The invention relates to a method for increasing the compatibility between at least two polymers, which comprises: (a) selecting at least two immiscible polymers (A) and (B), at least one of which does not bear a nitrogenous heterocycle-based associative group, and (b) modifying the polymer (A) and/or the polymer (B) so as to obtain a blend of polymers (Pi) which are derived from the polymers (A) and (B) and which each bear nitrogenous heterocycle-based associative groups, said associative groups being present in sufficient amount for the polymers (Pi) to be more compatible with one another than the polymers (A) and (B). It also relates to the polymer composition that can be obtained according to this method.