onic polymers with at least one structural unit as per formula (I), those polymers are preferred as per the invention, which satisfies at least one of the following conditions: R.sub.1 is a methyl groupR.sub.2, R.sub.3 and R.sub.4 are methyl groups m has the value 2.Possible physiologically compatible counterions X.sup.- as per the formula (I), are for example the halogenide ions, sulphate ions, p