polvinylidene

Polvinylidene is not a widely recognized term in polymer science. It may be a misspelling or shorthand for polyvinylidene, a class of polymers derived from vinylidene monomers. The best-known members are polyvinylidene fluoride (PVDF) and polyvinylidene chloride (PVDC), which are valued for chemical resistance and barrier properties.

In terms of structure, PVDF contains repeating units of -CH2-CF2- and PVDC contains repeating units of -CH2-CCl2-. Both polymers are prepared by polymerizing the corresponding vinylidene monomers (vinylidene difluoride for PVDF and vinylidene chloride for PVDC). The resulting materials are high-molar-mass, semicrystalline polymers with tunable grades.

Production methods include free-radical polymerization in emulsion, suspension, or solution systems, with processing routes such as extrusion, melt processing, or solution casting for films and coatings. Co-polymers and blends are used to tailor properties.

Properties and applications: PVDF offers high chemical resistance, good mechanical properties, and heat stability, making it suitable for chemical processing equipment, corrosion-resistant coatings, membranes, and electrical insulation. PVDC provides exceptional barrier properties against moisture and gases, and is widely used in food packaging films and coatings. Both are used in specialty applications requiring durability and chemical stability.

Safety and environmental notes: Monomers such as vinylidene difluoride and vinylidene chloride are reactive and hazardous; polymerization requires controlled facilities. The polymers themselves are generally stable, but PVDC can release hydrogen chloride upon combustion. Recycling, disposal, and lifecycle considerations apply to these materials. See also PVDF, PVDC, and vinylidene derivatives.