Influence of comb-like copolymer dispersants with different molecular structures on the performance of CaCO3 suspension in organic system

A series of comb-like copolymer poly(styrene-co-maleic anhydride)-graft-poly(ε-caprolactone) (SMA-g-PCL, SP) with variation in PCL side chain length and side chain density were synthesized and employed as an efficient dispersant for CaCO₃ suspension in organic solvent. The effects of molecular structures of comb-like copolymer on adsorption, rheological behavior, and suspension stability were investigated systemically to elucidate the governing dispersing mechanism. The molecular structures of comb-like copolymer not only significantly influenced the adsorption behavior but also the rheological behavior and suspension stability. Calculations based on the scaling law and Flory theory made a profound understanding of the impact of the molecular structure of comb-like copolymer on dispersion property. The results revealed that the steric repulsive force was enhanced by increasing of side chain length or density. However, the surface area for one molecule on CaCO₃ surface was also increased for its larger radius of the hemispheres of comb-like copolymer. This led to the worse activity of adsorption. The dispersion of CaCO₃ was due to the synergistic effects of adsorption and steric hindrance effect, which resulted that the comb-like copolymer with moderate length and density of side chain presented the best dispersability.