Comparison of the Porous Structure of Polymeric Beads Obtained by Modified Suspension and Multi-Step Swelling Polymerizations

Abstract

The porous structures of the polymeric beads obtained by modified suspension and multi-step swelling polymerizations were studied. A porous styrene–divinylbenzene copolymer (ST–DVB) was synthesized in the modified suspension polymerization. In the multi-step polymerization, porous ST–DVB layers of the same chemical composition as obtained in the suspension polymerization were embedded onto polystyrene seed particles obtained in the first step. Three methods were used for investigating the porous structures generated. These were inverse exclusion chromatography, nitrogen adsorption and small X-ray scattering (SAXS). The former was used to characterize the polymer in the swollen state, whereas the latter two were employed with dry polymer samples. The results obtained showed that polystyrene seed particles are porous in the swollen state. However, such pores could not be detected either by nitrogen adsorption or SAXS methods.