Switching flow and phase behavior in surfactant systems via photochemical reactions

Nees, Dieter; Blenkle, Martin; Koschade, A.; Wolff, Thomas; Baglioni, Piero; Dei, Luigi

doi:10.1007/bfb0114447

Cited by 7 publications

(7 citation statements)

References 34 publications

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“…In some of our previous investigationss, we had already discussed transformations of the micellar hydration shells as a cause for photorheological effects . In one paper (covering CTAB and Triton X-100), the differing of the local viscosities within hydration shells before and after the photochemical conversion of solubilizates was proven by spin probe experiments . It may be true that when the hydration shell is thick already in the pure aqueous micelles (as in CTBAB) the observed rheological and photorheological effects are smaller because the influence of the solubilizate has to extend over a larger distance.…”

Section: Discussionmentioning

confidence: 99%

Rheological and Photorheological Effects of 6-Alkyl Coumarins in Aqueous Micellar Solutions

Wolff

2003

Langmuir

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Viscosities of aqueous micellar solutions of cetyltrimethylammonium bromide (CTAB) and Triton X-100 were measured in the presence and absence of coumarin derivatives, mainly 6-alkyl coumarins with alkyl substituents between methyl and cetyl. The coumarins generally increased the viscosity; the extent of the increase was specific: alkyl chains of medium length showed the largest effects. In situ photodimerization of the coumarins led to a further rise in the viscosity for short alkyl substituents but to a drop in the viscosity in CTAB for long alkyl substituents. Thermodynamic parameters of micelle formation, determined from surface tension measurements, correlate with rheological changes and indicate an increased hydration of the micelles in the cases exhibiting a high viscosity.

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Section: Discussionmentioning

confidence: 99%

Rheological and Photorheological Effects of 6-Alkyl Coumarins in Aqueous Micellar Solutions

Wolff

2003

Langmuir

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“…The melting points were measured with a Laboratory Devices MEL-TEMP II and are not corrected. Compounds 7, [13] 8, [14] 9, [15] and 10 [16] were prepared by the methods described before. Elemental analyses were performed by the Microanalytical Laboratory at the Department of Chemistry, Faculty of Science, Kyushu University.…”

Section: Methodsmentioning

confidence: 99%

“…Compounds 6, [12] 7, [13] 8, [14] 9, [15] and 10 [16] are known compounds. Bromofluorothiophenes 11Ϫ13 were obtained by adding (PhSO 2 ) 2 NF to lithiated dibromothiophenes.…”

Section: Synthesismentioning

confidence: 99%

Photochromism of Dithienylethenes Containing Fluorinated Thiophene Rings

et al. 2004

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Keywords: Density functional calculations / Diarylethenes / Fluorine / Photochromism / UV/Vis spectroscopy Bis(3-thienyl)perfluorocyclopentenes containing partially fluorinated thiophene rings were synthesized and their behaviors examined. Dithienylethenes containing chlorinated thiophene rings were also prepared as reference compounds. The absorption maxima of the closed-ring isomers, their thermal stabilities, and their quantum yields varied depending on the substitution position. The absorption maxima showed a red shift upon fluorine substitution at the 2-or 4-positions of the thiophene ring, whereas a blue shift was observed upon substitution at the 5-position. This shift was explained by the shape of the HOMO and LUMO and was well repro-

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“…For a 43.5 % sample the phase transition temperature T HI (hexagonal liquid crystal  isotropic micellar phase) is 37°C. In the work of Nees et al, this system was found to be very sensitive to the presence of small amounts of compounds like 4-hydroxystilbene and other substituted stilbenes, depending on whether the trans or cis isomer was present (130). Solubilization of ≤ 1% w/w of trans-stilbenes caused a reduction, with T HI~-12°C, whereas isomerization to the cis form had the opposite effect and T HI was found to be + 7.5°C.…”

Section: Photo-induced Aggregation Changes Involving Liquid Crystal Pmentioning

confidence: 99%

“…Such aggregation change implies the transition from a highly organized structure, with at least one (lamellar), two (hexagonal and rectangular) or three (cubic) dimensional translational order, into a much simpler isotropic (micellar) phase with no directional order. (125)(126)(127)(128)(129)(130). Different kinds of phase transitions have been achieved, for example, from micellar isotropic to hexagonal (126)(127)(128)(129), nematic (127)(128)(129)(130)(131), inverse hexagonal (125,127), and lamellar phases (125,130).…”

Section: Photo-induced Aggregation Changes Involving Liquid Crystal Pmentioning

confidence: 99%

Changes in self-assemblies induced by temperature concentration and light

González‐Pérez

2013

Front Biosci

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In this review, changes in aggregation induced by thermodynamic parameters, namely concentration and temperature are discussed. Most of these changes are concerned with sphere-to-rod transitions. On the other hand, the use of an external trigger such as light can induce large aggregation changes in photosurfactant systems. This is discussed in the second part of this review and several examples of light-induced aggregation changes are included, demonstrating the usefulness of this approach.

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Switching flow and phase behavior in surfactant systems via photochemical reactions

Cited by 7 publications

References 34 publications

Rheological and Photorheological Effects of 6-Alkyl Coumarins in Aqueous Micellar Solutions

Rheological and Photorheological Effects of 6-Alkyl Coumarins in Aqueous Micellar Solutions

Photochromism of Dithienylethenes Containing Fluorinated Thiophene Rings

Changes in self-assemblies induced by temperature concentration and light

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