Effects of particle softness on shear thickening of microgel suspensions
writer：Zhi Zhou; Javoris Hollingsworth; Song Hong; Guangmin Wei; He Cheng; Charles C. Han
keywords：shear thickening, softness parameter
source：期刊
specific source：Soft Matter, accepted
Issue time：2014年
A
series of microgel particles composed of a polystyrene (PS) core and thermo-sensitive
poly (N-isopropylacrylamide) (PNIPAM) shell with different shell thicknesses were
investigated to elucidate the effect of microgel softness on its shear
thickening behavior. Since the softness of the microgels increases with decreasing
temperature through the volume phase transition effect of PNIPAM shell, the measured
softness parameter, n, which is
derived from the Zwanzig-Mountain equation, was used to measure and describe
the combined influences of temperature and shell thickness. Confocal microscopy
is used to investigate the interaction potential between microgel particles
with different softness parameter. According to our results, the softness
parameter is able to estimate the shear thickening behavior of microgel
suspensions at least semi-quantitatively.