Inspired by chromophores: A intelligent transparent bamboo with intrinsic photo- and pH-responsiveness

Abstract

The color of bamboo itself mainly comes from the chromophores in lignin, tannin and other resinous compounds, while bamboo can achieve the bleaching effect by delignification. Inspired by chromophore coloration strategies, this study employed a thermosetting epoxy resin Ag-80/DDM with responsive diarylmethane chromophores, which was impregnated into delignified bamboo via vacuum impregnation. This resulted in the creation of an intelligent transparent bamboo with intrinsic photo- and pH-responsiveness. The diarylmethane chromophores in the thermosetting epoxy resin system are capable of undergoing reversible color changes through electron transfer, thereby avoiding potential leakage issues associated with externally added functional agents. Additionally, the intelligent transparent bamboo exhibited high light transmittance (89%) and excitation fluorescence, as well as low thermal conductivity (0.2496 W/mK at −20 ℃, 0.2569 W/mK at 55 ℃). And it maintained its original quality even after 30 days of immersion in strong acid or alkaline solutions. Moreover, intelligent transparent bamboo showed excellent mechanical properties with longitudinal and radial tensile strengths of 173.6 MPa and 11.5 MPa, respectively. This paper proposes a new viewpoint and basic information for manufacturing functional bamboo that is transparent, which establishes the foundation for potential applications in intelligent windows and energy-efficient buildings.