ISSN:
1572-9567
Keywords:
anisotropy
;
Couette flow
;
living polymers
;
polydispersity
;
rods
;
shear alignment
;
small-angle neutron scattering
;
worm-like micelles
Source:
Springer Online Journal Archives 1860-2000
Topics:
Physics
Notes:
Abstract The structure of a cationic worm-like cylindrical micelle was investigated by SANS (small-angle neutron scattering). Intensities from 0.1% by weight solutions in D2O, at rest and under shear, were measured on the NIST Cold Neutron Research facility 30-m spectrometer in the wave vector range 0.03⩽Q (nm1)⩽-2.0. Scattered intensity patterns from the solutions subjected to shears equal to or greater than 40s1 showed pronounced anisotropy, but such anisotropy could not be detected below this apparent threshold shear. The threshold was characterized by a relaxation time since anisotropy was detected only after several minutes of shearing. In contrast, the anisotropy was apparent immediately the shear was applied at the higher shears. The data were analyzed based on the assumption that the micelles behave as rigid rods. Estimates of the radii and length under shear are given. Polydispersity in rod length is discussed, and we argue that it contributes significantly to the scattering patterns.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF01458825
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