β-Cyclodextrin-based Zwitterionic Polymers as Clay-Tolerance Sacrificial Agents of Polycarboxylate Superplasticizers

Abstract

β-Cyclodextrin (β-CD)-based zwitterionic polymer (β-CD-PDMAPS) was synthesized via activators regenerated by electron transfer for atom transfer radical polymerization (ARGET ATRP). As a clay-tolerance sacrificial agent, β-CD-PDMAPS combined with common polycarboxylate superplasticizer (CPC) can result in modified polycarboxylate superplasticizer (MPC). The dispersion and the dispersive retention of MPC in a cement system in the absence and presence of clay were investigated. The results indicated that MPC possesses excellent dispersing ability and can effectively inhibit the preferential adsorption of CPC onto the surface of clay. Compared to CPC, MPC displayed enhanced robustness toward clay. This can be attributed to the easy adsorption of the β-CD-PDMAPS onto clay and the steric hindrance derived from β-CD, which can inhibit CPC from incorporating into the lattice structure of the clay. This work provides new insight into the development of polycarboxylate superplasticizers with enhanced clay tolerance.