Uptake and release of surfactants from polyampholyte microgel particles

Polyampholyte microgel particles, containing both methacrylic acid and 2-(dimethylamino) ethyl methacrylate (a weak base), in a mainly N-isopropyl acrylamide network, have been prepared by free-radical dispersion polymerisation. The swelling properties of the particles have been shown to be pH and temperature dependent and to exhibit a minimum in size at the iso-electric point. The uptake and release of cetylpyridinium chloride and Triton X-100, into and from, the polyampholyte microgel particles have been investigated as a function of pH. The absorbed amounts at different pH values have been related to various specific interactions between the surfactant and the microgel network.