Effect of polymerized ionic liquids on thermal stability of poly(methyl methacrylate)

An increasing number of applications of ionic liquids (ILs) as solvents for organic synthesis have been reported in recent years, but the use in polymer synthesis is still limited. In the last few years, it has been shown that ILs can also be advantageously used for polymer synthesis. The thermal stability of polymerized ionic liquids is of great interest as it is applied to solid state electrolytes for electrochemical and electromechanical applications. In this study, the bulk copolymerization of methyl methacrylate with 1-vinyl-3-butylimidazolium hexafluorophate (VbimPF 6 ), 1-vinyl-3-hexylimidazolium hexafluorophate (VhimPF 6 ) 1-vinyl-3-octylimidazolium hexafluorophate (VoimPF 6 ), 1-vinyl-3-octyl imidazolium tetrafluoroborate (VoimBF 4 ) at 70 °C were separately proceeded at ILs doping levels of 2 mass%, 5 mass% and 8 mass%. Then the oxidative and non-oxidative thermal stability of copolymers were investigated as a function of copolymer compositions in comparison with PMMA homopolymer. Copolymerization of ILs can significantly improve the thermal stability and thermal oxidative stability of copolymers by 100 °C and 30 °C, respectively. Meanwhile, the thermal stability under nitrogen and air atmosphere increased with increasing of ILs composition.