Polyelectrolyte behavior of three copolymers of 2-acrylamido-2-methyl-propanesulfonic acid and N-acryloyl-N′-methylpiperazine studied by ultrafiltration

The behavior of polyelectrolytes and chelating polymers in ultrafiltration experiments is analyzed in order to establish whether these two kinds of polymers can be differentiated by this technique. Three copolymers of 2-acrylamido-2-methyl-propanesulfonic acid and N-acryloyl-N′-methylpiperazine, and their corresponding homopolymers, are studied analyzing qualitatively their interaction patterns with divalent metal ions such as Cu2+, Cd2+, Co2+, Ni2+, Pb2+, and Zn2+. Although all copolymers have sulfonate charged groups on their structure, only the one that have them in excess over the piperazine groups has a polyelectrolyte behavior, suggesting the existence of interactions between the sulfonate groups and the amino groups by charge transfer forces or hydrogen-bonded forces.