383: Effect of microstructure in acrylic acid and styrenesulfonate based copolymer on calcium sulfate hemihydrate dispersion

Effect of microstructure in acrylic acid and styrenesulfonate based copolymer on calcium sulfate hemihydrate dispersion

Aruna Kumar Mohanty,  Hanyoung Kim, Jongwook Ahn, and Hyun-jong Paik^*

Department of Polymer Science and Engineering, Pusan National University, Busan 46241, Republic of Korea.

^*hpaik@pusan.ac.kr

Superplasticisers are indispensable for enhancing the dispersion of cementitious particles while reducing the amount of water. These additives improve slurry workability and contribute to the production of dense and high-strength materials. In this study, we highlight the synergistic effect of carboxylate (-COO^˗) and sulfonate (-SO₃^˗) groups through precise microstructure control for high-performance superplasticization in gypsum. Using acrylic acid (AA) and sodium 4-styrenesulfonate (SS) as monomers, we synthesized homopolymers, random copolymers, and block copolymers via RAFT polymerization. The synthesized polymers were evaluated based on adsorption capacity, zeta potential, and adsorption layer thickness. Our results demonstrated that the tailored distribution of -COO^˗ and -SO₃^˗ groups within the block microstructure of polymer significantly enhanced adsorption efficiency, electrostatic interactions, and steric repulsions resulting in superior fluidity in CSH slurry. The block copolymer exhibited an impressive water reduction ratio of 57.7%, outperforming the conventional superplasticizers (15–30%).^[1] Additionally, a higher proportion of SS in the block copolymer effectively offsets the usual delayed hydration effects of PAA. This work highlights the significance of microstructure optimisation in copolymer design for achieving advanced gypsum superplasticiser performance.

Figure 1. Schematic representation of the mechanism of CSH dispersion by different polymer microstructures for  water reduction.

Reference

[1] Vo, M.L.; Plank, J;. Dispersing effectiveness of a phosphated polycarboxylate in α- and β-calcium sulfate hemihydrate systems. Constr. Build. Mater. 2020, 237, 117731. DOI: 10.1016/j.conbuildmat.2019.117731