Today's consumer electronics, such as cell phones, tablets and other portable electronic devices, are typically made of non-renewable, non-biodegradable, and sometimes potentially toxic (for example, gallium arsenide) materials. These consumer electronics are frequently upgraded or discarded, leading to serious environmental contamination. Thus, electronic systems consisting of renewable and biodegradable materials and minimal amount of potentially toxic materials are desirable. Here we report high-performance flexible microwave and digital electronics that consume the smallest amount of potentially toxic materials on biobased, biodegradable and flexible cellulose nanofibril papers. Furthermore, we demonstrate gallium arsenide microwave devices, the consumer wireless workhorse, in a transferrable thin-film form. Successful fabrication of key electrical components on the flexible cellulose nanofibril paper with comparable performance to their rigid counterparts and clear demonstration of fungal biodegradation of the cellulose-nanofibril-based electronics suggest that it is feasible to fabricate high-performance flexible electronics using ecofriendly materials.
Aqueous monosaccharide solutions including glucose or fructose have been hydrothermally treated in a closed system to form colloidal carbon spheres. In-situ Raman and 13 C NMR have been used to quantify the intramolecular dehydration moiety, HMF, as an intermediate. An aqueous glucose solution forms a carbon sphere via an intermolecular dehydration route without forming HMF during initial hydrothermal treatment and followed by carbonization at 170-180 °C. However, an aqueous fructose solution initially forms HMF by intramolecular dehydration at 120-140 °C. Upon subsequent polymerization, microscopic carbon-containing spheres assemble to larger spheres, thereby generating a grain-like surface morphology. The carbon sphere contains a dense hydrophobic carbon core and a hydrophilic shell.
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