The effect of polymer on the cloud point of a series of triblock nonionic surfactants in aqueous solution

A series of triblock nonionic surfactants with different Propylene oxide an d ethylene oxide chain: lengths were synthesized. The triblock nonionic sur factants and poly(ethylene glycols) with different molecular weight were us ed, to find the effects of polymer chain length and size of the micelles on the cloud point of the surfactants. Two possible models are considered on the basis of cloud point changes of the solutions, to describe the polymer- surfactant interactions. One model suggests that flocculation depletion fo r the polymer chains exist between two regular micelles. This provides the driving force for the neighboring micelles to approach each other and desta bilize the colloidal system. The flocculation effect is more important for polymers with a shorter chain block the approach of the micelles, since the re is no typical polymer-surfactant association formed but just simple smal l molecule associations in which the steric and solvation effects of the po lymer chains make the inter-micelles interactions repulsive. The other mode l considers that intra-chain micelles of polysoap are formed among the surf actant monomers and long polymer chains. The bridging attraction between tw o intra-chain micelles in such structures can enhance the collisions among the micelles, due to the exchange of amphiphilic monomers among the neighbo ring micelles.