Herein two novel synthetic strategies for the synthesis of sub-millimetre sized core–shell particles comprising a polyelectrolyte core and a porous hydrophobic shell are presented. In the first method, a water-in-oil-in-water (W/O/W) double-emulsion was used as a template for the simultaneous polymerisation of both the internal aqueous and the intermediate oil phases, via suspension polymerisation, leading to the formation of a cross-linked poly(acrylic acid-co-bisacrylamide) core contained in a porous poly(4-tert-butylstyrene-co-divinylbenzene) shell. It was found that the formation of core–shell morphology was favoured by the effect of acrylic acid which was responsible for the selective destabilization of the internal aqueous/oil (W/O) interface. It was found that rapid internal phase coarsening promoted the formation of single-core structures. A rapid gel-point of the oil phase, on the other hand, reduced the internal aqueous phase diffusion towards the external phase. The detrimental effect over internal emulsion stability was replicated using ethanol, 2-propanol, n-butanol and propionic acid which were used as a co-solvent in the internal aqueous phase to promote core/shell morphology formation. The second method involved the use of a flow-focusing device for the formation of monodisperse W/O/W emulsion droplets which were photo-polymerised. Anionic poly(sodium acrylate), poly(sodium vinyl sulfonate), and cationic poly(3-acrylamidopropyl)trimethylammonium chloride) hydrogels were encapsulated within a porous poly(trimethylolpropane triacrylate-co-methyl methacrylate) shell. Control over both particle diameter and shell thickness was achieved by tuning the flow rates of the different phases. The use of these novel hydrogel core/shell particles as novel material for environmental applications, including the scavenging of radionuclides, was investigated. It was found that hydrophilic substances including dyes and metal ions were rapidly adsorbed and encapsulated within the core region after diffusing through the permeable porous shell. Part of the results obtained in this work have been published in the article J. Mater. Chem. A, 2013, 1, 12553-12559.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:634936 |
| Date | January 2015 |
| Creators | Menzel, Cristian |
| Publisher | University of Manchester |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | https://www.research.manchester.ac.uk/portal/en/theses/polyelectrolyte-corehydrophobic-shell-polymer-particles-by-double-emulsion-templating-polymerisation-for-environmental-applications(0fa106d3-770c-48e0-9f4e-7ba29ae9caf1).html |
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