Adsorption Studies of Poly(N-vinylcarbazole) on Sapphire by a Fiber-Optic UV-Attenuated Total Reflection Technique

摘要

The adsorption of polydisperse poly(N-vinylcarbazole) on the surface of alpha-Al2O3 (sapphire) was studied from four solution concentrations in toluene at the temperature (37 deg C). The technique of attenuated total reflection (ATR) using the evanescent wave was employed in the ultraviolet (UV) region by designing an optical setup based on a specially designed ATR crystal and a fiber-optic UV spectrometer. The adsorption kinetics occurred over a period of 10 h. The concentration profiles of the adsorbed layers in contact with solution were examined by performing angle-resolved experiments, which probe about a thousand-angstrom range. An exponential concentration profile was used to extract characteristic adsorption parameters. The adsorbed amount was found to be in the range of 1.4-1.8 mg/c(2). The adsorption isotherm was rounded and seemed to level off at the highest solution concentration. The root-mean-square thickness was found to be in the range of 300-400 Angstroms, which is less than 2 times the radius of gyration at the 0 condition. On the other hand, the mean thickness values of the adsorbed layer were comparable to the radius of gyration. Adsorption of polymer, Sapphire surface, Fiber-optic UV-VIS, Spectrometry concentration profile, Adsorbed amount and thickness.