This means that for all values of 0 < χ χ ≲ ≲ 1 / 2 the monomer-solvent effective interaction is weakly repulsive, but this is too weak to cause liquid/liquid separation. However, when χ χ > 1 / 2 , there is separation into two coexisting phases, one richer in polymer but poorer in solvent, than the other.