Time-controlled stearic acid modification of silver-coated Scots pine wood for durable superhydrophobicity

Natural wood is inherently hydrophilic, rendering it prone to rapid moisture absorption, dimensional instability, and surface deterioration under environmental exposure. In this study, a simple, scalable, fluorine-free, and resource-efficient approach was used to fabricate a superhydrophobic coating on Scots pine wood. Silver nanoparticles were deposited on the wood surface by immersing the wood in a diamminesilver complex solution, followed by reduction with formaldehyde and subsequent modification using stearic acid. The effect of stearic acid immersion time on surface wettability was systematically investigated. The surface morphology and wettability were characterized using SEM and EDS, confirming uniform silver nanoparticle coverage. Contact angle measurements identified an optimal stearic acid immersion time of 11 h, yielding stable superhydrophobic behavior with a water contact angle of 156.8 degrees. The modified wood exhibited high durability as well as excellent water repellency toward common liquids. In addition, the modified wood showed good thermal stability under prolonged exposure to low and high temperatures (−18 °C and 120 °C for 2 h to 6 h) and good chemical stability across a wide pH range (3–9). The use of low silver and chemical concentrations significantly reduces material consumption, making the process economically feasible and suitable for practical applications.