Vinylidenebased

Vinylidenebased refers to chemical species, materials, or polymers that incorporate the vinylidene unit, typically the divalent fragment CH2=C(X)2, where X can be halogens such as Cl or F. In practice, the term is most often used to describe polymers derived from vinylidene monomers, in which the repeating unit is formed by opening the double bond of the vinylidene group. Common vinylidene-based polymers include polyvinylidene chloride (PVDC) and polyvinylidene difluoride (PVDF).

A key feature of vinylidene-based polymers is their backbone structure, usually represented as -(CH2-CX2)-n, with X corresponding to Cl or F. This arrangement gives these materials distinct properties compared with other vinyl polymers, including enhanced barrier performance, chemical resistance, or thermal stability, depending on the substituents. Copolymerization and blending with other monomers are common strategies to tailor mechanical and barrier properties for specific applications.

Synthesis is typically achieved through radical polymerization of vinylidene monomers such as vinylidene chloride or vinylidene difluoride, often under controlled conditions to manage molecular weight and processing behavior. Processing methods for vinylidene-based polymers include extrusion, film casting, and coating, with PVDC widely used as a high-barrier plastic film layer in food packaging, while PVDF is valued for chemical resistance, flame resistance, and piezoelectric or ferroelectric properties in specialized applications.

Environmental and safety considerations include the persistence and handling of fluorinated or halogenated polymers, flame and incineration byproducts, and recycling challenges.