The film -forming substances are in their main majority polymers, among the main properties of which there are hardness, strength and at the same time elasticity, moreover, all these characteristics directly depend on the molecular mass of this polymer. The properties of polymers divided into molecules and turned into films will differ from each other in their properties and areas of application. High -molecular polymers presented in the film are always more elastic than low molecular weight. The consequence of their mixing allows us to talk about such polymers as universal substances that can have many at first glance incompatible properties. The properties of such polymers are more dependent on the original monomers in this chain, as well as the presence of functional groups and multiple ties. The same monomers that have no more than two functional groups or functional connections form chains of a linear type of macromolecules, which are associated with each other only with the help of polar interaction. Subject to deformation, such molecules are able to slide relatively each other, this is the property of the elasticity of polymers. Polymers of the film -forming properties include fluoroplasts, chlorinated rubber, perchlorvinyl resin, esters of cellulose polyacrylate, and others.
The so -called reversible coatings are formed and created on the basis of these polymers, they can dissolve in organic any solvents. The simplest example of such polymers is nail polish. But the polyurethane paints after processing with their solvent are irreversible coatings, and therefore they do not dissolve at all or dissolve poorly. Irreversible coatings are always more rigid and hard than reversible. Irreversible coatings are obtained on the basis of completely different polymers, which are called stitched or metro. The polycondensation reaction of this kind of molecules occurs followed by the release of water, as well as other side substances. Glyftal and pentifal resins obtained from glycerol belong to such polymers.
