Exfoliation of layered double hydroxides by use of zwitterionic surfactants in aqueous solution

Abstract

A new strategy to exfoliate inorganic layered double hydroxide (LDH) solids to micrometer-sized and positively-charged nanosheets in aqueous solution is presented. The procedure involves intercalation of zwitterionic surfactant into the decarbonated LDH by ion exchange, followed by simply stirring the surfactant-intercalated LDH in an aqueous solution of pH = 2. Since the charge of zwitterionic surfactant can be varied from anionic to cationic by adjusting the pH, the zwitterionic ions present in the interlayer were converted to cationic at pH = 2, resulting in the exfoliation of LDH by electrostatic repulsion. The delaminated LDHs nanosheets were confirmed by XRD, TEM, and AFM analyses. This simple method did not need reflux at high temperature, overcame the drawback of using organic solvents, and even resulted in a stably colloidal dispersion of nanosheets.

Graphical Abstract

Keywords:

• Exfoliation
• LDH
• intercalation
• nanosheet
• zwitterionic surfactant

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

We are grateful for the financial support from the Startup fund for doctoral scholars of Taiyuan University of Science and Technology (No. 20142042), Coal-based key Science and Technology Development Program of Shanxi (MJH2014-12), and National Natural Science Foundation of China (No. 21673132)