SYNTHESIS AND CHARACTERIZATION OF STYRENE-DIVINYLBENZENE LOADED WITH DI(2-ETHYLHEXYL)PHOSPHONIC ACID - I - INFLUENCE OF DILUENT MIXTURE ON THE POROUS STRUCTURE OF THE COPOLYMER

Styrene-divinylbenzene copolymers were synthesized in the presence of di(2-ethylhexyl)phosphonic acid (EHEHPA) to be applied in the separati on of rare earths by extraction chromatography. The copolymers were pr epared by suspension polymerization in the presence of pure EHEHPA or in a mixture with isooctane, heptane, or toluene. The composition of t he diluent mixture employed in the synthesis was varied. The apparent density, fixed pore volume, and surface area of the copolymers were de termined. The content of EHEHPA retained in the copolymer beads was al so determined, and it was found to be independent of the porous struct ure of the copolymer matrix. That content was only dependent on the am ount of EHEHPA present in the diluent mixture. The toluene/EHEHPA mixt ures produced the copolymers with the best properties required for ext raction chromatography supports. (C) 1998 John Wiley & Sons, Inc.