Release Date:2023/5/11 18:46:00

From the above structural characteristics, we can infer that the unique properties of fluorocarbon surfactants are directly related to the fluorocarbon chain, and furthermore depend on the unique properties of the fluorine element. In short, compared with other surfactants, the most notable features of fluorocarbon surfactants are: high efficiency and stability, that is, high surface activity, high thermodynamic and chemical stability.

  Fluorine is the most electronegative element. It has high oxidation potential and high ionization energy. On the one hand, this characteristic results in high bond energy of the fluorine-carbon bond (F-C) (in fact, the fluorine-carbon bond is a known bond The covalent bond with the highest energy), so the fluorocarbon chain structure is far more stable than the hydrocarbon structure; on the other hand, the fluorine atoms are very difficult to be polarized, making the fluorocarbon chain less polar than the hydrocarbon chain.It is precisely because of this low polarity that the hydrophobic effect of the fluorocarbon chain is much stronger than that of the hydrocarbon chain (in fact, the low polarity not only makes the fluorocarbon chain hydrophobic, but also oleophobic-here oil refers to hydrocarbons);In addition, low polarity leads to weak interaction between fluorocarbon chains.These two factors work together to make the fluorocarbon surfactant molecules in the aqueous solution have a stronger tendency than other surfactant molecules to break away from the aqueous solution, and to gather and arrange molecular films on the liquid/air interface, so that it has the same characteristics as other surfactants. Two different characteristics of surfactants.

  1. It can significantly reduce the surface tension of aqueous solution at very low application concentration. Some fluorocarbon surfactants can reduce the surface tension of the aqueous solution to 18-20dyn/cm at 50-100ppm. This is mainly due to the strong hydrophobic effect of the fluorocarbon chain and the weak interaction between molecules.
  2. High surface activity, which can reduce the surface tension of the aqueous solution to an extremely low level. For example, perfluorocarboxylic acid can reduce the surface tension of aqueous solution to 15-16 dyn/cm. This is because the fluorocarbon chains in the fluorocarbon surfactant form a neatly arranged monomolecular film on the surface of the aqueous solution, just like a layer of fluorocarbons is laid on the surface of the solution, and fluorocarbons are typical low surface energy materials, such as The surface energy of polytetrafluoroethylene is 19dyn/cm.
  In addition, fluorocarbon surfactants also have extremely high stability. This is because on the one hand, the fluorine-carbon bond (F-C) has high bond energy and is difficult to be destroyed; on the other hand, the fluorine atom has a shielding effect on the carbon-carbon bond (C-C). The radius of the fluorine atom is larger than that of the hydrogen atom, which can effectively shield and protect the perfluorinated carbon-carbon bond (C-C), reducing the possibility of the carbon-carbon bond (C-C) being destroyed, but at the same time the fluorine atom The radius is not large enough to cause steric tension in the perfluorocarbon chain, thus making the fluorocarbon chain more stable. This stability is embodied in the following three aspects:
  1. High thermal stability. Perfluorosulfonate can not decompose at 350-400°C, perfluorocarboxylic acid can exist stably at 400°C, and perfluorocarboxylate can also be used in high-temperature systems at 250°C;
  2. Good chemical stability. Fluorocarbon surfactants can stably and effectively play their role as surfactants in special application systems such as strong acids, strong alkalis, and strong oxidizing media, and will not react or decompose with the system. If perfluorosulfonate is stored in 98% sulfuric acid solution containing chromium oxide (10G/L) at 90°C for 28 days, its performance will not change;
 3. Good compatibility. High chemical stability means high chemical inertness. Fluorocarbon surfactants are well compatible with other active agents and can be applied to almost all formulation systems.
  In fact, the stability of other groups in the fluorocarbon surfactant molecule is often worse than that of the fluorocarbon chain, which reduces the stability of the fluorocarbon surfactant as a whole. In other words, the stability of fluorocarbon surfactants depends on the stability of non-fluorine groups (such as hydrophilic groups) they contain.
  In summary,fluorocarbon surfactants have the following characteristics that other non-fluorosurfactants cannot possess:
  1. At a very low concentration (50-100ppm), the surface tension of the aqueous solution can be reduced to a very low level (18-20dyn/cm);
  2、High thermodynamic and chemical stability, can be used in high temperature, strong acid, strong alkali, strong oxidizing medium and other systems;
  3、 Excellent compatibility, can be widely used in various PH value ranges, various water-based, solvent-based, powder or radiation curing systems, and can be well compatible with other surfactants and components in the system.

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