Influence of plasma treatment on the dissolution of cellulose in lithium chloride–dimethylacetamide

The development of biodegradable food packaging materials continues to be of significant interest because of its benefits. Among these materials, cellulose-based composites are candidates to replace conventional, petroleum-based food packaging materials. However, incomplete dissolution of cellulose has hindered its large-scale application. Since undissolved cellulose can affect the mechanical properties of the film, full dissolution is preferred. This work explores the use of plasma irradiation as a pretreatment step before the dissolution of cellulose in lithium chloride–N,N-dimethylacetamide (LiCl–DMAc) solvent. Prior to swelling, the cellulose was exposed to subatmospheric oxygen (O\(_2\)) plasma to initiate glycosidic bond cleavage without intense degradation of cellulose. Fourier transform infrared, Raman, and X-ray photoelectron spectral analyses revealed decrystallization and oxidation of the surface after plasma treatment which enhanced the dissolution of cellulose in LiCl–DMAc. Mechanical tests of drop-casted films revealed that plasma-treated cellulose greatly enhanced the mechanical strength of the film compared to that of untreated cellulose whose film was too weak for the tensile test. This work showed that exposure to O\(_2\) plasma as a pretreatment step can improve the dissolution of cellulose via decrystallization and thereby can be coupled with other natural materials as alternative to food packaging materials.