From wet to dry: Controlling the adaption process at the nanofibrillated cellulose surfaces

When cellulosic material is removed from aqueous media, the hydrophilic surface has to adapt to the new ambient conditions, in order to remain chemically stable. In the case of macroscopic cellulose fibers, this adaptation leads to surfaces with very low and stable contamination levels. However, in the case of nanofibrillated cellulose (NFC) the accumulation of carbonaceous material on the fibril surfaces is not only significantly enhanced but also unpredictable. Yet clean cellulosic surface and retained nanofibrillar structure are crucial factors in a successful modification of NFC.We have combined XPS, AFM and water sorption studies in order to investigate the surface characteristics of never dried NFC when it is exposed to non-hydrophilic media. A simple silylation reaction confirmed that the NFC surface accessibility was significantly enhanced when a cellulose compatible solvent was used as the reaction media.