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Dual Role of Zirconium Oxoclusters in Hybrid Nanoparticles: Cross-Linkers and Catalytic Sites
journal contribution
posted on 2016-09-09, 00:00 authored by Cesare Benedetti, Alessandro Cazzolaro, Mauro Carraro, Robert Graf, Katharina Landfester, Silvia Gross, Rafael Muñoz-EspíOrganic–inorganic
hybrid nanoparticles are prepared by free-radical
copolymerization of methyl methacrylate (MMA) with the structurally
well-defined methacrylate-functionalized zirconium oxocluster Zr4O2(methacrylate)12. The polymerization
process occurs in the confined space of miniemulsion droplets. The
formation of covalent chemical bonds between the organic and the inorganic
counterparts improves the distribution of the guest species (oxoclusters)
in the polymer particles, overcoming problems related to migration,
leaching, and stability. Because of the presence of a high number
of double bonds (12 per oxocluster), the oxoclusters act as efficient
cross-linking units for the resulting polymer matrix, thus ruling
its swelling behavior in organic solvents. The synthesized hybrid
nanostructures are applied as heterogeneous systems in the catalytic
oxidation of an organic sulfide to the corresponding sulfoxide and
sulfone by hydrogen peroxide, displaying quantitative sulfide conversion
in 4–24 h, with overall turnover numbers (TON) up to 8000 after
4 cycles.
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hydrogen peroxideminiemulsion dropletsZirconium Oxoclusterscovalent chemical bondsguest speciesDual Rolesulfide conversioncross-linking unitsoxoclusters actfree-radical copolymerizationmethyl methacrylateHybrid Nanoparticlespolymerization processMMApolymer matrixturnover numbersmethacrylate-functionalized zirconium oxocluster Zr 4 O 24 cyclespolymer particles