AbstractsChemistry

The acid-triggered formation of Silica-Polyelectrolyte (S–PE) nanocomposites prepared by condensation of poly(silicic acid) (PSA) in the presence of polyelectrolytes in aqueous solution is presented. Poly(2-(dimethylamino)ethyl methacrylate) (PDMAEMA) and block copolymers of DMAEMA and oligo(ethylene glycol) methyl ether methacrylate (OEGMA) were synthesized by Reversible Addition Fragmentation chain Transfer (RAFT) polymerization and fulfilled the role of weak polyelectrolytes used in S–PE composite formation. The strong polyelectrolyte poly(methacryloxyethyl trimethylammonium iodide) (PMOTAI) is prepared by quaternization of PDMAEMA. Quaternization of P(DMAEMA-block-OEGMA) is also achieved. The effect of polyelectrolyte strength, the OEGMA block and the polymer molecular weight on the formation of S–PE composites is assessed with respect to S–PE composites prepared using the PDMAEMA homopolymer. Water-dispersible and precipitate S–PE particles are prepared and analysed by Dynamic Light Scattering (DLS), Thermogravimetric Analysis (TGA) and Scanning Electron Microscopy (SEM). The size of the prepared water-dispersible S–PE composites is presented as a function of the solution pH at which the composite formation was achieved. Recent developments in the synthesis of silica-polymer nanocomposites and polymeric hybrids containing silicon are discussed. RAFT and Atom Transfer Radical Polymerization (ATRP) are presented as effective techniques for the synthesis of well-defined polymers used in the preparation of polymeric hybrids containing silicon. This research was conducted under the supervision of Dr. Vladimir Aseyev and MSc Erno Karjalainen in the Polymer Chemistry Laboratory of the University of Helsinki. The reported work was achieved within the wider aims of the ERA.Net RUS project entitled Bioinspired Synthesis of Silica Materials and Nanocomposites Based on Smart Polymers as Matrices, also known as SILICAMPS. Vain tiivistelmä. Opinnäytteiden arkistokappaleet ovat luettavissa Helsingin yliopiston kirjastossa. Hae HELKA-tietokannasta (http://www.helsinki.fi/helka/index.htm). Abstract only. The paper copy of the whole thesis is available for reading room use at the Helsinki University Library. Search HELKA online catalog (http://www.helsinki.fi/helka/index.htm). Endast avhandlingens sammandrag. Pappersexemplaret av hela avhandlingen finns för läsesalsbruk i Helsingfors universitets bibliotek. Sök i HELKA-databasen (http://www.helsinki.fi/helka/index.htm).