Silicone is a typical porous inorganic adsorbent material and carrier, with a molecular formula of mSiO2 · nH2O. Due to the basic skeleton of silica gel formed by the stacking of Si-O tetrahedra, it has a rich pore structure, a large specific surface area, and high mechanical strength. Its physical properties are stable in synthesis, application, and modification processes. The H2O in the chemical formula is mainly connected to silicon atoms in the form of hydroxyl groups (- OH) to form silicon hydroxyl groups (Si OH), which cover the surface of silica gel. It is a strong adsorption site and easy to modify, making the surface of silica gel highly chemically active and conducive to modification. In addition, silica gel is not easily corroded by acidic solutions except hydrofluoric acid, and its chemical properties are quite stable. However, non-polar silicone surfaces lack reactive polar groups, making it difficult to effectively bond with other materials and becoming a challenge in bonding technology. Therefore, more and more researchers are modifying silicone substrates by introducing polar groups on the surface of the substrate, thereby improving the wetting and bonding properties of the silicone surface.

At present, silicone is usually treated with surface coating agents to increase the adhesion of the silicone surface, thereby improving the adhesion of the silicone surface. However, the treatment agents contain volatile organic solvents such as benzene and ketones, which are very harmful to human health and the environment; In addition, it is inconvenient to flip the silicone during the product manufacturing process, and it needs to enter the secondary assembly line for double-sided processing of the product, which reduces work efficiency.

Plasma treatment technology can generate active groups on the surface of silica gel, which can quickly and efficiently improve the hydrophilicity of the silica gel surface. It has the advantages of high efficiency and significant effects. Plasma surface treatment machines do not require solvents and have no harmful effects on the atmospheric environment. They can also handle substrates with complex shapes well.

Principle of improving adhesion with silicone plasma surface treatment machine

Plasma, first used in 1879 to describe the fourth state of matter besides solid, liquid, and gas states, is mainly a gaseous substance composed of molecules, atoms, and the positive and negative electrons produced by ionization. After plasma modification, polymer materials will generate free functional groups on their surfaces, which can continue to participate in reactions and introduce various functional groups on the surface, thereby changing the hydrophilicity and surface tension of the material, enhancing its adhesion and biocompatibility. Nowadays, it is widely used in fields including microelectronics industry, biomedical materials, nanoetching, etc.

Figure 1-1 shows the principle diagram of surface modification of silica gel by O2 plasma. Due to the presence of a large amount of O+, O -, O2-, O3, ozone ions, free electrons, and other particles in the plasma of oxygen or air atmosphere, various types of reactions, including physical or chemical reactions, occur with the surface of silicone rubber. As a result, a large number of oxygen-containing polar groups are introduced to the surface of silicone rubber. When polar groups come into contact with air, hydrophilic groups are formed on the surface, improving the surface hydrophilicity; And surface erosion occurs, forming cross-linked structural layers and etching effects.

Figure 1-1 Schematic diagram of surface modification of silica gel by O2 plasma

In summary, the formed silicone surface does not have active polar groups, making it difficult to bond other substances. Oxygen is introduced through a plasma surface treatment machine and discharged onto the surface of silica gel, causing chemical and physical reactions to occur on its surface. Hydrophilic polar groups are generated on the surface, which can interact with other substances and produce good adhesion.