Experimental Details

Materials. The PEDOT:PSS (Clevios PH 1000, 1 wt%) aqueous dispersion was purchased from Heraeus. Waterborne polyurethane (PU) was provided by DSM (China). Poly(dimethylsiloxane) (PDMS, Sylgard 184, Dow Corning) prepolymer was prepared by mixing base silicone gel with a curing agent in a 10:1 weight ratio. Dimethyl sulfoxide (DMSO) was purchased from Aladdin Chemistry Co., Ltd., Shanghai, China. Ethyl acetate and hydrochloric acid (HCl) were obtained from Shanghai Lingfeng Chemical Reagent Co., Ltd., Shanghai, China. All reactants were analytical purity and used as received. Deionized (DI) water was used throughout the experiments. Fabrication of G/PEDOT:PSS/PDMS composite The nickel (Ni) foam was cut into desired size followed by soaked in 1M HCl for 15 min, and washed with distilled water. After immersed in ethanol for 1 min and dried at 50 °C for 5 min (0.1 Mpa), the Ni foam was taken out rapidly and put into a horizontal furnace. The furnace was heated to 1000 °C within 100 min under a mixed air source of hydrogen (H2, 200 s.c.c.m.) and argon (Ar, 500 s.c.c.m.), and kept for 5 min to remove a few layers of Ni oxide on Ni surface. Later, methane (CH4) as a carbon source was introduced with a flow rate of 10 s.c.c.m., and the reaction time was controlled between 5 min to 20 min. Then the CH4 was closed and the furnace was cooled to room temperature with the rate of 100 °C/min. Finally, the CVD graphene/Ni foam (GF) was obtained. The waterborne PU was mixed with PEDOT:PSS aqueous solution (with 5 wt% DMSO), and their weight ration was set at 1:5. Then the GF sample was dipped into the prepared solution, and vibrated for 10 min. Afterwards, the sample was dried at 90 °C for 10 min and then taken out to cool to ambient temperature. The fabricated GF/PEDOT:PSS composite was immersed into a dilute PDMS organic solution (a mixture of PDMS base agent, curing agent and ethyl acetate in a ratio of 30:3:100) for 30 min, and followed by thermally curing at 100 °C for 1 h in vacuum. The Ni was etched by ferric nitrate (Fe(NO3)3) solution (1M). Finally, after dried by freeze-drying, the porous CVD graphene/PEDOT:PSS/PDMS (CGPP) was obtained. In this article, porous CVD graphene/PDMS (CGP) was also prepared as a reference sample. The Ni foam/CVD graphene was directly immersed into the dilute PDMS organic solution for 30 min and cured at 100 °C for 1 h in vacuum. After removing Ni by 1M Fe(NO3)3 solution, the CGP was successfully prepared.