Citation

S. Komura et al., Dynamical fluctuation of the mesoscopic structure in ternary C12E5-water-n-octane amphiphile system - art. no. 041402, PHYS REV E, 6304(4), 2001, pp. 1402

Citations number

34

Language

INGLESE

art.tipo

Article

Categorie Soggetti

Physics

Journal title

PHYSICAL REVIEW E

ISSN journal

1063-651X
→ ACNP

Volume

6304

Issue

4

Year of publication

2001

Part

1

Database

ISI

SICI code

1063-651X(200104)6304:4<1402:DFOTMS>2.0.ZU;2-S

Abstract

Dynamical fluctuations of the bicontinuous microemulsion and lamellar struc
tures in ternary C12E5-water-n-octane amphiphilic system are studied by mea
ns of neutron spin echo (NSE) spectrometry. The decay rates of the time cor
relation of the concentration were analyzed in terms of three theories: (1)
A. G. Zilman and R. Granek. Phys. Rev. Lett. 77, 4788 (1996), (2) M. Nonom
ura and T. Ohta, J. Chem. Phys. 110, 7516 (1999), and (3) R. Granek and M.
E. Cates, Phys. Rev. A 46, 3319 (1992), in the first of which a Langevin eq
uation for membrane plaquettes and in the latter two of which time-dependen
t Ginzburg-Landau equations for the order parameters are considered. The re
sult shows that the intermediate correlation functions I(q,t) for the range
s of 0<t<15 ns and 0<q<0.2 Angstrom (-1) are well fitted to a stretched exp
onential function in time, I(q,t) = exp[-(Gammat)(2/3)], for the bicontinuo
us microemulsion and the lamellar phases of the same systems with the relax
ation rate Gamma increasing as q(3) in agreement with theory (1) from which
the bending modulus of the membrane kappa was estimated. For more restrict
ed ranges of 0<t<5 ns and 0.05<q<0.15 Angstrom (-1) the NSE result can be e
xpressed by an exponential function in time in agreement with theory (2) de
termined exclusively by hydrodynamic interactions and for extended range of
0<t<10 ns and 0.03<q<0.15 Angstrom (-1) by a nonexponential function in ag
reement with theory (3), from both of which the effective viscosities eta (
0) and eta (eff) of the system were estimated. The effective viscosity from
the nonexponential eta (eff) is five times greater than that from the simp
le exponential eta (0) that is almost the same as the literature value. The
implication of this result is discussed in terms of the effective viscosit
y eta (eff) that takes into account the renormalization of the bending modu
lus of the membrane.