SynopsisA series of porous ethylvinylbenzene-divinylbenzene (EVB-DVB) copolymers with DVB contents ranging from 22.0 to 98.4% were prepared using various amounts of toluene as the inert diluent, and studies were made on the copolymers as to their swelling properties, the stability of their pore structure, and the relationship between swelling in nonsolvents and variations in their pore structure. The swelling experiments showed that the ethanol regains of the copolymers were closely related to the course of phase separation, and the increases in both the DVB content and the volume fraction of monomers in the organic phase resulted in enhanced capacity of the highly crosslinked copolymers to keep swelling in solvents having extremely small affinity for these copolymers. The variations in pore structure, sometimes quite considerable, for copolymers pretreated with different solvents were observed even at DVB content up to 98.496, and further studies showed that a consistent relationship existed between pore volume variation and volume swelling ratio in ethanol for toluene modified copolymers.

SYNOPSISThe swollen pore structure of a series of microporous isoporous resins (7.4-140 A ) are investigated with inverse GPC, n-alkylbenzenes and linear polystyrenes being used as probe molecules. The results indicated that, with the lowering of crosslinking degree of isoporous resins, the average pore diameter increased and the pore distribution curve broadened. All pore volume distribution obeyed a log-normal distribution. Based on the linear regression method, the experimental data were fitted to a monotonously declining exponential function and a normal distribution function by a computer, and some important structural parameters such as average pore diameter, pore volume distribution, specific surface area, etc. were obtained. The specific surface area of swollen gels were found much greater than those in the dry state measured by N2 adsorption.I NTRODU CTlO N Porous polymer materials are widely used as ion exchange resins, adsorbents, and carriers for catalysts; they are usually used in the swollen state, which makes their porous structure highly dependent on the medium employed. The classical methods for determining porous structure such as nitrogen adsorption and mercury porosimetry are only good for dry samples and cannot be used to provide information on pore structure in the moistened or swollen state.Gel permeation chromatography (GPC) is a widely employed method for separation of dissolved substances-mostly polymer mixtures-according to their molecular size. Conversely, by means of the retention data of probes of known molecular size, pore volume distribution and other pore structural parameters can be determined when porous materials are used as the stationary phase. This where V, is the pore volume of the porous system and Vo is the interstitial volume of the column.Although several investigations on the determination of macroporous organic gels by IGPC have been reports on the determination of microporous system in the swollen state are The purpose of the present work is to characterize the pore structure of a new type of crosslinked copolymer, isoporous resin, inspect the homogeneity of its structure, and study the effect of crosslinking degree on the pore structure. We hope to establish a quantitative relationship between the distribution coefficient K and the dimensions of probe molecules through fitting with the chromatographic data using a computer and find from this the pore structural parameters of isoporous resins.Crosslinked styrene-divinylbenzene copolymer is a widely used polymeric carrier, but the distribution of crosslinking bridges in it is not uniform. In comparison with this, isoporous gels having a statistical distribution of crosslinking bridges, can be obtained by crosslinking of polystyrene chains with bifunc- 959