For the bonded interactions, a simple harmonic potential U B ij = 1 2 k b (r -r 0 ) 2 is used between connected DPD beads, with r 0 equal to 0.29 and 0.39 for CH 3 -CH 2 CH 2 and CH 2 CH 2 -CH 2 CH 2 respectively, and a single bond constant k b = 150 (DPD units) adopted throughout. To stiffen the molecules we introduce bond rigidity by including a harmonic angular potential between pairs of bonds. We adopt the three-body angular potential used by Smit and collaborators,