Assembled block copolymer stabilized high internal phase emulsion hydrogels for enhancing oil safety

Accidental spills and subsequent fires during oil storage and transportation periods cause serious damage to environments. Herein, we present a novel route to enhance oil safety by transforming oils into high internal phase emulsion (HIPE) hydrogels. These HIPE hydrogels are stabilized by solvent- or pH-driven assembled block copolymer (BCP), namely poly(4-vinylpyridine)-block-poly(ethylene glycol)-block-poly(4-vinylpyridine) (4VPm-EGn-4VPm). The assembled BCP shows high efficiency to stabilize HIPE hydrogels with a low concentration of 1.0 (w/v) % relative to the continuous aqueous phase. The volume fraction of the dispersed organic phase can be as high as 89% with a variety of oils, including toluene, xylene, blended vegetable oil, canola oil, gasoline, diesel, and engine oil. These smelly and flammable liquids were formed into HIPE hydrogels and thus their safety was enhanced. As the assembly is pH sensitive, oils trapped in the HIPE hydrogels can be released by simply tuning pH values of the continuous aqueous phase. The aqueous phase containing BCP can be reused to stabilize HIPE hydrogels after naturalization. These assembled BCP stabilized HIPE hydrogels offer a novel and safe approach to preserve and transport these smelly and flammable liquid oils, avoiding environmental damage.