Preparation of porous PTFE/C composite foam and its application in gravity‐driven oil–water separation

Porous superhydrophobic filtration media with durable performance that can be used in harsh environments remain an urgent requirement. Here, we designed and prepared a porous polytetrafluoroethylene (PTFE)/C composite foam derived from PTFE/glutaraldehyde‐crosslinked poly(vinyl formal) foam via a method of low‐temperature in situ carbonization by the combination of sintering in nitrogen atmosphere and oxygen atmosphere. The as‐prepared porous PTFE/C composite foam had an interconnected macropore structure and wettability of superhydrophobicity. Meanwhile, the porous skeleton of the PTFE/C composite foam showed a skin–core microstructure with the functional skin layer of PTFE continuous phase and the support core of PTFE and carbon in situ composite phase. The PTFE functional layer was anchored to the support composite layer in a root‐like branching, which endows the porous PTFE/C composite foam with an extremely durable performance. In gravity‐driven oil–water separation, the porous PTFE/C composite foam achieved considerable oil flux (from 27 174 to 73 242 L h−1 m−2) and purity (as high as 99.83 wt%). Meanwhile, the porous PTFE/C composite foam presented resistance to strong acids, strong alkalis, chemical solvents and friction. Even after it had been mechanically damaged, the superhydrophobic properties of the foam were not degraded. The as‐prepared porous PTFE/C composite foam showed great potential in all kinds of harsh environments. © 2021 Society of Industrial Chemistry. The PTFE functional layer of a porous PTFE/C composite foam skeleton was anchored to the support composite layer in a root‐like branching.