PVA-FeCl3 composites as substrate and packaging materials for the controlled degradation of non-degradable metals in transient electronics

Progress in transient electronics depends largely on the availability of components and materials that can decompose in aqueous solutions. However, some of the most important electrically conductive materials, such as copper or aluminum, do not fall into this category. Here, we report a concept for solving this problem based on the preparation of a new water-soluble polymer composite as a packaging material that, when dissolved, releases a chemical etchant that decomposes these two metals. We investigate the synthesis, chemical properties, and solubility kinetics of a polyvinyl alcohol-iron chloride (PVA-FeCl3) composite, its degradation properties, and the associated dissolution mechanisms of metallic Al and Cu films and traces. The results show that Cu films dissolve in a rapid and uniform fashion and produce copper(i) chloride as the end product, while Al films exhibit inconsistent dissolution behavior. Moreover, the timescale for complete dissolution of Cu and Al can be adjusted by simply varying the amount of FeCl3 in the composite. The distinct advantages of this triggered transience mode include low cost, simplicity, precise control of the dissolution process by varying the polymer composition, and a universal degradation mechanism that can be extended to numerous transient electronic devices.