KCS

Liquid chromatography (LC) has been used widely for the characterization of natural and synthetic macromolecules that are often heterogeneous in molecular weight, molecular architecture as well as in chemical composition. Among numerous variations of LC techniques, size exclusion chromatography (SEC) has been the most popular method for the analysis of the molecular weight distribution of synthetic polymers. SEC separates the polymer molecules in terms of the size of a single polymer molecule in the elution solvent. Therefore SEC is often inefficient in the separation of copolymers, polymer mixtures, branched polymers, polymers with different stereoregularity or end-group difference, and so on. Furthermore, the resolution of SEC is limited due to the band-broadening problem. In contrast to SEC, interaction chromatography (IC) utilizes mainly the enthalpic interaction, adsorption or partition of solute molecules to the stationary phase, thus IC can be more efficient for the applications in which SEC does not work well. In this presentation, IC methods for the characterization of polymers will be discussed with an emphasis on the temperature gradient interaction chromatography (TGIC) that was developed in our laboratory. In TGIC the column temperature is varied during the elution in a pre-programmed manner to control the solute retention. Successful applications include; 1.Precise characterization of the molecular weight distribution of the polymers made by anionic polymerization. 2.High-resolution separation of branched polymers, ring polymers, polymer mixtures, block copolymers, end-functional polymers, and stereoregular polymers.