β-Cyclodextrin as Pendant Groups of a Polycarboxylate Superplasticizer for Enhancing Clay Tolerance

Abstract

A novel monovinyl β-cyclodextrin monomer (MA-β-CD; MA = methacrylate) was employed to synthesize polycarboxylate superplasticizers modified with β-CD as pendant groups, and their dispersing performance was tested in the absence and presence of montmorillonite. Adsorption measurement and X-ray diffraciton analysis indicated that their interactions with Ca-montmorillonite originated from electrostatic attractions between carboxylate groups and the positive charge of Camontmorillonite particle. Compared with conventional polycarboxylate superplasticizers (PCEs) only with poly(ethylene oxide) (PEO) chains, polycarboxylate superplasticizers with β-CD as pendants displayed enhanced robustness toward clay. This was attributed to the steric hindrance instigated from β-CD groups with the structure of a hollow truncated cone by hindering the sorption of polycarboxylate polymers on the surfaces of Ca-montmorillonite.

Regulating the arm structure of star‐shaped polycarboxylate superplasticizers as a means to enhance cement paste workability

“…For cementitious system, it is widely accepted that the improved cement workability was resulted from the steric hindrance imposed by PCEs . With regard to star‐shaped PCEs, it could be deduced that anion anchoring groups were absorbed onto the cement particles to create double electrical layers, with the arms of star‐shaped PCEs stretched into solution to exhibit a steric hindrance effect as shown in Figure .…”

“…Due to the effects of PCE adsorption and steric space effect, the release of cement particle ions is hindered, which delays the hydration reaction. Figure (a) shows the effect of arm length and density of the PEO side‐chains in the arms on the hydration kinetics.…”

Comb‐like polymer with sulfo groups and its dispersion and rheological properties in aqueous ceramic suspensions

“…The copolymer PC 1 was synthesized by the free‐radical polymerization of TPEG, MA, and AA . The copolymer PC 2 was synthesized by the free‐radical polymerization of TPEG, MA, AA, and SMAS as a chain‐transfer agent.…”

Investigation of the clay sensitivity and cement hydration process of modified HPEG‐type polycarboxylate superplasticizers

“…The majority of these modifications have focused on the introduction of new pendant groups to PC molecules. Xu et al . synthesized a kind of PC based on a novel monovinyl β‐cyclodextrin monomer.…”