Difference in the preparation of two-dimensional nanosheets of montmorillonite from different regions: Role of the layer charge density

Montmorillonite (MMT), having special property of hydration expansion, can be easily exfoliated into twodimensional (2D) nanosheets, which are the promising blocks for making multifunctional nanocomposites. In this work, the exfoliation performances of MMTs from different region including Inner Mongolia (IM), Zhejiang (ZJ) and Liaoning (LN) were investigated from the perspective of layer charge density. All the MMTs were prepared as Na-MMTs first to avoid the effect of the interlaminar ion. Atomic force microscope (AFM) measurements indicated that the exfoliation performance increased as: IM-MMT < ZJ-MMT < LN-MMT. Alkyl ammonium ion exchanged method was applied to study the layer charge density of the MMTs. It was found that the exfoliation performance decreased with the layer charge density of MMT increased. The characterizations of zeta potential, swelling index and BET specific surface area were used to reveal the effects of layer charge density on the exfoliation performance of MMT. The results showed that with increasing the layer charge density, MMT was with more negative zeta potential, thus leading to the stronger binding forces between the layers. The swelling index of LN-MMT was the highest who had the lowest layer charge density, demonstrated by the largest

Automated summary

The study revealed that the exfoliation performance of montmorillonite decreases as its layer charge density increases, leading to a more negative zeta potential and stronger binding forces between the layers.