Technical Glossary Gel

[Gel]

A network of polymer chains created by crosslinking is generally called a gel. Gels are non-fluids, which swell, but do not dissolve, upon contact with solvents. There are different types of crosslinking, including covalent bonds, coordinate bonds, and hydrogen bonds.
Network structured gels that contain water or organic solvents are called hydrogels and organogels, respectively. Aerogels (also called xerogels) are highly porous and light materials, in which the dispersion medium, such as water, has been dried off.
Examples of foods which are also water containing gels are agar-agar, tofu, konnyaku and jelly. The word "gel" derives from the Latin verb "gelare (to freeze)." In contrast to hardened gels, a fluid colloidal solution is called a sol. One example of this is the sol-gel process, which synthesizes ceramic out of a colloidal solution of a precursor, such as metal alkoxide. When superabsorbent polymers were invented in the 1970s and products such as paper diapers entered the market, hydrogels received a lot of attention. Furthermore, polymer gel research advanced greatly in 1978, when Toyoichi Tanaka discovered the phase transition phenomenon.
Silicone polymers where crosslinking has occurred within silicone oil are called elastomers. Soft elastomers which contain silicone oil where crosslinking has only partially occurred are sometimes called silicone gels.
Silicone gels display exceptional shock absorption and vibration damping properties.