Synthesis of amphiphilic polycarboxylate copolymer and its notable dispersion and adsorption characteristics onto cement and clay

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.