As the most widely used lubricant, PDMS is applied on glass, elastomeric seals, plastics, and metals to form a hydrophobic film on the surface of components. This film improves the extraction of pharmaceutical liquids, enhances the processability and compatibility of components, particularly in the case of injection vials and seals. Additionally, silicone oil is also used in plastic syringes and glass cartridges to facilitate the smoother movement of the plunger within the syringe or barrel, thereby improving user experience. Moreover, silicone oil assists in reducing friction and drag when subcutaneous injection needles penetrate human tissues, thereby minimizing pain sensations.

Given that PDMS is the most commonly used lubricant, the process of treating these components is referred to as siliconization.


Benefits of siliconization

1. Improving machine performance

Taking the plunger as an example, siliconization can significantly reduce the friction between the plunger and the metal surface of the machine. Additionally, in an oscillating container, lubrication can greatly reduce the occurrence of material buildup, making the feeding process smooth. Lubricated plungers can further enter the guide rails, eliminating potential issues. It's important to note that production costs are high, and every moment counts, so wasting time is not an option.

2. Reducing plunger insertion resistance

When assembling the plunger with the injection vial, lubrication can effectively reduce the resistance during the plunger insertion process. As shown in Figure 4, a lubricated red plunger can easily be inserted into the vial. However, excessive lubrication may lead to plunger bounce.

3. Minimizing needle insertion and injection force

Needle insertion resistance and injection force are crucial parameters during usage. Just imagine getting a shot where the medication doesn't come out for a long time or is extremely slow. It would undoubtedly be a painful experience. By lubricating the inner wall of the syringe, friction can be significantly reduced, making the process smoother.

3. Reducing medication residue

Finally, let's briefly discuss medication residue, which was also mentioned in the previous discussion. Because silicone oil increases the hydrophobicity of the inner surface, the residual amount during medication extraction is greatly reduced.