Cellulose nanofibrils prepared by gentle drying methods reveal the limits of helium ion microscopy imaging

摘要: TEMPO-oxidized cellulose nanofibrils (TCNFs) have unique properties, which can be utilised in many application fields from printed electronics to packaging. Visual characterisation of TCNFs has been commonly performed using Scanning Electron Microscopy (SEM). However, a novel imaging technique, Helium Ion (HIM), offers benefits over SEM, including higher resolution and the possibility non-conductive samples uncoated. HIM not widely utilized so far, this study capability for was evaluated. Freeze drying critical point (CPD) techniques were applied preserve open fibril structure gel-like TCNFs. Both methods worked well, but CPD better resulting specific surface area 386 m2 g−1 when compared 172 42 freeze dried frozen propane nitrogen, respectively. successful high magnification challenging because ion beam tended degrade The effect parameters on degradation studied an dose as low 0.9 per nm2 required prevent damage. This points out differences between gentle demonstrates damage during like none previously reported with HIM. results future studies or other biological materials there is growing interest both technique bio-based materials.