Formação da estrutura porosa em microesferas de poli(acrilonitrila-co-divinilbenzeno) obtidas por polimerização em suspensão

Abstract

In this dissertation, acrylonitrile-divinylbenzene copolymers were synthesized by suspension polymerization, in the presence of three porogenic agents (methyl benzoate, toluene and heptane) in different dilution degrees and different levels of the crosslinking agent divinylbenzene. The copolymers were characterized in terms of bulk density, pore volume and pore diameter. The beads morphology were also analyzed by optical and scanning electron microscopy, while the chemical structure were determined by infrared spectroscopy. Hildebrand and Hansen solubility parameters were used to predict the porous structure of the beads and their predictions were compared to the characteristics of the copolymers. The results showed the formation of different porous structures, mainly due to the type of diluent used. The increase in the degree of dilution favored the increase in the pore size of the resins. The increase in the content of cross-linking agent had different behaviors, depending on the type of diluent used in the synthesis. The most solvating diluent, methyl benzoate, generated microporous beads, while the less solvating diluent,heptane, generated macroporous microspheres. The beads synthesized in the presence of toluene have a large distribution of pore sizes, depending on the composition of the monomeric mixture used. The predictions made by Hansen solubility parameters were very assertive regarding the morphology obtained with each diluent. Methyl benzoate proved to be a good solvent for the copolymers synthesized with all of the monomers composition studied in this dissertation.