Challenges in the Emulsion Co- and Terpolymerization of Vinylidene Fluoride.

The feasibility of co- and terpolymerizing vinylidene fluoride (VDF) with ethylene (C2) and/or vinyl acetate in an emulsion polymerization process was studied for different C2 pressures, initiator concentration, surfactant concentration, pH, C2 injection protocols, and the influence of vinyl acetate (VAc) in the reaction medium. Pressure drop and temperature profiles as well as gravimetry were used to follow the rate of polymerization. The microstructure of the synthesized products was assessed by fluorine and hydrogen nuclear magnetic resonance spectroscopy (19F and 1H NMR). C2 was found to cause an inhibition/retardation effect on the copolymerization with VDF (and with VDF/VAc). However, statistical copolymers containing VAc and VDF were synthesized by reducing as much as possible the homogeneous nucleation of the VAc in the water phase. This was done by adding VAc into the reaction after the homogeneous-coagulative nucleation of VDF takes place (around 5 min after initiator injection).