fig3

Figure 3. SEM results of freeze-dried materials and hydrogels (A) GO; (B) rGO; (C) rGO/PDA; (D) pure PVA; (E) PDA-PVA; and (F) rGO/PDA-Gly-PVA. Gly: glycerol; PDA: polydopamine; PVA: polyvinyl alcohol; rGO: reduced graphene oxide; SEM: scanning electron microscopy.