Dynamic light scattering, small-angle neutron scattering, and binding isotherm measurements have been performed on an aqueous poly(N-isopropylacrylamide) microgel particle in the presence of the surfactant sodium dodecyl sulfate (SDS). In the presence of the microgel, at concentrations just above the normal cmc the surfactant existed as small, polymer-bound aggregates of less than five monomer units rather than larger micelles. This is in stark contrast to other homopolymer/surfactant systems such as SDS/poly(ethylene oxide) where the polymer-bound micelles have structures similar to those of free micelles obtained without polymers. Both dynamic light scattering and small-angle neutron scattering measurements showed that the microgel swells in the presence of surfactant. Two surfactant concentrations (1% w/w and 0.3% w/w) were used for the neutron scattering experiments, and through selective deuteration of the solvent, the different components, either the poly(N-isopropylacrylamide) gel or the SDS, were rendered ‘invisible' to the neutrons.

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Dynamic light scattering and small-angle neutron scattering measurements have been performed on aqueous polystyrene latex dispersions with physisorbed polymer, poly(ethylene oxide), in the presence of the surfactant sodium dodecyl sulfate (SDS). Dynamic light scattering measurements suggested that the polymer layer is partially desorbed at surfactant concentrations close to the critical micelle concentration. At surfactant concentrations above the normal critical micelle concentration, the hydrodynamic thickness increased close to the value in the absence of surfactant. Small-angle neutron scattering measurements suggested that as the normal critical micelle concentration of the surfactant was approached, very thin layers were formed. It was possible to obtain the volume fraction profiles of the adsorbed polymer layer, along with information on the structure of the surfactant micelles. Two types of SDS structures were observed, one corresponding to SDS existing bound to bulk polymer and the other to SDS bound to adsorbed polymer.

1H NMR solvent relaxation has been used to probe the effect of SDS on the adsorption of poly(ethylene oxide) at the silica−water interface. In the absence of SDS an enhancement in the water relaxation rate resulting from the adsorption of PEO was observed while for PEO in the absence of particles only a negligible enhancement was observed. However, upon addition of SDS to the PEO/silica system a sequential reduction in the relaxation rate with increasing SDS was found. The results are discussed in terms of the levels of adsorbed polymer and its conformation at the interface.