Dynamic desorption of macromolecules from solid surfaces by low-molecular-weight displacers

A novel dynamic approach to polymer desorption study has been tested. The a dsorbent under study was packed into an HPLC-like adsorption-desorption col umn (ADC). Constant amount of polymer was dynamically preadsorbed within th e ADC from an adsorption promoting liquid (adsorli) and desorbed subsequent ly by changing composition of a displacer consisting of an adsorli and a de sorption promoting liquid (desorli). Polymer in the ADC effluent was detect ed with help of an evaporative light scattering detector using an appropria te calibration for each system. Dynamic integral desorption isotherms were obtained by plotting desorbed amount of polymer versus displacer compositio n. Both the attachment and detachment of polymer onto/from nonporous silica adsorbent surface were found to be very fast as far as the adsorbent surfa ce was undersaturated. The courses of desorption isotherms were measured an d compared for various systems, viz. polymer nature, polymer molar mass and molar mass distribution as well as adsorli and desorli nature. The effects of experimental conditions such as flow rate, temperature, amount of pread sorbed polymer and ADC size on the shapes of desorption isotherms were eval uated, as well. All above parameters influence the courses of desorption is otherms and it is shown that the described measurements can give valuable i nformation on the desorption processes in the dynamic systems. The describe d dynamic desorption measurements are fast and the results obtained are rep eatable. Moreover, both the sample and the sorbent consumption are low. (C) 2000 Elsevier Science B.V. All rights reserved.