Figure 1.

PAAm hydrogel and its experimental setup for thermal conductivity measurement. (a) Optical image of the as-prepared PAAm hydrogel sample; (b) Schematic of the polymer network with covalent crosslinking through MBAm (green circles) and the molecular structures of the covalently crosslinked polymer chains; (c) Schematic of 3ω method setup for thermal conductivity measurement of hydrogels. A platinum wire is deeply immersed in hydrogels and wired out with four copper probes for applied current and voltage measurements. The four brown rods are copper probes and the white line in hydrogel is the Pt wire; (d) Schematic of 3ω method for thermal conductivity measurement of hydrogels at different water contents and temperatures. The four Au squares (2 mm in length) on a 1 mm thick glass substrate serve as both the heater and thermometer.