Enhancing Aging Resistance of Transparent Paper: Structural Modification of Wood Fibers via Carboxymethylation

The use of chemically modified cellulose fibers in creating transparent paper for electronic applications has attracted significant interest due to its suitability for roll-to-roll manufacturing. However, chemical modifications (such as sulfate esterification) unavoidably not only inflict damage on the molecular chain of cellulose but also introduce chromophores into cellulose chains, thus leading to a reduction in fiber's resistance against heat or UV light. Consequently, this detrimentally affects the performance and life span of paper electronics. In this study, we achieved the preparation of transparent paper with exceptional resistance to heat and UV aging by structurally modifying wood fibers through carboxymethylation. When exposure to 180 °C for 2 h, only a marginal reduction in light transmission (4%) and tensile strength (10%) was observed compared to the untreated counterpart. Remarkably, even after exposure to UV light at 340 nm for 192 h (8 days), the paper maintained stable light transmittance and strength. Furthermore, we integrated this aging-resistant paper with poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) to create a thermoelectric generator, demonstrating its potential in thermoelectric applications.