Biomass-Derived, Highly Conductive Aqueous Inks for Superior Electromagnetic Interference Shielding, Joule Heating, and Strain Sensing

Conductive composite inks are widely used in various applications such as flexible electronics. However, grand challenges still remain associated with their relatively low electrical conductivity and require heavy use of organic solvents, which may limit their high performance in broad applications and cause environmental concerns. Here, we report a generalized and eco-friendly strategy to fabricate highly conductive aqueous inks using silver nanowires (AgNWs) and biomass-derived organic salts, including succinic acid-chitosan (SA-chitosan) and sebacic acid-chitosan. SA-chitosan/AgNW composite coatings can be prepared by directly casting conductive aqueous inks on various substrates, followed by subsequently heating for cross-linking. The composite coatings exhibit an ultrahigh electrical conductivity up to 1.4 × 104 S/cm, which are stable after being treated with various organic solvents and/or kept at a high temperature of 150 °C, indicating their high chemical and thermal resistance. The flexibility and performance durability of these composite coatings were demonstrated by a suite of characterization methods, including bending, folding, and adhesion tests. Moreover, a high electromagnetic interference shielding (EMI) effectiveness of 73.3 dB is achieved for SA-chitosan/AgNW composite coatings at a thickness of only 10 μm due to the ultrahigh electrical conductivity. Additionally, we further demonstrated that such conductive composite inks can be used for fabricating functional textiles for a variety of applications with high performance, such as EMI shielding, Joule heating, and strain sensing. The robust and highly conductive inks prepared by this simple and environmental-friendly method hold great promise as important material candidates for the potential large-scale manufacturing of flexible and wearable electronics.