Swelling of porous ethylvinylbenzene–divinylbenzene copolymers and the stability of the pore structure

Abstract

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.

Pore collapse during the fabrication process of rubber‐like polymer scaffolds

“…The difference in the pore structure between the swollen and the dry states has shown in the literature25, 26 for systems with much smaller pores. In addition, the influence of the type of the solvent used has also been reported 27–42. Polymer porous structures dried from bad solvents show maximum porosity that is close to the porosity in the swollen state 35.…”

Pore memory of macroporous styrene-divinylbenzene copolymers

“…Krska et al were the first to show the difference in the pore structure of S–DVB copolymers between the swollen and the dried states 21. It was also found that the pore structure of these copolymers varies with the type of the solvent used to treat the network 22–38. For instance, the copolymers dried from nonsolvents show a “maximum porosity,” which is close to the porosity in the swollen state 31.…”

Formation of macroporous styrene–divinylbenzene copolymer networks: Theory vs. experiments

“…It is seen that the final porosity of S-DVB networks strongly depends both on the degree of dilution v 2 00 and on the extent of the thermodynamic interactions between the diluent and network segments 12 sol . For comparison, some of the reported porosity data of S-DVB copolymer networks 2,11,16,18,19 are collected in Figures 5 and 6 as a function of the quality and the amount of the diluent, respectively. Experimental data shown in Figures 5 and 6 are for different di- shown as a function of the monomer conversion x at various initial monomer concentrations.…”

“…The difference between the solubility parameters of the diluent and the polymer is shown in the figure. Experimental data points are from Seidl et al, 2 Wieczorek et al, 11 Okay, 18 and Jun et al 19 The curves only show the trend of the data. DVB ϭ 20%, diluent ϭ methanol 2 (ƒ), n-butanol 2 (F), isooctane 2 (‚), and toluene/cyclohexanol (1/3) mixture 18 (OE).…”