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

Annika E. Ketola, Miika Leppänen, Tuomas Turpeinen, Petri Papponen, Anders Strand, Anna Sundberg, Kai Arstila, Elias Retulainen

    Tutkimustuotos: LehtiartikkeliArtikkeliTieteellinenvertaisarvioitu

    7 Sitaatiot (Scopus)

    Abstrakti

    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 Microscopy (HIM), offers benefits over SEM, including higher resolution and the possibility of imaging non-conductive samples uncoated. HIM has not been widely utilized so far, and in this study the capability of HIM for imaging of TCNFs was evaluated. Freeze drying and critical point drying (CPD) techniques were applied to preserve the open fibril structure of the gel-like TCNFs. Both drying methods worked well, but CPD performed better resulting in the specific surface area of 386 m(2) g(-1) when compared to 172 m(2) g(-1) and 42 m(2) g(-1) of freeze dried samples frozen in propane and nitrogen, respectively. HIM imaging of TCNFs was successful but high magnification imaging was challenging because the ion beam tended to degrade the TCNFs. The effect of the imaging parameters on the degradation was studied and an ion dose as low as 0.9 ion per nm(2) was required to prevent the damage. This study points out the differences between the gentle drying methods of TCNFs and demonstrates beam damage during imaging like none previously reported with HIM. The results can be utilized in future studies of cellulose or other biological materials as there is a growing interest for both the HIM technique and bio-based materials.
    AlkuperäiskieliEi tiedossa
    Sivut15668–15677
    Sivumäärä10
    JulkaisuRSC Advances
    Vuosikerta9
    DOI - pysyväislinkit
    TilaJulkaistu - 2019
    OKM-julkaisutyyppiA1 Julkaistu artikkeli, soviteltu

    Keywords

    • Nanocellulose
    • microscopy

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