Efficient electromagnetic interference shielding of three-dimensional hydrophobic Cu/wood/Cu porous composites

Three-dimensional hydrophobic and efficient electromagnetic shielding Cu/wood/Cu laminated composites were prepared by a simple one-step electroless Cu process. The number of electroless Cu on wood surface and the treatment time of electroless Cu were used as variables. The effects of independent variables in the range from 0.3 ×10−3 to 3.0 GHz (L-band) on the conductivity, water contact angle and electromagnetic shielding effectiveness of the composite were analyzed. The Cu particles are fully filled in the wood hierarchical porous structure, and the metal coating uniformly covers the entire wood surface. After three times of electroless Cu, the conductivity of the composite can reach 7255 S/cm, the contact angle is 130.8° when the time is 12 min, showing good hydrophobic properties, and the average electromagnetic shielding effectiveness is as high as 96 dB. Compared with the L-band (94 dB), the twice electroless sample has a maximum shielding effectiveness of 85.6 dB in the X-band (8.2-12.4 GHz), which can shield a large number of incident electromagnetic waves to achieve high absorption and low reflection. The anisotropic internal porous structure of wood matrix and the multi-interface polarization between wood and Cu are the main reasons for the effective electromagnetic interference shielding performance of Cu/wood/Cu laminated composites.