The continuous advancement of modern electronic equipment requires increasing the conductivity of electrically conductive adhesives (ECAs), but the gap between discrete silver flakes in conventional ECAs considerably hinder electron transport. In this work, we demonstrated 1500fold enhancement in electrical conductivity by adding a kind of polythiophene nanoparticle (PTh nanoparticles) in the polyurethane-based ECAs with an optimal value of 3.2 × 10 4 S/cm. These PTh nanoparticles have exceptionally high conductivity and are capable of forming a stable colloidal suspension in various kinds of organic solvents. These properties enable PTh nanoparticles to be well-distributed in the polymer matrix and enable gap-filling among Ag flakes to fabricate high-performance ECAs. In the presence of PTh nanoparticles, the resulting ECA has not only outstanding conductivity but also excellent electrical stability under high mechanical deformation. The electrical resistivity of the pattern made by the PTh nanoparticles-containing ECAs remained stable after being wrapped in a 6 mm bend radius for over 7500 cycles or pressed under 1000 kPa. In addition, when the ECAs were stored for 2 weeks at 80 °C and 60% relative humidity, no significant change in conductivity of the ECAs was observed. A flexible printed circuit was fabricated using the above-mentioned ECAs containing PTh nanoparticles, demonstrating their potential for advanced flexible electronic devices.

It is essential to develop a novel and versatile strategy for constructing electrically conductive adhesives (ECAs) that have superior conductivity and high mechanical properties. In this work, easily synthesized polyaniline@cellulose (PANI@CNs) nanowhiskers with a high aspect ratio and excellent solubility in 1,4-dioxane were prepared and added to conventional Ag-containing adhesives. A small amount of PANI@CNs can dramatically tune the structure of the ECAs’ conductive network and significantly improve the conductivity of the ECAs. Good solubility of PANI@CNs in solvents brings excellent dispersion in the polymer matrix. Thus, a three-dimensional (3D) conducting network formed with dispersed PANI@CNs and Ag flakes can enhance the conductivity of ECAs. The conductivity of the ECAs (with 1.5 wt% PANI@CNs and 55 wt% Ag flakes) showed three orders of magnitude higher than that of the ECAs filled with 55 wt% Ag flakes and 65 wt% Ag flakes. Meanwhile, the integration of PANI@CNs with Ag flakes in polymer matrices also significantly enhanced the mechanical compliance of the resulted ECAs. The resistivity remained unchanged after rolling the PANI@CNs-containing ECAs’ film into a 4 mm bending radius for over 1500 cycles. A bendable printed circuit was fabricated using the above PANI@CNs-containing ECAs, which demonstrated their future potential in the field of flexible electronics.

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