High purity magnesium oxide has a large specific surface area and is an important raw material for the preparation of highly functional fine inorganic materials, electronic components, inks, and adsorbents for harmful gases.
Solid-liquid critical surface tension
Like the properties of surfactants in solution, surfactants can also be attached to the solid surface through physical or chemical methods to change the surface energy of the solid. The free energy on the surface of hard solids such as metals, ceramics, and glass is relatively high, usually above 10-5J/cm². The greater the hardness and the higher the melting point, the higher the surface free energy.
Due to the tight arrangement of the molecules inside the solid material, ptfe powder mixer this causes uneven forces on the inside and the surface of the molecules, and the surface shows a large residual free energy. A solid surface with a high surface free energy is called a “high-energy surface”, such as Metal, diamond, metal oxide, etc. If the above substances are treated with fluorocarbon surfactants, the “high-energy surface” can be reduced to 10-6J/cm² and become a low-energy surface, which is of great significance for practical applications. The surface free energy of a solid can be measured by the contact angle method. The contact angle measured by a group of liquids in the same series is extrapolated to a surface tension value of 6=0°, which is called the critical surface tension of the solid, and is expressed as y. Express. Strictly speaking, this is not the actual value of the free energy of the solid surface, but the surface free energy of the solid-liquid equilibrium after the solid is completely wetted by the liquid.
Synthesis and application of fluorocarbon surfactants
Synthesis of fluorocarbon surfactants
The synthesis of fluorine-containing surfactants is generally divided into three steps: firstly, the synthesis contains 6~10
The perfluoroalkyl chain compound of carbon atoms is then converted into an ptfe wax lubricant intermediate that is easy to introduce various hydrophilic groups, and finally various hydrophilic groups are introduced into this intermediate. In the process of synthesizing fluorocarbon surfactants, the most difficult step is to introduce fluorine-containing long carbon chain groups into the molecule. At present, there are basically the following methods for the industrial production of long carbon chain fluorides.
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