Coil to globule collapse transitions of polymers: The effect of adsorbed surfactants

Recent experimental studies of the coil-to-globule transition of polymer ch ains in the presence of adsorbing anionic surfactants have shown a variety of novel transition curves. In this paper we theoretically model this syste m using a modified mean-field model. We show that as the surfactant concent ration is increased, the transition becomes a strong first-order transition and occurs in the worse than theta regime. This is due to the adsorbed sur factants abruptly moving off the chain. We also implement a nonconstant den sity model in an attempt; to understand the gradual collapse of these chain s before the first-order transition.