Yoldi, M. (María)
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- Electrophoretic deposition of colloidal crystals assisted by hydrodynamic flows(2006) Yoldi, M. (María); Sirera-Bejarano, R. (Rafael); Arcos, M.C. (M. Cristina); Gonzalez-Viñas, W. (Wenceslao)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.
- On the parameters influencing the deposition of polystyrene colloidal crystals(2008) Yoldi, M. (María); Sirera-Bejarano, R. (Rafael); Görnitz, E. (E.); Arcos, M.C. (M. Cristina); Gonzalez-Viñas, W. (Wenceslao); Paulke, B. (B.)Colloidal crystals of polystyrene particles of 1.0, 1.4 and 2.8 μm diameter have been prepared by vertical deposition. The influence of parameters such as temperature, particle size and concentration as well as dispersion medium has been studied. The size of domain and the crystalline structure of the particle arrays have been analyzed by optical microscopy. The quality of the crystals has been improved (minimizing cracks) by controlling sedimentation (density matching), evaporation (volatility of the medium) and drying (co-solvents).
- Influence of the application of von Kármán-like flows on the colloidal crystallization of polystirene particles(Influence of the application of von Kármán-like flows on the colloidal crystallization of polystirene particles, 2004) Yoldi, M. (María); Sirera-Bejarano, R. (Rafael); Arcos, M.C. (M. Cristina); Gonzalez-Viñas, W. (Wenceslao)
- Preparation and characterization of inverted opals(Servicio de Publicaciones de la Universidad de Navarra, 2010) Yoldi, M. (María); Sirera-Bejarano, R. (Rafael); Gonzalez-Viñas, W. (Wenceslao)The aims of this study were the preparation and the characterization of optical materials based on three dimensional ordered arrays of colloidal latex particles, which are also called colloidal crystals (CCs). Although these multilayered latex particles arrays do not exhibit a photonic bandgap (PBG), the fabrication and the research of the optical properties of CCs based on polymeric colloidal particles are not only useful as templates to synthesize PCs but also because, due to their composition and their structure, they could present very interesting applications, such as those derived of the interaction with light (difraction, interference, scattering, absorption, inhibition, ...), maximal packing density, maximal structural stability, maximal catalytic and reactivity inside them and the ability to create media for information storage (pre{formatted substrates), among others. Lots of different techniques and sources of knowledge contribute to develop and explain the photonic phenomena. Physicists, chemists and engineers work together in the photonic field. This interdisciplinary nature of the problem enriches it. The main ideas of polymerization and colloidal crystallization are commented in the Introduction. In chapter 1, not only modified emulsion and dispersion poly- merization techniques based in styrene and acrylate monomers, but also the surface functionalization and the purification and characterization of the colloidal latex particles synthesized are explained in detail. In chapter 2, the fabrication of 3D ordered arrays of colloidal particles by vertical deposition and sedimentation methods, and the investigation of the optical properties and crystalline structure of the colloidal crystals by spectroscopy, optical microscopy and optical diffraction techniques are explained. Finally, the conclusions of the study are reported in the last chapter.