|Title||Size exclusion chromatography does not require pores|
|Publication Type||Journal Article|
|Year of Publication||2000|
|Authors||Brooks, DE, Haynes, CA, Hritcu, D, Steels, BM, Muller, W|
|Journal||Proceedings of the National Academy of Sciences of the United States of America|
|Type of Article||Article|
Separation of macromolecules on the basis of their molecular weight by size exclusion chromatography has long been considered to be caused by the geometry-dependent partition of macromolecules between a continuous phase and the porous interior of a gel or cross-linked bead. The volume of a pore accessible to a solute is limited by its relative dimensions, so larger molecules will have access to a smaller volume and will remain in a bead for a shorter time than smaller solutes. Our recent alternate picture proposes that the partition coefficient can be calculated from a thermodynamic model for the free energy of mixing of the solute with the gel phase. Size-dependent exclusion caused by the unfavorable entropy of mixing associated with the partition is predicted; the magnitude of the effect is modified by enthalpic: interactions between the solute and the gel phase. This concept is extended here to describe the partition of macromolecules into a layer of terminally attached polymer chains grafted onto a solid bead. Both simple mean field and self-consistent field theory calculations predict size-dependent entropic exclusion, Experimental results obtained with neutral polymer chains grafted onto solid polystyrene latex beads confirm the predictions.
|URL||<Go to ISI>://000087811600027|