Anionic synthesis of epoxy end-capped polymers

The reaction of living anions of polystyrene (PS) or poly(methyl methacrylate) (PMMA) with epibromohydrin for the synthesis of well-defined epoxy end-functionalized polymers is reported. Polyanions were reacted with an excess of epibromohydrin in tetrahydrofuran (THF) at -78 degrees C. The functionalities of the resulting polymers were analyzed by matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS), NMR, and size exclusion chromatography (SEC). The epoxy end groups were reacted with 1,1-diphenyl- hexyllithium, and MALDI-TOF MS and NMR before and after this chemical modification were used to determine the presence of the epoxy end groups. The presence of the epoxy end group was confirmed by anionically polymerizing ethylene oxide from these epoxy end group. The formation of a block copolymer due to the epoxy end groups was proved by SEC analysis. The combined MALDI-TOF MS, H-1 NMR, and SEC results indicate that epoxy end-capped PS was obtained in quantitative yield. The method was extended to the synthesis of epoxy end-capped PMMA. With this polymer the extent of end-functionalization was high but not quantitative, with non-dimeric byproducts detected by MALDI-TOF MS.