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 H-1-NM R. These four different dispersants contained carboxylic acid groups and ex hibited characteristics indicative of anionic, cationic, zwitterionic, or n onionic surfactants as pH was changed. The charge properties of these copol ymers changes with pH, and their ability to disperse clay particles under l ow and high pH were assessed by measuring viscosity or sedimentation, as we ll as Scanning Electron Microscopy (SEM). The results showed that the dispe rsing abilities are functions of pH of the system. It was found that SMA-N [Poly(styrene-co-beta-N,N-dimethylpropylamino) maleic acid, sodium salt)] e xhibits the best dispersing ability, the fastest rate of sedimentation, and the smallest sedimentation volume at pH = 2, and SMA-Na [poly(styrene-co-m aleic acid, disodium salt)] exhibits the better dispersing ability at pH = 7 and 12. In addition, the aggregation behavior of the dispersants characte rized 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 a cid, disodium salt)] < SMA-N < SMA-Q [poly(styrene-co-beta-imino-propyl-N-t rimethylammonium sulfate) maleic acid, sodium salt)]. (C) 2000 John Wiley & Sons, Inc.