Synthesis of SMA by RAFT polymerization and its dispersion of TiO₂ in aqueous solution

Styrene-maleic anhydride copolymer (SMA) with controlled molecular weight (M _n) and narrow dispersity was prepared by RAFT polymerization. The effect of reaction time on monomer conversion was investigated, and the conversion of monomer could achieve 99.1% after 24 h at the temperature of 55 °C. The synthesized SMA was characterized by Fourier transform infrared spectroscopy (FTIR), nuclear magnetic resonance (NMR) and size exclusion chromatography (SEC). The result demonstrated that the polymerization of SMA was well controlled and the dispersity (Đ) of SMA was lower than 1.20. Furthermore, SMA copolymers with narrow dispersity and well-regulated M _n (denoted SMA1500, SMA3000, SMA5000, SMA8000, and SMA15800, respectively) were obtained by adjusting the molar ratio of monomer to the chain transfer agent. Moreover, the synthesized SMA was hydrolyzed in NaOH aqueous solution. Then the dispersion of TiO₂ in aqueous solution by the hydrolyzed SMA and SZ40005 (the industrial product) were studied. The agglomerate size, the viscosity and the fluidity of TiO₂ slurry were tested. The results show that the performance of dispersity for TiO₂ in water by SMA prepared via RAFT was better than that of SZ40005. It was found that the viscosity of the TiO₂ slurry dispersed by SMA5000 was the lowest among the SMA copolymers tested, and the viscosity value of the TiO₂ slurry with a pigment loading of 75% was only 76.6 cp.