Anomalous decrease in lamellar spacing by shear flow in a nonionic surfactant/water system

Tadashi Kato, Koji Minewaki, Youhei Kawabata, Masayuki Imai, Yoshiaki Takahashi

Research output: Contribution to journalArticle

8 Citations (Scopus)

Abstract

We study the effects of shear flow on the structure of a lamellar phase in a C16E7 [hepta(oxyethylene glycol)-n-hexadecyl ether]/water system (40-55 wt % of C16E7) at 70 °C using small-angle neutron scattering in the range of shear rate of 10 -3-30 s-1. At the shear rate 0.1-1 s-1, the repeat distance (d) is decreased significantly (down to about 40% of d at rest in the most significant case) and discontinuously with increasing shear rate. With the further increase in the shear rate, d increases through a sharp minimum (referred to as d*). Such a shear rate dependence of d is obtained for all the principal orientations of lamellae. As the concentration of C 16E7 decreases from 55 to 40 wt %, d increases from 6.5 to 8.5 nm at rest whereas d* remains almost constant (≅5 nm). Moreover, d* is found to be almost equal to the thickness of bilayers obtained from the line shape analysis of small-angle X-ray scattering at rest. The results strongly suggest that the water layer is excluded by shear flow and that the lamellar phase segregates into surfactant-rich and water-rich regions, although these regions do not reach macroscopic size.

Original languageEnglish
Pages (from-to)3504-3508
Number of pages5
JournalLangmuir
Volume20
Issue number9
DOIs
Publication statusPublished - Apr 27 2004

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Nonionic surfactants
Shear flow
shear flow
Shear deformation
surfactants
spacing
shear
Water
water
Glycols
lamella
Neutron scattering
X ray scattering
Surface-Active Agents
Ether
line shape
glycols
Ethers
ethers
neutron scattering

All Science Journal Classification (ASJC) codes

  • Materials Science(all)
  • Condensed Matter Physics
  • Surfaces and Interfaces
  • Spectroscopy
  • Electrochemistry

Cite this

Anomalous decrease in lamellar spacing by shear flow in a nonionic surfactant/water system. / Kato, Tadashi; Minewaki, Koji; Kawabata, Youhei; Imai, Masayuki; Takahashi, Yoshiaki.

In: Langmuir, Vol. 20, No. 9, 27.04.2004, p. 3504-3508.

Research output: Contribution to journalArticle

Kato, Tadashi ; Minewaki, Koji ; Kawabata, Youhei ; Imai, Masayuki ; Takahashi, Yoshiaki. / Anomalous decrease in lamellar spacing by shear flow in a nonionic surfactant/water system. In: Langmuir. 2004 ; Vol. 20, No. 9. pp. 3504-3508.
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