Clay platelets and silica nanoparticles are used as Pickering stabilizers in the fabrication of hybrid armored polymer particles through a Pickering emulsion polymerization process. A variety of hydrophobic comonomers (i.e., styrene-co- (n-butyl acrylate) (Sty:BA), methyl methacrylate-co-(n-butyl acrylate) (MMA:BA)), styrene-co-(2-ethyl hexyl acrylate) (Sty:2-EHA), vinyl acetate (VAc) and vinyl pivalate (VPiv) are used as organic film forming components. Polymerization kinetics and particle size distributions were examined as a function of monomer conversion. Additionally, key mechanistic features of the polymerization process by quantitatively analyzing the concentration of silica nanoparticles in the water phase during monomer conversion by disc centrifugation are unraveled. It is also showed the crucial role of Laponite clay discs in the particle formation (nucleation) of the Pickering emulsion polymerization process. Increasing amounts of clay nanodiscs leads to smaller average particles sizes, but broader particle size distributions. Polymer films of poly(styrene-co-n-butyl acrylate) armored with Laponite clay were studied as a function of clay amount. Improvements in mechanical, thermal and surface topography provided by clay platelets are reported. In addition, advantages are shown in use of hybrid polymer particles in comparison with simple blend mixtures of polymer particles plus inorganic particles. Humidity properties of poly(styrene-co-n-butyl acrylate) films as a function of clay content are investigated. It is demonstrated that the presence of Laponite clay improves the water storage capacity of polymer films. Also water barrier properties are improved when clay platelets are applied. Finally, a versatile two step Pickering emulsion polymerization for the fabrication of core-shell particles armored with Laponite clay XLS is developed. The obtained particles contain a "hard" core and a "soft" shell armored with clay. The different in the refractive indexes between the core and shell makes these core-shell particles interesting for possible use as colloidal crystals.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:560110 |
| Date | January 2011 |
| Creators | Teixeira, Roberto F. A. |
| Publisher | University of Warwick |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | http://wrap.warwick.ac.uk/45871/ |
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