On the structure of macroreticular styrene‐divinylbenzene copolymers

Abstract

The influence of the removal of various diluents, pore forming agents from the porous styrene-ethylstyrene-acrylonitrile-divinylbenzene copolymers on the structure of the matrix was investigated by several methods. The most advantageous pathway to preserve the initial structural edifice of the porous networks performed in the presence of solvating diluents consisted in the removal of the inert media with methanol as it was noticed from the experimental data. If the steam treatment is applied, the collapse effect takes place and the anion exchangers prepared from such matrices exchange/adsorb less dye stuff by comparison with ones formed from beads treated with methanol, because the pore size was changed. It was also noticed that the porous copolymers performed in the presence of the solvating diluents (mixtures of solvatings and precipitants) swell very well in methanol though it is a precipitating medium for the polystyrenic macromolecular chains. ZUSAMMENFASSUNG:Mit Hilfe verschiedener Methoden wurde der EinfluR der Entfernung unterschiedlicher porenbildender VerdUnner aus porOsen Styrol-Ethylstyrol-Acrylnitril-Divinylbenzol-Copolymeren auf die Netzwerkstruktur untersucht. Der gtinstigste Weg, den urspriinglichen strukturellen Bau des porOsen Netzwerkes zu bewahren, welches in Gegenwart von solvatisierenden Verdiinnern erhalten wurde, ist das Entfernen des inerten Mediums mit Methanol. Wenn die Wasserdampfmethode angewendet wird, findet der sog. Kollapseffekt statt, und die aus solchen Harzen hergestellten Anionenaustauscher adsorbieren weniger Farbstoff im Vergleich zu jenen, die aus Perlen hergestellt worden sind, die mit Methanol behandelt wurden; Grund hierfiir ist die durch den Kollaps verlnderte Porengr6De. Es wurde ebenfalls festgestellt, da8 die in Anwesenheit von solvatisierenden Verdiinnern (Mischungen aus Quellungs-und FBllmitteln) hergestellten Copolymeren in Methanol sehr gut quellen, obwohl dieses ein FBllungsmittel ftir Polystyrol ist.

Imprinted polymers prepared by aqueous suspension polymerization

“…To this end, several bulk polymers were prepared in hexane, toluene, and propan‐2‐ol containing mixtures, the resulting materials exhibiting a range of surface areas varying from about 2 to 440 m 2 g −1 (Table I). In accordance with the data obtained in simple model systems,53, 54 our results confirm that vastly different morphologies can be obtained for chemically identical materials, merely by changing the nature of the porogen. Thus, a small increase in the proportion of toluene in hexane from 1:9 to 1:4 led to a 5‐fold increase in surface area for EDGMA‐based imprinted materials ( BI2 and BI3 ).…”

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

“…The critical DVB concentration decreases with increasing degree of dilution of the monomers. In Figure 10, experimental porosity data of S-DVB networks published in the literature 16,18,43 shows that the predictions of the model are in excellent agreement with the experimental data. The slight decrease in the porosity of S-DVB networks above 60 % DVB (Fig.…”

“…The difference between the solubility parameters of the diluent and the polymer is shown. Experimental data points are from Poinescu et al 43 and Okay. 16,18 The curves only show the trend of the data.…”

“…v 2 00 ϭ 0.50, diluent ϭ cyclohexanol 16 (F), toluene/cyclohexanol (1/ 3) 18 (E), toluene/cyclohexanol (1/1) 18 (OE), and toluene 16 (). v 2 00 ϭ 0.40, diluent ϭ toluene/gasoline (1/100) 43 (V).…”

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.…”