Facile and scalable fabrication of superhydrophobic and superoleophilic PDMS-co-PMHS coating on porous substrates for highly effective oil/water separation

Superhydrophobic/superoleophilic (SHBOI) porous materials have attracted significant interest in the field of oil/water separation, however, fabricating SHBOI porous materials though a low cost, one-step and simple strategy is still a great challenge. In this work, a facile approach is developed for scaling the production of SHBOI porous materials by the deposition of SHBIO PDMS-co-PMHS coating onto porous materials via a facile surface coating method without the use of nanoparticles and fluorinated compounds. Meanwhile, the PDMS-co-PMHS coating is constructed by hydrosilylation reaction between vinyl bonds of vinyl-terminated-poly(dimethylsiloxane) (VPDMS) and silicon-hydrogen bond of trimethylsilyl-terminated-poly-(dimethylsiloxane)-co-polymethylhydrosiloxane (TPDMS-co-PMHS), and simultaneously attached on various porous substrates including sponge (SP), fiber paper (FP), glass fiber (GF) membrane, etc. As a result, PDMS-co-PMHS coating provides SHBOI and excellent oil/water separation characteristics to the porous substrates. According to the results, PDMS-co-PMHS@SP possesses SHBOI characteristics, high oil-adsorption capacity (up to 143 times its original weight) and excellent recyclability. PDMS-co-PMHS@FP can efficiently separate a series of immiscible oil/water mixtures in a single-step based on its high oil or organic solvents fluxes (about 2000-3000 L.m(-2).h(-1)) and SHBOI characteristics. In addition, PDMS-co-PMHS@GF membrane exhibits great water rejection (similar to 99.90%) for separating water-in-oil emulsions under gravity-driven condition. Thus, a new strategy employing PDMS-co-PMHS as a coating material to modify porous substrates has great potential for developing a scalable method of fabricating SHBOI porous materials for oil/water separation.