Online Rheological Investigation on Ion-Induced Micelle Transition for Amphiphilic Polystyrene-block-Poly(acrylic acid) Diblock Copolymer in Dilute Solution
writer：Yuping Sheng, Nan Yan, Yutian Zhu,* and Wei Jiang*
keywords：rheology, self-assembly
source：期刊
specific source：Langmuir
Issue time：2014年
The ion-induced micellar transition is online-investigated by the
time dependence of the viscosity of the solution under shear flow for the first
time. During the morphological transition, the change in the micellar structure
can be tracked by the change in viscosity. Adding HCl or CaCl2 into preprepared
spherical micelle solution from the self-assembly of polystyrene-blockpoly(
acrylic acid) (PS144-b-PAA22) in the N,N-dimethylformamide (DMF)/
water mixture, the micellar structures change into short cylinders, long,
entangled cylinders, and then lamellae or vesicles, corresponding to the
viscosity increasing first and then declining. When HCl or CaCl2 is added to
the pre-prepared spherical micelle solution formed by PS144-b-PAA50 in the
dioxane/water mixture, the micellar structures are quickly transformed into
cylinders or lamellae before carrying out the rheological measurement and then
are turned to vesicles or spheres under the shearing, corresponding to a gradual
decline in viscosity. This study shows that the rheology can be a very simple
and effective online method on the investigation of the micellization, which plays an important role in understanding the
micellization mechanism and micellar transition pathway of block copolymers in dilute solution.