island pattern can be transformed to the ordered honeycomb pattern. The effects of the amount of Triton X-100 on the surface morphology evolution and the pattern transformation are discussed in terms of the collapse of Triton X-100, phase separation between Triton X-100/P2VP and PS, the interfacial interaction between Triton X-100/P2VP and the mica substrate, and the Benard-Marangoni convection.

The influencing factors on the macroporous formation in polymer films by water droplet templating

Regular micrometer-size porous polystyrene film is prepared by water droplet templating, i.e. breath figures are stabilized by the polymer in solution and thermocapillary flow arranges them into ordered packing. The influences of polystyrene molecular weight, solvent properties, and the relative humidity of atmosphere on the pattern formation and hole sizes are investigated. Two different kinds of hole packing fashion are also observed and their formation mechanisms are discussed.