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"Lyophobic" is a descriptive term for the state of some matter particles when combined in a solution. The term comes from the breakdown of lyo, meaning "solvents," and phobic, meaning "hating." Lyophobic materials hate all solvents, unlike hydrophobic materials that only hate water.
Solvent-hating materials such as iron, mercury, arsenic, and precious metals such as gold and platinum require special handling. These materials usually combine in solutions called colloidal solutions; lyophobic colloids are one of the two main types of colloidal solutions. As solvent-hating materials do not readily form solutions, various elaborate preparations are made to present them in a useful compound.
The properties of lyophobic materials include their irreversibility and their instability. They are considered irreversible organic compounds because, if the solvent is removed, they do not easily form another compound by mere introduction of solvent once again. Lyophilic colloid materials, which are considered solvent-loving, are considered reversible as they readily recombine. The lyophobic materials in solution are considered less stable, because their forces of interaction with other materials are so weak compared to the strong bonds of lyophilic materials. Their molecules repel other materials, thus must be manipulated to make it possible to create colloidal solutions.
One of the properties of lyophobic colloidal solutions that differentiate them from lyophilic colloidal solutions is their behavior under positive and negative electrical charges. Lyophobic solutions under an electrical field will immediately move to the negative if a negative charge is applied and to the positive if a positive charge is applied. Lyophilic solutions do not respond to electrical charges at all, unless the dispersing agent they were dissolved in responds to the charge — in which case, they follow their dispersant. The lyophobic solutions of starches, proteins, and sulphurs have a similar or equal viscosity as their dispersal solvents, whereas lyophilic solutions are far more tacky than their dispersal solvent.
As the liquid-hating substances require manipulations and stabilizers to achieve compound solutions, several preparations have been developed according to the essential nature of the particular lyophobic material. For instance, to achieve a colloidal compound with gold, reducing agents like formaldehyde or hydrogen peroxide can be used to treat gold's salts to produce a gold solution that has a purple tint. Mercury is prepared by changing its physical state when its vapors are passed through a cold-water bath with a stabilizer such as ammonium salt added. Varnishes, paints, and black inks are lyophobic colloidal materials that pass through a mechanical colloidal mill that grinds the solution between two rotating discs to create a shearing force to combine them when the particles are at nanometer size.
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