The repetitive N-alkylation reaction, at first used by Marvel, turned
out to be a very versatile method for the synthesis of polycations. Re
mbaum introduced the name ''ionenes'' for this type of polymers. In th
e first part of the lecture some examples of single-stranded ionenes a
re described. The second part shows how the repetitive N-alkylation ca
n be used for the synthesis of spiro polymers. In these double-strande
d polymers two spiro-conjugated rings of the main chain have a central
quaternary nitrogen in common (spiro-ionenes or spiro-azonia polymers
). Starting from tetrabromides (for instance 1,2,4,5 tetrabromomethylb
enzene) and different cyclic diamines soluble polymers (with more or l
ess stretched shape) with the typical properties of polyelectrolytes a
re obtained.