Ethyl cellulose/carbonized spent coffee ground-based biocomposites for superior hydrophobicity and electric protection performance

Endowing naturally-derived electric protection materials with hydrophobicity is required to guarantee their service reliability under harsh environments and eco-friendly disposal. Herein, a conductive biocomposite was designed and fabricated using a melt-processable ethyl cellulose (EC) matrix, and a carbonized spent coffee ground (CSCG) filler with a nitrogen-doped sp² hybridized carbon structure. In terms of functional groups, defects, and crystal structure, CSCG prepared at 1000 °C was the best suited for improving the electrical conductivity and electromagnetic interference shielding effectiveness (EMI SE) of the fabricated composites. The EC composite containing 70 wt% CSCG prepared at 1000 °C exhibited an electrical conductivity of 6.79 × 10¹ S/m, an EMI SE/thickness of 13.2 dB/mm, and a water contact angle of ∼ 104°. Therefore, the material design strategy used in this study can provide insight into the development of naturally-derived electric protection materials with hydrophobicity.