ADSORPTION OF ETHYL(HYDROXYETHYL)CELLULOSE AT POLYSTYRENE

The temperature-dependent adsorption of ethyl(hydroxyethyl)cellulose (EHEC) at polystyrene has been studied. By means of ellipsometry it was found that EHEC adsorbs rather sparsely at this substrate (GAMMA almost-equal-to 1 mg/m2 at 20-degrees-C), forming adsorbed layers with a mean thickness (delta(e)) of about 32-35 nm. However, the adsorbed layer contains a fraction of highly extended and dilute tails, as evidenced by the high hydrodynamic thickness (delta(h) almost-equal-to 110 nm at 20-degrees-C). With an increase in the temperature, the adsorbed amount increases, whereas the adsorbed layer contracts. The adsorbed amount at hydrophobized silica is much higher than that at polystyrene, while the adsorbed layer thickness is similar in the two cases. Furthermore, similar trends were observed on increasing the temperature. Finally, the polystyrene dispersion was stable even at temperatures well above the cloud point. Comparison is made with previously obtained data on the interfacial behavior of EHEC.