Deposition of halogen-free flame retardant and water-repellent coatings on firwood surfaces using the new version of DBD

Abstract

Abstract In this study, a rapid, cost-effective, and environmentally-friendly approach was developed for the production of high-performance thin films to reduce the flammability of firwood as well as controlling its wettability. In this regard, a hydrophobic and flame-resistant organic thin coating was prepared through halogen-free plasma polymerization using a novel version of dielectric barrier discharge (DBD) apparatus optimized at atmospheric pressure. The home-made device does not require expensive vacuum instruments and operates in open-air using an organosilicon precursor (hexamethyldisiloxane (HMDSO)) as a liquid monomer. The morphology, composition, and chemical structure of the deposited polydimethylsiloxane-like (PDMS-like) thin films were comprehensively evaluated through FESEM, AFM, XPS, FTIR, EDX, and DTA-TG. The samples showed remarkable cross-linking. This innovative strategy made it possible to achieve the desired characteristics within a concise treatment time. The modifications include the increase in the static contact angle of super-hydrophilic firwood surfaces to 137.73°, enhancement of the surface roughness from 573 pm to 22.5 nm, and a significant reduction in the maximum rate of wood thermal decomposition from 0.94 to 0.65 mg min−1. Applying a creative and simple approach combining the image processing method with the heater test indicated that plasma modification of the wood surfaces improved their thermal stability without altering their aspect ratio or color surface. Therefore, the plasma-synthesized PHMDSO layers prepared by this device could be a promising candidate for fire retardancy and water repellency applications.