硅酸盐学报

磺化改性聚羧酸减水剂吸附行为的分子动力学模拟

PDF下载

管佳男 ¹ , 刘少静 ¹ , 刘晓 ² , 朱海堂 ¹

硅酸盐学报 | 研究论文 2024,52(10): 3283-3290

收起

硅酸盐学报 |研究论文 2024 , 52 (10) : 3283 -3290

磺化改性聚羧酸减水剂吸附行为的分子动力学模拟

全屏

管佳男¹, 刘少静¹, 刘晓², 朱海堂¹

作者信息

^1．河南工程学院土木工程学院，郑州 451191

^2．北京工业大学材料科学与工程学院，北京 100124

作者简介:

管佳男（1988—），男，博士，讲师。

Molecular Dynamics Simulation of Adsorption Behavior of Sulfonation Modification of Polycarboxylate Superplasticizer

Jianan GUAN¹, Shaojing LIU¹, Xiao LIU², Haitang ZHU¹

Affiliations

^1.College of Civil Engineering, Henan University of Engineering, Zhengzhou 451191

^2.College of Materials Science and Engineering, Beijing University of Technology, Beijing 100124

GUAN Jianan (1988-), male, Ph.D., Lecturer. E-mail: jiananguan@yeah.net

出版时间: 2024-10-20 doi: 10.14062/j.issn.0454-5648.20240124

文章导航

摘要

收起

聚羧酸减水剂（PCE）的吸附行为是其性能发挥的关键，但现有的研究缺少从原子或分子尺度上揭示其吸附机制。采用全原子分子动力学（MD）模拟研究磺化改性PCE（PAA-g-PALS）和传统结构PCE（PAA-g-HPEG）在水泥浆体环境下的构象及界面连接的结构、动力学和稳定性的差异。结果表明：水泥浆环境下PAA-g-HPEG和PAA-g-PALS分别趋于梳状和网络状构象；磺化改性分散了PCE与基底的结合点的分布，提高了PCE与基底的结合力，使聚合物朝远离基底方向伸展，显著增大渗透体积（增大约132.64%）。本研究结果不仅从原子水平上为PCE的作用机制提供新的见解，还为促进水泥基材料高性能发展提供理论依据。

关键词

聚羧酸减水剂 / 磺化改性 / 吸附 / 界面 / 分子动力学模拟

Abstract

收起

Introduction

Relying on their advantages of high water reducing rate, low dosage, and strong molecular structure design ability, polycarboxylate superplasticizers (PCEs) have become the most widely used admixture in the field of concrete admixtures. Adsorption of PCEs onto the surfaces of cement particles is the prerequisite for the dispersing performance of PCE molecules. Therefore, the influences of PCE molecules with different structures on the dispersion properties of cement slurry can be understood by revealing the adsorption process of PCE and the conformation characteristics of PCE after adsorption.

It should be noted that both the adsorption process and the conformation of the adsorbed PCE involve interfacial interactions between the organic and inorganic phases, which is the dominant factor determining the overall properties of the material. Recently, molecular dynamics (MD) simulations have been applied to the PCEs to elucidate its working mechanism. However, the molecular size of these model PCEs was much smaller than those typically used for industrial applications in order to reduce computation cost. Furthermore, only pure water was used, or only Na⁺, Ca²⁺ and Cl^- were additionally added to mimic a cement pore solution. The above methods make the results unable to accurately reflect the adsorption mechanism of PCE. Therefore, to better understand and effectively control the performance of PCE, more in-depth studies at the atomic and molecular scales are needed. Our research team innovatively used MD simulations in which the molecular size of the model PCE is consistent with that of PCE commonly used for industrial applications and simulates cement pore solutions. In addition, the adsorption mechanism of sulfonation modification of PCE was studied by combining the structure, dynamics and stability of interfacial connections.

Methods

The MD simulations used the Gromacs-4.6.7 software package and a conventional oplsaa force field with RESP charges. The UFF force field was used for the substrate. The equilibrium MD simulation was conducted under the NPT ensemble for a total run time of 20 ns at a relaxed liquid configuration (25 ℃). The solution environment simulations were performed using 3000 water molecules. A relaxation system was selected and the energy was minimized by the steepest descent method with a termination gradient of 100 kJ/(mol∙nm) before the relaxation. The system temperature maintained constant through a Nosé-Hoover thermostat, and periodic boundary conditions were applied to all three dimensions. Long-range electrostatics within a relative tolerance of 1×10^-6 is calculated by the particle mesh Ewald method and a cut-off distance of 1 nm was used as the Ewald interaction and van der Waals interactions. The bond lengths of hydrogen atoms were constrained by the LINCS algorithm. A leap-frog algorithm was used with a time step of 1 fs.

