Repeatable oil-water separation with a highly-elastic and tough amino-terminated polydimethylsiloxane-based sponge synthesized using a self-foaming method.

A 3D porous sponge based on amino-terminated polydimethylsiloxane (PDMS) and graphene oxide (GO) was prepared using a simple one-pot method under mild conditions. Condensing agents combined GO and PDMS with covalent bonds, and simultaneously acted as the pore-foaming agents. Scanning electron microscopy and Mercury intrusion porosimetry revealed that the joint action of GO and condensing agents contributes to the formation of the porous structure. Cyclic compression demonstrated high toughness and elasticity. No deformation occurs after 20 compression cycles at over 80% strain, owing to the assistance of dynamic hydrogen bonds. GO content significantly influences the mechanical strength, hydrophobicity, as well as adsorption capacity for oil. Notably, the sponge can be repeatedly used with a simple squeezing method, and the adsorption capacity can still reach 96.30% of the first adsorption after 30 cycles of adsorption. Besides, the sponge was used to adsorb oil on the seawater surface experimentally. The stable structure, high mechanical strength, and excellent adsorption property suggest the sponge be a promising material for the treatment of oil leakage and oily wastewater purification in practice. This self-foaming method can be a common method for fabricating porous and stable porous materials.

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