To confirm that the scaled solvent parameters were reasonable representations of the behaviour of P(NDI2OD-T2) in a better and a poorer solvent than DCB, we calculated the free energy as a function of backbone centre-of-mass separation in AA systems of two P(NDI2OD-T2) monomers in DCB, 1-chloronaphthalene (a better solvent than DCB), and toluene (a poorer solvent than DCB, and one of those shown to promote extended rod-like structures experimentally ). This free energy was compared with the equivalent free energy calculated for CG monomers with the poor, intermediate, and "good" solvent parameters. Free energies were calculated using on-the-fly probability enhanced sampling (OPES), which, similarly to metadynamics, facilitates the exploration of the probability distribution of interest (here that of the centre-of-mass separation) by depositing small repulsive Gaussians (kernels) in collective-variable space over the course of the simulation in order to bias the system against exploring regions it has already visited. Further details on the method are given in the ESI, Section S4.1. These calculations were carried out using the PLUMED software package, version 2.5.4. Comparing the final free energy curves as a function of centre-of-mass separation showed good agreement between the "good" solvent parameters and 1-chloronaphthalene, the as-parameterised DCB model and its AA equivalent, and the poor solvent parameters and toluene (ESI Fig. ). This finding confirms that the poor solvent conditions used here should be a reasonable representation of the conditions that have been experimentally been shown to give extended rod-like aggregates.