## 3 Results and Analysis
### Wetting Properties of \"Environmentally Friendly\" Copper-Plated Wood-Based Composite Materials  
The surface wettability of the wood veneer is represented by the contact angle of the liquid on its surface. The larger the contact angle, the lower the surface wettability. When the surface static contact  
\begin{table}
\begin{tabular}{c c c c} \hline \hline \multirow{2}{*}{**Number**} & **Different Processing Methods** & **Cellulose Relative Crystallinity** & **Standard Deviation of Crystallinity** \\ \hline \multirow{4}{*}{a} & Ultrasonic treated wood & 74.4\% & 0.543\% \\  & The original wood & 67.9\% & 0.666\% \\  & \multicolumn{1}{c}{Sputtering for 50 s} & 74.1\% & 0.743\% \\ \hline \multirow{4}{*}{b} & Ultrasonic treated wood & 72.2\% & 0.333\% \\  & The original wood & 69.5\% & 0.447\% \\  & \multicolumn{1}{c}{Sputtering for 150 s} & 74.8\% & 0.438\% \\ \hline \multirow{4}{*}{c} & Ultrasonic treated wood & 68.3\% & 0.537\% \\  & The original wood & 63.8\% & 0.486\% \\  & \multicolumn{1}{c}{Sputtering for 10 min} & 67.2\% & 0.876\% \\ \hline \multirow{4}{*}{d} & Ultrasonic treated wood & 80.6\% & 0.810\% \\  & The original wood & 79.7\% & 0.743\% \\  & \multicolumn{1}{c}{Sputtering for 15 min} & 74.8\% & 0.857\% \\ \hline \multirow{4}{*}{e} & Ultrasonic treated wood & 69.9\% & 0.600\% \\  & The original wood & 71.9\% & 1.057\% \\ \cline{1-1}  & \multicolumn{1}{c}{Sputtering for 15 min} & 71.4\% & 0.982\% \\ \hline \hline \end{tabular}
\end{table}
Table 2: Crystallinity of samples after different treatment.  
Figure 4: XRD map of wood veneer under different treatments in the range of 40\({}^{\circ}\) to 80\({}^{\circ}\).  
angle is greater than 90\({}^{\circ}\), it indicates that the surface of the test piece is a hydrophobic surface and the opposite indicates a hydrophilic surface [29]. The water contact angle of the \"environmentally friendly\" wood-based nano-metal composite material is shown in Figure 5. The contact angle of the untreated original wood is 53.5\({}^{\circ}\)--that is, water can partially wet the original wood, which indicates that the porous structure of wood itself and the large number of polar functional groups on the surface of wood can attract and combine with water droplets, thus showing certain wettability. When the sputtering time is 50 s, the water contact angle is 130.6\({}^{\circ}\). When the sputtering time is 150 s, the contact angle is 135\({}^{\circ}\). The water contact angle of samples with magnetron sputtering times of 10 min and 15 min is over 145\({}^{\circ}\). The contact angle of the sample with a sputtering time of 15 min (200 \({}^{\circ}\)C) is 149.9\({}^{\circ}\), which almost possesses superhydrophobic properties. Since the wood itself is a porous material and the structure is loose, the sputtered copper is directly filled into the pores of the wood, and copper film is formed on the surface of the wood to construct a hydrophobic system on the surface of the wood. In addition, the hydrophobicity of the material is related to the roughness of the surface of the material. The rougher the surface of hydrophobic materials, the better their hydrophobicity [30]. Table 3 shows the contact angle and standard deviation of the wood veneer surface before and after coating.  
\begin{table}
\begin{tabular}{c c c c} \hline \hline
**Number** & **Sputtering Time** & **Contact Angle** & **Standard Deviation of Contact Angle** \\ \hline a & 0 s & 53.5 & 0.985 \\ b & 50 s & 130.6 & 0.656 \\ c & 150 s & 135 & 0.529 \\ d & 10 min & 145.8 & 0.529 \\ e & 15 min & 147 & 0.346 \\ f & 15 min (200 \({}^{\circ}\)C) & 149.9 & 0.361 \\ \hline \hline \end{tabular}
\end{table}
Table 3: Contact angle and standard deviation of surface of wood veneer before and after coating.  
Figure 5: Water contact angle of copper-plated wood veneer, (**a**) is the original wood; (**b**) Magnetron sputtering for 50 s; (**c**) Magnetron sputtering for 150 s; (**d**) Magnetron sputtering for 10 min; (**e**) Magnetron sputtering for 15 min; (**f**) Magnetron sputtering for 15 min (200 \({}^{\circ}\)C).