Results and discussion

Under cement solution conditions, the side chains of PAA-g-PALS molecules were not entangled with the backbone (present a network-like conformation), while a small part of the side chains of PAA-g-HPEG molecules will curl onto the backbone (most of the side chains curled into a mushroom shape). In addition, the rotation radius of PAA-g-PALS (7.8 nm) was significantly larger than PAA-g-HPEG (7.1 nm) due to the large amount of —SO₃^- with strong electrostatic repulsion.

Part of the backbone of PAA-g-HPEG was adsorbed to the particles (the side chains curl and wrap the backbone), while PAA-g-PALS was adsorbed to the substrate surface by the "flat" mode of the individual side chains (the backbone and other side chains extend into the solution). Compared with PAA-g-HPEG, the binding point of sulfation modified PCE and the substrate is relatively scattered and increases the binding surface with the substrate, which is consistent with the calculation of binding force PAA-g-PALS (174.3 kJ/mol)> PAA-g-HPEG (134.5 kJ/mol).

The vertical heights of the individual PAA-g-HPEG and PAA-g-PALS molecules on the substrate surface were 6.8 nm and 19.7 nm, respectively, and the coverage rate was 26.4% and 21.2%, respectively. When considering the polymer cross-dimensions parallel and perpendicular to the particle surface, the penetration volume formed by PAA-g-PALS on the substrate surface increased by 132.64% relative to PAA-g-HPEG.

Conclusions

The main conclusions of this paper are summarized as following. PAA-g-HPEG and PAA-g-PALS tend to be comb and network conformations in cement slurry environment, respectively. Sulfonated modification dispersed the distribution of binding points between PCE and the substrate, improved the binding force between PCE and the substrate, extended the polymer far away from the substrate, and significantly increase the permeability volume (by about 132.64%). The present results not only provide new insights into the action mechanism of PCE at the atomic level, but also provide a theoretical basis for promoting the development of high performance cement-based materials.

Key words

polycarboxylate superplasticizer / sulfonation modification / adsorption / interface / molecular dynamics simulation

引用本文

管佳男, 刘少静, 刘晓, 朱海堂. 磺化改性聚羧酸减水剂吸附行为的分子动力学模拟. 硅酸盐学报, 2024 , 52 (10) : 3283 -3290 . DOI: 10.14062/j.issn.0454-5648.20240124

Jianan GUAN, Shaojing LIU, Xiao LIU, Haitang ZHU. Molecular Dynamics Simulation of Adsorption Behavior of Sulfonation Modification of Polycarboxylate Superplasticizer[J]. Journal of the Chinese Ceramic Society, 2024 , 52 (10) : 3283 -3290 . DOI: 10.14062/j.issn.0454-5648.20240124

基金

收起

国家自然科学基金青年基金项目(52302020)
国家自然科学基金面上基金项目(52372020)
河南省高等学校重点科研项目(24A560004)
河南省科技攻关项目(242102230138)

参考文献

收起

文献

收起

参考文献引证文献

排序方式：

2024年第52卷第10期

PDF下载

引用本文

BibTeX

文章信息

doi: 10.14062/j.issn.0454-5648.20240124

接收时间：2024-02-11
首发时间：2026-10-22
出版时间：2024-10-20

补充材料

相关文章

文章信息

作者

出版历史

收稿日期：2024-02-11
修回日期：2024-04-18

基金

国家自然科学基金青年基金项目(52302020)

国家自然科学基金面上基金项目(52372020)

河南省高等学校重点科研项目(24A560004)

河南省科技攻关项目(242102230138)

作者信息

^1．河南工程学院土木工程学院，郑州 451191

^2．北京工业大学材料科学与工程学院，北京 100124

参考文献

分享链接

https://castjournals.cast.org.cn/joweb/gsyxb/CN/10.14062/j.issn.0454-5648.20240124

分享至

全文二维码

扫描看全文

引用本文

BibTeX

本文的引用情况

2种不同金属材料的力学参数

科 Family	属数 Number of genus	种数 Number of species	占总种数比例 Percentage of total species (%)	属 Genus	种数 Number of species	占总种数比例 Percentage of total species (%)
鹅膏菌科Amanitaceae	2	11	5.26	鹅膏菌属 Amanita	10	4.78
小菇科 Mycenaceae	2	12	5.74	丝盖伞属 Inocybe	5	2.39
多孔菌科 Polyporaceae	8	14	6.70	蜡蘑属 Laccaria	5	2.39
红菇科 Russulaceae	3	23	11.00	小皮伞属 Marasmius	6	2.87
				小菇属 Mycena	11	5.26
				光柄菇属 Pluteus	5	2.39
				红菇属 Russula	17	8.13
				栓菌属 Trametes	5	2.39

关闭全屏

BibTeX
EndNote
RefWorks
TxT