  The viscosity enhancement of a solvent produced by the addition of thickening
branched polymers is predicted as a function of polymer concentration, branch
length and persistence length, and strength of the covalent bonding
interactions. Non equilibrium, stationary state Poiseuille numerical
simulations are performed using the dissipative particle dynamics model to
obtain the viscosity of the fluid. It is found that the clustering of the
polymers into aggregates raises the viscosity and that it is more strongly
affected by the strength of the bonding interactions. General scaling
relationships are found for the viscosity as a function of the variables
studied, which are expected to be useful for the design and synthesis of new
viscosifying polymers. It is argued that our results can be applied to aqueous
thickeners, of importance for colloidal fluids such as paints and coatings, and
also for nonpolar fluids such as supercritical CO2, which is a promising non
hydraulic fracking fluid also useful in enhanced oil recovery.
