Drilling by light: ice-templated photo-patterning enabled by a dynamically crosslinked hydrogel

Dynamic covalent polymer networks exhibit a unique stress relaxation behavior under mechanical deformation, which enables sophisticated shape manipulation in addition to their widely recognized capabilities of self-healing and thermoset recycling. Here we present an unusual ice-templated photo-patterning technique employing a disulfide-crosslinked hydrogel capable of photo-induced network rearrangement. First, freezing creates internal mechanical stress since the resulting ice crystals squeeze the polymer chains. Secondly, spatio-temporal UV light irradiation at this frozen state leads to localized stress relaxation via disulfide bond exchange. At the last step, subsequent ice melting leads to pore patterns, the porosity of which can be controlled by the light dosage. Taking advantage of the stimuli-responsiveness of the hydrogel, one single patterned sample is used as an adaptive stamp to produce multiple functional devices (e.g. antenna).