Conductive, superhydrophobic, and microwave-absorbing cotton fabric by dip-coating of aqueous silk nanofibers stabilized MWCNTs and octadecanoyl chain bonding

Compared to previously reported methods, we developed a facile dip-coating method to endow cotton fabric (CF) with satisfactory conductivity, superhydrophobicity and microwave absorption performance based on the combination of multi-walled carbon nanotubes (MWCNTs) and hydrophobic octadecanoyl chain bonding. Silk nanofibers (SNFs) derived from silk were adopted as dispersant to prepare individually dispersed MWCNTs via ultrasonication and homogenization processes. The non-covalent functionalization of MWCNTs enabled by SNFs wrapping was superior to organic functionalization, which could keep the carbon backbone of MWCNTs intact and thus preserved their complete electron tube structure and electronic properties. The adhesion of MWCNTs coated to CF (MWCNT-CF) was enhanced via dipping coating and thermal treatment induced chemical immobilization cycles. Octadecanoyl chain-tethered MWCNT-CF (C18-MWCNT-CF) was manufactured by further treatment with stearoyl chloride to achieve superhydrophobicity. Compared with pristine CF (1.04 \(\times\) 10 10 Ω/sq), the C18-MWCNT-CF exhibited excellent conductive property with surface resistivity reaching 55 Ω/sq with the MWCNT loading content of 247.5 mg/g and possessed a relatively greater microwave absorption performance of − 36.08 dB at 9.28 GHz with merely 2.7 mm thickness. Compared with other similar materials, the as-prepared C18-MWCNT-CF showed outstanding comprehensive performance, which was the highest value reported in the literature. Meanwhile, C18-MWCNT-CF exhibited robust superhydrophobicity even after 20 scratching cycles due to the combination of octadecanoyl group tethering and the increased surface roughness. The biodegradable and recyclable C18-MWCNT-CF exhibited reasonable electrical conductivity, superhydrophobicity and microwave absorption that promises an ideal application prospect in the field of smart textile and wearable electronic devices. Graphical abstract