HYDROLYSIS OF DEXTRIN IN THE PRESENCE OF SULFONATED CROSS-LINKED POLYSTYRENE BEADS WITH GRAFTED CHAIN AS SPACER

Abstract

Polystyrene-grafted cross-linked polystyrene beads were prepared with a two-step polymerization, consisting of the first step; suspension polymerization of styrene containing small amount of divinyl benzene using tetraethylthiuram disulfide as an initiator, and the second step; polymerization of styrene onto the cross-linked polystyrene beads. Both percent grafting and grafting efficiency by this method were higher than those by conventional graft polymerization onto the beads using benzoyl peroxide as an initiator. In sulfonation by 1, 4-dioxane-sulfur trioxide adduct, the higher the percent grafting, the fewer sulfonic acid groups were introduced into the beads. Catalytic activity of the sulfonated beads on the hydrolysis of dextrin, however, increased with the increasing percent grafting, especially at the percent graftings higher than 200%. The catalyses followed ordinary second-order kinetics. The results showed that the increase in the catalytic activity with the increasing percent grafting was due to the effect of grafted chain as a spacer to separate the sulfonic acid group from the insoluble matrix.