PMSE 421 |
| In this research, polymerizable surfactants are used to modify clay nanoparticles in order to enhance exfoliation and improve photopolymerization rates. Clay surfaces are first modified with quaternary ammonium surfactants bearing acrylate functional groups. Michael addition reactions of multifunctional thiol monomers with the acrylated quaternary ammonium surfactants result in thiol organoclays. Dispersion of these organoclays in an acrylate formulation, and their photopolymerization behavior were studied by small angle x-ray scattering (SAXS) and photo-differential scanning calorimetry (photo-DSC). Near-exfoliated organoclay domains exists before photopolymerizing all the samples and subsequent polymerization exfoliates the clay nanoparticles. Di-functional thiol modified clay systems photopolymerize at the same rate as unfilled monomer systems while an approximately 20% decrease in rate occurs with a tetra- and sixteen-functional thiol organoclay. The photopolymerization rate decreases by 50% when a non-polymerizable organoclay is incorporated into the formulation. The enhanced photopolymerization rate is due to diffusion limitations from immobilizing reactive species in the medium. These results exemplify a unique way of improving photopolymerization rates and enhancing exfoliation in clay-photopolymer nanocomposites. |
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Synthesis and Self-Assembly Approaches to Polymer-Inorganic Hybrid Nanoparticles
1:30 PM-4:10 PM, Wednesday, April 9, 2008 Hilton New Orleans Riverside -- Grand Salon 24, Oral
Division of Polymeric Materials: Science & Engineering |