Teixeira, Roberto F. A. (2011) Multi-layered nanocomposite polymer latexes and films. PhD thesis, University of Warwick.

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Abstract

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.

Item Type:	Thesis or Dissertation (PhD)
Subjects:	Q Science > QD Chemistry
Library of Congress Subject Headings (LCSH):	Stabilizing agents, Emulsion polymerization
Official Date:	December 2011
Dates:	Date Event December 2011 Submitted
Institution:	University of Warwick
Theses Department:	Department of Chemistry
Thesis Type:	PhD
Publication Status:	Unpublished
Supervisor(s)/Advisor:	Bon, Stefan Antonius Franciscus
Sponsors:	BASF Aktiengesellschaft ; Advantage West Midlands (AWM) ; European Regional Development Fund (ERDF)
Extent:	xxi, 221 leaves : ill., charts
Language:	eng

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