Page 39 - Read Online

Page 10 of 28 Zhang et al. Soft Sci 2024;4:39 https://dx.doi.org/10.20517/ss.2024.34

Figure 5. Bio-inspired design for the enhancement of water retention and conductivity. (A and B) Skin-inspired double-hydrophobic
coating [86] ; (C and D) A self-lubricating spinning method for hydrogel fibers with ionic cross-linking and crystalline structures inspired by
spider silk [87] ; (E and F) Skin-inspired biogel for water retention and ionic conductivity [88] .

3+
hydrogels were first immersed in FeCl . The Fe ions diffused into the gel matrix and interact with carboxyl
3
groups to form the cationic domains. Due to the large ionic radius of Fe , a dense cross-linked polymer
3+
3+
network formed through diffusion within the hydrogel. As swelling time increases, Fe gradually
restructured and optimized the network. As a result, it became a tough double-network hydrogel with a soft
core and hard shell structure, which can significantly enhance its anti-swelling and mechanical properties.
As shown in Figure 6D and E, Li et al. reported a conductive hydrogel with excellent anti-swelling
properties and biocompatibility. In the hydrogel, PVA and cellulose nanofibers (CNF) were used as
biocompatible polymer matrices and nanofiber-reinforced fillers, respectively . The PEDOT:PSS was used
[90]
as the conductive material. With the combination of uniaxial pre-stretching and drying/rehydration
processes, dense polymer chains were formed by PVA, CNF, and PEDOT. The dense hydrogen bonds and
crystalline domains effectively resist water. Therefore, the hydrogel shows excellent anti-swelling properties.