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

Abstract

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.