s of the general types AN X and B, which are connected by methylene groups, said units AN X being derived from com pounds of the general formula (R R ),,R N X wherein X is the anion of an aliphatic monosulfonic acid with one to six carbon atoms, p is an integer from 1 to 3, R, is a carbocyclic or heterocyclic aromatic group, having at least one condensable position, R is an arylene group of the be