Films for passive de-icing and electromagnetic shielding

Scientists have developed conductive and superhydrophobic Ag/PDMS films with high stability for passive de-icing and electromagnetic shielding. Their high electromagnetic shielding effectiveness has been maintained even for servicing in harsh environments.

A laboratory scene.
The addition of ceria with a content of 5 wt% was the most effective to enhance hydrophobicity. Image source: totojang1977 (symbol image)

In a recently conducted work, silver nanoparticles (AgNPs) were synthesised and sprayed onto the surface of cotton fabric to produce a conductive film. Then a layer of poly(dimethyl siloxane) (PDMS) was deposited onto the film to prepare Ag/PDMS composite film. The Ag film is with FCC crystalline and particle-like morphology, while layers of organic PDMS are cladding the Ag micro-nano structures. With increasing spraying time, nano‑silver particles changed from round spherical to worm-like, resulting rougher and higher electrical conductivity.

Enhanced stability

By optimising the PDMS coatings, the contact angle of surface winkled-like microstructure reached 163° and volume resistivity was 9.2 × 10−3 Ω·cm. In addition to the improvement of interfacial adhesion, the introduction of PDMS made the loose particles closely connected, which enhanced the stability of the structure. Meanwhile, the films exhibited great electron-thermal effects, which could be applied in high-speed deicing. Combined with superhydrophobicity, the electromagnetic shielding efficiency can reach 75 dB. The Ag/PDMS films maintained high electromagnetic shielding effectiveness even for servicing in harsh environments, showing that this conductive superhydrophobic fabric composite can be applied as a new electromagnetic shielding material for flexible electronic devices.

The study has been published in Progress in Organic Coatings, Volume 169, August 2022.

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