Investigations about dissolution of cellulose in the 1-allyl-3-alkylimidazolium chloride ionic liquids

► We synthesized 1-allyl-3-alkylimidazolium chloride ionic liquids by increasing carbon atoms (n ≤ 6) of alkyl chains on 3-imidazole ring. ► Asymmetrical structure on two sides of 3-imidazole ring (n = 1, 2, 6) exhibited alkalinity, lower thermal stabilities, and perfect solubility. ► Ionic liquids with symmetrical structure on two sides of 3-imidazole ring (n = 3, 4) had weak solubility of cellulose at 60-120 °C. ► AEIMCl was more capable of dissolving cellulose at 100 or 120 °C, whereas AHIMCl showed perfect cellulose solubility at low temperature of 60 °C. ► The ionic liquids treated cellulose samples had poor crystal structures and thermal stabilities compared with the untreated cellulose samples.