Effect of carboxylate content in comb-like AA–IPEG copolymer as a dispersant for cement-based systems

AA–IPEG comb-like copolymer is a kind of polycarboxylate-based dispersant for cement-based systems. Copolymers with different carboxylate contents were synthesised using isoprenyl oxy polyethylene glycol ether (IPEG) and acrylic acid (AA) as raw materials, further modified with maleic anhydride. The copolymers were characterised by Fourier transform infrared spectroscopy, gel permeation chromatography and surface tension measurements. The dispersion of cement paste mixed with copolymer was studied by means of the zeta potential, adsorption behaviour, cement paste fluidity, setting time and scanning electron microscopy. It was found that the copolymer with a higher carboxylate content exhibited lower adsorption on the surface of cement particles and more negative zeta potential, and resulted in longer retention dispersion and setting time at the same dosage; however, excessive carboxylate content decreased the dispersing force of cement particles. Therefore, for more efficient dispersants for cement-based systems, there is a proper proportion between carboxylate content and poly(ethylene oxide) chains as the side groups on backbone chains.