Flexible and thin multifunctional waterborne polyurethane/Ag film for high-efficiency electromagnetic interference shielding, electro-thermal and strain sensing performances

With the rapid development of the flexible electronics industry, the range of multifunctional applications of materials has become extensive. But it is still a challenge to apply flexible materials to different fields while ensuring corresponding performance. Herein, a simple and available approach is addressed to fabricate conductive polymer composite films supported on Ag flakes and waterborne polyurethane (WPU) by spraying. The WPU/Ag films with uniform structure show outstanding flexibility and electromagnetic interference shielding effectiveness of 68.9 dB with thickness of only 50 μm, and could sustain a high standard even undergoing excessive mechanical deformations. Besides, the resulted films possess prominent electro-thermal effect, which can achieve a temperature of over 120 °C by applying a low voltage of 2 V, and the heat can be dissipated rapidly along with the connecting Ag network. Moreover, it shows a high gauge factor (229.2), good durability and reproductivity (over 1000 cycles), and rapid response time to strain (50 ms), which can be potentially used in the field of human movement monitoring and wearable electronic devices. These results indicate the multifunction of the WPU/Ag film, which could widen its practical applications after the corresponding treatment.