Superhydrophobic covalent organic frameworks prepared via nucleophilic substitution reaction for effective oil/water separation

Oil-spill accidents have caused great loss of valuable natural resources to marine ecosystems. Thus, it is highly desirable to develop an efficient and environment-friendly approach for oil/water separation. Herein, we report a bottom-up strategy for the synthesis of superhydrophobic covalent organic frameworks (COFs) and show an in situ growth approach for the fabrication of COF-functionalized foam. 2,5-dihydroxyterephthalaldehyde (Da) is first modified with octyl to form superhydrophobic monomer Da-octyl via nucleophilic substitution reaction. Da-octyl was then condensed with 1,3,5-(1,3,5-Triazine-2,4,6-triyl)trianiline (Tz) to synthesis a superhydrophobic COF TzDa-octyl. TzDa-octyl can be used in complex environment due to the high thermal and chemical stability. Besides, TzDa-octyl can be in situ growth on the melamine foam for oil/water separation. The prepared foam exhibits high adsorption capacity and good reusability for oil/water separation. This work not only offers a strategy for the construction of functional COFs, but also opens an avenue for the growth of COFs on different substrates for oil/water separation.