ISSN:0193-2691    

DOI:10.1080/01932699908943884

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

Cetostearyl alcohol has been incorporated into cosmetic or pharmaceutial emulsions to give them an appropriate consistency and a long term stability. It is well known that cetostearyl alcohol forms a gel phase with a nonionic surfactant in an aqueous system, and the properties of the gel phase depend on several factors such as the ratio of fatty alcohols. The aim of the present paper is to investigate the effect of the structural difference of the lipophilic part of surfactants on the stability of the gel phase in the nonionic surfactant / cetostearyl alcohol / water ternary systems using differential scanning calorimeter.

ISSN:0193-2691    

DOI:10.1080/01932699908943885

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

The conductances of tetradecyltrimethylammonium bromide (TTAB) + dodecyltrimethylammonium bromide (DTAB) mixtures over the entire mole fraction range of TTAB (αOITTAB) were measured in aqueous polyethylene glycol 1000 (PEG) containing 1, 2, 5 and 10 wt% of PEG at 30 °C. From the conductivity data, various micellar parameters were computed. The results have been explained on the basis of the medium effects as well as the adsorption of additive molecules at micelle-solution interface. The non-ideality in TTAB+DTAB mixtures was evaluated by using the regular solution theory and Motomura's formulation based on the excess thermodynamic quantities. It has been found that the regular solution interaction parameter (β) and micellar mole fraction (¯xm2) remain almost unaffected even in the presence of upto 10 wt% of PEG. These results suggest that the additive remains only in the aqueous phase and perhaps only changing the environment surrounding the micelles by adsorbing at the micelle-solution interface.

ISSN:0193-2691    

DOI:10.1080/01932699908943886

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

The adsorption and solution properties of cationic surfactants dodecylammonium chloride, tetradecylammonium chloride, and hexadecylammonium chloride, as well as hexadecyltrimtehylammonium bromide in pure and mixed states, were studied by surface tension and conductance measurements. The surfactants mixed non-ideally in both mixed monolayer and in the mixed micelles. The regular solution theory was used for evaluating the non-ideal interactions between molecules in adsorbed and micellar states. Similar values of the mixed monolayer and mixed micelle molecular interaction parameters in a mixture imply the molecules at the interface and in the mixed micelle have similar interactions. No synergism in surface tension effectiveness was observed. The adsorbed film at the air/water interface and mixed micelles were richer in more surface-active component.

ISSN:0193-2691    

DOI:10.1080/01932699908943887

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

The foamability of two commercial PEO-PPO-PEO triblock copolymers (Synperonic P85 and F108, ICI) was studied and compared to the properties of single foam films. The volume of a steady-state foam column created with a combined pneumatic-mechanical device is used as a measure of the copolymers foamability. Experiments were carried out at bulk copolymer concentrations corresponding to full surface coverage,i.e. constant area per molecule, under equilibrium conditions. The foamability of F108 solutions was higher than that of P85 although the surface activity of both copolymers was similar. The foam volume increases with increasing the bulk copolymer concentration. Higher electrolyte concentration or lower pH caused the foam volume to diminish. A pronounced parallelism between the properties of dynamic foams and single microscopic foam films was observed: when thicker single foam films were formed (from F108 solutions) the steady

ISSN:0193-2691    

DOI:10.1080/01932699908943888

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

The possibility of substitution of the conventional pentanol as cosurfactant by butyl lactate, on the preparation of OAV microemulsions in a system with SDS as anionic surfactant, is investigated. Whereas a narrow region of OAV microemulsion is described for the system with pentanol for a critical ratio 85/15 between water and SDS, butyl lactate leads to wider regions of solubility for different water/surfactant proportions, making easy the preparation of these microemulsions. Besides this advantage, being butyl lactate obtained from renewable resources and considered as a safe and biodegradable product, the microemulsions prepared with this cosurfactant could be applied in technological fields as cosmetic and dermopharmaceutical, where the biological agressivity of pentanol could avoid any practical application. As a complementary study, the influence that 1,3-buryleneglycol as polar cosolvent exert on the microemulsion regions, was also considered. Although according to experimental data given in the paper 1,3-butyleneglycol affects only slightly the OAV region of microemulsions, it can be foreseen that its presence could provide emollient characteristics to the final compositions.

ISSN:0193-2691    

DOI:10.1080/01932699908943889

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

Copolymerization of sodium acrylamidostearate (NaAAS) and oleic acid was performed in the lamellar liquid crystal (LLC) formed by NaAAS, oleic acid and water, in the absence of N.N’-methylenebisacrylamide (MBAA) and in the presence of MBAA, respectively. In the absence of MBAA, after the polymerization the lamellar structure remained, and the disorder of the lamellar liquid crystal was, to some extent, enhanced. Surface tension, small-angle X-ray diffraction, viscosity, and fluorescence methods were used to study the properties of the linear copolymer. The linear polymeric surfactant behaves like

ISSN:0193-2691    

DOI:10.1080/01932699908943890

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

The influence of different amounts of anionic copolymers of N-Methyl N-vinyl acetamide (NMVA) and acrylic acid with various charge densities on the formation of the lamellar liquid crystal formed by sodium dodecyl sulfate (SDS)/decanol/water was investigated by means of polarization microscopy, small angle x-ray scattering (SAXS), transmission electron microscopy and rheology. On the contrary to the incorporation of poly(acrylic acid)

ISSN:0193-2691    

DOI:10.1080/01932699908943891

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

The ternary complex kinetic model for metallomicellar catalysis was employed to investigate the effect of Zn2+ion or Ni2+ion complexes of long alkyl-pyridines with hydroxyl groups in micellar solution on the hydrolysis of p-nitrophenyl picolinate in this paper. The kinetic and the thermodynamic parameters (KN,Kr,KM) were obtained. More worthily, the effect of pH on the hydrolysis of p-nitrophenyl picolinate in metallomicellar phase was discussed quantitatively. The rate constant (KN) of the hydrolysis of p-nitrophenyl picolinate in metallomicellar phase was obtained and compared with Cu2+ion complex system. The results indicated that Cu2+ion micelle, Ni2+ion micelle and Zn2+ion micelle all exhibited great catalytic effects on the hydrolysis of p-nitrophenyl picolinate. and the order of activity is:Cu2+ion micelle ≥ Ni2+ion micelle ≥ Zn2+ion micell. Moreover, the reasonability of the ternary complex kinetic model was verified further.

ISSN:0193-2691    

DOI:10.1080/01932699908943892

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

The ability of three matrices to model the barrier properties of the lipid domain of stratum corneum (SC) against permeation of seven steroids was studied. Model matrices were water and oleic acid/oleate; a mixture of unsaturated and saturated fatty acids/soap; or a more complex matrix also containing phospholipids, sphingolipids, cholesterol and ceramides.

ISSN:0193-2691    

DOI:10.1080/01932699908943893

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor