Fabrication of superhydrophobic PVDF membrane based on thiol-ene click chemistry reaction for humidification

To improve the air humidification capacity of polyvinylidene fluoride hollow fiber membranes, surface coating method is applied to superhydrophobicly modify the hollow fiber membranes to achieve high performance. Chemical bonds were used as a bridge to connect the membrane and the coating. Silica is loaded on the membrane surface firstly, and then, polyhedral oligomeric silsesquioxane (POSS) and polydimethylsiloxane containing mercapto groups (PDMS) were introduced on the surface of the membrane through the click reaction to build a superhydrophobic surface with a reentrant structure. Then the effect of the content of POSS and PDMS on the humidification performance was explored. The superhydrophobic membrane coated with SiO2-PDMS-POSS was obtained, and the surface contact angle was 156.2°. The modification process occurs only on the outer surface of the hollow fiber membrane and not in the cross-sectional pores of the fiber. Besides, the coating of the modified superhydrophobic membrane exhibited excellent mechanical stability. The reentrant structure produced by nano-SiO2, POSS and the low surface energy of PDMS together gives the composite membrane superhydrophobic characteristics. The results of the humidification experiment shows that the humidification efficiency increased from 48.26 to 58.21%.