ABSTRACT

The aggregation behaviors of two cationic surfactants, namely, N-dodecyl-N-2-hydroxyethyl-N,N-dimethyl ammonium bromide (C12HDAB) and N-dodecyl-N,N-2-dihydroxyethyl-N-methyl ammonium bromide (C12DHAB), were studied by measurements of density, conductivity, and steady-state fluorescence quenching. The aggregation number, the volumetric properties, and the standard Gibbs energy (?Gmic0) of micellization were obtained, and the surface area (Amic) of the surfactant headgroups and the radius (r) of the micelles were estimated. It was found that substituting the methyl group with the hydroxyethyl group in the head of the surfactant led to the increase of the volume change of micellization and the decreases of the critical micelle concentration, association degree of the counterion, and the value of ?Gmic0, while the aggregation number of those surfactants in aqueous solutions was little affected by introducing the hydroxyethyl group. It was also found that the values of Amic and r increase with the hydroxyethyl group.

Compounds

#	Formula	Name
1	C17H38BrNO2	N,N-bis(2-hydroxyethyl)-N-methyldodecan-1-aminium bromide
2	C16H36BrNO	dodecyl(2-hydroxyethyl)dimethylammonium bromide
3	C15H34BrN	dodecyltrimethylammonium bromide
4	H2O	water

Datasets

The table above is generated from the ThermoML associated json file (link above). POMD and RXND refer to PureOrMixture and Reaction Datasets. The compound numbers are included in properties, variables, and phases, if specificied; the numbers refer to the table of compounds on the left.
Type	Compound-#	Property	Variable	Constraint	Phase	Method	#Points
POMD	4	Mass density, kg/m3 ; Liquid	Temperature, K; Liquid	Pressure, kPa; Liquid	Liquid	Pycnometric method	6
POMD	3 4	Mass density, kg/m3 ; Liquid	Temperature, K; Liquid Molality, mol/kg - 3; Liquid	Pressure, kPa; Liquid	Liquid	Pycnometric method	132
POMD	2 4	Mass density, kg/m3 ; Liquid	Temperature, K; Liquid Molality, mol/kg - 2; Liquid	Pressure, kPa; Liquid	Liquid	Pycnometric method	108
POMD	4 1	Mass density, kg/m3 ; Liquid	Temperature, K; Liquid Molality, mol/kg - 1; Liquid	Pressure, kPa; Liquid	Liquid	Pycnometric method	120

Thermodynamics Research Center / ThermoML | Journal of Chemical and Engineering Data

Densities, Conductivities, and Aggregation Numbers of Aqueous Solutions of Quaternary Ammonium Surfactants with Hydroxyethyl Substituents in the Headgroups

Zhang, Z.[Zhiguo], Wang, H.[Huanhuan], Shen, W.[Weiguo]

ABSTRACT