TY - JOUR
T1 - Effect of cation alkyl chain length on surface forces and physical properties in deep eutectic solvents
AU - Chen, Zhengfei
AU - Ludwig, Michael
AU - Warr, Gregory G.
AU - Atkin, Rob
PY - 2017/5/15
Y1 - 2017/5/15
N2 - Deep eutectic solvents (DESs) have been prepared from mixtures of alkyl ammonium bromide salts (ethylammonium bromide, propylammonium bromide and butylammonium bromide) and glycerol at a 1: 2 M ratio. These DESs reveal the effect of cation alkyl chain length on interfacial structure at mica (a model anionic) surface. As the cation chain length is increased it becomes more amphiphilic and solvophobic, leading to stronger association of alkyl chains, as revealed by atomic force microscope force curve measurements. The effect of increasing cation alkyl chain length on phase transition and thermal decomposition temperatures, density, refractive index, viscosity, ionic and thermal conductivity and air liquid surface tension are also probed. Combined, these studies reveal the length of the cation alkyl chain weakly affects composition dependent properties (e.g. density, refractive index, thermal conduction, etc.) but has a stronger effect where intermolecular (ionic) forces play a role, such as on viscosity, and on surface tension and interfacial structure. To the authors knowledge, this is the first report of amphiphilic nanostructure in DESs and the first systematic study of the effect of cation alkyl chain length on physical properties.
AB - Deep eutectic solvents (DESs) have been prepared from mixtures of alkyl ammonium bromide salts (ethylammonium bromide, propylammonium bromide and butylammonium bromide) and glycerol at a 1: 2 M ratio. These DESs reveal the effect of cation alkyl chain length on interfacial structure at mica (a model anionic) surface. As the cation chain length is increased it becomes more amphiphilic and solvophobic, leading to stronger association of alkyl chains, as revealed by atomic force microscope force curve measurements. The effect of increasing cation alkyl chain length on phase transition and thermal decomposition temperatures, density, refractive index, viscosity, ionic and thermal conductivity and air liquid surface tension are also probed. Combined, these studies reveal the length of the cation alkyl chain weakly affects composition dependent properties (e.g. density, refractive index, thermal conduction, etc.) but has a stronger effect where intermolecular (ionic) forces play a role, such as on viscosity, and on surface tension and interfacial structure. To the authors knowledge, this is the first report of amphiphilic nanostructure in DESs and the first systematic study of the effect of cation alkyl chain length on physical properties.
KW - Atomic Force Microscope
KW - Deep eutectic solvents
KW - Nanostructure
KW - Surfaces forces
UR - http://www.scopus.com/inward/record.url?scp=85012273288&partnerID=8YFLogxK
U2 - 10.1016/j.jcis.2017.01.109
DO - 10.1016/j.jcis.2017.01.109
M3 - Article
C2 - 28167425
AN - SCOPUS:85012273288
SN - 0021-9797
VL - 494
SP - 373
EP - 379
JO - Journal of Colloid and Interface Science
JF - Journal of Colloid and Interface Science
ER -