Agreement between the behaviour of a real macromolecule and a gaussian chain during adsorption in pores

Abstract

Results of “machine experiments” with model lattice chains in slitted pores were compared with those of chromatographic experiments of the adsorption of PS by large pore silica gel. It was found possible to use the Gaussian chain in a slitted pore for the qualitative description of relations of polymer adsorption by porous adsorbents. The agreement between real and model chains suggests that phase transition of the first type predicted theoretically during the adsorption of macromolecules by porous adsorbents does, in fact, take place. The critical energy corresponding to the transition point is independent of the molecular weight of the polymer chain and the dimensions of adsorbent pores. With this energy of interaction the mechanism of chromatographic separation varies from the molecule sieve to the adsorption type. It is proposed to use the linear relation between the chromotographically measured variation of free energy of the chain −†F (or the logarithm of the distribution coefficient K d ) and the M D 2 ratio or the <R 2> D 2 ratio ( M, < R 2> being the molecular weight and the mean square radius of inertia of the macromolecular chain; D, average pore size of the adsorbent) for calibration in chromatographic analysis of polymers.