Rheology of associative telechelic polymer - latex suspension

We report a computational study on the rheology of latex suspension, where the interparticle interactions are mediated by associative polymers such as hydrophobically-modified ethylene oxide urethane. The polymer is modelled as a FENE dumbbell and the particle as WCA repulsive spheres. Suspension viscosity and normal stress differences are measured from non-equilibrium Brownian dynamics simulation by imposing shear. The microstructure is controlled by polymer dynamics such as bridging (a polymer attaching to two different particles at either ends), looping (both ends of a polymer attaching to the same particle), and dangling (one end of a polymer is attached to a particle while the other end is free). All these polymer dynamics are affected by shear, modifying the microstructure and hence the viscosity. The polymer-latex system shows shear thinning behavior over a range of shear rates, interspaced between two Newtonian regions. The first normal stress difference is found to be positive. Rheology of the suspension is studied for various polymer-latex attractive strengths, a key parameter varied in experiments. By treating polymer and particle degrees of freedom explicitly, we elucidate the dynamics covering a wide range of length and time scales, and their effects on rheology.