title: Redispersible hybrid nanopowders: cerium oxide nanoparticle complexes with phosphonated-PEG oligomers.
abstract: Rare earth cerium oxide (ceria) nanoparticles are stabilized using end-functional phosphonated-PEG oligomers. The complexation process and structure of the resulting hybrid core-shell singlet nanocolloids are described, characterized, and modeled using light and neutron scattering data. The adsorption mechanism is nonstoichiometric, yielding the number of adsorbed chains per particle N(ads) = 270 at saturation. Adsorption isotherms show a high affinity of the phosphonate head for the ceria surface (adsorption energy DeltaG(ads) approximately -16kT) suggesting an electrostatic driving force for the complexation. The ease, efficiency, and integrity of the complexation is highlighted by the formation of nanometric sized cerium oxide particles covered with a well anchored PEG layer, maintaining the characteristics of the original sol. This solvating brushlike layer is sufficient to solubilize the particles and greatly expand the stability range of the original sol (<pH 3) up to pH = 9. We underscore two key attributes of the tailored sol: (i) strong UV absorption capability after functionalization and (ii) ability to redisperse after freeze-drying as powder in aqueous or organic solvents in varying concentrations as singlet nanocolloids. This robust platform enables translation of intrinsic properties of mineral oxide nanoparticles to critical end use.
authors.affiliation: Complex Fluid Laboratory, UMR CNRS/Rhodia 166, CRTB Rhodia Inc., 350 G. Patterson Boulevard, Bristol, Pennsylvania 19007, USA.
authors.forename: Ling
authors.initials: L
authors.lastname: Qi
authors.forename: Amit
authors.initials: A
authors.lastname: Sehgal
authors.forename: Jean-Christophe
authors.initials: JC
authors.lastname: Castaing
authors.forename: Jean-Paul
authors.initials: JP
authors.lastname: Chapel
authors.forename: Jérôme
authors.initials: J
authors.lastname: Fresnais
authors.forename: Jean-François
authors.initials: JF
authors.lastname: Berret
authors.forename: Fabrice
authors.initials: F
authors.lastname: Cousin
mesh_terms: D002563:Cerium / Q000737:chemistry*; D003102:Colloids / Q000737:chemistry; D003460:Crystallization / Q000379:methods*; D046911:Macromolecular Substances / Q000737:chemistry; D008422:Materials Testing; D008968:Molecular Conformation; D049329:Nanostructures / Q000737:chemistry* / Q000648:ultrastructure*; D036103:Nanotechnology / Q000379:methods*; D010316:Particle Size; D011092:Polyethylene Glycols / Q000737:chemistry*; D011208:Powders; D012995:Solubility; D013499:Surface Properties; D013696:Temperature
chemical_list: D003102:Colloids; D046911:Macromolecular Substances; D011208:Powders; D002563:Cerium; D011092:Polyethylene Glycols; C030583:ceric oxide