Noncovalent modification of self-assembled functionalized COF by PNIPAM and its properties of Pickering emulsion

Based on a facile and universal method using noncovalent bonding, here, polymer-modified covalent organic framework materials (COFs) were rapidly prepared. PNIPAM-modified COF (COF-PNIPAM) was synthesized by electrostatic self-assembly between COF prepared by low-cost melamine and terephthalaldehyde and carboxyl-terminated poly(N-isopropylacrylamide) (PNIPAM) prepared via reversible addition-fragmentation chain transfer polymerization. The carboxyl-terminated PNIPAM was characterized by Gel Permeation Chromatography and Ultraviolet and Visible Spectroscopy (UV–vis). COF and COF-PNIPAM were characterized by Fourier Transform Infrared Spectroscopes, Scanning Electron Microscope, Transmission Electron Microscope, X-Ray Diffractomer (XRD), and Brunner-Emmet-Teller (BET) measurements. The results showed that the COF-PNIPAM was successfully prepared. The Pickering emulsion properties of the COF-PNIPAM in a water-to-toluene mixed system were studied, and when the water-to-oil ratio is 2:1, a stable emulsion can be obtained. However, the results show that the PNIPAM chains of COF-PNIPAM nearly lose their temperature responsiveness.