Effect surface micro-wrinkles and micro-cracks on microwave shielding performance of copper-coated carbon nanotubes/polydimethylsiloxane composites

Surface where microwaves reach firstly is significantly important on microwave shielding. However, the construction of surface multiple structure to enhance microwave shielding property is still a great challenge. Herein, conductive micro-cracks and micro-wrinkles are designed on surface of flexible copper/polydimethylsiloxanecarbon nanotubes to enhance excellent shielding performance. The surface microstructures can be tuned by controllably tailoring the carbon nanotube (CNT) concentration, substrate thickness, and pre-stretching strain before copper sputtering deposition. At the same thickness and CNT content, the amount of micro-cracks and micro-wrinkles grows as pre-stretching strain increases, which effectively boosts specific surface area and microcapacitance effect on the surface, thus enhancing the electromagnetic wave shielding effectiveness of the composites. Meanwhile, the micro-cracks can cause the surface conductivity to be considerably orientated, which in turn severely affected the field distribution and conduction losses on the surface of the composites. Furthermore, the experimental and simulation results are consistent concerning the effect of surface micro-cracks and microwrinkles on microwave shielding performance.