Emulsion homopolymerization of chlorotrifluoroethylene toward new waterborne fluorocarbon coatings

Abstract

To solve the problems of environmental unfriendliness brought by long fluoroalkyl chain surfactant used in the homopolymerization of chlorotrifluoroethylene (CTFE) monomers as well as film forming difficulty and poor adhesion of PCTFE resins at the same time, a short fluoroalkyl capping waterborne polyurethane (F-WPU) dispersion was firstly synthesized in this work based on the processes of self-emulsification and phase inversion. The prepared fluorinated polyurethane dispersions could reduce the surface tension of water to 17.81–19.04 mN/m, showing high surface activity. Subsequently, the PCTFE (Poly(chlorotrifluoroethylene)/F-WPU composite latex was successfully prepared by emulsion homopolymerization, of which the F-WPU was used as the stabilizer and microreactor of system to emulsify CTFE monomers and then the corresponding composite coatings were further fabricated. Effects of the type and addition amount of F-WPU on emulsion homopolymerization of CTFE and the stability of composite emulsion were systematically studied. As a result, the PCTFE/F-WPU composite latex exhibits excellent wetting ability on various low surface energy substrates, and the composite coating displayed excellent adhesion and UV (Ultraviolet) resistance due to the synergistic action of F-WPU and PCTFE. The synthesis of F-WPU not only opens up a new route for the preparation of fluorinated surfactants, but also provides a new method for the emulsion homopolymerization of fluoroethylene monomers, and accelerates the wide application of fluorocarbon latex coating.