Partially sulfonated polystyrenes: A new gypsum superplasticizer

Calcium sulfate hemihydrate is widely used for gypsum product fabrication; however, it requires superplasticizers to improve its fluidity and workability. In this study, we aimed to develop a novel superplasticizer based on partially sulfonated polystyrene (PStSS-fSS) for calcium sulfate hemihydrate. We synthesized PStSS-fSS by polymerization of styrene and sodium 4-styrenesulfonate and compared its performance with polynapthalene sulfonate (PNS) in terms of fluidity, zeta potential, hydration rate, and water resistance. PStSS-fSS exhibited higher fluidity than PNS without hydration delay of hemihydrate. The higher fluidity was attributed to the enhanced polymer adsorption on the hemihydrate surface because of the hydrophobic units. PStSS-fSS also imparted better water-resist properties to the gypsum products. PStSS-fSS is confirmed as a better superplasticizer than PNS for calcium sulfate hemihydrate, providing higher fluidity and improved water resistance.