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Microrheology of chemically crosslinked polymer gels by diffusing‐wave spectroscopy
Author(s) -
Narita Tetsuharu,
Knaebel Alexandra,
Munch JeanPierre,
Zrínyi Miklós,
Candau Sauveur Jean
Publication year - 2004
Publication title -
macromolecular symposia
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.257
H-Index - 76
eISSN - 1521-3900
pISSN - 1022-1360
DOI - 10.1002/masy.200450302
Subject(s) - microrheology , materials science , rheometry , polymer , vinyl alcohol , dynamic light scattering , self healing hydrogels , viscosity , viscoelasticity , brownian motion , particle (ecology) , relaxation (psychology) , composite material , polymer chemistry , nanotechnology , nanoparticle , oceanography , physics , quantum mechanics , geology , psychology , social psychology
Abstract The Brownian motion of probe particles in aqueous solutions of poly(vinyl alcohol)(PVA) and in chemically crosslinked PVA gels has been studied by diffusing‐wave spectroscopy (DWS). At long time scales the measurements allow us to determine the effect of the crosslinking ratio on the macroscopic viscosity of sols and the shear modulus of gels. The local shear modulus of gels as obtained from the characteristic length of the Brownian cage was found to agree with that measured by classical rheometry and dynamic light scattering (DLS). These microrheological techniques were applied to two polymer gel systems. Substrate induced gradient structure of hydrogels was studied from a microrheological point of view using DLS. It is clearly seen that hydrophobic substrate induces weakly crosslinked network formation at the interface region up to a few millimeters as expected from other experimental facts. Magnetic particle motion in gels under external magnetic field was investigated by DWS. The translational motion of the magnetic particles in gels due to the alternating magnetic force can be detected and found to be superimposed on the relaxation due to the thermal motion.