## 3 Results  
A typical requirement for EPD is the colloidal stability of charged species in the deposition bath. The charging agent selection plays an essential role in the control of bath stability and the rate of electrophoresis. However, strong repulsion of charged particles inhibits film formation. Therefore, when selecting charging surface agents for EPD it is important to consider not only bulk suspension stability but also the ability of the agents to facilitate particle discharge and coagulation at the substrate surface. Our strategy is based on the charging of particles by CBX\({}^{2-}\) species in CBXNa\({}_{2}\) solutions and their discharge in electrode reactions. The ability to form films from pure CBXNa\({}_{2}\) solutions is a favorable factor for EPD of materials. The deposition mechanism involved electrolysis of water in an anodic reaction [24; 25; 31; 32]:  
\[2\mathrm{H}_{2}\mathrm{O}\rightarrow\mathrm{O}_{2}+2\mathrm{H}^{+}+2\mathrm{e }^{-} \tag{1}\]  
The electromigration of CBX\({}^{2-}\) species led to their discharge at the anode and formation of CBXH\({}_{2}\) films:  
\[\mathrm{CBX}^{2-}+2\mathrm{H}^{+}\rightarrow\mathrm{CBXH}_{2} \tag{2}\]  
Reaction (2) is critical for the deposition process, because it results in the discharge of CBX\({}^{2-}\) and deposition of insoluble CBXH\({}_{2}\). The deposition mechanism described in Reactions (1) and (2) is similar to that used for anodic deposition of other small organic molecules and macromolecules [24; 25; 33; 34]. Water is an important component of an electrodeposition bath because it is necessary for the H\({}^{+}\) generation in Reaction (1). However, organic solvents offer several benefits for EPD of materials. The EPD yield is proportional to the electric field in the suspension [35]. The generation of high electric fields in aqueous suspensions by the application of high voltages presents difficulties due to the high conductivity of aqueous suspensions, which results in high currents, significant O\({}_{2}\) gas evolution and enhanced H\({}^{+}\) generation in Reaction (1). The high rate of H\({}^{+}\) generation can result in expansion of a low pH region away from the anode. This can potentially lead to the precipitation of CBXH\({}_{2}\) at some distance from the electrode surface. Moreover, significant O\({}_{2}\) evolution results in porous films. The use of ethanol-water mixture as a solvent is beneficial for EPD at relatively high voltages and a reduced rate of Reaction (1). The dispersion of hydrophobic PTFE in water presented difficulties. However, PTFE suspensions were formed in an ethanol-water mixture. The deposition of pure CBXH\({}_{2}\) films was studied using water and ethanol-water (5% water) solvents. The deposition yield was analyzed by in situ method, based on continuous QCM monitoring of deposit mass during the deposition. This technique has limitations, because it can be used for relatively low deposition yields. Therefore, QCM analysis was performed at relatively low voltages and low solution concentrations. The deposition yield data presented in Figure 1B showed continuous mass increase with time due to film growth. The increase in the applied voltage led to a higher rate of deposition. The rate of mass gain reduced with EPD time due to the continuous rise of the voltage drop in the deposit and reduction of electric field strength in the solution [35]. EPD from aqueous CBXNa\({}_{2}\) solutions at voltages below 15V led to the formation of continuous films which were crack-free (Figure 2A,B). However, the deposition at higher voltages resulted in the formation of pinholes, due to the O\({}_{2}\) evolution. In contrast, significantly higher voltages can be applied for the EPD of films from the solutions of CBXNa\({}_{2}\) in the ethanol-water mixture.