Issue 32, 2020

Rapid and high-concentration exfoliation of montmorillonite into high-quality and mono-layered nanosheets

Abstract

After montmorillonite (MTM) was first exfoliated into nanosheets as a reinforcing filler in the 1980s, layered clay became a hotspot of interest. However, to date, the exfoliation of the resource-rich and inexpensive layered MTM into high-quality nanosheets still remains a significant challenge. Herein, a simple and effective strategy to exfoliate layered MTM into mono-layered sheets via the aggregation of polyethyl–phosphate glycol ester (Exolit OP 550) is proposed. A significant decrease in exfoliation time from 120 min to 3 min was observed at room temperature only via a gentle stirring process. Moreover, various factors that reduce the viscosity of the mixture could be utilized to boost the exfoliated concentration to a record high value of 100 wt%, which is an increase of 460–2400% compared with that in other works. A tentative model was also proposed to illustrate the exfoliation mechanism based on the detection of segmental confined movement, structural evolution, and polymer-clay interaction. Particularly, the as-observed critical concentration of 200 wt% MTM indicated a saturation effect for the surface-adsorbed polymer. The critical concentration for the onset of exfoliation was 150 wt%. In addition, the structure of the exfoliated nanosheets in Exolit OP 550 underwent a temperature-sensitive and irreversible transformation. Thus, our study may provide new insight for the exfoliation of clay.

Graphical abstract: Rapid and high-concentration exfoliation of montmorillonite into high-quality and mono-layered nanosheets

Supplementary files

Article information

Article type
Paper
Submitted
14 Jun 2020
Accepted
31 Jul 2020
First published
31 Jul 2020

Nanoscale, 2020,12, 17083-17092

Rapid and high-concentration exfoliation of montmorillonite into high-quality and mono-layered nanosheets

Z. Ding, J. Li, B. Zhang and Y. Luo, Nanoscale, 2020, 12, 17083 DOI: 10.1039/D0NR04514D

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