Nanocomposite Coatings to Induce Pigment Precipitation for Durable Paper-Based Foldable Electronics

In this work, a laponite/poly(vinyl alcohol) (PVA) nanocomposite coating was formulated to increase the mechanical stability of foldable printed circuits on paper. A multivalent laponite nanoclay coating was first designed to serve as a flocculant to trigger immediate particle precipitation in printed ink tracks. The flocculation-induced ink deposition resulted in a dense silver nanoplate stacking, and thus the printed circuits on the coated paper showed good conductivity (>105 S/m) after printing without any high-temperature sintering process. To increase the strain durability of the coating in the folding process, laponite and PVA were cross-linked with paper fibers to form a reinforced network with good foldability. The printed conductive circuits adhered well on the coating and showed high electrical stability. The resistance only varied less than 18% in 1000 folding–unfolding cycles and was restored to the original value after unfolding. Several examples were also given to demonstrate the possibility to apply this coating method for paper-based foldable electronics with good portability and reliable electrical functionality.