The copolymerization of glycidyl methacrylate (GMA) and carbon dioxide was performed without any solvent in the presence of ionic liquid as catalyst. The reaction was carried out in a batch autoclave reactor. The conversion of glycidyl methacrylate was carried out in a batch autoclave reactor. The conversion of glycidyl methacrylate was carried out in a batch autoclave reactor. The conversion of glycidyl methacrylate was affected by the structure of imidazolium salt ionic liquid; the one with the cation of bulkier alkyl chain length and with more nucleophilic anion showed better reactivity. However, the yield of carbon dioxide addition decreased when hexyl and octyl group containing ionic liquids are used in place of butyl group in 1-alkyl-3-methyl imidazolium salts. The conversion of glycidyl methacrylate increased as reaction temperature and CO₂ pressure increased.