10 resultados para Solvents.
em Deakin Research Online - Australia
Resumo:
A series of N-methyl-N-alkylpyrrolidinium tetrafluoroborate salts were synthesised. The spectroscopic, physical and electrochemical characteristics of this family of salts have been investigated with respect to potential usage as ionic solvents and electrolytes. The lowest melting point among the family is 64°C for the N-methyl-N-propylpyrrolidinium tetrafluoroborate (P13BF4). This is sufficiently low to enable this salt to be useful as an ionic liquid in chemical synthesis involving reactions above 70°C. Most of the compounds exhibit one or more solid–solid transitions below the melting point, this behaviour is thought to indicate the existence of plastic crystal phases.
Resumo:
We have shown that protic ionic liquids, pILs, are effective coagulation solvents for the regenerated of silk fibroin, RSF. We show that the choice of pIL has a dramatic effect on the composition of the RSF. Additionally the use of pILs as the coagulator eliminates the need for volatile organic solvents in silk processing.
Resumo:
There are few reports of non-cryogenic preservation methods for marine invertebrates, so potable alcohol and acetone-based nail varnish remover (NVR) are for the first time evaluated against absolute ethanol as short-term preservatives of whole barnacles. Performance of ethanol and NVR-preserved material was comparable, but potable alcohol was significantly worse. These results are of practical importance for fieldwork in remote areas where laboratory chemicals are unattainable but potable alcohol or NVR are locally available. Of these, acetone-based NVR would be the solvent of preference.
An improved understanding of the dispersion of multi-walled carbon nanotubes in non-aqueous solvents
Resumo:
The homogeneous and stable dispersion of carbon nanotubes (CNTs) in solvents is often a prerequisite for their use in advanced materials. Dispersion procedures, reagent concentration as well as the interactions among reagent, defective CNTs and near-perfect CNTs will affect the resulting CNT dispersion properties. This study, for the first time, presents a detailed comparison between two different approaches for dispersing CNTs. The results enhance our understanding of the interactions between surfactant, defective CNTs and near-perfect CNTs and thus provide insight into the mechanism of CNT dispersion. Dispersions of "as-produced" short multi-walled carbon nanotubes (MWCNTs) in N,N-dimethylformamide were prepared by two different surfactant (Triton X-100) assisted methods: ultrasonication and ultrasonication followed by centrifugation, decanting the supernatant and redispersing the precipitate. Visual observation and UV-visible spectroscopy results showed that the latter method produce a more stable dispersion with higher MWCNT content compared to dispersions produced by ultrasonication alone. Transmission electron microscopy and Raman spectroscopic investigations revealed that the centrifugation/ decanting step removed highly defective nanotubes, amorphous carbon and excess surfactant from the readily re-dispersible near-perfect CNT precipitate. This is contrary to other published findings where the dispersed MWCNTs were found in the supernatant. Thermogravimetric analysis showed that 95 % of Triton X-100 was removed by centrifugation/decanting step, and the remainder of the Triton X-100 molecules is likely randomly adsorbed onto the MWCNT surface. Infrared spectral analysis suggests that the methylene groups of the polyoxyethylene (aliphatic ether) chains of the residual Triton X-100 molecules are interacting with the MWCNTs. © 2014 Springer Science+Business Media.
Resumo:
The tris(2,2′-bipyridyl) complexes of cobalt(II) and (III) ([Co(bpy)