Effect of sodium gluconate on molecular conformation of polycarboxylate superplasticizer studied by the molecular dynamics simulation

Huahui Qi; Baoguo Ma; Hongbo Tan; Chunbao Li; Zhenzhen Zhi; Hui Wang; Xiaohai Liu; Qi Yang

doi:10.1007/s00894-020-4309-8

Effect of sodium gluconate on molecular conformation of polycarboxylate superplasticizer studied by the molecular dynamics simulation

J Mol Model. 2020 Feb 3;26(3):45. doi: 10.1007/s00894-020-4309-8.

Authors

Huahui Qi¹, Baoguo Ma¹, Hongbo Tan², Chunbao Li¹, Zhenzhen Zhi³, Hui Wang⁴, Xiaohai Liu¹, Qi Yang¹

Affiliations

¹ State Key Laboratory of Silicate Materials for Architectures, Wuhan University of Technology, Wuhan, 430070, Hubei, China.
² State Key Laboratory of Silicate Materials for Architectures, Wuhan University of Technology, Wuhan, 430070, Hubei, China. thbwhut@whut.edu.cn.
³ School of materials science and engineering, Luoyang Institute of Science and Technology, Luoyang, 471023, Henan, China.
⁴ Faculty of Architectural, Civil Engineering and Environment, Ningbo University, Ningbo, 315000, China.

PMID: 32009188
DOI: 10.1007/s00894-020-4309-8

Abstract

Sodium gluconate (SG) has been accepted as one of the main additional components in polycarboxylate superplasticizer (PCE) system, due to its excellent retarding effect. While the negative effect on dispersion of PCE was reported in the literature, the reason was not completely revealed. In this study, molecular dynamics simulation was used to investigate the mutual influence between SG and PCE in calcium hydroxide (CH) solution. Radial distribution function (RDF) was used to analyze the effects of SG on the complexation of PCE with Ca²⁺. Radius of gyration (Rg) was adopted to characterize the conformations of the backbone and side chains of PCE in CH solution. Finally, several adsorption and dispersion models were proposed. The results showed that the presence of SG would perturb adsorption of PCE, which was one of the main reasons that affected the dispersion ability of PCE. SG could preferentially combine with Ca²⁺ so that less amount of Ca²⁺ is available for combination of PCE, and this could extend the main chain of PCE and show advantage for PCE adsorption. Besides, adding SG could squeeze the side chains of PCE, which would put a negative effect on the dispersion. These findings gave deeper insight into understanding the dispersion mechanism of PCE-SG system.

Keywords: All-atom molecular dynamics simulations; Conformation; Dispersion ability; Polycarboxylate superplasticizer; Sodium gluconate.

Abstract

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