Highly thermally stable and robust polydimethylsiloxane coating on wood material synergistically induced by high-voltage electric field and MgO particles

The cracks and delamination are peculiarly prone to occur in the wood surface coating when exposed to high-temperature environment, adversely to the bonding behavior and thermal resistance of coating. To address this issue, we proposed an efficient, facile, and environmentally-friendly approach to improve the thermal stability and mechanical properties of polydimethylsiloxane (PDMS) coatings on wood surfaces under a synergistic treatment involving MgO particles and a high-voltage electric field (HVEF). Physicochemical and morphological analyses indicated that HVEF treatment increased PDMS and MgO particles aggregation on the wood surface. Additional Si-O3 functional groups were established at the wood surface-coating interface, with a bonding strength increase of 250 %, suggesting an enhanced cross-linking reaction between the PDMS coating and the wood. Improved abrasive resistance was also observed, with a reduction of 62 % in mass loss. A continuous, uniformly distributed coating layer was obtained and the coating thickness was enhanced from 25.11 to 119.33 μm, with higher surface roughness. Moreover, after 200 °C thermal and 1300 °C flaming treatments, the coated samples subjected to HVEF treatment maintained their original microstructure morphology and mechanical properties at the bonding interphase. In particular, under the 1300 °C flaming treatment for 60 s, the surface temperature of the coated samples only reached 35 °C. Furthermore, lower mass loss and higher O/Si content with smaller pore size were observed in the combustion product. Dynamic thermomechanical testing demonstrated that no significant dynamic storage modulus loss occurred for HVEF-coated samples, especially for the flame-treated samples with a loss of 28 %. The synergistic treatment of MgO particles and HVEF can effectively enhance the thermal stability and mechanical properties of wood surface coatings, which are crucial for the preparation of thermally stable wood-based composites.