Work

Microscopic Distribution of Quaternary Ammonium Salt Organic Modifiers in the Interlayer Space of Montmorillonite: Molecular Simulation Study

Year: 2025

Type: article

Abstract: This study employs molecular dynamics simulations to construct designed unit cells of organic montmorillonite (OMMT) modified with four types of quaternary ammonium salts. The effects of modifier type and quantity on the basal spacing of montmorillonite (MMT) were analyzed. Molecular motion, morphology, interaction energy (Eint), and hydrogen bonding interactions were investigated to elucidate the molecular-level mechanisms between modifiers and MMT. The results indicate that the organic modification of MMT proceeds in three distinct stages: the filled stage, saturated stage, and supersaturated stage. During the filled stage, the basal spacing remains largely unchanged while Eint increases rapidly. In the saturated stage, the basal spacing expands as the growth rate of Eint slows. In the supersaturated stage, the basal spacing continues to increase while Eint stabilizes. The transition from the filled to saturated stage is governed by the van der Waals space occupied by the modifiers. Within the MMT interlayer, the modifiers adopt a bilayer morphology, with the nitrogen atom heads adhering to the MMT surfaces and the tails self-assembling. These findings provide theoretical insights into the basal spacing expansion and organic modification mechanisms of MMT, thereby facilitating improved material compatibility.

Source: Materials

DOI: 10.3390/ma18102338

Authors: Wenxi Yu, Xijian Yi, Jianwei Yan, Juan Cheng, Siyu Ou, Qiong Xue

Institutions: Hunan University of Technology, East China Jiaotong University, Jinan University

Language: English

Topic: Clay minerals and soil interactions

Subfield: Biomaterials

Field: Materials Science

Domain: Physical Sciences

Open Access status: gold

Estimated APC paid: $3,137

Funder: Natural Science Foundation of Hunan Province