Adsorption and Aggregation Behaviors of Tetrasiloxane-Tailed Gemini Surfactants with (EO)m Spacers
摘要:
Adsorption and aggregation behaviors of novel tetrasiloxane-tailed gemini surfactants N,N'-ditetrasiloxane-N,N'-digluconamide oligo ethylene glycol diglycidyl (Si-m-Si, where m is the number of ethylene glycol of 1, 2, and 3) were investigasted using surface tension, bromophenol blue encapsulation, dynamic light scattering (DLS), and transmission electron microscope (TEM) methods. The static surface tension of the aqueous Si-m-Si solutions measured at the critical aggregate concentration (CAC) was observed to be lower than that of traditional hydrocarbon gemini surfactants. This suggests that these newly synthesized gemini surfactants are capable of forming a closely packed monolayer film at the air/aqueous solution interface. With a combination of DLS data, TEM measurements, and bromophenol blue entrapment studies, formations of vesicles in Si-m-Si solutions appear to occur at a concentration well above the CAC. Moreover, the size of vesicles depended on their m values.
Transetherification of Organosilicon Amines with Cellosolve and Trimethylsilanol
摘要:
Kinetics of transetherification of (3-aminopropyl)trimethoxysilane, [3-N-(2-aminoethyl)aminopropyl]trimethoxysilane and (3-aminopropyl)triethoxysilana with Cellosolve and trimethylsilanol were studied. The example of [3-N-(2-aminoethyl)aminopropyl]trimethoxysilane was used to show that the activation energies of the direct and reverse reactions are equal to each other both in the first and in the second stages, which points to independence of the equilibrium constant on temperature (DeltaHapproximate to0). With methoxysilanes, the rate constant of the reverse reaction in the second stage of the transetherification with Cellosolve is higher than that of the direct reaction.
Synthesis and properties of new dicephalic tetrasiloxane surfactants containing sugar
作者:Dianlong Zhang、Yan Qiao
DOI:10.1007/s11164-013-1414-7
日期:2015.5
A series of dicephalic tetrasiloxane surfactants containing sugar were synthesized. Their structure was confirmed by infrared spectroscopy and 1H nuclear magnetic resonance spectroscopy. Their surface activity and wetting ability on low energy substrates were also investigated. The results showed that the target surfactants exhibited excellent surface activity, which could reduce the surface tension of water to a minimum value of 20–21 mN m−1, and excellent wetting ability, which could completely wet parafilm.
Adsorption and Aggregation Behavior of Tetrasiloxane-Tailed Surfactants Containing Oligo(ethylene oxide) Methyl Ether and a Sugar Moiety
作者:Guoyong Wang、Wenshan Qu、Zhiping Du、Qianyong Cao、Qiuxiao Li
DOI:10.1021/jp110578u
日期:2011.4.14
Three novel amphiphilic dicephalic (double-headed) surfactants containing oligo(ethylene-oxide)methyl-ether and a sugar moiety TGA-m (m = 1, 2, and 3) that incorporate a tetrasiloxane at the terminus of a hydrocarbon chain were designed and synthesized. Their surface activity and aggregation behavior in aqueous solution were systematically investigated by surface tension, dynamic light scattering (DLS), and transmission electron microscopy (TEM) techniques at 298 K. The surface tension measurements provided the critical aggregation concentration (CAC) and the surface tension at the CAC (gamma(cac)). In addition, with application of the Gibbs adsorption isotherm, the maximum surface excess concentration (Gamma(max)) and the minimum surface area/molecule (A(min)) at the air-water interface were estimated. The effect of EO chain length on the surface activity and aggregation behavior was also investigated. It was found that both the gamma(cac) and the CAC were lower than those for reported traditional hydrocarbon surfactants. Aggregates of three surfactants, TGA-m (m = 1, 2, and 3), formed in aqueous solutions could be assigned as spherical vesicles as suggested by analysis using DLS and TEM. Moreover the formation of vesicles can be confirmed by the encapsulation of bromophenol blue. These results indicate that these three surfactants have excellent efficiencies of vesicle formation and surface tension reduction in the aqueous phase.
Transetherification of Organosilicon Amines with Cellosolve and Trimethylsilanol
作者:V. A. Kovyazin、A. V. Nikitin、V. M. Kopylov、I. B. Sokol'skaya
DOI:10.1023/b:rugc.0000015983.75580.9c
日期:2003.9
Kinetics of transetherification of (3-aminopropyl)trimethoxysilane, [3-N-(2-aminoethyl)aminopropyl]trimethoxysilane and (3-aminopropyl)triethoxysilana with Cellosolve and trimethylsilanol were studied. The example of [3-N-(2-aminoethyl)aminopropyl]trimethoxysilane was used to show that the activation energies of the direct and reverse reactions are equal to each other both in the first and in the second stages, which points to independence of the equilibrium constant on temperature (DeltaHapproximate to0). With methoxysilanes, the rate constant of the reverse reaction in the second stage of the transetherification with Cellosolve is higher than that of the direct reaction.
Adsorption and Aggregation Behaviors of Tetrasiloxane-Tailed Gemini Surfactants with (EO)<sub><i>m</i></sub> Spacers
Adsorption and aggregation behaviors of novel tetrasiloxane-tailed gemini surfactants N,N'-ditetrasiloxane-N,N'-digluconamide oligo ethylene glycol diglycidyl (Si-m-Si, where m is the number of ethylene glycol of 1, 2, and 3) were investigasted using surface tension, bromophenol blue encapsulation, dynamic light scattering (DLS), and transmission electron microscope (TEM) methods. The static surface tension of the aqueous Si-m-Si solutions measured at the critical aggregate concentration (CAC) was observed to be lower than that of traditional hydrocarbon gemini surfactants. This suggests that these newly synthesized gemini surfactants are capable of forming a closely packed monolayer film at the air/aqueous solution interface. With a combination of DLS data, TEM measurements, and bromophenol blue entrapment studies, formations of vesicles in Si-m-Si solutions appear to occur at a concentration well above the CAC. Moreover, the size of vesicles depended on their m values.