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1. Nucleic acid bases in 1-alkyl-3-methylimidazolium acetate ionic liquids: A thermophysical and ionic conductivity analysis

Author

Araújo, J.M.M., Pereiro, A.B., Alves, F., Marrucho, I.M., and Rebelo, L.P.N.

Subjects
*NUCLEIC acids, *ALKYL compounds, *IMIDAZOLES, *ACETATES, *IONIC liquids, *THERMAL properties, *IONIC conductivity
Abstract

Abstract: The use of ionic liquids as a media for dissolving DNA holds great promise for the development of new base materials in electrochemistry. This paper reports the systematic study of the effect of two nucleic acid bases, uracil and adenine, on the ionicity of 1-alkyl-3-methylimidazolium acetates achieved by monitoring several thermodynamic and transport properties. Density, dynamic viscosity, speed of sound, refractive index and ionic conductivity of 1-ethyl-3-methylimidazolium acetate and 1-butyl-3-methylimidazolium acetate were studied as a function of temperature at atmospheric pressure. The thermal expansion coefficients and molar volumes of these ionic liquids were calculated from the experimental density values. The various properties of the binary mixtures 1-ethyl-3-methylimidazolium acetate with uracil or adenine, namely, their ionic conductivity, density and viscosity in the temperature range 298K–343K were determined as a function of the nucleobase content. Walden plots were determined and used to clarify the role of the nucleobases in the ionic liquids ionicity. [Copyright &y& Elsevier]

Published
2013
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2. Characteristics of starch-based films plasticised by glycerol and by the ionic liquid 1-ethyl-3-methylimidazolium acetate: A comparative study

Author

Andrew K. Whittaker, Bernadine M. Flanagan, Julia L. Shamshina, Rowan Truss, Ming Li, Tony McNally, Michael J. Gidley, Ekaterina Strounina, Fengwei Xie, Robin D. Rogers, Peter J. Halley, Parveen Sangwan, and Katherine Dean

Subjects
TP, Glycerol, Thermogravimetric analysis, Materials science, Polymers and Plastics, Starch, Ionic Liquids, Acetates, Crystallinity, chemistry.chemical_compound, Plasticizers, Elastic Modulus, Materials Chemistry, Organic chemistry, Organic Chemistry, Imidazoles, Plasticizer, food and beverages, Dynamic mechanical analysis, Biodegradation, chemistry, Ionic liquid, Crystallization, Nuclear chemistry
Abstract

This paper reports the plasticisation effect of the ionic liquid, 1-ethyl-3-methylimidazolium acetate ([Emim][OAc]), as compared with the traditionally used plasticiser, glycerol, on the characteristics of starch-based films. For minimising the additional effect of processing, a simple compression moulding process (which involves minimal shear) was used for preparation of starch-based films. The results show that [Emim][OAc] was favourable for plasticisation, i.e., disruption of starch granules (by scanning electron microscopy), and could result in a more amorphous structure in the starch-based materials (by X-ray diffraction and dynamic mechanical analysis). 13C CP/MAS and SPE/MAS NMR spectroscopy revealed that not only was the crystallinity reduced by [Emim][OAc], but also the amorphous starch present was plasticised to a more mobile form as indicated by the appearance of amorphous starch in the SPE/MAS spectrum. Mechanical results illustrate that, when either glycerol or [Emim][OAc] was used, a higher plasticiser content could contribute to higher flexibility. In spite of the accelerated thermal degradation of starch by [Emim][OAc] as shown by thermogravimetric analysis, the biodegradation study revealed the antimicrobial effect of [Emim][OAc] on the starch-based materials. Considering the high-amylose starch used here which is typically difficult to gelatinise in a traditional plasticiser (water and/or glycerol), [Emim][OAc] is demonstrated to be a promising plasticiser for starch to develop “green” flexible antimicrobial materials for novel applications.\ud

Published
2014