Reaction engineering of the emulsion homopolymerization of vinylidene fluoride: Progress and challenges

Monomer Equilibrium and Transport in Emulsion and Miniemulsion Polymerization

The dual concepts of monomer equilibrium and monomer transport in emulsion and miniemulsion polymerization are discussed in depth. The concepts must be considered together since, first, dispersed-phase polymerizations (in this case emulsion and miniemulsion polymerizations) are by their nature multiphase systems that function only due to interphase mass transfer; and second, because phase equilibrium determines the driving force for monomer transport in these (and all heterophase reaction) systems. Concepts of polymer particle swelling are reviewed, and the question first addressed by Paul Flory in the 1950s: Are emulsion polymerizations transport or reaction limited? is revisited in detail.

Surfactant-free emulsion polymerization of vinylidene fluoride mediated by RAFT/MADIX reactive poly(ethylene glycol) polymer chains

Vinylidene fluoride (VDF) emulsion polymerization is conducted in the presence of xanthate-end functionalized poly(ethylene glycol)s leading to stable PVDF latexes.

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).