Colard, Catheline A. L. (2010) Hybrid supracolloidal structures through interface driven assembly. PhD thesis, University of Warwick.

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Abstract

We investigated different strategies for the preparation of armoured polymer
particles. Inorganic nanoparticles, such as clay platelets and Ludox colloidal
silica grades, were used as solids-stabilisers in processes such as miniemulsion,
suspension and/or emulsion polymerisations. These nanoparticles were either
assembled at liquid-liquid interfaces for the stabilisation of monomer droplets or
adsorbed onto solid surfaces in the case of poly(vinyl acetate) latex particles.
Colloidal assembly was promoted by modifying the pH and/or the ionic strength
of the dispersion medium, thereby tuning the surface properties of the
nanoparticles. When prepared in miniemulsion polymerisation, latexes with
controlled particle size distributions were obtained. Their diameter was dictated
by the amount of solids-stabiliser (Laponite clay) or by the dimensions of the
building blocks (Ludox colloidal silica).
We developed a versatile emulsion polymerisation process leading to silicaarmoured
poly(vinyl acetate) particles and showed that quantitative disc
centrifugation analyses throughout the polymerisation process unravelled
mechanistic aspects of particle formation and growth. Stability of the armoured
particles was studied in dispersion and after spray-drying the hybrid dispersions.
The thickness of the silica shell on the polymer particles had an important role
in limiting polymer inter-diffusion upon film formation. The obtained powders
were tested as additives in cement-based formulations for tile adhesives.
However, desired performance characteristics were not obtained in comparison
to standard formulations.
Soft polymer composite foams were prepared through freeze-drying a
mixture of colloids. ‘Large-soft’ particles of poly(vinyl laurate) reinforced by an
armouring layer of ‘small-hard’ nanoparticles of colloidal silica led to the
formation of highly porous open-cell foams. Upon addition of a third conducting
colloidal component, this newly designed material proved promising results as a
gas sensor.

Item Type:	Thesis (PhD)
Subjects:	Q Science > QD Chemistry
Library of Congress Subject Headings (LCSH):	Nanoparticles, Colloids, Interfaces (Physical sciences)
Official Date:	September 2010
Dates:	Date Event September 2010 Submitted
Institution:	University of Warwick
Theses Department:	Department of Chemistry
Thesis Type:	PhD
Publication Status:	Unpublished
Supervisor(s)/Advisor:	Bon, Stefan Antonius Franciscus ; Hergeth, Wolf-Dieter
Sponsors:	Wacker-Chemie GmbH
Extent:	xxii, 217 leaves : ill., charts
Language:	eng

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