Research on the Synthesis and Properties of Tricarboxylate Terminated <scp>EPEG</scp> Polycarboxylate Superplasticizer

ABSTRACT Excessive length of the side chains in conventional polycarboxylate superplasticizers (PCEs) results in their coiled and collapsed conformation, impairing their dispersing performance. To reduce this impact and improve the dispersion performance of PCEs, tricarboxylate terminated side chain macromonomers were designed and synthesized by modifying ethylene glycol monovinyl polyethylene glycol (EPEG) with 1,2,3,4‐butanetetracarboxylic acid (BTCA). Furthermore, high‐performance PCEs with tricarboxylate terminated side chains (XPCE‐3000 and XPCE‐5000) were prepared via free radical polymerization at ambient temperature (25°C). Compared to conventional PCEs, the XPCEs showed superior dispersion performance. They exhibit higher negative charge density and adsorption capacity, while electrostatic repulsion between side chains promotes a more extended polymer conformation and a thicker adsorption layer. For XPCE‐3000, the adsorption layer thickness increased from 3.92 to 5.57 nm, achieving effective synergy between steric hindrance and electrostatic repulsion. The cement paste fluidity reached 28.2 cm. Cement paste containing XPCE‐3000 exhibited a denser hydration product microstructure, with its 3‐ and 28‐day compressive strengths reaching 44.1 and 52.65 MPa respectively, which were 14.7 and 8.75 MPa higher than paste with conventional PCEs. This study confirms that tricarboxylate termination of EPEG side chains is an effective strategy for regulating PCEs performance.