The Exploration To Synthesize Novel Poly-Trifluorostyrene Via Arene C-H Activation/Borylation Reactions

Aryl boric acid or borate ester are considered as important intermediates and structural unitsin the field of organic synthesis. They show the characteristics of easy preparation and good airstabilities. In recent years, the rapid development of aromatic C-H activation/borylation reactionsprovide an efficient approach to synthesize the complex compounds using the relatively simpleprecursors. However, these reactions have rarely been applied in the preparation of boron-containing polymers. In this work, we focus on exploring the feasibilities to prepare the novel poly-trifluorostyrene via iridium-catalyzed aromatic C-H activitation/borylation reactions andsubsequent Suzuki-Miyaura coupling reactions. The main research work consists of three parts asfollows:Firstly, we have successfully prepared the PTFS through emulsion polymerization technologyand then explored the reaction conditions of directly incorporating boron moieties into PTFS viairidium-catalyzed aromatic C-H activitation/borylation reactions. With the optimum conditions inhand, we have afforded controlled functionalization of PTFS by changing the ratio of boron reagentto PTFS repeating unit. The structures of the polymers were confirmed by1H NMR,13C NMR,11BNMR and FT-IR spectrum. In addition, GPC was used to measure the Mnand PDI of the PTFS andPTFS-Bpin.Secondly, we have attempted to directly introduce trifluorovinyl ether groups to PTFS as thecross-link group via Suzuki-Miyaura coupling reactions. However, gelation was observed duringthe process of Suzuki-Miyaura coupling reactions. Then we explored the compatibilities offunctional groups during the Suzuki-Miyaura coupling reactions. The results indicated that meoxyl,carbonyl and fluoro atom actived by sulfone or cyano goups showed good compatibilities. Thus, inorder to prepare the polymers containning trifluorovinyl ether groups, we determined to introducefluoro atom actived by sulfone or cyano goups to PTFS as reactive sites that could be furthermodificated via nucleophilic aromatic substitution reactions using4-((1,2,2-trifluorovinyl)oxy)phenol as the nucleophilic reagent.Thirdly, the related properties such as XRD, solubilities and thermal stabilities of polymerswere tested and the results indicated that all the polymers exhibited amorphous structures, goodsolubilities in most of the common solvents and excellent thermal stabilites. The glass transitiontemperatures of polymers were above200oC. The temperatures where5%weight loss and where10%weight loss were observed within the range312~353oC and329~371oC respectively under N2atmosphere, being able to fulfill the requirements when operated under intermedium or elevatedtemperatures.