Pore size distribution and effect of solvent absorption and desorption properties of styrene-divinylbenzene beads

Abstract

The styrene-divinylbenzene copolymer beads were prepared by conventional-and seeded-suspension polymerizations in various quantities of diluents, toluene and n-heptane, with various nitrogen flow rates. The beads which were obtained from the conventional suspension polymerization were of small sizes. To enlarge the bead size by seeded suspension polymerization, the beads were sieved and soaked in the excess monomer solution until saturation was achieved. After being separated from the excess monomer solution, the saturated beads were repolymerization. The optimum condition for the polymerization werte found as follows: the suspending agents were the mixture of 2.53% HPMC and 1.32%HEC;hydroquinone 0.16%; the monomer phase volume fraction was 0.075;the amount of crosslinking monomer was 1%; temperature and time schedules for the conventional and seeded polymerizations were 70°C, 4 hr and then 90°C, 3 hr; and 70°C, 4 hr and then 90°C, 2 hr; respectively. After various characterizations the best synthesized had the follow properties : specific surface area 139.87 m² /g, pore volume 0.12 m1/g, average pre diameter 33.6 Å , desity 0.9667 g/cm³ , swelling ratio in toluene 15.6 for 50 min. The advantage of these styrene-divinylbenzene beads is capable of sorption and desorption of a certain organic solvents with the solubility parameters of approximately 18.6 (MPa) ¹/2 Detailed discussion of the synthesis methods and properties of the beads were given. This research has put several attempts to discuss the behavior of bead size, pore size and their influences on absorption and desorption of the appropriate organic solvents.