Adsorption of polymers and surfactants from solution onto the solid-liquid interface.

Experimental studies of the adsorption of polymers and surfactants onto the solid-liquid interface have been conducted. The goal is to investigate the kinetics of adsorption and identify the type of interaction between the adsorbate and the adsorbing surface. The results of this study can be applied in the processes involved in mineral flotation, adhesion, microelectronic packaging, device interconnections applications and enhanced oil recovery. The polymer system studied is polystyrene/carbon-tetrachloride/germanium, and the surfactants are sodium dodecyl sulfate and sodium laurate in aqueous solutions adsorbing onto an alumina surface. The systems were monitored using Fourier transform infrared attenuated total reflection spectroscopy (FTIR-ATR), a powerful method for the investigation of thin films and interfacial effects. The adsorption of polystyrene of relatively high molecular weights has shown a strong dependence on the bulk solution concentration and the molecular weight of the adsorbing polymer. The rate limiting step for the adsorption process has been determined to be the entry of new macromolecular chains in the immediately formed and highly constrained polymer layer. A theoretical model based on the scaling concepts, first introduced by deGennes is proposed and its predictions compare favorably with the experimental data. The data also suggest the presence of a highly constrained layer (glassy-like), with a structure that depends highly on the parameters of the system. For the adsorption of sodium laurate onto alumina we have identified the type of interaction between the solid and the laurate. We have also identified two adsorbed phases, one irreversibly and one reversibly adsorbed onto the surface. For the adsorption from binary mixtures of sodium dodecyl sulfate and sodium laurate, we have observed competitive adsorption, and displacement of one surfactant by the other. These results have been explained using the same principles found in micellization of mixtures of surfactants. Finally, additional problems and extensions are being suggested.PhDChemical EngineeringUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/103063/1/9303724.pdfDescription of 9303724.pdf : Restricted to UM users only