Nanostructured polyanilines (PANI) of various morphologies were synthesized by polymerization of aniline with ammonium peroxodisulfate in acidic aqueous medium. The influence of the type of IL and the aniline/IL mole ratio on the morphology and properties of formed PANIs was investigated. Ionic liquids used (IL) with imidazolium, pyridinium and quaternary ammonium cations were used. In the series of imidazolium ILs the lenght of the alkyl side chain was varied. The presence of ionic liquids in the reaction mixture controls the PANI morphology toward nanowires and various complex two- and three-dimensional structures, in contrast to the agglomerated granular particles, which is typical morphology of PANIs prepared in the absence of IL, as it was observed by the scanning electron microscopy (SEM). The UV-Vis, IR and Raman spectra of PANIs showed that the used ILs do not affect the chemical structure of PANI, which indicates that they do not affect the formation of PANI molecules but only their assembling during polymerization. The DLS measurements indicate that ILs as well as their mixtures with an oxidant and aniline form in 1 M HCl ordered micellar structures. The micellar structures most likely act as soft templates that assemble growing PANI chains and/or aniline molecules into particular nanostructures and/or their precursors. The fact that the structure of PANI nanoparticles is, in general, a function of the type of IL and IL/aniline concentration ratio, indicates that the architecture of micelles depends on the same variables.
B.04 Guest lecture
COBISS.SI-ID: 5067546Mentorship to a Ph.D. student: M. Žigon was a mentor to David Pahovnik at the Faculty of Chemistry and Chemical Technology, University of Ljubljana. David Pahovnik defended his Ph.D. thesis on /20/04/2012. Nanostructured polyanilines (PANIs) of various morphologies were synthesized by the oxidative polymerization of aniline with ammonium peroxodisulfate in acidic aqueous medium containing ionic liquids with imidazolium, pyridinium, pyrrolidinium and quaternary ammonium cations. In the case of imidazolium type ionic liquids, the length of one of the side chains was varied using methyl, ethyl, butyl, octyl, decyl and hexadecyl groups. The influence of the reaction conditions such as the aniline to ionic liquid mole ratio, the initial aniline concentration and the type of the ionic liquid on the morphology and properties of formed PANIs was investigated. The presence of ionic liquids in the reaction mixture controls the PANI morphology toward nanowires and various complex three-dimensional structures, as it was observed by the scanning electron microscopy (SEM). These nanostructures strongly contrast with the agglomerated granular particles - morphology pattern typical of PANIs prepared by the standard procedure. The type of ionic liquid and the aniline to ionic liquid mole ratio have the highest impact on the PANI morphology. The UV-Vis, IR and Raman spectra as well as size-exclusion chromatography analyses of PANIs have shown that the chemical structure and molecular-weight characteristics are almost not affected by ionic liquids, which indicates that their presence does not affect formation of PANI molecules but only their consecutive assembly during aniline polymerization with peroxodisulfate anions. The analysis done by the dynamic light scattering method indicated that ionic liquids form micelles in 1M HCl. The micelles most likely act as soft templates that assemble aniline molecules and/or growing PANI chains into particular nanostructures and/or their precursors. As the micelle architecture is, in general, a function of the type of IL and the IL/aniline concentration ratio, differently structured PANI nanoparticles can be formed: columnar micelles can give rise to nanowires and lamellar micelles to PANI lamellas.
D.09 Tutoring for postgraduate students
COBISS.SI-ID: 261579520We prepared nanostructured PANI by chemical oxidation of aniline using an acidic water solution of the ionic liquid 1-butyl-3-methylimidazolium chloride and ammonium persulfate as an oxidant. In this contribution we presented the correlation between experimental conditions, i.e. selected molar ratios of the ionic liquid and aniline, different starting aniline concentration, and the properties as well as morphology of the formed PANI. The nanoparticles were characterized using scanning electronic microscopy (SEM), spectroscopic methods (NMR, IR, UV-VIS), size exclusion chromatography (SEC), thermal methods (differential scanning calorimetry – DSC and thermogravimetric analysis – TGA) and impedance spectroscopy.
B.06 Other
COBISS.SI-ID: 4282650Nanostructured polyanilines (PANIs) of various morphologies were synthesized by the oxidative polymerization of aniline with ammonium peroxodisulfate (APS) in acidic aqueous medium containing ionic liquids with imidazolium, pyridinium, pyrrolidinium and quaternary ammonium cations. The influence of the type of the ionic liquid and the aniline to ionic liquid mole ratio on the morphology and properties of formed PANIs was investigated. Our investigation suggests that species of IL form soft templates that assemble growing PANI molecules into particular nanostructures. This idea was supported by the DLS measurements that showed that ILs did get organized in the solution and that the added oxidant and aniline changed this organization. DLS results indicate that ILs behave as surfactants and can form various types of micelles depending on the type and concentration of IL. These micelles can then act as soft templates assembling monomer and growing PANI molecules into the resulting nanostructures: the columnar micelles can give rise to nanowires and the lamellar ones to PANI lamellas.
B.06 Other
COBISS.SI-ID: 5052186Polyaniline (PANI) nanostructures combine properties of organic conductors with properties of materials with large surface area, which makes them a very promising material for applications in various fields. We prepared nanostructured PANI of different morphologies in acidic aqueous solutions with water miscible ionic liquids, mainly 3-alkyl-1-methylimidazolium chlorides. The influence of the type of an ionic liquid as well as the effects of varying reaction conditions, i.e. molar ratio of aniline to ionic liquid and initial aniline concentration, on morphology and properties of synthesized PANI were investigated. The morphologies of PANI as studied by scanning electron microscopy (SEM) range from nanowires to complex three dimensional structures and were influenced particularly by the molar ratio of aniline to ionic liquid. The chemical structure and molecular weight characteristics as determined by FT-IR, UV-Vis spectroscopy and size exclusion chromatography (SEC), were not affected by reaction conditions indicating that aniline polymerization mechanism was not changed in the presence of the ionic liquid.
B.06 Other
COBISS.SI-ID: 4461082