Search

A method for the synthesis of a protic ion-crosslinked polymeric ionic liquid (PIL) which turns into a liquid state at a temperature below 50 °C using a reaction of basic and acidic linear oligomers was developed. Th e product of interaction of α,ω-diglycidyl ester of oligoethylene oxide MM 1000 with an excess of 1-(3-aminopropyl)imidazole (PEO–2Im) was used as the basic oligomer. It contains two types of basic centers with a signifi cant diff erence in basicity (aliphatic secondary amino groups and imidazole heterocycles), as well as secondary hydroxyl groups at the ends of oligoether chain. A linear oligomer with terminal sulfonic acid groups (PEO–2SO3H) was obtained by the interaction of of oligoethylene oxide MM 1000 with 2-sulfobenzoic acid cyclic anhydride. Protic ion-crosslinked PIL was synthesized by completely neutralization of basic centers of oligomer PEO–2Im by acidic oligomer PEO–2SO3 H at their molar ratio 1:2 respectively. Th e structure of the obtained PIL was characterized by FTIR and 1 Н NMR- spectroscopy methods. According to DSC, the synthesized ion-crosslinked PIL contains two types of crystalline formations with melting temperatures of 36,3 °C and 45,8 °C formed by fragments of oligoethylene oxide during the transfer of protons between diff erent types of ion centers. Determined by the TGA method the temperature of the onset of decomposition, which corresponds to 5% mass loss, is 265 °C. Th e proton conductivity of the ion-crosslinked PIL was studied by the DRS method in anhydrous conditions in the temperature range from 40 to 100 °C. At a temperature of 100 °C, the proton conductivity is 3,1·10-4 S/cm. Th e achieved values of proton conductivity and thermal stability make the obtained compound promising as a proton-conducting medium for various electrochemical devices. [ABSTRACT FROM AUTHOR]

A method for synthesis of silver nanoparticles (AgNPs) in the presence of proposed by us protic anionic oligomeric ionic liquid (OIL) of hyperbranched structure as a stabilizer of their surface was developed. Reduction of Ag(I) silver cations was carried out with trisodium citrate in an aqueous environment at temperature of 100°C for an hour. The OIL proposed and used by us as a surface stabilizer of colloidal AgNPs is a product of exhaustive acylation of hyperbranched oligoester polyol of the 3rd generation (contains 32 terminal primary aliphatic hydroxyl groups) with cyclic 2-sulfobenzoic anhydride and subsequent neutralization of the resulting sulfonic compound with N-methylimidazole. The synthesized AgNPs stabilized with the OIL are powders soluble in water that opens up wide possibilities of using the developed AgNPs to obtain nanodisperse systems, in particular hydrosols and nanocomposite functional polymer materials. The formation of «guest-host» type complexes between the OIL and silver ions Ag(I) and the adsorption of carbonyl and ionic (their cationic component) groups on the surface of the formed AgNPs were established by FTIR. According to FTIR data trisodium citrate is also partially adsorbed on the surface of the formed silver nanoparticles and takes part in complex formation. The formation of AgNPs was also confirmed by X-ray analysis. The X-ray diff ractograms of the obtained AgNPs show reflections at 38.0, 44.2, 64.4 and 77.3°, which are correspondingly related to (111), (200), (220) and (311) reflections of crystal planes and indicates the formation of silver nanoparticles with a face-centered cubic structure. It should be noted that the intensity of the above-mentioned reflexes increases with an increase in amount of the OIL used in the synthesis that confirms the stabilizing effect of the OIL in relation to the AgNPs and favoring the formation of the last ones due to autoreduction of silver. X-ray data evidences presence of trisodium citrate in the composition of the AgNPs being absorbed on the surface or as the complex with silver ions. The formation of AgNPs is also confirmed by TEM data. The TEM micrograph shows nanosized spherical particles of the «core-shell» type, where according to FTIR and X-ray analys a reduced silver is the core, and the OIL and trisodium citrate forms the shell as a stabilizer. These nanoparticles form swarm-like structures. Analysis of the microphotograph showed that the obtained AgNPs are characterized by a narrow size distribution in the range of 5-10 nm. The synthesized AgNPs stabilized with OIL and trisodium citrate are powders soluble in water, which opens up wide possibilities of their use for obtaining highly dispersed systems, in particular hydrosols and nanocomposite functional polymer materials based on them. [ABSTRACT FROM AUTHOR]