a) SEM imaging on the surface and sectioning of uncoated PU, superglue and DURA-Z coated substrates (scale bar = 100 μm), b) water contact angles on bare PU, superglue and DURA-Z coated substrates, c) IR spectra of bare PU surface, superglue coated PU surface, DURA-Z coated surface and zwitterionic PCBAA hydrogel surface, and d) illustration of the formation of DURA-Z coating.