The Polyacrylonitrile (PAN), of general formula (C₃H₃N)_n, is a polymer obtained by the polymerization of the acrylonitrile vinyl monomer (C₃H₃N).

Among its main characteristics is the ability to cyclise its polymer chain by heating - making it rigid - and the versatility to undergo chemical modification due to the presence of the nitrile group (CN), which allows the production of the most diverse types of materials, such as carbon fiber, gel fiber, adhesives, engineering plastics, superabsorbent polymers, viscous fluids and filtration membranes.