Living/Controlled Radical Polymerization Of Chlorotrifluoroethylene And Hexafluoropropylene

Since the invention of the first perfluoropolymer, polytetrafluoroethylene (PTFE) by DuPont Company, fluorinated polymers have attracted much attention in the field of polymer. Due to the fluorinated polymers exhibiting many high-performance features, such as heat and chemical resistance, low surface energy, low dielectric constants, low refractive index, excellent inertness to acids or bases, and long durability, they have been widely used in many applications such as fuel cell membranes, protective coatings, microelectronics, and novel elastomers. Over the past two decades, three major living/controlled radical polymerizations, including reversible addition-fragmentation chain transfer (RAFT) polymerization, atom transfer radical polymerization (ATRP), and nitroxide-mediated polymerization (NMP), have been extensively studied and developed as a powerful tool for the synthesis of well-defined polymers with predetermined molecular weight, narrow molecular weight distribution, various architectures, and useful end-functionalities. Although these methods have been successfully used in living/controlled polymerization of fluorinated monomers such as fluorinated methacrylates, acrylates, and styrene, there are very few papers about the living/controlled radical polymerization of fluoroolefins, such as tetrafuoroethylene (TFE), chlorotrifluoroethylene (CTFE) and hexafluoropropylene (HFP). In this paper we respectively explored the living/controlled polymerization of CTFE and HFP via ATRP and RAFT polymerization.Firstly, a chain transfer agent called S-benzyl O-ethyl carbonodithioate was synthesized and used in the RAFT copolymerization of CTFE and butyl vinyl ether (BVE). The polymerization results demonstrated that the process exhibits all the characteristics of living/controlled radical polymerization. Furthermore, The block copolymer (poly(CTFE-alt-BVE)-b-PVAc) has been prepared by the chain extension polymerization of vinyl acetate, which can be further hydrolyzed to prepare fluorinated amphiphilic polymer.Secondly, using the same chain transfer agent, the living/controlled radical copolymerization of CTFE and vinyl acetate was fulfilled. The molecular weight, the molecular weight polydispersity and the structure of the copolymers were characterized by GPC, 1H and 19F NMR spectroscopy.Thirdly, a macro-CTA based on the polyphenylene oxide and the ATRP initiator 1,3-dibromo-5-(bromomethyl) benzene were synthesized, which were further used in the polymerization of HFP. The results were analyzed through 1H and 19F NMR spectroscopyFourthly, using the coordination complex (copper(I) bromide/2,2'-bipyridyl ) as catalyst and acetonitrile as solvent, the dimerization of hexafluoropropylene was fulfilled at room temperature. The structure of the dimmer was characterized by 19F NMR spectroscopy.