Design and characterization of porous double‐network hydrogels (PDNs). a) PDNs can be used for tissue repair and perfusion devices. They form a tough matrix with micropores in situ in a cytocompatible fashion. b) Thermal gelation kinetics of PDN mixture when the temperature is raised from room temperature (R.T.) to 37 °C. c) Storage moduli and d) half‐life time of stress relaxation (τ
1/2) of NSN, PSN, and PDNs. e) Confocal images (top) and fluorescent signal distribution (bottom) of hydrogels containing FITC‐labeled chitosan and glycol–chitosan, showing the network configurations. f) Pore size and g) porosity of NSN, PSN, and PDNs. Sample size, N = 4; ** represents P < 0.01, *** P < 0.001, **** P < 0.0001, n.s. represents P ≥ 0.05.