Synthesis of precision polymers with regularly placed perfluoroalkyl segments and sulfonic acid groups via ADMET polymerization and internal alkene modification

• Published in: Polymer (Guilford) 2018-09, Vol.153, p.123-130
• Main Authors: Lv, An, Li, Zi-Long, Wu, Yu-Huan, Du, Fu-Sheng, Li, Zi-Chen
• Format: Article
• Language: English
• Subjects: ADMET; Chemical synthesis; Fluoridation; Fluoropolymer; Hexadiene; Hydrocarbons; Hydrogen peroxide; Membranes; Metathesis; Monomers; NMR; Nuclear magnetic resonance; Oxidation; Perfluoro compounds; Perfluoroalkyl & polyfluoroalkyl substances; Polyethylene; Polyethylenes; Polymerization; Polymers; Post-polymerization modification; Proton exchange membrane; Protons; Segments; Sulfonic acid; Sulfuric acid; Thermal properties; Thermal stability; Thermodynamic properties
• ISSN: 0032-3861; 1873-2291
• DOI: 10.1016/j.polymer.2018.08.011

We demonstrate the facile synthesis of a new type of precision polymers containing periodically placed perfluoroalkyl segments and sulfonic acid groups via acyclic diene metathesis (ADMET) polymerization of designed diene monomers and the subsequent postmodification of the internal CC bonds. Two diene monomers containing perfluoroalkyl segments [-(CF2)n-, n = 4 and 6] were synthesized through the atom transfer radical addition (ATRA) of dodecafluoro-1, 6-diiodohexane and octafluoro-1, 4-diiodobutane with 1,5-hexadiene and the subsequent deiodination. ADMET polymerization of these two monomers with Grubbs-I catalyst led to periodic polymers containing perfluoroalkyl segments and internal CC bonds. Subsequent postpolymerization modification with thiolacetic acid and the following oxidation with hydrogen peroxide afforded the final polymers. The polymers were characterized by NMR, GPC, and FTIR, and the thermal properties of the final copolymers were investigated by DSC and TGA. These polymers exhibited high thermal stability as compared to other precisely sulfonated polyethylene analogues; therefore, they may be potentially investigated as efficient proton transport membranes. [Display omitted] •New synthetic method for diene monomers containing perfluoroalkyl segments was developed.•ADMET of the diene monomers afforded high-molecular weight unsaturated polymers.•Efficient chemical transformation of the internal CC bonds into sulfonic acid groups was realized.•Thermally stable precise sulfonated polymers are potentially good candidates as proton exchange membranes.