Alumina nanoparticles are widely used as nanofillers for polymer nanocomposites. Among several different polymorphs of alumina, α-alumina has the most desirable combination of physical properties. Hence, the attachment of polymer chains to α-alumina to enhance compatibility in polymeric matrixes is an important goal. However, the chemical inertness and low concentration of surface hydroxyl groups have rendered polymer modification of α-alumina a long-standing challenge. Herein, we report that activation of α-alumina in concentrated or molten NaOH as well as in molten K2S2O7 increased polymer graft density up to 50%, thereby facilitating the synthesis of α-alumina brush particles with uniform grafting density of 0.05 nm(-2) that are readily miscible or dispersible in organic solvents or in chemically compatible polymeric hosts.
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http://dx.doi.org/10.1021/acsami.5b12311 | DOI Listing |
Dent Mater
January 2019
Department of Prosthodontics, Sydney Dental School, Faculty of Medicine and Health, The University of Sydney, Westmead, NSW, 2145, Australia.
Objective: The aims of this study were to compare micro-tensile bond strength and characterize the bond of ceramic-coated versus air-abraded and chemically treated zirconia specimens.
Methods: Eight zirconia blocks were fabricated and assigned to two groups as follows: AA-alumina air-abrasion; and CC-DCMhotbond coating followed by alumina air-abrasion and hydrofluoric acid etching. For each group, two identically pre-treated zirconia blocks were applied G-Multi Primer, cemented together with G-Cem Linkforce cement and cut into 30 stick-shaped specimens (1×1×9mm).
Carbohydr Polym
November 2017
Faculty of Radiochemistry and Chemistry of Colloids, Department of Chemistry, Maria Curie-Skłodowska University, M. Skłodowskiej - Curie 3 Sq., 20-031 Lublin, Poland.
The influence of ionic (CTAB; SDS) and non-ionic (TX-100; TX-165 and TX-405) surfactants as well as pH of the solution on the stability, adsorption and electrokinetic properties of the alginic acid (AA)/alumina (AlO) suspensions was studied. The results obtained using the spectrophotometric method show that the addition of ionic surfactants is an effective way to obtain stable AA/AlO suspensions whereas the changes in pH are not sufficient. Surface tension measurements together with the adsorption data show that the macromolecules of alginic acid are able to form complexes with CTAB, however, they compete for the adsorption centers on the metal oxide surface with SDS.
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