Study on the synthesis and properties of benzoate modified with hydroxyl-terminated of the side chains of polycarboxylic superplasticizer

• Published in: Journal of dispersion science and technology Vol. 44; no. 5; pp. 787 - 794
• Main Authors: Zheng, Yuqin, Chen, Gang, Shan, Hailin, He, Jiarong, Lei, Jiaheng
• Format: Journal Article
• Language: English
• Published: Philadelphia Taylor & Francis 19.04.2023; Taylor & Francis Ltd
• Subjects: Acrylic acid; adsorption; Benzoates; benzoic anhydride; Cement; Copolymerization; Copolymers; dispersion; Esterification; Graft copolymers; Hydrophobicity; hydroxyl-terminated; Mortars (material); Polycarboxylate superplasticizer; Polyoxyethylene; Steric hindrance; Superplasticizers; Zeta potential
• ISSN: 0193-2691; 1532-2351
• DOI: 10.1080/01932691.2021.1974872

By the esterification of benzoic anhydride (BA) with polyoxyethylene ether (HPEG), the modified macromonomer (BA-HPEG) with benzoate of HPEG was prepared. Then, BA-HPEG and HPEG were copolymerized with acrylic acid (AA) with an alkyd ratio of 2:1 to obtain three novel polycarboxylate superplasticizer BA-PCE-10, BA-PCE-20 and BA-PCE-30 with good flow retaining behaviors of cement mortars. The effects of the benzoate content in the copolymers on adsorption, dispersion, Zeta potential and hydrodynamic radius for cement suspensions were investigated to elucidate the governing dispersing mechanism. The absorption of the modified copolymers on the cement surfaces was controlled by COO - and hydrophobic phenyl content in copolymers and polymer conformation in solution. The fluidity of cement slurry increases with the adsorbed amount to increase dispersion effect. The copolymers grafted with benzoate exhibited a high dispersion performance than that of the unmodified molecule, which could be explained as the hydrophobic modified polycarboxylate superplasticizer mainly dispersing cement particles by the main repulsion of steric hindrance and electrostatic repulsion, so as to improve the dispersion performance of cement. The study shows that the flow retaining behaviors of polycarboxylate superplasticizer can be significantly improved by BA modified with hydroxyl-terminated of the side chains of polycarboxylic superplasticizer.