The molecular structure of PFPE lubricant is basically similar to that of hydrocarbon lubricant, but fluorine atoms replace hydrogen atoms in PFPE molecules, thus replacing the c-H bonds in hydrocarbons with stronger c-F bonds. The presence of strong covalent bonds between c-o and c-c, as well as the neutral nature of PFPE molecules, make PFPE have high thermal stability and oxidation stability, as well as good chemical inertness and insulation properties. PFPE with higher molecular weight also has low volatility, a wider liquid temperature range, and excellent viscosity temperature characteristics. In addition, the main physical and chemical properties of PFPE polymers include detection stability, biological inertness, low surface energy, good lubricity, and compatibility with plastics, metals, and synthetic rubber.
Characteristics of Perfluoropolyether
The main chain of perfluoropolyether is composed of ether chains such as – CF2-O-CF2-, which is different from the perfluoroolefin chain of – CF2CF2CF2-. It has flexibility, low glass transition temperature, and a wide range of eutectic temperatures (from freezing point to boiling point). On the other hand, due to the strong electron withdrawing effect of fluorine, the polymer does not exhibit ether like properties, thus it has good heat resistance, chemical stability, oxidation stability, and complete non flammability.
However, this substance lacks hygroscopicity and does not dissolve in organic solvents, only showing mutual solubility in perfluorooil or fluorohexane 113 (triaromatic trifluoroethane). This property makes it almost harmless to plastics and rubber.
Perfluoropolyether has a high specific gravity, but its surface tension and refractive index are very low. It has the characteristics of perfluorinated compounds and is a highly transparent oil substance. The LD56 value of oral acute toxicity test on mice is very high, and there is no accumulation in the body, so it is almost non-toxic. However, during decomposition, extremely toxic substances are produced. When used in environments where decomposition is expected to occur, ventilation equipment must be installed and should not be taken lightly due to the stability of this fluorinated oil.