Aqueous suspension polymerization, PVDF

Reaction temperature ranges between 10 and 150°C at pressure of 1 MPa or higher. Similar to TFE, emulsion polymerization of vinylidene fluoride requires a stable fluorinated surfactant and an initiator such as peroxide or persulfate. Suspension polymerization is conducted in an aqueous medium, sometimes in the presence of a colloidal dispersant like hydroxy cellulose. Solution polymerization of VDF in solvents uses free radical initiators. PVDF is commercially produced by aqueous emulsion or suspension processes [72]. 

Poly(vinylidene fluoride), PVDF or PVF2, is usually manufactured from radical initiated batch polymerization process in aqueous emulsion or suspension of CH2=CF2 monomer. PVDF is a thermoplastic that exhibits interesting properties, such as piezoelectric, pyroelectrical, and ferroelectric behaviors. PVDF has even superior dielectric permittivity arising from the strong polymerization originating from C—F bonds, and the spontaneous orientation of dipoles in the crystalline phases makes it a polar polymer with good compatibility with polar chemicals. 

The first successful aqueous polymerization of vi-nylidene fluoride was reported in 1948 [83] using a peroxide initiator in water at 50-150°C and 30 MPa. No surfactants or suspending agents were present in the polymerization recipe. PVDF has been polymerized by a number of methods including emulsion, suspension, solution, and bulk. Later, copolymers of vinylidene fluoride with ethylene and halogenated ethylene monomers were also produced [84]. In 1960, a manufacturing process was developed and PVDF was introduced to the market. 

---