Viskoelastische Tensidlösungen

Non-ionic microemulsions were investigated by viscoelastic measurements in the kHz region. We found that in some parts of the phase diagram our systems consisted of a dispersion of spherical oil doplets, stabilized by a non-ionic surfactant, in a continuous phase of almost pure water. Because of the simplicity of the system used it was relatively easy to interpret our measurements in terms of two rheological models developed by 01droyd. Using these models, we could calculate the interracial tension between the continuous and the dispersed phase. In other parts of the phase diagram, however, our results indicate the presence of a fluctuating network of oil-swollen cylindrical micelles.

Section: \ ~Ls+ ~La ]supporting

confidence: 71%

Section: Rheological Measurements For Systems With a More Complicatedmentioning

confidence: 99%

Viscoelasticity and microstructure of non-ionic microemulsions

Eshuis

Mellema

1984

“…The evaluation of LS data becomes, in such cases, difficult or ambiguous, and then other methods have to be applied in addition. Electron microscopy [18][19][20][21][22][23][24][25][26], electric birefringence (Kerr effect) [27], and viscoelastic measurements [28,29,30] may be very helpful.…”

Section: Introductionmentioning

confidence: 99%

Investigations of a series of nonionic surfactants of sugar-lipid hybrids by light scattering and electron microscopy

Denkinger

Kunz

Burchard

1990

Sugar-lipid hybrids of the type CnCm were prepared by coupling an alkane chain (Cn) with a maltooligosaccharide (Gin) over an amide linkage. Coupling was performed with maltobionolactone (G2) and n-alkylamine chains Cn with n = 8,10,12,14,16, i.e. variation of the hydrophobic part of the molecule, and with hexadecylamine (CI6) and different maltooligosaccharides (Gm, m = 2,3,4,6). The solution properties of the various products were studied by means of static and dynamic light scattering (LS) and by electron-microscopy (EM). The results may be summarized as follows: If the alkane chain is shorter than n = 14, small spherical micelles with a radius of about 3 nm are observed. In time these micelles aggregate further to form increasingly larger spherical clusters which eventually precipitate. Long rod-like micelles form when n > 14. Contour length and chain stiffness were determined by applying theories of semiflexible chains. A qualitative confirmation of the light scattering results, i.e., micelle size and shape, was obtained from electron microscopy.

“…Among them, the micelle shape and size in some cationic surfactant solution systems with aromatic additives, have become the focus of interest, since the systems show a remarkable viscoelastic behaviour. Many reports have indirectly supported the occurrence of rod-shaped micelles, based on measurements of, e. g. nmr [4], light scattering [5], neutron scattering [6], etc.…”

mentioning

confidence: 99%

Electron microscope study of viscoelastic cationic surfactant systems

Sakaiguchi¹,

Shikata²,

Urakami

et al. 1987

Some cationic surfactants such as cetyhrimethylammonium bromide (CTAB) show a very spectacular viscoelasticity in solution, in even very diluted states, with some aromatic substances added, such as salicylic acid. Formerly, the authors established that the remarkable solution behaviour was the result of the entanglement of such enormously elongated giant micelles, based on recognition of the existence of large aggregates, through direct observation of them as substantial images under the electron microscope.In this report, we further confirm the relation between micelle length and solution viscoelasticity after arbitrarily obtaining different size aggregates by altering the media pH, or by admixing shorter chain length surfactants than CTAB, which alone did not induce viscoelasticity.Key words: Cationic surfactant micelle, rod-like micelle, viscoelastic cationic surfactant system, electron micrographical micelle image, micelle length dependence on viscoelasticity.