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Zwitterionic (ZI) polymers have great potential for dispersion and adsorption effects because of their dual functional groups (acidic and basic) grafted on polymer matrices. The ZI monomer 3-(2-(methacryloyloxy) ethyl) dimethylammonio-propane-1-sulfonate (DMAPS) and novel amphiphilic polycarboxylate copolymers (APCs) were prepared and characterised. The dispersion and adsorption behaviours of APCs as superplasticisers in a cement system in the absence and presence of clay were investigated. The results indicated that APCs had excellent dispersing ability, and a notable feature was that APCs could effectively inhibit the preferential adsorption of APCs into clay. A mechanistic study including dispersion, adsorption, zeta potential and x-ray diffraction revealed that, compared with traditional polycarboxylate superplasticisers, APCs with ZI groups were more easily adsorbed on the surface of clay but were not incorporated into the layer structure of the clay. This work not only fabricated a new superplasticiser with potential for development, but also provided a concept for preparing new superplasticisers to solve problems involved in their application. [ABSTRACT FROM AUTHOR]

Highlights: [•] MA and SMAS were introduced into the TPEG-type PCEs to improve the dispersion and flow retention abilities. [•] This paper discussed the dispersion and adsorption effects of TPEG-type PCEs compared with conventional MPEG-type PCEs. [•] PCE2 has excellent water-reducing and flow-retaining abilities, which is attributed to the synergistic effects of steric hindrance and electrostatic repulsive force. [•] Application results showed that PCE2 can be used as high-range water reducer in practical applications. [Copyright &y& Elsevier]

Abstract: Comb-like polycarboxylate copolymers (PCs) were synthesized and first used as the dispersants for kaolin suspensions. The apparent viscosity, adsorption behavior, zeta potential, rheological behavior, and TEM images of concentrated kaolin slurries deflocculated with these copolymers were systematically investigated. Sodium acrylate homopolymer (SA) was selected as a reference in order to contribute to the knowledge of how the electrostatic interaction and molecular structure of these copolymers influenced the dispersion, adsorption, and rheological properties of colloidal kaolin suspensions. The results showed that the dispersion of kaolin slurries mainly depended on the synergistic effects of electrostatic interaction and steric hindrance for APEG type comb-like copolymers. PC2 bearing proper carboxylic groups and side chains produced stable dispersion and fluidity in concentrated kaolin slurries. Based on the electrostatic and steric effect of comb-like copolymers, the kaolin slurries displayed a shear thickening behavior, and the Herschel–Bulkley model well described their rheological behaviors. [Copyright &y& Elsevier]