Figure 1: SEM micrographs of the surface sections of PVA hydrogel and PVA with additives: ((a1), (b1)) IPN1 with 15% w/v PVA; ((a2), (b2)) IPN2 with 2% w/v gelatin; ((a3), (b3)) IPN3 with 5% w/v gelatin; ((a4), (b4)) IPN4 with 7% w/v gelatin; after 1 and 3 of freezingthawing cycles, respectively. Scale bar (a1)–(a4): 100 (μm); (b1)–(b4): 50 (μm). 
