title: Synthesis and characterization of self-assembled polyaniline nanotubes/silica nanocomposites.
abstract: Self-assembled semiconducting, paramagnetic polyaniline nanotubes have been synthesized by the oxidative polymerization of aniline with ammonium peroxydisulfate in aqueous medium in the presence of colloidal silica particles of an average diameter approximately 12 nm, without added acid. The electrical conductivity of polyaniline nanotubes/silica nanocomposites is in the range (3.3-4.0)x10(-3) S cm(-1). The presence of paramagnetic polaronic emeraldine salt form of polyaniline and phenazine units in nanocomposites was proved by FTIR, Raman, and EPR spectroscopies. The influence of the initial silica/aniline weight ratio on the morphology of polyaniline/silica nanocomposites was studied by scanning and transmission electron microscopies. Nanocomposites synthesized by using the initial weight ratio silica/aniline<or=0.2 contain polyaniline nanotubes which have a typical outer diameter of 100-250 nm and an inner diameter of 10-80 nm, and nanorods with a diameter of 60-100 nm, accompanied with polyaniline/silica nanogranules, while the nanocomposite synthesized at weight ratio silica/aniline approximately 2 contains polyaniline/silica nanogranules with an average diameter of 35-70 nm. The evolution of molecular and supramolecular structure of polyaniline in the presence of colloidal silica is discussed.
authors.affiliation: Faculty of Physical Chemistry, University of Belgrade, Studentski trg 12-16, 11158 Belgrade, Serbia. gordana@ffh.bg.ac.yu
authors.forename: Gordana
authors.initials: G
authors.lastname: Cirić-Marjanović
authors.forename: Ljiljana
authors.initials: L
authors.lastname: Dragicević
authors.forename: Maja
authors.initials: M
authors.lastname: Milojević
authors.forename: Milos
authors.initials: M
authors.lastname: Mojović
authors.forename: Slavko
authors.initials: S
authors.lastname: Mentus
authors.forename: Biljana
authors.initials: B
authors.lastname: Dojcinović
authors.forename: Budimir
authors.initials: B
authors.lastname: Marjanović
authors.forename: Jaroslav
authors.initials: J
authors.lastname: Stejskal