Preparation of two-dimensional direct opals by controlled assembly of silica spheres

  p. 1355 - 1358

This paper has been devoted to the preparation of hard colloidal crystals by a self-assembly process. The aim of the study has been to find the precise conditions governing this process, in order to make it controllable. To accomplish our goal, we have studied the influence of factors such as: the type of solvent, system temperature, particle volume fraction and size of the silica spheres. These are synthesized following a Stöber procedure where the size is precisely controlled by a seeded-growth technique. In some of the experiments, the silica spheres are deposited in the presence of different surfactants (SDS, CTAB), thus varying the magnitude of the ζ-potential. The material of the substrate (glass or silicon) also plays a crucial part in the deposition process and during the sintering procedure. The structural regularity is characterized by scanning electron microscopy and optical absorption spectra