INFLUENCE OF POLYMER ARCHITECTURE AND POLYMER-SURFACE INTERACTION ON THE ELUTION CHROMATOGRAPHY OF MACROMOLECULES THROUGH A MICROPOROUS MEDIA

The elution chromatography of flexible polymer molecules flowing throu gh a microporous particle media is described by a combination of the C asassa model of flow segregation and the Di Marzio-Rubin lattice metho d for calculating the partition function of confined polymers. This co mbination of models allows for the treatment of polymer-surface intera ctions so that polymer chromatography in the exclusion and adsorption regimes can be described within a unified framework. The compensation point where repulsive polymer-surface excluded volume forces and short -range polymer surface attractive forces counterbalance each other off ers opportunities for separating complex molecules. For example, calcu lations for a diblock copolymer where one of the components is at the compensation point (''adsorption Theta point'') indicate that only the remaining block influences the elution of the block copolymer as a wh ole. This theoretical result accords with experiments on block copolym ers. This singular observation provides support for the Casassa viewpo int of molecular partitioning dominated polymer elution. The chromatog raphy of triblock copolymers, stars, and combs is also examined to det ermine the selectivity of elution chromatography for separating these molecular architectures. The theoretical development in the present pa per should lead to improved methods for the characterization of polyme rs with different molecular architectures. These developments also sug gest new tools for studying polymer adsorption from dilute solution.