That which cannot be mixed is immiscible.
The word immiscible is not included in the dictionary of the Royal Spanish Academy (RAE) but, even so, it is widely used in the field of chemistry . As can be deduced from practice, it is a concept that derives from miscibility , as it is known as the particularity or property of certain substances to combine or mix in different proportions and form a homogeneous solution from it.
The most common thing is that this notion is applied to liquids , although it can also refer to solid materials or gases. When two substances have the ability to constitute a homogeneous solution beyond the proportions involved, they are said to be miscible . On the other hand, if they do not have this capacity, they will be classified as immiscible .
This means that any substance that fails to form a homogeneous strip in any way is immiscible. An example of an immiscible substance is water with ethyl ether . The miscibility of organic substances and lipids with water is determined by the properties of the hydrocarbon chain.
Properties of immiscible mixtures
When determining or establishing the properties of the so-called immiscible mixtures that take place within the chemical sector, it must be emphasized that various elements take center stage, such as the glass transition temperature. This value is represented as Tg, and it must be emphasized that it is double in any type of immiscible mixture since each of the two amorphous polymers that give rise to it maintain their own temperature of this type.
This means that if any scientist begins to analyze a given mixture and only discovers one glass transition temperature, his main conclusion will be that it is completely miscible.
In addition to this highlighted hallmark, it is also important to make clear that these immiscible mixtures are much more fragile than those that are not of the same type. However, there are a series of techniques to achieve greater resistance.
Water and ethyl ether are immiscible.
Techniques to provide more resistance
Thus, among the methods used to achieve this objective is, for example, processing them under flow thanks to the formation of rods that function as fibers of a reinforced composite material.
Another second technique widely used to achieve the hardness of immiscible mixtures is to use equivalent quantities of the two polymers that give shape to them. The third method that can be used is to opt for including a compatibilizer thanks to which the union is achieved in a much more compact way.
Immiscible metals
When metals are immiscible, they cannot form alloys . Mixing is only possible through smelting , although if these metals freeze, they will separate again into differentiated phases or layers. Copper and cobalt are two immiscible metals, to cite one example.
It is possible to associate miscibility with the entropy of substances: the greater the entropy, the greater the miscibility. This explains why gases are generally miscible, unlike solids which are usually immiscible. There are, however, various exceptions, as is the case with solid combinations of nickel and copper .