Emulsion Stability Studies and correlation with porous microspheres synthesis

13/09/2021

Porous silica microspheres play an essential role in several applications. They can serve as porous support materials for environmental remediation, biomedical devices, energy storage and conversion. These porous microspheres are prepared via sol-gel technique combined with phase separation through spinodal decomposition in water-in-decahydronaphthalene (decalin) emulsion droplets that serve as soft templates. The present thesis provides an insight on the emulsions properties and establishes a new tool to tailor and customize silica porous microspheres. The effect of surfactant and water concentration on the emulsion’s stability was investigated via gravitational separation tests. To enhance the stability of these systems, surfactant blends (SPAN®80 combined with TWEEN®20, TWEEN®80, TWEEN®85, PluronicP123, DABCO®DC193 or SDS) were employed and studied. Emulsion characterisation by dynamic light scattering and rheological tests allows to complement our knowledge of how these factors correlate with the destabilisation mechanisms. In the last stage of this work, several syntheses were performed to see the effect of each parameter in the final product. Water-in-oil (W/O) emulsions with blends of SPAN®80, together with other non-ionic surfactants, such as TWEEN®20 (12 μm – 30 μm) and TWEEN®80 (2 μm – 12 μm), resulted in spherical microparticles with a decreased overall size and improved porosity, compared with the emulsions stabilized only by SPAN®80 (19 μm – 400 μm). Silicone surfactant DABCO® DC 193 was used for the first for this type of reaction, improving both superficial and internal porosity. Blends with the SDS increased the stability of W/O emulsions, however poor results were obtained regarding the final particles.

Autores da comunidade :

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  A

  António Real Rodrigues da Luz Mariquito

  ist181043

Orientadores desta instituição:

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  A

  António José Boavida Correia Diogo

  ist12172

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  A

  Ana Clara Lopes Marques

  ist45873

industrial-biotechnology - Biotecnologia Industrial

eng - Inglês

Instituto Superior Técnico