Efficient dispersion of high-content SiO2 particles across a broad pH range with anionic block copolymer in aqueous solution: An experiment and mechanism study

Dispersion of SiO₂ particles in aqueous solutions using block copolymers remains challenging, particularly due to degradation in highly alkaline environments and difficulty in achieving high solid content. Herein, we report the synthesis of an anionic block copolymer, poly(glyceryl methacrylate-b-sodium p-styrenesulfonate) (PGGMA-b-PSSS), containing abundant hydroxyl groups, via reversible addition-fragmentation chain transfer (RAFT) polymerization of sodium p-styrenesulfonate and glycidyl methacrylate monomers. The hydroxyl groups in PGGMA-b-PSSS serve as anchoring points, producing a steric hindrance effect between SiO₂ particles by interacting with silanol groups on the particle surface. Furthermore, electrostatic repulsion from the poly(sodium p-styrenesulfonate) block significantly enhances the dispersibility of PGGMA-b-PSSS in aqueous systems. A systematic investigation of the dispersibility of SiO₂ particles was conducted under various compositions and concentrations of PGGMA-b-PSSS across a wide alkaline pH range. Our results show the effective dispersion of sub-micron and micron-sized SiO₂ particles, achieving solid contents of up to 35 wt% over a wide pH range (3–13).