Oscillatory shear rheology of dilute solutions of flexible polymers interacting with oppositely charged particles



Fluids with both attractions and repulsions among its constituents can exist in multiple states depending on nature of the interactions. An external flow can induce such systems to transition between the different states, such as the globule-stretch transition for polymers in poor solvents. Brownian dynamics simulations of a dilute solution of polymers and colloids interacting via short-ranged potentials are presented. For some values of the strength and range of interactions, compact structures of polymers and colloids are formed. An external flow is capable of pulling these globules apart, causing the polymers to stretch at a critical shear rate. In oscillatory shear, the shear rate can cycle between being above and below this critical shear rate leading to interesting dynamics. These dynamics are quantified using the rheological response in large amplitude oscillatory shear. © 2014 American Institute of Chemical Engineers AIChE J, 60: 1365–1371, 2014