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SynopsisThe texture and the pore size distribution of a set of styrene divinylbenzene copolymers, prepared by suspension polymerization with various compositions and various amounts of ethyl-2-hexanoic acid as diluent, have been studied using nitrogen adsorption-desorption isotherms, mercury porosimetry, and scanning-electron microscopy. It appears that pore volume and surface area may be well predicted in a large range of conditions (divinylbenzene contents between 20 and 60%, ethyl-2-hexanoic acid contents between 35% and 60%). In this range of conditions there are three structures: the elementary nuclei are spherical particles of about 100-200 8, in diameter. They are organized in microspheres of about 500-1000 A, and the microspheres form aggregates (2500-5000 8,) more or less separated by large holes. The smaller pores (<40 8,) are in the microspheres, between the nuclei; they are present only if the amount of divinylbenzene is high enough. Intermediate pores (40-500 A) are, in the aggregates, between the microspheres, although the larger pores between the aggregates range from about 500 8, t o more than 10,000 A, depending on the amount of diluent.

A critical analysis of the styrene-divinylbenzene resin infra-red spectra was made using previous works and new results. A method for the determination of pendent double bonds and also crosslinking degree and composition of the resin is drawn. A few examples of application are given. 0250-9733/8

Styrenedivinylbenzene macroporous resins were prepared with the same composition (13% DVB), but varying diluent amount of benzyl alcohol. From sample analysis, the copolymerization kinetics concerning both monomer consumption and residual double bond amount were determined. Porous texture and morphology analyses by BET**, BJH***, mercury porosimetry, and scanning electron microscopy were carried out, too. Depending on diluent amount, the final product is classified as inside or outside the macroporous domain. Texture evolution is clearly different for the two classes of products, although their chemical evolutions are almost the same. A qualitative discussion of porous texture formation is presented, based on occurrence of three critical events: gelation, phase separation and molecular overlap. ZUSAMMENFASSUNG:Es wurden makropor6se Styrol-Divinylbenzol-Harze bei gleicher Zusammensetzung (1 3% Divinylbenzol), aber mit variierenden Verdiinnunganteilen von Benzylalkohol, hergestellt. Aus der Analyse der Proben wurde die Copolymerisationskinetik sowohl aufgrund des Monomerverbrauchs als auch des Doppelbindungsanteils bestimmt. Ebenso wurden Porenstruktur-und Morphologieanalysen mittels BET, BJH, Quecksilberporosimetrie und Rasterelektronenmikroskopie durchgefiihrt. In Abhtingigkeit vom Anteil an Verdiinnungsmittel wurde das Endprodukt als innerer oder ilu-Derer makropor0ser Bereich klassifiziert. Die Strukturbildung ist fur die zwei Produktklassen unterschiedlich, obwohl ihre chemische Entstehung nahezu gleich ist. Es wird eine qualitative Diskussion iiber die Bildung der lockeren Struktur gegeben, die auf drei kritischen Erscheinungen beruht: Gelbildung, Phasentrennung und molekulare Uberlappung.

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