The shear viscosity η of the PEG-water mixtures was evaluated using a non-equilibrium method . In short, a static, cosinusoidal acceleration A cos(2πz/L z ) was applied along the x-direction, where A = 0.03 nm/ps 2 (A = 0.1 nm/ps 2 for G-CG) is the amplitude and L z is the box height. The viscosity was then calculated from the generated velocity profile, see Ref. for details. For the AA simulations, the GROMACS implementation was used , and for the G-CG simulations, a homemade implementation on the Python level in ESPResSo was used.