Fabrication of smart coatings based on wood substrates with photoresponsive behavior and hydrophobic performance

• A smart response wood surface with photochromic property was fabricated.
• The wood surface exhibited photochromism under UV light.
• The colored wood surface can change to the original color under visible light.
• The photoresponse rate including coloration time and fading time was very high.
• A hydrophobic performance was obtained on the wood surfaces.

A smart coating based on wood substrate with photochromic behavior and hydrophobic performance was successfully fabricated by depositing modified organic photochromic material (PM) on wood surface using a simple drop-coating method. The prepared samples were characterized by the scanning electron microscopy (SEM) and attenuated total reflectance–Fourier transformation infrared (ATR–FTIR) techniques. The colorimetric parameters L*, a*, b*, and ΔE* of the samples under ultraviolet (UV) irradiation and visible (VIS) irradiation were measured, respectively. The response time of samples was calculated and the water contact angles (CAs) were also measured. The ATR–FTIR spectra and the SEM analysis demonstrate that PM modified by polyvinyl alcohol and the dextrin deposited on the wood surface, and the resulted coating was firmly adhered to wood by adhesion test results. With the PM concentrations increasing from 0 to 3.0%, the ΔE* values of samples remarkably increased from 3.7 to 58.2. Furthermore, the coloration time and fading time in the cross section were longer than the radial and tangential sections. Through the octadecyltrichlorosilane (OTS) treatment, the sample surface exhibited hydrophobic property with a contact angle of 134°, broadening the applications of the photoresponsive coatings in a harsh environment such as prolonged exposure under UV light or rain.

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