The simulations were carried out according to the following protocol: after an energy minimisation, two successive equilibration steps were performed, respectively, a NVT step of 5 ps with a timestep of 0.1 fs, a first NPT step of 1 ns with imposed pressure of 1000 bar and timestep of 1 fs, and a second NPT step of 1 ns with imposed pressure of 1 bar and timestep of 1 fs. Then, production runs of total duration t tot were performed in the NPT ensemble with a timestep of 1 fs. Trajectories were recorded with a dumping period ∆t. For the systems with the lowest viscosity, corresponding to the lowest PEG concentration, c PEG < 1, t tot was chosen equal to 50 ns, and ∆t was chosen equal to 0.2 ps. For the systems with the highest viscosity, c PEG ≥ 1, t tot was chosen equal to 500 ns, and ∆t was chosen equal to 2 ps. We ensured that the dumping period ∆t had no significant impact on the result by performing convergence tests (Fig. ). For the lowest PEG concentrations c PEG = 0.01 and 0.03, up to six independent production runs were performed in order to improve the statistics.