MOLECULAR PROBING OF POLYMERIC MICROSTRUCTURE AND NONRANDOM PARTITIONING OF SOLVENTS ABSORBED IN POLYMERS BY INVERSE GAS-CHROMATOGRAPHY

The microscopic structure of amorphous polymers was studied by using d ifferent molecular probes in finite dilution inverse gas chromatograph y (FDIGC) experiments. This molecular probe technique allows one to st udy nonrandom partitioning of solvent molecules and spatial correlatio n of polymer chain segments in a bulk. A novel approach was developed to determine cluster integrals as defined in the Kirkwood-Buff theory of mixtures. Solvent self-cluster integrals, a combination of cluster integrals expressing preferential solvation, and the values of the mea n cluster size were determined for different polymer systems as a func tion of the volume fraction of the probe in the bulk of the polymers. Polymers with different polarities [a substituted poly(thionylphosphaz ene), a saturated polyester poly(diethylene glycol-succinic acid), and an essentially apolar poly(dimethylsiloxane)] were used as model mate rials. The microstructure and the solvent-polymer interaction are disc ussed in detail for each system. The results obtained allowed us to ga in novel insight into the polymeric microstructure and short-range ord er, thus giving credibility to our approach to study microstructure by cluster integrals from inverse gas chromatography (IGC) data.