Tesis doctoral de Karim Patricia Gonzalez Matheus
This thesis has focused in the study of the pickering stabilization on the polymerization of a mixture of vinyl acetate and vinyl neodecanoate, 80/20 wt/wt. Pickering stabilization consist in the use of solids particles which adsorb on the interface, (monomer ¿ water in this case) forming a emulsion. Silica had been used as a stabilizer, their surface had to be modified in order to decrease the effects of ph and ionic strength that presents their full of silanol groups surface and to obtain the suitable contact angle on the interface to create the monomer in water emulsion. It was study the level of modification (different contact angles) on polymerization. It was shown that an intermediate modification it is necessary to obtain a lower particle size. It was evidenced coalescence at the beginning of the polymerization but no macroscopic coagulation was observed. Different initiators were tested; it was observed that oil soluble initiators led to coagulum free stable latexes in miniemulsion polymerization. Variations on silica concentration determined that this aspect was similar to conventional emulsifiers, increasing the silica concentration led to smaller particle sizes. It is worth pointing that these latexes presented good stability in presence of increased in the ionic strength. Film formation was studied or the latexes prepared, it was found that the presence of silica increased the minimum film formation temperature in comparison with latexes synthesised using conventional emulsifiers. Pickering stabilized latexes forms films with the silica forming a honeycomb. Pickering stabilization was studied in acrylics systems using commercial silica, in this case was used emulsion polymerization a cationic initiator, it was found that to stabilize the systems was necessary concentrations equals or higher of 15 wt. % Based on monomer. Pu system stabilized with silica led to gelation.
Datos académicos de la tesis doctoral «Pickering stabilized latexes«
- Título de la tesis: Pickering stabilized latexes
- Autor: Karim Patricia Gonzalez Matheus
- Universidad: País vasco/euskal herriko unibertsitatea
- Fecha de lectura de la tesis: 21/11/2014
Dirección y tribunal
- Director de la tesis
- José María Asua Gonzalez
- Tribunal
- Presidente del tribunal: José ramon Leiza recondo
- muriel Lansalot — (vocal)
- stefan Bon (vocal)
- Ana María Urtiaga mendia (vocal)