Preparation and characterization of PU/PDA/PPy/Ag flexible film for electric heating

In order to construct a more perfect and uniform conductive network, we use polyurethane (PU) as the substrate, polydopamine (PDA) and polypyrrole (PPy) as the intermediate layer, and silver (Ag) as the outer layer, and combine magnetron sputtering with the three-step method of film scraping, surface grafting, and in situ polymerization, to prepare the PU/PDA/PPy/Ag composite film. The effects of different sputtering times on the properties of PU/PDA/PPy/Ag electrically heated composite films were investigated. Based on the results, the PU/PDA/PPy/Ag composite film exhibits superior electrical conductivity compared with the original PU/PDA/PPy composite film. Optimal electrical and thermal conductivity is achieved with a sputtering time of 120 s. When a voltage of 5 V is applied, the peak temperature of the PU/PDA/PPy/Ag composite film reaches 112°C, which is 31°C higher than that of the PU/PDA/PPy composite film, which only reaches 81°C under the same voltage. At the same time, the mechanical properties of the composite film were significantly improved, with a fracture strength of 6.9 MPa, which has a good potential for application and development value.