Preparation of high diameter-thickness ratio thin-layer phlogopite-vermiculite nano-functional material by liquid phase exfoliation

Abstract A high expansion factor expanded vermiculite (HEV-M/HEV-R) was prepared by chemical microwave/calcining method based on the inlaid structure of phlogopite, hydrophlogopite and vermiculite in the industrial vermiculite from Yuli, Xinjiang. And the thin-layer phlogopite-vermiculite nanosheet (TPVN) was prepared from HEV by high speed homogenizer shear pretreatment-ultrasonic exfoliation method. The exfoliability difference of HEV-M/HEV-R in the process of liquid phase ultrasonic exfoliation was revealed by comparative study. The experimental results show that HEV with sufficient lamination and high expansion factor had good exfoliation property, which could be exfoliated well by liquid phase exfoliation method and the exfoliability of expanded vermiculite was positively correlated with the expansion factor, and HEV-R were easier to exfoliate than HEV-M. No damage was caused to the TPVN structure by shear pretreatment and ultrasonic peeling, and the sample showed obvious lamellar structure, with a diameter of 0.3–1 μm, a thickness less than 10 nm, and a maximum diameter-thickness ratio of 128 times. The thermal stability of TPVN was the same as that of industrial vermiculite, and the mass loss rate of TPVN was lower than that of raw Verm sample, which shows that TPVN was fully exfoliated and its crystal layer stacking was not obvious. Most of the TPVN samples were structurally intact and had no obvious defects. Such as high diameter-thickness ratio and high specific surface area, based on the advantages of TPVN, more complex self-assembled nanostructures can be designed to realize the diversified applications of vermiculite in different fields.