Four different pH- and electrolyte-responsive polymers were synthesized from ethyl piperazine with four different Counter ions viz., chloride, bromide, sulfate, and nitrate. IR and NMR spectroscopic techniques confirmed the structure of monomers and polymers. Thermal properties of these polymers were investigated by TGA and DSC analysis. The dilute solution properties in pure water, in inorganic simple salt solutions, and pH-responsive behavior of these polymers were studied by the measurement of viscosity by Ubbelohde viscometer. Flocculation behavior of these polymers was investigated by turbidity studies with bentonite suspension. (c) 2006 Wiley Periodicals, Inc.