Fluorinated Graphene Thermally Conductive Hydrogel with a Solid–Liquid Interpenetrating Heat Conduction Network

Hydrogels with excellent mechanical flexibility are widely used in flexible electronic devices. However, it is difficult to meet further applications of high-power integrated flexible electronics as a result of their low thermal conductivity. Herein, highly thermally conductive composite hydrogels with a solid–liquid interpenetrating thermal conductivity network are constructed by aromatic polyamide nanofibers (ANF) and fluorinated graphene (FG) reinforced poly(vinyl alcohol) (PVA) and cross-linked by tannic acid (TA) solution immersion to obtain a hydrogel with a double cross-linked network. The PVA–ANF–FG3T-11.1% composite hydrogel exhibits good mechanical properties compared to PVA–ANFT, with a tensile modulus of up to 0.89 MPa, a tensile strength of up to 1.23 MPa, and an energy of rupture of up to 3.45 MJ cm–3, which is mainly attributed to the multihydrogen bonding interactions in the composite hydrogel. In addition, the friction coefficient of the PVA–ANF–FG3T-11.1% composite hydrogel is 0.178, making it suitable for use in high-friction coefficient applications. The thermal conductivity of the PVA–ANF–FG3T-11.1% composite hydrogel is 1.42 W m–1 K–1, which is attributed to the synergistic effect of the solid thermal conductivity network and the liquid convection network, resulting in a high thermal conductivity of the composite hydrogel. The high thermal conductivity of the PVA–ANF–FG3T-11.1% composite hydrogel shows great potential for flexible wearable electronics and cooling paste applications.