polyvinylidene

Polyvinylidene refers to a class of polymers derived from vinylidene monomers, typically formed by polymerizing species with the vinylidene structure CH2=CX2, where X is a halogen or other substituent. The name is most often encountered in reference to polyvinylidene chloride (PVDC) and polyvinylidene fluoride (PVDF), which are among the best-known members of this family. In PVDC the repeating unit is -CH2-CCl2-, whereas in PVDF the repeating unit is -CH2-CF2-. The term can also apply to copolymers derived from vinylidene monomers.

Two commercially important polyvinylidene derivatives are PVDC and PVDF. PVDC offers superior barrier properties against moisture and gases, making it a common component in multilayer food packaging coatings and films. Its chlorine content, however, requires careful handling, disposal, and recycling considerations. PVDF, by contrast, is prized for chemical resistance, high thermal stability, and favorable electrical properties, including dielectric and piezoelectric behavior. PVDF is used in chemical processing equipment, membranes for water treatment, protective coatings, and various electronic and sensor applications.

Polymerization methods for vinylidene-based polymers typically involve free-radical processes, including emulsion, suspension, or melt polymerization. Copolymerization with comonomers such as hexafluoropropylene (to form PVDF-HFP) or trifluoroethylene derivatives allows tuning of crystallinity, toughness, and flexibility. Processing methods adjust to the polymer’s crystallinity and desired properties, with PVDC often deployed as thin barrier layers and PVDF as a versatile engineering plastic and functional material.

See also: polyvinylidene difluoride, polyvinylidene chloride.