TY - JOUR
T1 - Electrophoretic microrheology of a dilute lamellar phase
T2 - Relaxation mechanisms in frequency-dependent mobility of nanometer-sized particles between soft membranes
AU - Mizuno, Daisuke
AU - Kimura, Yasuyuki
AU - Hayakawa, Reinosuke
N1 - Funding Information:
This work is supported by a Grant-in-Aid for Scientific Research from the Japan Society for the Promotion of Science and from Ministry of Education, Culture, Sports, Science and Technology of Japan. D.M. is also supported by a grant from the Research Fellowship of Japan Society for the Promotion of Science. The authors thank T. Nishino for his technical assistance. They also thank Professor K. Ito and Dr. H. Furusawa of the University of Tokyo for kindly giving them a chance to access their fluorescent microscope in this study.
PY - 2004
Y1 - 2004
N2 - Viscoelastic properties of complex fluids in the microscopic scale can be studied by measuring the transport properties of small, embedded probe particles. We have measured the complex electrophoretic mobility [Formula presented] of nanometer-sized particles dispersed in a lyotropic lamellar phase, which shows two relaxation processes at approximately [Formula presented] (high frequency relaxation, HF) and [Formula presented] (low frequency relaxation, LF). It is shown quantitatively that these processes are caused by the trapping of particles within two local structures of characteristic size in the lamellar phase: the interbilayer distance and the persistence length. The origin of observed relaxations is further investigated and augmented in this study with data obtained by two other complementary methods, dielectric spectroscopy and the direct observation of fluorescently labelled probe particles under an optical microscope. It is shown that the local distortion field of the lamellar phase is induced by the extra steric interaction involving the collision of a colloidal particle with the membrane. The resulting distortion field hinders the Brownian motion of colloidal particles parallel to the membranes (not vertical), and causes the observed HF relaxation. On the other hand, the origin of LF relaxation is presumably a result of the defects in the lamellar structure. Since the results of this study show that the transport property is strongly influenced by microscopic environments, this method is referred to as electrophoretic microrheology.
AB - Viscoelastic properties of complex fluids in the microscopic scale can be studied by measuring the transport properties of small, embedded probe particles. We have measured the complex electrophoretic mobility [Formula presented] of nanometer-sized particles dispersed in a lyotropic lamellar phase, which shows two relaxation processes at approximately [Formula presented] (high frequency relaxation, HF) and [Formula presented] (low frequency relaxation, LF). It is shown quantitatively that these processes are caused by the trapping of particles within two local structures of characteristic size in the lamellar phase: the interbilayer distance and the persistence length. The origin of observed relaxations is further investigated and augmented in this study with data obtained by two other complementary methods, dielectric spectroscopy and the direct observation of fluorescently labelled probe particles under an optical microscope. It is shown that the local distortion field of the lamellar phase is induced by the extra steric interaction involving the collision of a colloidal particle with the membrane. The resulting distortion field hinders the Brownian motion of colloidal particles parallel to the membranes (not vertical), and causes the observed HF relaxation. On the other hand, the origin of LF relaxation is presumably a result of the defects in the lamellar structure. Since the results of this study show that the transport property is strongly influenced by microscopic environments, this method is referred to as electrophoretic microrheology.
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U2 - 10.1103/PhysRevE.70.011509
DO - 10.1103/PhysRevE.70.011509
M3 - Article
C2 - 15324058
AN - SCOPUS:42749102783
VL - 70
SP - 17
JO - Physical Review E
JF - Physical Review E
SN - 2470-0045
IS - 1
ER -