Surface modification of cellulose nanocrystals using radio-frequency plasma

In this study, the effect of radiofrequency plasma of hexamethyl disiloxane (HMDSO) on the physical properties and hydrophobicity of cellulose nanocrystals (CNC) was examined. Hence, crystallinity index, changes in functional groups, films surface topography, thermal stability (TGA) of pure CNC and plasma modified CNC (mCNC), dispersion in polar and non-polar solvents and static contact angle were investigated. The XRD spectroscopy showed no changes in CNC crystallinity index due to plasma treatment. Partial replacement of hydroxyl groups with Si groups was demonstrated by FTIR spectroscopy. Atomic force microscopy (AFM) images showed that the roughness of the mCNC film surface increased and thermogravimetric analyses (TGA) demonstrated more thermal stability of the mCNC compared to pure CNC. Hydrophobicity improvement of mCNC was also demonstrated by contact angle measurements. Also, the study of dispersion of mCNC in acetone showed that HMDSO plasma treatment is a suitable method to prepare better and more stable dispersion of mCNC in non-polar solvents.