title: Hierarchically nanostructured barium sulfate fibers.
abstract: BaSO(4) nanostructures with controlled morphologies were successfully produced via one-step process through precipitation of BaSO(4) in aqueous and organic media. The synthesis is carried out by mixing solutions of BaCl(2) and Na(2)SO(4) in presence of EDTA (disodium ethylenediaminetetraacetic acid) at room temperature. The influence of the reaction conditions such as initial reactants concentration, pH, EDTA/[Ba(2+)] ratio and aging on the BaSO(4) nanoparticles organization is studied. Using EDTA in aqueous media, spherical secondary particles of 500 nm diameter are obtained, which are formed by 4 nm size primary particles. With dimethyl sulfoxide and small amounts of water (5%) and EDTA, the aging process allows the production of long homogeneous fibers, related to hierarchical organization of BaSO(4) nanoparticles. Direct observation of self-assembling of primary particles by HRTEM allows proposing a mechanism for fiber formation, which is based on multipolar attractions that lead to a brick-by-brick organization along a preferential orientation. Results evidence the role of EDTA as controlling agent of the morphology and primary and secondary mean particle size.
authors.affiliation: Instituto de Investigaciones en Materiales, Universidad Nacional Autónoma de México, Ciudad Universitaria, Coyoacán 04510, México DF, México.
authors.forename: Issis C
authors.initials: IC
authors.lastname: Romero-Ibarra
authors.forename: Geonel
authors.initials: G
authors.lastname: Rodríguez-Gattorno
authors.forename: Mario F
authors.initials: MF
authors.lastname: García-Sánchez
authors.forename: Antonio
authors.initials: A
authors.lastname: Sánchez-Solís
authors.forename: Octavio
authors.initials: O
authors.lastname: Manero
mesh_terms: D001466:Barium Sulfate / Q000138:chemical synthesis / Q000737:chemistry*; D004492:Edetic Acid / Q000737:chemistry; D008567:Membranes, Artificial; D049329:Nanostructures / Q000737:chemistry*; D010316:Particle Size; D013499:Surface Properties
chemical_list: D008567:Membranes, Artificial; D001466:Barium Sulfate; D004492:Edetic Acid