STRUCTURAL AND DYNAMIC TRANSFORMATIONS BETWEEN NEIGHBORING DENSE MICROEMULSION PHASES

被引:37
作者
KOTLARCHYK, M
SHEU, EY
CAPEL, M
机构
[1] TEXACO USA INC, RES CTR, BEACON, NY 12508 USA
[2] BROOKHAVEN NATL LAB, DEPT BIOL, UPTON, NY 11973 USA
来源
PHYSICAL REVIEW A | 1992年 / 46卷 / 02期
关键词
D O I
10.1103/PhysRevA.46.928
中图分类号
O43 [光学];
学科分类号
070207 ; 0803 ;
摘要
A small-angle x-ray scattering (SAXS) study of dense AOT-water-decane microemulsions [AOT denotes sodium bis(2-ethylhexyl) sulfosuccinate] was undertaken in order to delineate clearly the phase behavior and corresponding structural transitions for AOT-plus-water volume fractions ranging from phi=0.60 to 0.95. Spectra were collected for temperatures between T=3 and 65-degrees-C. The resulting T-vs-phi phase diagram indicates three distinct structural domains when the water-to-AOT molar ratio is fixed at W=40.8, namely, the previously investigated L2 droplet phase, a high-temperature L(alpha) lamellar phase, and a low-temperature L3 phase consisting of randomly connected lamellar sheets. A significantly wide coexistence region accompanies the droplet-to-lamellar phase transition, which is demonstrated to be first order. For W between 15 and 40, an analysis of the lamellar structure using a one-dimensional paracrystal model produces a Hosemann g factor indicative of an approximately constant variation in the lamellar spacing of about 8%. The SAXS study was supplemented by dielectric-relaxation, shear-viscosity, and quasielastic light-scattering measurements in order to substantiate the observed phase transitions and further our understanding of the structural and dynamical properties of the L3 phase. It was found that the L3 phase exhibits Newtonian behavior up to a shear rate of 790 s-1, in contradiction to previous theoretical considerations. The phase exhibits two distinct relaxation modes. A relaxation time of approximately 1 ms characterizes the Brownian motion of a single lamellar sheet, while the motion of the entire interconnected sheet assembly has a relaxation time on the order of 1 s.
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收藏
页码:928 / 939
页数:12
相关论文
共 36 条
[1]   CONCENTRATED WINSOR MICROEMULSIONS - A SMALL-ANGLE X-RAY-SCATTERING STUDY [J].
AUVRAY, L ;
COTTON, JP ;
OBER, R ;
TAUPIN, C .
JOURNAL DE PHYSIQUE, 1984, 45 (05) :913-928
[2]   THE ISOTROPIC (SPONGE) TO LAMELLAR TRANSITION IN DILUTE SURFACTANT SYSTEMS [J].
CATES, ME .
PHYSICA A, 1991, 176 (01) :187-199
[3]   RANDOM SURFACE MODEL FOR THE L3-PHASE OF DILUTE SURFACTANT SOLUTIONS [J].
CATES, ME ;
ROUX, D ;
ANDELMAN, D ;
MILNER, ST ;
SAFRAN, SA .
EUROPHYSICS LETTERS, 1988, 5 (08) :733-739
[4]   ROLE OF SHEAR IN THE ISOTROPIC-TO-LAMELLAR TRANSITION [J].
CATES, ME ;
MILNER, ST .
PHYSICAL REVIEW LETTERS, 1989, 62 (16) :1856-1859
[5]   RANDOM BILAYER PHASES OF DILUTE SURFACTANT SOLUTIONS [J].
CATES, ME ;
ROUX, D .
JOURNAL OF PHYSICS-CONDENSED MATTER, 1990, 2 :SA339-SA346
[6]   SMALL-ANGLE NEUTRON-SCATTERING INVESTIGATION OF STRUCTURAL INVERSION IN A 3-COMPONENT IONIC MICROEMULSION [J].
CHEN, SH ;
CHANG, SL ;
STREY, R ;
THIYAGARAJAN, P .
JOURNAL OF PHYSICS-CONDENSED MATTER, 1991, 3 (42) :F91-F107
[7]   DYNAMIC SLOWING-DOWN AND NONEXPONENTIAL DECAY OF THE DENSITY CORRELATION-FUNCTION IN DENSE MICROEMULSIONS [J].
CHEN, SH ;
HUANG, JS .
PHYSICAL REVIEW LETTERS, 1985, 55 (18) :1888-1891
[8]   NONEXPONENTIAL RELAXATION IN DENSE MICROEMULSIONS [J].
CHEN, SH ;
ROUCH, J ;
TARTAGLIA, P .
JOURNAL OF NON-CRYSTALLINE SOLIDS, 1991, 131 :275-281
[9]  
CHEN SH, 1987, PHYSICS COMPLEX SUPE, P285
[10]   MICRO-EMULSIONS AND THE FLEXIBILITY OF OIL-WATER INTERFACES [J].
DEGENNES, PG ;
TAUPIN, C .
JOURNAL OF PHYSICAL CHEMISTRY, 1982, 86 (13) :2294-2304