Superhydrophobic and conductive carbon nanofiber/PTFE composite coatings for EMI shielding

This paper presents a solvent-based, mild method to prepare superhydrophobic, carbon nanofiber/PTFE-filled polymer composite coatings with high electrical conductivity and reports the first data on the effectiveness of such coatings as electromagnetic interference (EMI) shielding materials. The coatings are fabricated by spraying dispersions of carbon nanofibers and sub-micron PTFE particles in a polymer blend solution of poly(vinyledene fluoride) and poly(methyl methacrylate) on cellulosic substrates. Upon drying, coatings display static water contact angles as high as 158° (superhydrophobic) and droplet roll-off angles of 10° indicating self-cleaning ability along with high electrical conductivities (up to 309 S/m). 100 μm-thick coatings are characterized in terms of their EMI shielding effectiveness in the X-band (8.2–12.4 GHz). Results show up to 25 dB of shielding effectiveness, which changed little with frequency at a fixed composition, thus indicating the potential of these coatings for EMI shielding applications and other technologies requiring both extreme liquid repellency and high electrical conductivity.

Low-cost, superhydrophobic, carbon nanofiber (CNF) and polymer composite coatings with self-cleaning ability and high electrical conductivity have been fabricated. Their EMI shielding effectiveness was quantified in the frequency range 8.2–12.4 GHz.Figure optionsDownload high-quality image (104 K)Download as PowerPoint slideResearch highlights
► Superhydrophobic conductive large-area coatings were fabricated by a solution-based method.
► CNF content modified coating behavior from fully transmitting to fully reflecting.
► Wettability and self-cleaning ability of the coatings was independent of CNF content.
► Coating conductivity rose with CNF content, exceeding 300 S/m at 14 wt.% CNF content.
► EMI shielding effectiveness in X-band reached 25 dB (0.3% power transmission).