维生素C对表面活性剂体系相行为的影响

维生素Ｃ（ＶＣ）能提高表面活性剂十六烷基三甲基溴化铵（ＣＴＡＢ）在水中的溶解度,具有助溶作用;且能提高ｎ－Ｃ５Ｈ１１ＯＨ在Ｏ／Ｗ微乳液中的增溶量和水在Ｗ／Ｏ微乳液中的增溶量,Ｏ／Ｗ与Ｗ／Ｏ微乳液区域同时扩大,具有助溶－增溶作用。ＶＣ的助溶作用与助溶－增溶作用均具有一定的选择性,只对阳离子表面活性剂ＣＴＡＢ体系有效,ＶＣ助溶－增溶作用的机理是同时增加Ｗ／Ｏ和Ｏ／Ｗ微乳液的稳定性和层状液晶向双连续结构     

Ultrasound promoted efficient and green synthesis of β-amino carbonyl compounds in aqueous hydrotropic medium

Ultrasound promoted synthesis of β-amino carbonyl compounds in aqueous hydrotropic medium at ambient temperature is reported. The remarkable features of the new procedure are shorter reaction time, excellent yields in aqueous medium, cleaner reaction profile and simple experimental and work-up procedure.     

丙烯酰胺对Span80-Tween85/Isopar M/丙烯酰胺-H2O拟三元体系相行为的影响

考察了丙烯酰胺对水/IsoparM界面张力的影响以及对水溶液中非离子性乳化剂Tween85的助溶效果,并深入探讨了丙烯酰胺对Span80-Tween85/IsoparM/AM-H2O拟三元体系相行为的影响过程。结果表明,丙烯酰胺能够提高Tween85在水溶液中的溶解度,并可有效降低油水界面张力,进而能够扩大Span80-Tween85/IsoparM/AM-H2O拟三元相图的反相乳液区域面积。     

DISPERSION BEHAVIOR OF HEMATOPORPHYRIN IN MONOMOLECULAR FILM OF STEARIC ACID

Dispersion characteristics of the monomolecular films of hematoporphyrin mixed with stearic acid has been studied. The average molecular areas of mixed monolayers coincided approximately with the ideal additivity rule when the“solid” films were extrapolated to zero surface pressure. The orientation of the macrocycles was given by infrared dichroism with the tilting angle of 10. 1° to the plane of the film. The SERS of LB films deposited on silver island films was observed- The results showed that there are two possible contribution, i. e., electromagnetic and chemical interaction between the hematoporphyrin molecules and Ag island films.     

Hydrotropic Enhancement of Rate of the Browning Reaction; A Kinetic Study

The rate of a nonenzymatic browning reaction, that is, the reaction between reducing sugar and amino acid(commonly known as Millard reaction) is strongly enhanced in the presence of a common hydrotrope viz. sodium benzoate or sodium salicylate even below its minimal hydrotropic concentration (MHC). The effect of hydrotrope on the rate has been studied in four systems taking combination of different reducing sugars (glucose and fructose) and amino acids (glycine and alanine) in alkaline conditions. The kinetic data support the formation of the mixed aggregation between the hydrotrope and the reactants. The kinetic rate law consistent with experimental results has been derived on the basis of the proposed mechanism.     

Hydrotrope Action of Vitamin C (VC) and Its Application in a Sunscreen

The solubility regions of the sunscreen 2-ethyIhexyl p-methoxycinnamate (E557) in the CTAB/ n-CsHnOH/ H₂ O system with and without the hydrotrope agent vitamin C (VC) are determined. E357 was only sohibilized in the bicontinuous microemulsion (BI), the W/ O microemulsion area and the lamellar liquid crystal region (LLC). The addition of VC in the system greatly enlarged the solubility amount of E₅₅₇in the bicontinuous region, but reduced h in the lamellar liquid crystal area. Small angle X-ray diffraction measurement was used to determine the location of E₅₅₇ in the lamellar liquid crystal showing the suncreen molecule penetrating between the hydrocarbon chains in the liquid crystal structure.The UV absorption spectra of E557 in various media was measured, surprisingly showing a dependence on the colloidal structure.     

Small-angle neutron scattering studies of sodium butyl benzene sulfonate aggregates in aqueous solution

The aggregation behaviour of a hydrotrope, sodiumn-butyl benzene sulfonate (Na-NBBS), in aqueous solutions is investigated by small-angle neutron scattering (SANS). Nearly ellipsoidal aggregates of Na-NBBS at concentrations well above its minimum hydrotrope concentration were detected by SANS. The hydrotrope seems to form self-assemblies with aggregation number of 36–40 with a substantial charge on the aggregate. This aggregation number is weakly affected by the hydrotrope concentration.     

Hydrotrope and hydrotrope-solubilization action of cephanone in CTAB/<Emphasis Type="Italic">n</Emphasis>-C<Subscript>5</Subscript>H<Subscript>11</Subscript>OH/H<Subscript>2</Subscript>O system

Cephanone is found to show the hydrotrope and hydrotrope-solubilization action in CTAB/n-C₅H₁₁OH/H₂O system. Cephanone can increase the solubilities of cationic surfactant CTAB or n-C₅H₁₁OH in water and water in n-C₅H₁₁OH. It can also increase the solubilization amount of n-C₅H₁₁OH in O/W microemulsion and that of water in W/O microemulsion, which makes the two regions of O/W and W/O microemulsion larger, and even linked together. The mechanism of the hydrotrope-solubilization action of cephanone is related to the location of cephanone in the palisade of microemulsion which causes the stability of O/W and W/O microemulsion to be enhanced and that of lamellar liquid crystal to be reduced. Therefore, the mechanism of hydrotrope-solubilization is the structural transition from lamellar liquid crystal to the bicontinuous structure.     

A facile route to design pH-responsive viscoelastic wormlike micelles: Smart use of hydrotropes

A simple and effective route to design pH-responsive viscoelastic wormlike micelles based on commercial compounds is reported. According to this route, pH-sensitive viscoelastic fluids can be easily obtained by introducing a pH-responsive hydrotrope into a surfactant solution. In this paper, the mixed system of cetyltrimethylammonium bromide (CTAB) and potassium phthalic acid (PPA) was studied in detail. This pH-sensitive fluid can be switched between a gellike state and a waterlike state within a narrow pH change. Rheology and DLS results revealed that the pH-sensitive flowing behavior was attributed to the microstructure transition between wormlike micelles and short cylindrical micelles. Combined with fluorescence anisotropy, NMR, and UV–vis, it was demonstrated that the pH response of viscoelastic fluid originated from the different binding abilities of hydrotrope to surfactant as pH varies. Furthermore, different kinds of hydrotropes can be utilized to prepare pH-responsive viscoelastic fluids in the desired pH areas.     

Effect of a hydrotrope on the viscoelastic properties of polymer-like micellar solutions

Low-viscosity micellar aqueous solutions of cetyltrimethylammonium bromide (CTAB) undergo a major change in the presence of the hydrotrope, potassium 1-phenylmethylsulfate (KPhMS), producing a highly viscoelastic entanglement network of polymer-like micelles. The system studied here shows typical shear banding flow behavior, which tends to disappear with increasing the hydrotrope-to-surfactant concentration ratio (C _H / C _S). The linear rheological response was analyzed with the model of Granek–Cates, whereas the nonlinear behavior was reproduced with the Bautista–Manero–Puig (BMP) model. Both models introduce a kinetic equation to account for the breaking and reformation of the micelles, and they predict the linear and nonlinear rheological data very well. This paper was presented at Annual European Rheology Conference (AERC) held in Hersonisos, Crete, Greece, April 27–29, 2006.