fig2

Figure 2. Preparation of different types of polyelectrolyte-based conductive hydrogels. (A) Schematic diagram of the preparation of agar/NaCl/polymerizing polyacrylamide (PAM) ionic DN hydrogels^[32]. (B) Schematic and mechanism of preparing final hydrogels (polymerizing AA-DMAEMA monomers/polymerizing AMPS-DMAEMA monomers/2,2-diphenyl-2H-naphtho [1,2-b] pyran-6-carbaldehyde) (PAD/PMD/DNPC) by free-radical polymerization of AMPS, AA and DMAEMA in deionized water at room temperature^[35]. (C) Schematic illustration of preparation procedures of densified hydrogen-bonded Fe/CTS/PAA hydrogel (DHB-Fe/CTS/PAA) through hydrogel network constrained polymerization and hydrogen-bonded network densification processes^[36]. (D) Schematic of physical hydrogels composed of polyampholytes. (i) Illustration of polyampholyte networks with ionic bonds of different strengths. The strong bonds serve as permanent crosslinking points and the weak bonds act as reversible sacrificial bonds that rupture under deformation. (ii) Chemical structures of monomers used in this work. Cationic monomers: 3-(methacryloylamino) propyl-trimethylammonium chloride (MPTC), N-dimethylamino ethylacrylate (DMAEA-Q); anionic monomers: sodium p-styrenesulphonate (NaSS), AMPS^[39]. (A) Reproduced with permission^[32]. Copyright 2019, Elsevier. (B) Reproduced with permission^[35]. Copyright 2022, Elsevier. (C) Reproduced with permission^[36]. Copyright 2021, Elsevier. (D) Reproduced with permission^[39]. Copyright 2013, Springer.