Molecular characterization of block copolymers by means of liquid chromatography I. Potential and limitations of full adsorption-desorption procedurein separation of block copolymers

The full adsorption-desorption (FAD) procedure was applied to the selected model di- and tri-block copolymers, The dynamic integral desorption isother ms were measured for various homo- and block-copolymers of poly(methyl meth acrylate) and poly(glycidyl methacrylate) in a system of non-porous silica- dichloroethane adsorlitetrahydrofuran desorli, The aim was to evaluate sepa ration selectivity of the FAD approach toward molar mass and chemical compo sition of macromolecules. It was demonstrated that under optimum conditions the FAD procedure can discriminate parent homopolymers from di-block copol ymers, as well as di-block from tri-block copolymers when the adsorptivitie s of blocks differ sufficiently. The molar mass of both kinds of polymer ch ains affected the course of their desorption in present system of adsorbent -adsorli/desorli. Consequently the block copolymers studied could not be ef fectively fractionated according to their composition by a single FAD proce dure. A combined method, full adsorption-desorption plus size exclusion chr omatography was proposed for the species with selectively adsorbing blocks to provide a two dimensional fractionation of block copolymers, (C) 2000 El sevier Science Ltd. All rights reserved.