Characterization of Smart Photochromic Transparent Wood With Enhanced Optical and Mechanical Properties

In the effort to multi-functionalize transparent wood, photochromic transparent wood (PTW) was investigated. However, previous studies reported unsatisfactory overall performance of PTW in terms of optical and light response time, posing significant challenges for its applications in areas such as photochromic lenses, smart doors, and windows. A transparent wood composite exhibiting rapid photochromic performance was fabricated by infusing delignified wood with a pre-polymerized methyl methacrylate (PMMA) solution containing microcapsules of 1,3,3-trimethylindoline-6′-(1-piperidinyl)spirooxazine and 3,3-dimethyl-3H-naphthaleno[2,1-b] pyran. Microcapsules were uniformly dispersed within the wood cell cavities and copolymerized with PMMA, thereby endowing the material with superior optical transparency (73%), enhanced mechanical strength (30.2 MPa), excellent photosensitivity (1 s response time, 390 s recovery time), and effective anti-glare performance. Compared with traditional photochromic materials, the composites developed in this study exhibit not only enhanced color-changing response speed but also improved stability, thereby ensuring their reliability for long-term applications (50 cycles). Owing to these distinctive properties, the photochromic transparent wood composite is poised for broad use in intelligent windows, energy-efficient buildings, privacy panels, and dynamic interior design, color-changing lenses, automotive and aerospace, solar energy and light management, and other intelligent optical devices.