4-(Iminomethyl)phenol and 4-(iminomethyl)benzoic acid terminated aliphatic polyethers were obtained by conversion of Jeffamines with respective aromatic aldehydes. Mixtures of these polymers with polyamidines showed improved compatibility or even complete miscibility because of ionic complexes formed between the end groups of the modified polyethers and the basic amidine groups. Depending on composition and molecular weight of the components, blends with two or one glass transitions were obtained. In the case of 4-(iminomethyl)phenol terminated polyethers, deprotonation of the end groups resulted in a distinct change of the UV/vis absorption spectrum. This spectral alteration is discussed with respect to quantification of interactions in polymer blends.