Nanostructured polyanilines (PANIs) with a variety of morphologies were synthesized in acidic aqueous solutions with an added ionic liquid. 1-butyl-3-methylimidazolium chIoride. The influence of various reaction conditions. i.e., the molar ratio of aniline to ionic liquid and initial aniline concentration. on the morphology and properties ofthe synthesized PANIs were investigated. The morphologies ofthe PANIs. 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 Fourier-transform infrared spectroscopy (FTIR). UV-Vis spectroscopy and size-exclusion chromatography (SEC). were not affected by the reaction conditions. indicating that the aniline polymerization mechanism did not change in the presence of the ionic liquid. which acted as a soft template. The conductivities of the prepared PANI samples, as measured by impedance spectroscopy, we re of the order of 10-2 S/cm.
COBISS.SI-ID: 4460570
Nanostructured polyanilines (PANI) with various morphology were synthesized by polymerization of aniline with ammonium peroxodisulfate in acidic aqueous medium containing ionic liquids (ILs) with imidazolium, pyridinium and quaternary ammonium cations. The influence of the type of IL and the aniline/IL mole ratio on the morphology and properties of formed PANIs was investigated. ILs added to reaction mixture control the PANI morphology toward nanowires or various complex two- and three-dimensional structures in contrast to the morphology of agglomerated granular particles that is typical of PANIs prepared in the absence of IL. 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.
COBISS.SI-ID: 5194522
The effect of the reaction conditions - feed monomer ratio, oxidant/monomers ratio, reaction time, reaction temperature, T, and HCl concentration - on the structure, conductivity and spectra of partly self-doped copolymers of 2-methoxyaniline (OMA) with the anilinic acids (ANIA) 2- and 3-aminobenzoic and the 2- and 3-aminobenzenesulfonic acids was studied using ICP-AES/elemental analysis, size exclusion chromatography, NMR, FT-IR, UV-vis and impedance spectroscopy. The molar fraction of the OMA units, F1, in a P(OMA/ANIA) copolymer always exceeded the OMA fraction, f1, in the feed monomer mixture since the OMA is much more reactive than any ANIA due to the electron-donating effect of the methoxy group. Increasing f1 consistently increased the yield and the molecular weight (MW) of the P(OMA/ANIA), and withan under-stoichiometric amount of oxidant or a shortened reaction time this favored the incorporation of the OMA into the copolymer chains. Increasing the acidity of the reaction mixture increased the yield, MW and F1 of the P(OMA/ANIA)s, while increasing T gave just the opposite effects. The unusual decrease in the yield (reaction rate) with an increase in the T was related to the increased population of low-reactivity ANIA units at the growing-chain-end positions. The electrical conductivity of the P(OMA/ANIA)s lies in the region typical for semiconductors (0.05-2.5 mS/cm) and is roughly an exponential growth function of F1 that differs significantly for P(OMA/ANIA)s with sulfonic and carboxylic groups. In contrast, a conjoint correlation for all P(OMA/ANIA)s was found between conductivity and the relative intensity of the UV/vis Q-band. The decrease in conductivity with the increasing fraction of ANIA units in the P(OMA/ANIA) is in accord with the electrostatic binding of positive polarons and bipolarons (electronic charge carries) with immobilized counter-anions.
COBISS.SI-ID: 4764954
Nanostructured polyanilines of different morphologies were prepared by chemical polymerization of aniline with ammonium peroxodisulfate in aqueous HCl using various inorganic and organic chlorides as additives with the aim to determine the effect of cations of the added electrolyte on the morphology, spectroscopic characteristics, and conductivity of formed polyanilines. Chlorides of basic metals: NaCl and CaCl2 did not show any significant effect while AlCl3 and organic electrolytesn were found to influence the morphology of polyanilines. The effect of organic-electrolyte additives, which actually are ionic liquids, is explained by the organization of their molecules to micellar structures that act as soft templates for emerging polyaniline nanoparticles. The effect of AlCl3 is ascribed to the transformation of its molecules to [AlCl4]− anions.
COBISS.SI-ID: 5192986