How to maintain the morphology of styrene-divinylbenzene copolymer beads during the sulfonation reaction

This work aims to describe the use of acetyl sulfate as sulfonating reagent of microporous beads based on styrene (STY) and divinylbenzene (DVB) which were prepared by aqueous suspension copolymerization. The copolymer was chemically modified by two different sulfonating agents, namely sulfuric acid and acetyl sulfate which is prepared “in situ” by mixing acetic anhydride and sulfuric acid. The morphologic features of resin beads were analyzed by optical microscopy (OM) and by scanning electron microscopy (SEM). The sulfonic group incorporation into the copolymer network was verified by infrared spectroscopy (FTIR) and quantified by using a standardized NaOH solution. The bead morphology maintenance depends on the sulfonating agent and reaction conditions.