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A modified polycarboxylate (MPC) superplasticizer was synthesized by the copolymerization of acrylic acid, methallyl sulfonic acid, allyl poly(ethylene glycol)s, and β‐cyclodextrin (β‐CD) grafted maleic anhydride. The molecular structure of the MPC was characterized by Fourier transform infrared spectroscopy and gel permeation chromatography. The effects of the content of β‐CD on the application performance of MPC were investigated with measurements of the cement paste fluidity, setting time, amount of adsorption of MPC on the cement particles, and ζ potentials of the cement particles and differential scanning calorimetry–thermogravimetric analysis of different hydration ages of the cement pastes. The results indicate that the initial fluidities and setting times of the cement pastes increased with increasing number of β‐CD side chains. The dispersion capacity of MPC on the cement particles mainly came from a steric hindrance effect and an air‐entraining effect of the β‐CD side chains. The better retarding performance of MPC was attributed to the solvation water film formed by the polyoxyethylene side chains and chelates formed by OH groups on the β‐CD structure combined with Ca2+ ions on the surface of the cement particles. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012

Polycarboxylate superplasticizers (PCs) with ether linkages and ester linkages between the main chains and the poly (ethylene glycol) (PEG) branch chains were synthesized, respectively. The effects of the PCs molecule linkage mode on the performance of concrete paste were investigated using the slump loss test and thermogravimetric analysis and analyzing fluidity, absorption, and setting time. Results showed that the linkage between main chains and PEG branch chains in PCs molecules had an important influence on the performance of cement paste and concrete prepared from them. PCs with ester linkages can endow the cement paste with higher fluidity and higher waterreduction ratio resulting from the higher absorption amount on the cement particles. This is related with the alternating distribution of the carboxyl groups and branch chains of PEG when different macromonomers are involved in the preparation of PCs. PCs containing ester linkages are more vulnerable than PCs with ether linkages in an alkali environment, leading to quicker slump loss and shorter setting times. In contrast, PCs with ether linkages had excellent fluidity and slump flow stability. A slightly different ettringite hydration product was observed during the early period of the hydration of cement paste that employed these two PCs.

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A novel monovinyl β-cyclodextrin monomer (β-P) is employed to synthesize polycarboxylate superplasticizers with β-cyclodextrin (β-CD) grafted on the end of side chain [PAA-g-(β-P) n HPEG, n is the mass ratio of β-P in macromonomer, n = 3%~9%]. β-P is synthesized through grafting β-CD on the polyoxyethylene (PEO) via click reaction, which is the first try to superimpose the steric hindrance effect of PEO and β-CD during the preparation of polycarboxylate superplasticizer. FTIR, 1 H NMR, GPC, and DLS are used to characterize the molecular structure of the intermediates and the products.Compared with PAA-g-HPEG (PCE0) only with PEO as side chains, cement paste containing PAA-g-(β-P) 7% HPEG has the largest fluidity; PAA-g-(β-P) 9% HPEG corresponds to the best fluidity retention performance; cement paste containing PAA-g-(β-P) n HPEG has shorter setting time. The DLS results reveal that the introduction of β-CD in PAA-g-(β-P) n HPEG extends the side chain length and increases the steric hindrance effect. The adsorption test results show that the novel PCE has good slump retention performance because it is adsorbed on cement particles less but more lives in the liquid phase with the n increasing. This study provides a new approach to synthesize high-performance polycarboxylate superplasticizer.