Relationships between solution parameters including concentration of polyeletrolyte and potassium bromide (KBr)

pH value of solution and the aggregation behavior for the micelles formed by the amphiphilic diblock polyeletrolyte

poly(styrene-b-acrylate acid) (PS-b-PAA) were studied.The effect of the micellar aggregation behavior on the rheological properties of the micellar latex was examined.Results revealed that increasing the copolymer concentration and salt concentration led to formation of greater irregular structure in polyelectrolyte micelles due to the aggregation of them

while the effect of pH value can be negligible due to the higher composition of PS block in the copolymer composed of a long hydrophobic block (PS) and a comparable short amphiphilic block (PAA).The aggregation structures were characterized through dynamic light scattering (DLS)

transmission electron microscopy (TEM)

and rheological properties of the micellar latex were tested using the stress-control rheometer AR-G2.All of the micellar latex exhibit shear thinning behavior

while the apparent viscosity increases with increasing copolymer concentration at lower shear rates

and approaches a constant value (0.01 Pa#8226;s) of ten times of magnitude greater than that of water.Furthermore

the presence of potassium bromide remarkably increases the latex viscosity

comparable with that without added salt

and newtonian plateaus at lower shear rates appeared when the salt concentration reached 4.31 g/L.It is suggested this phenomenon is resulted from the effect of corona expansion involving in the chargesshielding by the added ions.The obvious effect of pH value on the latex viscosity could hardly be observed due to the comparable short amhpihpilic block.