## 4 Conclusions  
In summary, the superhydrophobic GN\({}_{4}\)/PSt composite material with micro-nanopore structures was successfully fabricated using a facile, low-cost HIPE polymerization method. Compared with a neat porous material prepared with only PSt, the porous monolith prepared with 4 wt% GN was more hydrophobic (WCA increased from 140.5 \(\pm\) 0.7\({}^{\circ}\) to 150.9 \(\pm\) 0.6\({}^{\circ}\)) and more flexible. Due to the ideal wettability, excellent mechanical properties and high porosity (97.2%), the GN\({}_{4}\)/PSt composite monolith could be used to continuously separate immiscible oil/water mixtures with a separation efficiency above 99.6%. Arising from the lengthy micro-nanopore permeation path, the GN\({}_{4}\)/PSt enable efficient and continuous separation of surfactant-stabilized water-in-oil microemulsions. The special wettability, hierarchical pore structure with micro-nanopore and tortuous permeation channel play the significant roles in emulsion separation. The superhydrophobic GN\({}_{4}\)/PSt composite material prepared here showed great performance for the efficient and continuous separation of immiscible and emulsified oil/water mixtures and has promising application prospects in the practical large-scale treatment of oily wastewater.  
The following supporting information can be downloaded at: [[https://www.mdpi.com/article/10.3390/polym14112289/s1](https://www.mdpi.com/article/10.3390/polym14112289/s1)]([https://www.mdpi.com/article/10.3390/polym14112289/s1](https://www.mdpi.com/article/10.3390/polym14112289/s1)), Figure S1. Raman spectra of GN and GN4/PSt; Figure S2. The pore size distribution of GN4/PSt porous material.; Figure S3. (a) The process of removal of petroleum ether from oil/water mixture and the regeneration of the foam. (b) Regeneration of GN4/PSt sponge during the absorption of petroleum ether for 10 cycles.; Video 1: Continuous separation of immiscible light oil/water/heavy oil by GN4/PSt porous material with the assistance of a pump.; Video 2: Continuous separation of surfactant-stabilized water-in-oil microemulsions with the assistance of a pump.  
Conceptualization, C.Z. and Y.L.; methodology, H.H.; software, D.X. and Y.W.; validation, H.H. and J.L.; formal analysis, H.H., D.X. and Y.W.; investigation, H.H.; resources, C.Z. and M.Q.; data curation, H.H.; writing--original draft preparation, H.H.; writing--review and editing, C.Z. and Y.L; visualization, H.H. and G.W.; supervision, C.Z. and Y.L.; project administration, C.Z., H.H. and Y.L.; funding acquisition, C.Z and M.Q. All authors have read and agreed to the published version of the manuscript.  
Figure 8: Separation efficiency of water-in-oil emulsions.  
**Funding:** This work was supported by the Science and Technology Strategic Cooperation Special Project of Nanchong City and SWPU (SXHZ046), and the Innovation and Entrepreneurship Training Program for College Students of Sichuan Province (S202110615095).  
**Institutional Review Board Statement:** Not applicable.  
**Informed Consent Statement:** Not applicable.  
**Data Availability Statement:** Not applicable.  
**Conflicts of Interest:** The authors declare no conflict of interest.