High toughness and strong electromagnetic shielding properties of PAM/PEG dual network hydrogels

With the wide application of electromagnetic wave, a high performance electromagnetic shielding material is urgently needed to solve the harm caused by electromagnetic wave. Complete cross-linking strategy is adopted in this paper. Polyacrylamide (PAM) was synthesized by in-situ polymerization of acrylamide (AM) monomer. The obtained PAM was blended with polyethylene glycol (PEG) to prepare PAM/PEG hydrogels and form rigid support structures. Subsequently, the modified carbon nanotubes (S-CNTs) were incorporated into sodium alginate (SA) and PAM/PEG. Finally, Na⁺ was used to trigger SA self-assembly, which significantly improved the mechanical properties and electrical conductivity of the hydrogels, and prepared PAM/PEG/SA/S-CNTs-Na hydrogels with high toughness and strong electromagnetic interference (EMI) shielding efficiency (SE). The results showed that the compressive strength of PAM/PEG/SA/S-CNTs-Na hydrogel was 19.05 MPa, which was 7.69% higher than that of PAM/PEG hydrogel (17.69 MPa). More encouraging, the average EMI SE of PAM/PEG/SA/S-CNTs-Na hydrogels at a thickness of only 3 mm and a CNTs content of 20wt% was 32.92 dB, which is 113.21% higher than that of PAM/PEG hydrogels (15.44 dB).