The　dispersion　of　silicon　dioxide　(SiO2)　by　a　block　copolymer　under　highly　acidic　or　strongly　alkaline　conditions　in　water　is　still　a　challenge.　In　this　study,　block　copolymers　containing　repeating　units　of　methacrylic　acid　(MAA)　and　glycidyl　methacrylate　(GMA)　were　synthesized　using　reversible　addition-fragmentation　chain　transfer　(RAFT)　polymerization.　Subsequently,　the　epoxide　groups　underwent　ring-opening　reaction　and　the　polymer　chain　end　dithioester　groups　were　removed　through　one-step　hydrolysis,　leading　to　the　formation　of　a　block　copolymer　named　PMAA-b-PGGMA,　which　contained　abundant　hydroxyl　groups.　Hydroxyl　groups　act　as　anchoring　groups　and　interact　with　the　silanol　groups　on　the　surface　of　SiO2　particles　simultaneously,　resulting　in　a　steric　site-blocking　effect.　Besides,　the　electrostatic　repulsion　effect　of　PMAA　as　a　stable　group　with　a　negative　charge　on　SiO2.　The　block　copolymer　PMAA43-b-PGGMA50　can　effectively　disperse　sub-micron-　and　micron-sized　SiO2　even　at　high　SiO2　content　(35　wt%)　and　broad　pH　values　(3–13)　in　water.　©　2024　Elsevier　Ltd