Swelling and dissolution of cellulose. Part IV: Free floating cotton and wood fibres in ionic liquids

The objective of this paper is to investigate if the swelling and dissolution mechanisms found for aqueous solvents are valid for non-aqueous ones. Three different ionic liquids were used and the swelling and dissolution mechanisms were investigated by optical methods. Native and enzymatically treated cellulose fibres (cotton and wood fibres) are dipped into three ionic liquids (1-N-butyl-3-methylimidazolium chloride ([C4mim]+Cl−)/DMSO, allylmethylimidazolium bromide ([Amim]+Br−) and butenylmethylimidazolium bromide ([Bmim]+Br−). ([C4mim]+Cl−)/DMSO shows a swelling of cellulose by ballooning and then dissolution. ([Amim]+Br−) and ([Bmim]+Br−) show a homogeneous swelling but no dissolution. The swelling and dissolution mechanisms of cellulose in ionic liquids are similar to those observed in aqueous solvents. It indicates that the swelling and dissolution mechanisms are entirely due to the way cellulose fibres are structured, not depending on the type of solvent. The quality of the solvent is giving the type of mechanism.