Comprehensive optimization in electrical, optical, and mechanical properties of cellulose through supercritical composite treatment

Natural biomaterials play a crucial role in the development of sustainable electronics. Cellulose, renewable and widespread in nature, has garnered extensive attention in bioelectronics. However, the presence of stubborn small molecular impurities in cellulose severely affects its performance as an electronic material, impacting its electrical insulation, optical transparency, and mechanical flexibility. This study proposes an eco-friendly approach using supercritical carbon dioxide fluids with deionized water (DW-SCCO2) to optimize cellulose films and electronic devices. By leveraging the exceptional permeability and solubility of supercritical fluids, impurities within cellulose are dissolved and separated, thereby purifying the cellulose film and enhancing its electrical insulation and optical properties. DW-SCCO2-treated cellulose device exhibits significantly improved electrical insulation (with a 25-fold reduction in leakage current) and increased optical transparency. Moreover, the enhanced oxidizability of deionized water in supercritical fluid promotes cationic substitution and dehydration condensation reactions, and strengthens cross-linking among cellulose molecules, resulting in a remarkable 47.2 % increase in tensile strength and a 24.2 % increase in Young's modulus post-treatment. This supercritical method not only expands the potential applications of cellulose but also contributes to the promising future of sustainable and efficient bioelectronics by enhancing the comprehensive performance of materials and devices.