Green and Scalable Narrow-Gap Exfoliation of High-Quality Two-Dimensional Vermiculite Nanosheets as Poly (Vinyl Chloride) Thermal Stabilizers

Abstract

Layered vermiculite (VMT) nanosheets have received significant attention as inorganic additives in the field of nanocomposites; however, extremely low yields and efficiencies limit their large-scale utilization. Herein, we develop a narrow-gap exfoliation approach to achieve efficient and industrially scalable production of high-quality VMT nanosheets, where water instead of acid is used as green solvent. As compared with traditional approaches, the synergism between shear and collision overcomes the agglomeration of nanosheets, achieving efficient exfoliation of high-quality VMT nanosheets with a yield value of 82.7–84.9%. The narrow-gap exfoliation equipment is further used as a couple separation reactor for in-situ preparation of VMT-stabilized poly (vinyl chloride), which exhibits superior thermal stability. The aging blackening time and Congo red test time reaches 420 min and 48 min, respectively, which is comparable to the commercial lead-based thermal stabilizers. This work provides a potential strategy for scalable exfoliation of layered materials and opens new applications in in-situ preparation of inorganic-organic nanocomposites.

Keywords: vermiculite nanosheets, narrow-gap exfoliation, coupled separation reactor, thermal stabilizer