Synthesis of Sub-10 nm Two-Dimensional Covalent Organic Thin Film with Sharp Molecular Sieving Nanofiltration

• Published in: ACS applied materials & interfaces Vol. 10; no. 15; pp. 12295 - 12299
• Main Authors: Gadwal, Ikhlas, Sheng, Guan, Thankamony, Roshni Lilly, Liu, Yang, Li, Huifang, Lai, Zhiping
• Format: Journal Article
• Language: English
• Published: United States American Chemical Society 18.04.2018
• Subjects: air; atomic force microscopy; desalination; imines; light microscopy; magnesium sulfate; materials science; molecular weight; nanofiltration; porosity; scanning electron microscopy; seawater; sieving; sodium chloride; transmission electron microscopy; imine bond; Langmuir−Blodgett; separation; two-dimensional (2D) membranes; nanofiltration
• ISSN: 1944-8244; 1944-8252; 1944-8252
• DOI: 10.1021/acsami.7b19450

We demonstrated here a novel and facile synthesis of two-dimensional (2D) covalent organic thin film with pore size around 1.5 nm using a planar, amphiphilic and substituted heptacyclic truxene based triamine and a simple dialdehyde as building blocks by dynamic imine bond formation at the air/water interface using Langmuir–Blodgett (LB) method. Optical microscopy (OM), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and atomic force microscopy (AFM), all unanimously showed the formation of large, molecularly thin and free-standing membrane that can be easily transferred on different substrate surfaces. The 2D membrane supported on a porous polysulfone showed a rejection rate of 64 and 71% for NaCl and MgSO4, respectively, and a clear molecular sieving at molecular size around 1.3 nm, which demonstrated a great potential in the application of pretreatment of seawater desalination and separation of organic molecules.