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

•A degradable crosslinker, 4-arm PCL containing a vinyl at the end of each arm, was synthesized.•Thermoset polyHIPE changed into thermoplastic one by degrading its cross-linking structure.•Replacing DVB with 4vPCL caused a much less brittle and friable PS polyHIPE.•The viscous 4vPCL promotes the formation of small voids in polyHIPE.•The polyHIPE could be used to continuously separate oils from a water–oil mixture.