Fig. 2.

Formation of PVA hydrogel films on swelling PAAm substrates. (A) Schematic representation of the experimental protocol: (i) a dry PAAm substrate is immersed in a PVA aqueous solution; (ii) the PAAm substrate swells inducing the formation of a PVA hydrogel film (dark red); (iii) the sample is collected and rinsed in water; (iv) the PVA hydrogel film can be peeled off from the swollen PAAm substrate. (B) Peeling of a PVA hydrogel film after 3-h immersion in a 15 wt% PVA aqueous solution. (C and D) Stability in water of the same films as in B: right after fabrication (C and D, Left) and after storage at 20 °C for 1 wk (C, Right) or after storage at 90 °C for 1 h (D, Right). (Scale bar: 1 cm.)