Harnessing wood’s natural ability to faintly glow has helped researchers create a new material that could ultimately aid applications including medical imaging, optical sensing, and even glow-in-the-dark dyes and paints.
In a study of the natural phosphorescent properties of lignin, a major component of wood, an international team from Northeast Forestry University (Harbin, China) and the University of Bath (Bath, UK) found that basswood, in particular, naturally and weakly phosphoresces and releases light for a few milliseconds “due to lignin being trapped within a 3D matrix of cellulose.”
The researchers were able to mimic the wood’s glowing properties by immobilizing lignin in a 3D polymer network. Existing phosphorescent materials are either toxic or difficult to prepare, according to the team, but this resulting new material overcomes issues related to such limitations.
“All lignin glows weakly, but most of the light energy is lost by vibration or movement of the lignin molecules, meaning it isn’t clearly visible to the naked eye,” says researcher Tony James, a professor at the University of Bath’s Centre for Sustainable Circular Technologies. “We’ve found that immobilizing the lignin in an acrylic polymer means more energy is emitted as light. In other words, the less it rattles about, the more it glows.”
The new material has demonstrated the ability to visibly glow for around one second. The duration of the phosphoresce could then be altered by modifying the network’s cavity sizes and varying drying times of the polymer.
The researchers say the new material also shows great potential for “making a more stable, sustainable, biodegradable non-toxic phosphorescent material.” In addition to medical imaging and optical sensing, the new material also could allow easier identification and protection against counterfeiting of luxury textiles or bags, as threads dyed with it could produce luminescent textiles. Reference: J. Yuan et al., Cell Rep. Phys. Sci. (Aug. 23, 2021); doi.org/10.1016/j.xcrp.2021.100542.
