mer molecules that are chemically bonded by their end This paper reports on the use of a polyoxyethylene alkylphenol groups onto colloidal particles in aqueous suspensions. Sevsurfactant to desorb adsorbed poly(ethylene oxide) from the sureral methods are available for grafting of relatively low mofaces of colloidal polystyrene particles in aqueous media. Adsorplecular weight polymers onto colloidal particles (2). In the tion and desorption were quantified by measurement of polymer absence of physical adsorption, grafting efficiency decreases solution concentrations before and after surfactant treatment. To with increasing polymer molecular weight, perhaps because do this, two calibration surfaces were developed and verified so the coiled configuration of the polymer molecule in solution that the solution concentrations of polymer and surfactant could effectively screens any interaction between the end groups be quantified simultaneously. Adsorption isotherms and data from and the surface-reactive sites. On the other hand, many high attempts to adsorb polymer onto particles with preadsorbed surfactant suggest that the surfactant should be able to desorb the molecular weight polymers spontaneously adsorb from solupolymer. However, desorption experiments in which the surfactant tion onto colloidal particles. Adsorption may be a prerequiattacks preadsorbed polymer layers show that significant desorpsite for end-grafting of high molecular weight polymers.
tion occurs only under certain conditions. The effects of starting
In order to test this hypothesis and assess the efficacy of polymer solution concentration, polymer molecular weight, surfacproposed grafting schemes, we must be able to quantify the tant concentration, and time on desorption behavior are illusrelative amounts of adsorbed and grafted polymer. One way trated. Information on polymer configurations can be inferred to do this is to use a displacer which, by definition, preferenfrom hydrodynamic layer thicknesses obtained through dynamic tially adsorbs with concurrent desorption of nongrafted mollight scattering. A simple physical picture involving the competiecules. Surfactants and other small molecules have been tion of polymer and surfactant for adsorption sites can rationalize used to displace polymers from various surfaces, but most all of the observations. ᭧ 1998 Academic Press previous experiments (3-7) were performed in organic sol-