Fabrication of emulsion-templated polystyrene absorbent using 4-arm star-shaped poly(ε-caprolactone) as property defining crosslinker

PolyHIPEs prepared by polymerizing high internal phase emulsions (HIPEs) normally have a cross-linked structure, with the cross-linking providing the mechanical stability to maintain the porous structure and prevent collapse during cure and uses. The most widely investigated polyHIPE (i.e., polystyrene (PS) polyHIPE) is cross-linked with divinylbenzene (DVB), making them rigid, brittle, and environmentally unfriendly. To address this issue, tough and recyclable PS based polyHIPEs are prepared in this work using 4-vinyl-arm star-shaped poly (e-caprolactone) (4vPCL) as property defining cross-linker. Comparing poly(S-co-DVB) polyHIPE, the poly(S-co-4vPCL) polyHIPE is much less brittle and friable, with its impact strength up to 3 times higher. The viscous 4vPCL promotes the formation of small voids in polyHIPEs. Moreover, the polyHIPEs are soluble in organic solvent after the PCL segments were degraded, suggesting that the cross-linking could be removed and the polymers are eventually recyclable. On this basis, the porous polymers could be used to continuously separate oils from the water-oil mixture. When it is used as oil absorbent, it has full preservation of both the porous morphology and the absorption capacity in the performed ten absorption/desorption cycles.

Automated summary

In this study, tough and recyclable PS based polyHIPEs were prepared using 4-vinyl-arm star-shaped poly (e-caprolactone) as the cross-linker, showing improved mechanical properties and 3 times higher impact strength compared to traditional PS/DVB cross-linked PolyHIPEs. By removing the cross-linker, the PolyHIPEs can be recycled, and they exhibit excellent oil absorption performance when used as oil absorbents.