Functional polymers for colloidal applications. XIV. Syntheses of styrene-maleic anhydride copolymers with different charges and their ability to disperse kaolinite particles

Four kinds of styrene/maleic-anhydride (SMA) copolymer-derived dispersants with different charged forms were synthesized and characterized with ¹H-NMR. These four different dispersants contained carboxylic acid groups and exhibited characteristics indicative of anionic, cationic, zwitterionic, or nonionic surfactants as pH was changed. The charge properties of these copolymers changes with pH, and their ability to disperse clay particles under low and high pH were assessed by measuring viscosity or sedimentation, as well as Scanning Electron Microscopy (SEM). The results showed that the dispersing abilities are functions of pH of the system. It was found that SMA-N [Poly(styrene-co-β-N,N-dimethylpropylamino) maleic acid, sodium salt)] exhibits the best dispersing ability, the fastest rate of sedimentation, and the smallest sedimentation volume at pH = 2, and SMA-Na [poly(styrene-co-maleic acid, disodium salt)] exhibits the better dispersing ability at pH = 7 and 12. In addition, the aggregation behavior of the dispersants characterized by fluorescence spectroscopy revealed that the degree of aggregation for all dispersants at high concentration increases in the order: SMA-Na < SMA-B [poly(styrene-co-B-imino-propyl-N-trimethylammonium acetate) maleic acid, disodium salt)] < SMA-N < SMA-Q [poly(styrene-co-β-imino-propyl-N-trimethylammonium sulfate) maleic acid, sodium salt)].