Effects of the crosslinking agent and diluents on bead properties of styrene-divinylbenzene copolymers

Styrene-divinylbenzene copolymer beads were synthesized by radical suspension polymerization. Effects of the divinylbenzene concentration and composition of the toluene/heptane diluent were studied regarding the polymer bead formation, surface morphology, solvent swelling ratio, and glass transition temperature. The crosslinking density and diluent composition were responsible for solvent swelling. Interaction between the polymer and the diluents is attributed to phase separation, which controls the formation of a network-type or pore-type polymer, or a combination. For an optimum bead swelling in toluene, a combined morphology of more flexible polymer networks and a small amount of pores is essential for the desired absorption-desorption behavior. This article also combines several current findings with work presented elsewhere to explain the bead formation phenomenon. (C) 2002 Wiley Periodicals, Inc.